NUTRITION, Chapter # 12 Theory & Question Answers

 Chapter # 12

Theory & Question AnswersNUTRITION
NUTRITION

NUTRITION:
Nutrition is the process by which the organisms obtain energy to maintain the function of life to build the matter and maintain their structure.

NUTRIENTS:
Nutrients are food or any substance which supplies elements and energy to the living body for its metabolic activity.

TYPES OF NUTRITION:
Autotrophic And Heterotrophic Nutrition:
Living organisms can be divided into two groups on the basis of their mode of nutrition.

• Autotrophic organisms prepare their own food from the raw material.
• Heterotrophic organisms obtain the prepared food from the surroundings.

Autotrophic nutrition is the type of nutrition in which organic compounds are manufactured by living organisms from available inorganic raw materials taken from their surroundings. These molecules of raw materials are small and are soluble enough to pass through cell membrane. In autotrophic nutrition the nutrients do not require to be pretreated or digested before taking them onto their cells. There are two methods of autotrophic nutrition i.e. phototrophic and chemotrophic nutrition.

Most of the autotrophic organisms have phototrophic nutrition although a few have chemotrophic nutrition. All the plants, algae and some bacteria are phototrophic while some bacteria are chemotrophic.

Heterotrophic nutrition is the type of nutrition in which organic compounds are not manufactured from simple inorganic nutrients. Such heterotrophic organisms must obtain pre-fabricated organic molecules from their environment. Many of the organic molecules found in nature are too large to be absorbed unaltered through cell-membranes, they must first be broken down into smaller, more easily absorbable molecular units i.e. they must be digested. Most bacteria, fungi and the main classes of organic compounds serving as energy and carbon sources for heterotrophic organisms.

Autotrophic Nutrition:
As we already discussed that the mode of nutrition in which organic molecules are manufactured from simple inorganic molecules by using light energy or chemical energy is called autotrophic nutrition.

There are two types of autotrophic nutrition:

• Phototrophic nutrition
• Chemotrophic nutrition

Phototrophic Nutrition: The organisms which have the ability to convert solar energy into food energy are called phototrophic organisms. The raw materials needed by these organisms are carbon dioxide and water which supply the carbon, hydrogen, and oxygen for the synthesis of organic molecules. CO₂ and H₂O are not the only nutrient materials for green plants. The minerals like Nitrogen, Phosphorus, Sulphur, and Magnesium etc. are also required to produce different molecules. It means three classes of nutrients are needed by green plants i.e. CO₂, H₂O, and minerals. Besides all these three types of nutrients, the phototrophic organisms require green pigments i.e. chlorophyll ‘a’, ‘b’ or other to absorb the energy from the universal source i.e. sunlight. In the presence of the light, these nutrients are used to synthesize energy-rich compounds, carbohydrates. This process is called photosynthesis.

$$6CO_2 + 12H_2O \xrightarrow{\text{Light}} \text{Chlorophyll} C_6H_{12}O_6 + 6O_2 + 6H_2O$$

Detailed process of photosynthesis is already discussed in chapter 11.

Other types of photosynthetic autotrophs are photosynthetic bacteria. They are unique because they are the only organism which is capable of synthesizing carbohydrate food without chlorophyll ‘a’. This photosynthesis is different from photosynthesis in green plants because they grow in light and usually in sulphur springs where hydrogen sulphide (H₂S) is normally present. Hydrogen is provided by donor substances such as H₂S instead of water and sunlight is used as a source of energy. Therefore, free oxygen is not released as a byproduct in bacterial photosynthesis. The process takes place at low expenditure of energy.

Two common examples of photosynthetic bacteria are the purple-sulphur bacteria and green sulphur bacteria. The former contain bacterio-chlorophyll and carotenoids as photosynthetic pigments and later chlorobium chlorophyll. Both use H₂S as a donor of hydrogen. Light splits hydrogen sulphide in both cases. Hydrogen combines with carbon dioxide to form CH₂O.

$$2H_2S + CO_2 \xrightarrow{\text{Light}} (CH_2O)_n + H_2O + 2S$$

There are non-sulphur purple and brown bacteria found in the mud and stagnant water. They are photosynthetic and contain bacteria chlorophyll pigment. They use organic hydrogen donors whereas sulphur is not the by-product in their cases. Light is still the source of energy.

Chemotrophic Nutrition: There is another mode of autotrophic nutrition in which light is not used as the source of energy for nutritional requirement. In this type of nutrition, energy is produced by the oxidation of certain inorganic substances such as ammonia, nitrates, nitrites, ferrous ions, hydrogen sulphide and a variety of metallic and non-metallic materials available in the environment. This energy is used for the synthesis of carbohydrates. This type of is called chemotrophic nutrition and the process of manufacturing food is called Chemosynthesis (chemo = chemical, synthesis = to

produce). The organisms which synthesize high energy organic compounds by chemosynthesis are called chemosynthetic organisms. Chemosynthetic organisms are mainly bacteria e.g. Ammonia using bacteria.

$$NH_4^+ + 3O_2 \rightarrow 2NO_2^- + 2H_2O + 4H^+ + \text{energy}$$

Another bacterium oxidizes nitrates $(NO_2^-)$ to nitrates.

$$2NO_2^- + O_2 \rightarrow 2NO_3^- + \text{energy}$$

Details of chemosynthetic bacteria are already discussed in section III, chapter 6.

The chemosynthetic bacteria that act on nitrogen compounds do play an extremely important role in the maintenance of nitrogen balance within the life system.

MINERAL NUTRITION IN PLANTS: In plants, the source of inorganic requirements are minerals obtained directly or indirectly from the soil. These elements are known as mineral nutrients and the nutrition is called mineral nutrition. Nitrogen is also included in the mineral nutrients because it is normally obtained by the plant from soil whereas it is not a mineral element.

Role Of Some Important Mineral Nutrients And Their Deficiency Symptoms: Analysis of plants shows the presence of a number of mineral elements. The amount and number of elements present in plants may also differ from plant to plant, place to place and medium to medium in which the plant grows. Some important minerals nutrients which are required in large quantities (macronutrients) are as follows:

• Nitrogen:

  • It is found in the soil in the form of nitrates or ammonium salts. It is an essential constituent of proteins, nucleotides, nucleic acids and many other organic molecules like chlorophyll, so the biosynthesis of these molecules require nitrogen.
  • Deficiency symptoms:
    • Absence or low supply of nitrogen develops the following symptoms:
      • Leaves turn pale yellow due to loss in chlorophyll content called chlorosis.
      • Processes of cell division and cell enlargement are inhibited.
      • Rate of respiration is affected.
      • In certain plants, veins turn purple or red due to the development of Anthocyanin pigment e.g., tomato and apple leaves.
      • Plant growth remains stunted and lateral buds remain dormant, as a result cereals do not show characteristic tillering.
      • Prolonged dormancy and early senescence including leaf falls.

• Phosphorous (P):

• Plants absorb phosphorous in the form of soluble phosphates such as $H_3PO_4$ and $HPO_4$. It is present abundantly in the growing and storage organs such as fruits and seeds. It promotes healthy root growth and fruit ripening by helping translocation of carbohydrates. It is an essential element involved in the formation of cell-membrane as phospholipids, nucleic acid, ...

co-enzyme (NAD and NADP) and organic molecules such as ATP and other phosphorylated products. It plays an important role in the energy transfer reaction in oxidation-reduction processes.

Deficiency Symptoms: In the case of phosphorus deficiency, a few symptoms resemble that of nitrogen deficiency, like premature leaf fall and development of purple-red anthocyanin pigment. Deficiency of phosphorus also shows some other symptoms:

• Cambial activity is checked.
• Tillering of crop plant is reduced.
• Dormancy is prolonged.
• Growth is retarded and dead necrotic patches appear on leaves, petioles, and fruits.
• Variable colors develop, e.g., plate green in Pisum, olive green in Phaseolus.
• Causes accumulation of carbohydrates.
• Thickening of tracheal cells are reduced, and phloem differentiation becomes incomplete.

Potassium (K): Potassium is widely distributed in soil minerals. It is strongly fixed in soil. Therefore, found in less available form. Exchangeable potassium appears to be readily available to the plants. The best known function of potassium is its role in stomatal opening and closing. It is found in the highest concentration in the meristematic regions of the plant. It is an essential activator for enzymes involved in the synthesis of certain peptide bonds and carbohydrate metabolism.

Deficiency Symptoms: The deficiency symptoms vary with the extent of the shortage of the element in acute deficiency.

• The color of leaf may turn into dull or bluish green.
• An irregular chlorosis occurs first, which is followed by the development of necrotic areas of the tip and margin of the leaf.
• Plant is stunted in growth with a pronounced shortening of internodes and reduced production of grains.
• Lamina of broad-leaved plants curl backward towards the under surface or roll forward towards the upper surface parallel with midrib.

Magnesium (Mg): Magnesium is present in the soil in water-soluble, exchangeable, and fixed form and is present in primary minerals. It is found as carbonates similar to that of calcium and held in soil as exchangeable base. It is a constituent of chlorophyll and therefore essential for the formation of green pigment. It acts as phosphorus carrier in plant, particularly in connection with the formation of seeds of high oil contents which contain compound lecithin. It is readily mobile and when its deficiency occurs, it is apparently transferred from older to young tissues where it can be reutilized in growth processes. Magnesium is essential for the synthesis of fats and metabolisms of carbohydrates and phosphorus.

Deficiency Symptoms:

• Deficiency symptoms develop first on the older leaves and then proceed systematically towards younger leaves.
• Chlorosis occurs.
• Severely affected leaves may wither and shed or absciss without the withering stage.
• Defoliation may be quite severe.
• Leaves, sometimes, develop necrotic spots.

Some kinds of plants have specific nutritional requirements that are not shared by others, e.g. silica, essential for the growth of many grasses, cobalt-necessary for the growth of nitrogen-fixing bacteria-essential for the growth of nodules and legumes. Nickel, essential for soybean. Sodium, important in maintaining osmotic and ionic balances, required by some desert and salt marsh species.

Heterotrophic and Special Mode of Nutrition in Plant: Some plants are not able to manufacture their own food material due to the lack of chlorophyll or some other reason, so they completely or partially depend upon other organisms. These are called heterotrophic plants, and the nutrition is known as heterotrophic nutrition.

These are two types of heterotrophic plants:

• Parasitic Plants: They obtain their food from living organisms.
• Saprophytic Plants: They obtain their food from dead or rotten organic remains of plants and animals.
• Carnivorous Plants: These plants obtain nitrogenous compounds from insects or other small animals.

Parasitic Plants: These plants obtain their food from other living organisms. These plants are of two types:

• Obligate Parasite: These plants entirely depend upon other living organisms for their food. They are also called total parasites.
• Obligate Parasites: These plants partially depend upon other organisms for their food. They are also called partially parasites.

The parasitic plants produce special root-like structures, called haustoria. These haustoria penetrate into host plant body and absorb food material.
The parasitic angiosperm plants are as follows:

• Partial stem parasite
• Total stem parasite
• Partial root parasite
• Total root parasite

Partial Stem Parasite:
These plants grow upon the stem of other host plants, they can manufacture some of their food due to the presence of chlorophyll and they partially depend upon host plant. The absorb nutrients and water from host plant by the help of haustoria.
Examples:

• Loranthus has thick green leaves, woody stem and haustoria. It grows up mango, Banana plant, rosaceous trees and many shrubs.
• Viscum
• Cassytha filiformis

Total Stem Parasite:
These plants completely depend upon host plants for their food. They produce haustoria into the body of host plant and absorb food material. Ultimately the host plant may die.
Example:

• Cuscuta plant (Amar bail).

Partial Root Parasite:
These plants get their food partially from the roots of other plants. For example Sandal wood tree. Its seeding does not grow independently. Its roots absorb nourishment from the roots of other plants.

Total Root Parasite:
These plants obtain their food completely from the roots of neighboring plants. These plants usually attack the plants of family Cruciferae and the Solanaceae. For example Orobanche, Cistanche. Striga. Cistanche parasites on the roots of Calotropis plant. Striga is a parasite on the roots of sugarcane, Sorghum or Jawar.

Saprophytic Plants:
These are special plants, which grow upon dead organic matters. These plants do not contain chlorophyll. Their roots are without root hairs and cannot absorb nourishment from the soil. They decompose dead organic food into simpler compounds and use them for their growth and development. For example Neothia (bird’s net or orchid), Monotropa. Roots of these plants form an association with fungi, which help in the absorption of food from dead bodies.

Carnivorous Plants:
Some plants use insects, so they are called carnivorous or insectivorous plants. These plants contain modifications to capture the insects. These plants contain chlorophyll and manufacture their own food but cannot prepare nitrogenous compounds and proteins, so to get these compounds the plants use insects. These plants usually grow in those regions where nitrogen is not sufficiently available, so they depend upon insects for nitrogen and proteins.
Some insectivorous plants are as follows:

• Pitcher plant
• Sundew plant
• Venus fly trap plant
  Utricularia or Bladder wort
  Water fly trap plant

Pitcher Plant:
In this plant leaves are modified into flask-shaped structures, called leaf pitcher. These pitchers are used to capture the insects. The pitcher also has a lid to close its mouth. When insects come on its mouth, they are slipped into the pitcher. From the inner surface of pitcher digestive enzymes are secreted, which help in the digestion of insects. e.g. Nepenthes, Sarracenia pupurea

Sundew Plant: (Drosera Intermedia)
It is a small herb plant with about half dozen leaves. Each leaf is covered on the upper surface with many glandular hairs, called tentacles. The glands secrete a fluid which glitters in the sunlight like dew, so the plant is called Sundew plant. The insects are attracted to the plant due to smell, these insects are captured by the tentacles, then they are digested by enzymes.

Venus Fly Trap Plant:
It is a herb plant, grows in moist places. The leaves of plants consist of two halves with midrib in the centre. Each half of leaf has 15 to 20 teeth like structures. In the central region of leaf glands are present to secrete enzymes. Each leaf also has three sensitive hairs. When insects come on the leaves, their teeth are interlocked with each other to capture them. After that they are digested by the enzymes.

Utricularia: (Bladder Wort)
It is a water living plant, in which leaves are modified into small cup-shaped structures, called bladders. The bladders are used to capture the insects. Each bladder has a small opening, which acts as a trap-door. The insects enter the bladder through trap-door. From the inner region of bladder enzymes are produced for the digestion of insects.

Water Fly Trap Plant:
It is a water-living free-floating plant. It is root less with whorls of leaves. The leaves are modified to capture the water flies. Each leaf has two lobes. Along the margin of leaf teeth like structures are present. It also has jointed hairs and stalked glands on the surface. When flies are captured enzymes are secreted from glands which take part in digestion of insects.

HETEROTROPHIC NUTRITION IN ANIMALS:
In heterotrophic nutrition the living organisms are not able to manufacture their own food, but they depend upon other organisms. All animals, fungi and many bacteria are included in heterotrophic organisms. These are called heterotrophs. In animals there are different types of heterotrophic nutrition.

• Holozoic nutrition
• Saprozoic nutrition
• Parasitic nutrition

Holozoic Nutrition:
In this nutrition the animals take solid organic food, it is digested by the action of enzymes, then it is assimilated to release energy by oxidation process.

Saprozoic Nutrition:
When the organisms take their food from dead organic substances, it is called saprozoic nutrition.

Parasitic Nutrition:
In this nutrition the organisms obtain their food from the body of host and cause great damage to their body.

TYPES OF ANIMALS ON THE BASIS OF FOOD:
On the basis of feeding system the animals are of following types:

Detritivores:
These animals take their food from organic debris (detritus). When the organic debris is decomposed, they use them as their food e.g. Earthworm.

Predators:
These animals attack other animals, kill them use as their food e.g. Lion.

Herbivores:
These animals use plants as their food e.g. Cow, Rabbit, Horse etc.

Carnivores:
These animals obtain their food from other animals e.g. Cats, Dogs.

Omnivores:
These animals use both plants and animals as their food i.e. eat meat and vegetable matter e.g. Man, Crow, Rat etc.

Filter Feeders:
These are water living animals, in their body food enters along with water. Food particles are used by the body, water is filtered out e.g. Sponges.

Fluid Feeders:
These animals take their food from other animals in the form of fluid e.g. Mosquitoes suck blood from man.

HETEROTROPHIC NUTRITION IN ANIMALS:
The heterotrophic nutrition is the nutrition in which the organisms are dependent upon other organisms, plants or animals for complex readymade organic food.

Types Of Heterotrophic Nutrition:
There are three main types of heterotrophic nutrition found in animals:

• Parasitic nutrition.
• Saprotrophic nutrition.
• Holozoic nutrition.

Parasitic Nutrition:
The nutrition in which living organism obtain their food from other living organism called parasitic nutrition.

Saprotrophic Nutrition:
The nutrition in which living organism obtain their food from dead organic matter called saprotrophic nutrition.

Holozoic Nutrition:
The nutrition in which animals first ingest the food then digest it into the alimentary canal, the digestive food is absorb in the body and metabolize inside cell and finally waste products are excrete out called holozoic nutrition.

OTHER MODES OF NUTRITION:
Animals have also other modes of nutrition which are as follows:

• Detritivores Nutrition:
  In this type of nutrition animals utilize the fragments of dead organic matter. E.g. earth worm.

• Predators:
  In this type of nutrition animals prey other animals e.g. Lion.

• Herbivores:
  In this type of nutrition animals utilize plants as food. E.g. Rabbit, Goat.

Carnivores:
In this type of nutrition animals utilize flesh as food. E.g. Cat, Dog.

Omnivores:
In this type of nutrition animals utilize both plants and flesh as the food. E.g. Man.

Filter Feeders:
In this type of nutrition animals obtain their food by filtering of water. E.g. Sponges.

Fluid Feeders:
In this type of nutrition animals utilize fluid as food. E.g. Mosquito.

Microphagous:
During this type of nutrition animals utilize small particles of dead organic matter. E.g. Amoeba.

Macrophagous:
During this type of nutrition animals utilize large size of dead organic matter. E.g. Hydra.

STEPS OF HOLOZOIC NUTRITION:
In animals holozoic nutrition is completed into five continuous steps:

• Ingestion of food.
• Digestion of food.
• Absorption of digested food.
• Assimilation of Absorbed food.
• Egestion of waste products.

Ingestion Of Food:
The entrance of food from environment to inside the body called ingestion of food. In animals ingestion of food mostly take place through the mouth while in some animals it is take place through Pseudopodia or openings which are present on the body.

Digestion Of Food:
The conversion of undigested food or un-diffusible food into digested or diffusible food by the physical and chemical action of alimentary canal is called digestion of food. It is take place inside cavity of alimentary canal or body cavity and inside the cell.

Absorption Of Digested Food:
After the digestion digested food is absorbed in the wall of alimentary canal then it accumulates with the blood and finally reaches to the body cells by the circulation of blood, this process is known as absorption of food. While in unicellular animals it is take place by simply diffusion.

Assimilation Of Absorbed Food:
Inside the cell food is break down in the presence of oxygen and enzymes. Food is break down into CO₂, H₂O and energy. The breaking of food and production of energy is known as assimilation of food.

Egestion Of Waste Products:
During the digestion food is not completely digesting because some parts of food are undigestable, these parts are known as waste products. The excretion of undigested food from the body called egestion of waste products.

TYPES OF DIGESTION:
There are four types of digestion found in animals:

• Intracellular Digestion.
• Extracellular Digestion.
• Physical Digestion.
• Chemical Digestion.

Intracellular Digestion:
It is combination of two words.
Intra means inside.
Cellular means cell.
i.e. the digestion which is take place inside the cell called intracellular digestion. It is take place through digestive enzymes of lysosome. This type of digestion found in unicellular and simple multi-cellular. e.g. Amoeba, Paramecium, Hydra, Planaria.

Extracellular Digestion:
It is also combination of two words.
Extra means outside.
Cellular means cell.
i.e. the digestion which is take place outside cell or body cavity or gastro intestinal cavity called extracellular digestion. it is take place through wall action and enzyme action of alimentary canal. This type of digestion found in simple multi-cellular and complex multi-cellular animals. e.g. Hydra, Planaria, Cockroach, Man.

Physical Digestion:
The digestion which is take place by the wall action (muscle contraction) of alimentary canal called physical digestion. This type of digestion is found in higher and complex animals. E.g. Man, Cockroach.

Chemical Digestion:
The digestion which is take place by the action of enzymes of cell and alimentary canal. This type of digestion found in simple multi-cellular and complex animals. E.g. Man, Amoeba, Cockroach.

Sac Like And Tube Like Digestive System:
In animals mostly digestive system is found in sac like and tube like.

Sac Like Digestive System:
The digestive system consists of cavity which has single opening called sac like digestive system. The single opening called mouth and ingestion of food and egestion of waste products both are take place through the mouth. In this type of digestive system food is digested by physically and chemically.

Tube Like Digestive System:
The digestive system consists of a tube and it has two openings called tube like digestive system. The upper opening called mouth which helps in ingest ion while lower opening called anus which helping egestion of waste products. In this type of digestion food is digested both physically and chemically. In tube like digestive system food is completely digested by the extracellular digestion. E.g. Cockroach, Man etc.

NUTRITION IN AMOEBA:
Amoeba is a unicellular animal. It belongs to phylum Protozoa. It has irregular shape and microscopic structure. Amoeba has intracellular digestion. It has holozoic nutrition which is take place through pseudopodia.

Food of Amoeba:
The food of amoeba consists of bacteria, small protozoan and dead organic particles of food. So amoeba is micro phagus animal.

Ingestion of Food:
In amoeba ingestion of food take place through pseudopodia by phagocytosis. When the food particle is contact with cell membrane then amoeba produce pseudopodia around the food. With the help of pseudopodia food is enter inside the cell in the form of food vacuole. Water is also enter inside cell during phagocytosis.

Digestion of Food:
After the ingestion several lysosomes are attached with the food vacuole. The membrane is dissolved between food vacuole and lysosome, then lysosome pour its digestive enzyme on the food. Due to the enzyme carbohydrate, proteins and fats are completely digested. Before the digestion food is acidic in nature but after digestion it becomes alkaline.

Absorption of Food:
After the digestion the digested food is absorb through out the cytoplasm by diffusion. food vacuole originates small tube like canals which produce contact between food vacuole and cytoplasm. These canals help in absorption of food by diffusion.

Assimilation of Digested Food:
After digestion the digested food is oxidized in the presence of oxygen which results CO₂, H₂O and energy are produced. This process is known as assimilation of food and it is take place inside the cell cytoplasm.

Egestion of Waste Products:
Undigested food and waste products are store in food vacuole now the food vacuole is known as contractile vacuole. When it is filled with waste products then it moves and attach with the cell membrane. Due to contraction of contractile vacuole, waste products are egested out by exocytosis.

NUTRITION IN HYDRA:
Hydra is simple multi-cellular animal. It belongs to phylum Coelentrata. Hydra has sac like digestive system because it has single opening called mouth. It has both extracellular and intracellular digestion. Hydra has diploblastic body. Tentacles of hydra are help in nutrition and catching of prey.

Food of Hydra:
Hydra is microphagous animal. Its food is consists of small insects, crustaceans, molluscas and larvae of animals.

Ingestion of Food:
In Hydra ingestion of food take place through mouth before the ingestion hydra prey the food. Catching of prey take place through specialized cells called “Nematocysts”. Nematocysts is consists of sharp pointed Cnidocil and poisonous substance. When the insect is contact with the hydra then hydra enter cnidocil inside insect. Is paralyzed due to poisonous substance then hydra capture the paralyzed insect through tentacles and enter inside the body through mouth.

Digestion Of Food:
Hydra has both extra cellular and intra cellular digestion.

Extracellular Digestion:
After the ingestion food is reached into Coelenterorn cavity. In this cavity both Physical and chemical digestion is occur. Physical digestion is due to the contraction of body wall, while chemical digestion is take place by the enzymes of glandular cells. But in hydra food is partially digested after the extracellular digestion.

Intracellular Digestion:
The partially digested food enters inside the flagellated cell by the phagocytosis. Inside the cell food is completely digest by the enzymes of lysosomes.

Absorption of Digested Food:
In hydra food is absorbed by simple diffusion after the digestion concentration of food is greater in endodermal cells. By the result of diffusion food is diffused into ectodermal cells from endoderm. Due to the continuous diffusion food is complete absorb through out the body cell.

Egestion of Waste Products:
Hydra has a single opening called mouth it is also help in egestion of waste products. After the digestion undigested food and other waste products are present in coelenteron cavity. Due to contraction of body wall waste products are egested out through mouth.

NUTRITION IN PLANARIA:
It is a simple multi-cellular animal. Belong to the phylum Platyhelminthes because it has dorso ventrally flattened body. Planaria has sac like digestive system. It has a single opening called mouth which helps in both ingestion and egestion of food. Planaria has both extracellular and intracellular digestion. It has holozoic nutrition.

Food of Planaria:
Planaria is a carnivorous animal it utilize small insects, small crustaceans, small molluscas and pieces of dead animals as the food.

Digestive System of Planaria:
Planaria has sac like digestive system. It consists of four organs.

• Mouth
• Pharynx
• Pharyngeal Sheet
• Intestine

Mouth is a small opening, present at the mid ventral surface of the body. Behind the mouth muscular tubular pharynx is present which is protruded outward. Pharynx is surrounded by muscular sheath called pharyngeal sheet. Pharynx is also open behind in a muscular tubular and branch intestine according to the position intestine is divided in three parts.

• Anterior Intestine
• Posterior or Lateral Intestine
• Diverticulum Intestine

Ingestion of Food:
Planaria prey the food during ingestion first the planaria come over the prey and secrets the mucus which result prey stuck and paralyze then planaria ingest the food through mouth.

Digestion of Food:
After the ingestion food is digest by the both extracellular and intracellular digestion.

Extracellular Digestion:
Extracellular digestion takes place by the physical and chemical action of digestive system. When the food is enter through mouth then it reach into pharynx where contraction of wall act on the food then food is expelled into intestine. Inside intestine food is partially digested by the physical and chemical action of intestine.

Intracellular Digestion:
Intracellular digestion take place in the wall of diverticulum the partially digested food is entering inside the cell by phagocytosis inside the cell food is completely digested by the enzyme of lysosome.

Absorption of Food:
In planaria absorption of food also take place through intestine. Diverticulums are present with in the deep tissues of body. The concentration of food is higher the wall of diverticulum while low into cells. The process of diffusion takes place and food is uniformly absorbs throughout body cells.

Egestion of Waste Products:
In planaria egestion of waste products is take place through mouth after digestion undigested food or waste product is present inside intestine. Due to contraction intestinal waste products are egested out through mouth.

NUTRITION IN COCKROACH:
Cockroach is a complex multi-cellular animal belongs to the Phylum Arthropoda. It has three pairs of jointed legs. It has a tube like digestive system which stars from mouth and end into anus. Cockroach has extracellular and it has holozoic nutrition.

Food of Cockroach:
Cockroach is omnivorous animal it utilize all types of organic substances as the food. E.g. Leather, cloth, paper and other food particles.

Digestive System of Cockroach:
Cockroach has developed digestive system. Digestive system is consists of long straight slightly coiled tube like structure called alimentary canal. Alimentary canal is present at the three parts of cockroach.

• Head.
• Thorax.
• Abdomen.

Inside the alimentary canal extracellular digestion take place and it is start from mouth and end into anus.

Parts of Alimentary Canal:
Digestive system of cockroach divided into three parts.

• Fore Gut or Stomodaeum.
• Mid Gut Mesenteron.
• Hind Gut or Proctodaeum.

Fore Gut or Stomodaeum:
It is first of alimentary canal. Fore gut is consists of following organs.

• Mouth.
• Oral cavity.
• Pharynx.
• Oesophagus.
• Crop.
• Gizzard.

Two types of glands also present in foregut.

• Salivary Gland
• Hepatic Caeca

Mid Gut Mesenteron:
It is second and middle part of alimentary canal. It consists of following organs.

• Mesenteron
• Ileum

Hind Gut or Proctodaeum:
It is third and last part of alimentary canal. It consists of following organs.

• Colon
• Rectum
• Anus

Fore Gut:

• Mouth:
  It is a small opening which is present at the terminal part of the head. Mouth is surrounded by four types of jaws.

  • Labrum.
  • Labium.
  • Maxillae.
  • Mandibles.

  Maxilla help in cutting and biting of food while mandibles are help in chewing of food.

• Oral Cavity:
  Mouth open behind in a small cavity called oral cavity. Inside oral cavity muscular structure is present called hypo pharynx. Salivary ducts are also open in oral cavity which brings the saliva. Saliva contain amylase enzyme which digest carbohydrate of food inside oral cavity.

• Pharynx and Oesophagus:
  Pharynx and Oesophagus are muscular tube like structures they help in physical digestion of food.

• Crop:
  Crop is muscular sac like structure. It is present inside thorax and abdomen. Inside the crop physical and chemical digestion is take place. Chemical digestion is take place through the enzyme of hepatic caeca.

• Gizzard:
  Gizzard is a pear shape structure. It is present inside abdomen. It has thick and muscular inside the gizzard vertical plates are present which crush the food. Gizzard also secretes substances which produce Chitinous like covering around the food. It is permeable for enzyme and absorption.

Mid Gut:

• Mesenteron:
  It is straight tube like structure. It has muscular wall. Mesenteron is divided into two parts, upper part called mesenteron while lower part called ileum. Inside the mesenteron complete digestion of food take place, while inside ileum absorption of food takes place.

Hind Gut:

• Colon:
  It is small segmented tube like structure having muscular wall inside colon, reabsorption of water is take place and formation of stool is also take place.

Rectum:
It is a small sac like structure. It has muscular wall, inside rectum storage of waste product take place.

Anus:
It is small opening which is present at the lower surface of abdomen, egestion of waste product take place through anus.

Digestive Glands:
There are two types of digestive glands found in cockroach.

• Salivary Gland.
• Hepatic Caeca.

Salivary Gland:
They are leaf like transparent gland. Salivary glands are one pair in number and present at the both side of oesophagus. Salivary gland produce saliva while reach to the oral cavity through salivary duct. Saliva contains an enzyme called “Ptyline” which digest the carbohydrate of food.

Hepatic Caeca:
Hepatic caeca are finger like glands. They are 6 to 8 in number and present at the junction of fore gut and mid gut. They produce digestive enzymes lipase, protease which digests fats and proteins of the food.

NUTRITION IN MAN:
Man is more complex and highly develop social living organism. It belongs to the Phylum Chordata. Man has complete tube like digestive system. It has complete extra cellular digestion. Man has holozoic mode of nutrition.

Food of Man:
According to nutrition man is omnivores. It utilizes both plants and flesh as the food. Food of man consists of vegetables, fruits, cereals, white meat, red meat, oil and other types of food.

Digestive System of Man:
Man has a complex and developed tube like digestive system. Digestive system of man is consists of long highly coiled tube like structure called alimentary canal. It is 9 meter long while 6 meter is length of small intestine. Alimentary canal has two opening upper opening called mouth while lower opening is known as anus. Alimentary canal is present in these parts of the body.

• Head.
• Thorax.
• Abdomen.

Parts Of Alimentary Canal:
The alimentary canal of man is divided into two parts:

• Digestive organs.
• Digestive Glands.

Digestive Organs:
Organs which help in digestion called digestive organs. Digestive organs of man are as follows:

• Mouth.
• Buccal cavity.
• Pharynx.
• Oesophagus.
• Stomach.
• Small intestine.
  • Duodenum
  • Jejunum
  • Ileum
• Large Intestine.
  • Caecum
  • Colon
  • Rectum
• Anus.

Digestive Gland:
Glands which are help in digestion are called digestive gland. Man has three types of digestive glands.

• Salivary Gland
• Liver
• Pancreas

Digestive Organs:

• Mouth:
  Mouth is a wide opening which is present at the terminal part of face beneath the nose. Mouth is surrounded by one pair of fleshy lips.

  • Upper lips
  • Lower lips

  Function:
  Mouth is help in ingestion of food. Lips are also help during ingestion.

• Buccal Cavity:
  Mouth open behind in a wide chamber like structure called buccal cavity. The roof of buccal cavity produce by palate, floor is produce by tongue and lower jaw while lateral sides are produce by the cheeks. Upper jaw is fixed while lower jaw is moveable. Upper jaw and lower jaw contains teeth.

  Teeth:
  Man has 32 teeth which are present in two sets (diphodont) teeth are unequal shapes and sizes called Heterodont. They are fixed inside and term as thecodont.

Types of Teeth:
Man has four types of teeth.

• Incisor
  Incisors are sharp teeth they are eight in number. Incisors are help in cutting and biting of food.

• Canine
  Canine are pointed teeth. They are four in number. Canine are help in capturing of food. In animals canine are long in size.

• Premolar
  Premolars are small flattened teeth, they are also eight in number. They are help in grinding of food.

• Molar
  They are large flattened teeth. Molar are twelve in number. They are help in chewing and mastication.

  Dental Formula:
  $(I\ 2/2, C\ 1/1, Pm\ 2/2, M\ 3/3) \times 2 = 32$

Plaque and Dental Diseases:

• Plaque:
  Mixture of bacteria and salivary material called plaque. It is harmful to the teeth and cause different diseases. Plaque also produces inflammation of teeth.

• Periodonatal Disease:
  The inflammation of periodontal layer of teeth called periodontal disease. Bacteria cause inflammation of gums. If this condition continues inflammation may spread to the root of tooth and destroy periodontal layer. Eventually tooth becomes loose and falls or may be extracted.

• Calculus:
  When plaque combines with chemicals of saliva to produce hard and calcified layer which deposit on the teeth called calculus. It cannot be removing by brushing.

• Dental Carries:
  Some of bacteria in plaque convert sugar into acid cause dental carries. In this disease enamel of teeth is slowly dissolved. When the dentine and pulp of tooth are attacked produce tooth ache and loss of tooth.

Prevention:
Prevention against dental carries may be achieved by adding fluoride in drinking water or food like milk or using fluoride tablets or fluoride tooth paste.

Tongue:
Tongue is a muscular structure which is present inside buccal cavity at the floor of lower jaw. It is attach posteriorly while free at the anterior end. Tongue contains taste receptors which sense food taste.

Function:
Tongue performs two important functions.

• It tastes the food and allows it to swallowing.
• It helps in mixing of saliva with the masticated food.

Salivary Glands and Saliva:
Salivary Glands:
Salivary glands are first digestive glands. They are present around buccal cavity. Man has three pairs of salivary glands.

• Parotid Gland.

• Sublingual Gland.

• Submandibular Gland.

• Parotid Gland:
  Parotid gland is present at the base of pinnae. It secretes saliva which is reach to the buccal cavity through a duct called salivary duct.

• Sublingual Gland:
  Sub lingual gland is present at the base of tongue. It also secretes saliva which is reach to the buccal cavity through salivary duct.

• Submandibular Gland:
  Submandibular gland is present beneath the lower jaw. It also secrets saliva which is reaches to the buccal cavity through salivary duct.

Saliva:
The secretion of salivary gland called saliva. Salivary gland secretes 1.5 dm³ saliva per day in man.

Composition:
Saliva is composed by water and other salivary material. Saliva consists of 95% water while 5% is consisting of mucous, lysozyme and amylase enzyme.

Function:
Saliva performs following functions:

• Mucous of saliva lubricate food which helps in swallowing.
• Water of saliva wet the food and allow to hydrolysis of enzyme.
• Lysozyme of saliva kills germs of food.
• Amylase enzyme of saliva acts on carbohydrate (starch) and convert it into Maltose. During the enzyme action starch is convert into dextrin and then it change into disaccharide.

Pharynx:
It is very small tube like structure which is present inside neck. It has muscular wall, pharynx has three openings.

• Buccal cavity opened into pharynx.
• Nasal cavity opened into pharynx.
• Glottis is also open into pharynx.
  Opening of glottis is guarded by a flapped structure called Epiglottis.

Functions:
Pharynx performs two important functions.

• Passage of food during digestion.
• Passage of air during respiration.

Oesophagus:
Oesophagus is a long narrow tube like structure. It starts from neck and end into abdomen. It has 25 cm length and muscular wall. Oesophagus has wave muscular movement called peristalsis.

Peristalsis:
Peristalsis is wave like propulsive muscular movement which is found throughout the alimentary canal. It helps in forward movement of food inside alimentary canal.

Anti Peristalsis:
Upward movement of food is caused by anti peristalsis. It is started by the sudden contract of stomach due to which food is moved in upward direction and muscular movement is started against peristalsis. The result of anti peristalsis is appearing in the form of vomiting.

Stomach:
Stomach is tubular sac like structure. It has muscular walls. It is present at the left side of abdomen below diaphragm.

Parts of Stomach:
Body of stomach is divided into three parts.

• Cardiac End:
  It is first part of stomach. It is present where oesophagus and stomach are joined to each other.

  • It also lies near heart. Cardiac end has a muscular ring called sphincter. It controls opening and closing of stomach.

• Fundus:
  It is second and middle part of stomach. The body of stomach largely consists of fundus. In the walls of fundus specialized glands are present called gastric gland.

Gastric Gland:
It consists of three types of cells.

• Mucous Secreting Cells:
  Mucous Secreting Cells secrete mucous which produce thick protective layer in the inner wall of stomach.

• Zymogen Cells:

  • Zymogen Cells secrete an inactive enzyme pepsinogen which is later on combine with HCl and convert into active Pepsin enzyme.
  • Those pepsin enzyme act on food protein and convert it into polypeptides.
  • In child another enzyme secrete from fundus called rennin. It acts on milk protein Caseinogen and convert it into insoluble protein called casein.

• Oxyntic Cells:
  Oxyntic cells secrete HCl whose pH is 1.5 - 2.5. It softens food, kills germs of food, and converts pepsinogen into Pepsin.

Pyloric End:
It is third and last part of stomach. It has a muscular ring called pyloric sphincter. It controls the gastric emptying time of stomach. At the pyloric end stomach is joined with small intestine.

Function:
Stomach performs three important functions.

• It helps in physical digestion by the contraction of walls.
• Inside stomach chemical digestion is take place by the help of Gastric Juice.
• Inside the stomach storage of food is also take place because food is stay 3-4 hours. By the result of physical and chemical digestion food is converted into white paste form called Chyme.

Small Intestine:
It is a long highly coiled tube like structure. It has muscular walls. Small intestine is six meter long. It is present inside the abdomen. (Diameter - 2.5 cm)

Parts of Small Intestine:
Small intestine is divided into three parts:

• Duodenum:
  It is first part of small intestine. Duodenum is 30 cm long. Inside duodenum common pancreatic duct is open which carry bile juice from liver and pancreatic juice from pancreas. Inside duodenum chemical digestion takes place by help of bile juice and pancreatic juice.

  Composition of Bile Salts:
  Bile juice is consisting into three types of salts. Commonly called as bile salts.

  • Sodium Bicarbonate
  • Sodium Touracholate
  • Sodium Glycolate

Bile juice also contains bile pigments, which produce by degradation of Hemoglobin.

• Bile Rubin (Yellow pigment)
• Biliverdin (Green pigment)

Functions of Bile Salts:
Bile salts perform following functions:

• NaHCO₃ neutralizes acidic chyme which comes from stomach.
• Sodium taurocholate and sodium glycolate emulsify fat molecules and convert fat into fatty droplets.

Composition of Pancreatic Juice:
Pancreatic juice is secreted from pancreas. Secretion of pancreatic juice is depend upon releasing of "Secretin" hormone of duodenum. Pancreatic juice consists of four types of enzymes.

• Trypsin
• Chymotrypsin
• Amylase
• Lipase

Function of Pancreatic Juice:
Pancreatic juice performs following functions:

• Trypsin is released in active form called "Trypsinogen". It combines with "Enterokinase" and converts into active form trypsin. Trypsin acts on protein and digests it into polypeptides or peptones.
• Chymotrypsin acts on milk, protein, and converts it into peptones and amino acids.
• Amylase acts on carbohydrate and converts it into Maltose or Disaccharide molecules.
• Lipase acts on fatty droplets and digests it into fatty acids and glycerol.
• Inside duodenum, fats are completely digested with the help of bile juice and pancreatic enzymes, while proteins and carbohydrates are partially digested.

Jejunum:
It is the second and middle part of the small intestine. It is 2.4 meters long. It has muscular walls. The wall of Jejunum secretes different types of enzymes which completely digest proteins and carbohydrates.

Functions of Jejunum:
Jejunum performs following functions:

• It secretes "sucrase" enzyme which acts on sucrose and converts it into simple or monosaccharide.
• Lactase acts on lactose and converts it into monosaccharide or simple sugar.
• Maltase acts on maltose and converts it into monosaccharide or simple sugar.
• Glactase acts on galactose and converts it into monosaccharide or simple sugar.
• Protease acts on polypeptide or peptones and converts it into amino acids.

Wall of jejunum also secrete Nucleotidase enzyme which act on amino acid and convert it into Nucleotides.
Inside jejunum food is completely digested.

Ileum:
It is also coiled tube and third part of small intestine. Ileum is 3.6 m long. It has muscular walls. Inside ileum finger-like projections are present called villi (singular villus).

Structure of Villi:
It is finger-like structure. The wall of villus is composed of permeable epithelial cells. Outer surface of villus has microscopic finger-like projections called microvilli. Each villus contains three types of vessels.

• Branch of Artery
• Branch of Vein
• Branch of Lymphatic System

Absorption of Food:
In man absorption of food takes place in the wall of ileum. After digestion monosaccharide or simple sugar, amino acid, and fatty acids or glycerol are formed. Monosaccharide and amino acid are small size molecules while fatty acid is large size molecule. Monosaccharide and amino acids are easily crossed the wall of villus and absorbed directly into the blood. While fatty acid first absorb inside epithelial cells of villus. Inside the epithelial cell it is converted into triglyceride which is also large molecule. This triglyceride is absorbed by the lacteal then it goes to the blood through opening of lymphatic vessel in large veins.

Large Intestine:
It is a long slightly coiled tube-like structure. It has muscular walls. Large intestine is present inside lower part of abdomen, large intestine is divided into three parts.

• Caecum:
  It is sac-like structure and first part of large intestine. Caecum is present at junction of small and large intestine. It has muscular walls. Caecum has 18 cm long finger-like structure called appendix. It caused the disease called appendicitis. Inside the caecum symbiotic bacteria are also present.

  Function:
  The symbiotic bacteria of caecum are help in digestion of cellulose. This is intake in the form of fruit and vegetables.

• Colon:
  It is long slightly coiled tube-like structure. Diameter of colon is 6.5 cm. The wall is muscular and externally segmented. Colon has wave-like muscular movement called peristalsis.

Parts of Colon:
According to the position, colon is divided in three parts.

• Ascending Colon
• Transverse Colon
• Descending Colon

Function:
Colon performs different functions.

• Inside the colon reabsorption of water and useful salts are take place.
• Colon has symbiotic bacteria which help in formation of stool or faeces.

Rectum:
It is a large intestine sac like structure. Rectum is present inside lower end of abdomen. It has a muscular wall. Rectum is open outside body through anus.

Function:
It is large sac like structure which is present at the pelvic region of abdomen. Inside the rectum storage of stool or faces is take place. It also helps in absorption of water useful salts and vitamin K. Inside the rectum symbiotic bacteria are also present which help in degradation of stool or faces.

Anus:
It is a small opening which is present between pelvic gridle. Rectum is open outside the body through it. The wall of anus has a double muscular ring called Anal Sphincter. One anal sphincter is composed by smooth muscles and it is present inside anus while other anal sphincter is composed by striated voluntary muscles and it is present out side the anus.

Function:
Anus helps in egestion of faeces. The process of defection is take place by the opening of both anal sphincters.

LIVER AND PANCREAS:
Liver:

• Liver is largest digestive gland it is also the largest organ of body and having weight of 1.5 kg.
• Liver has reddish brown colour and it is located at right side of abdomen.

Lobes of Liver:
Liver divided into two lobes by hepatic Vein.

• Right Lobe:
  Right lobe is larger than left lobe.

• Left Lobe:
  Left Lobe is further divided into two small lobes.

Supply of Blood:
Liver has dual blood supply.

• Blood supply through hepatic artery.
• Blood supply through hepatic portal vein.

Gall Bladder:
It is green color sac-like structure which is present at base of liver. Liver produces bile juice which is stored in gall bladder.

Duct System:
Two hepatic ducts arise from liver. Cystic duct also arises from gall bladder; all three ducts are combining and produce bile duct also combines with pancreatic duct and formed hepato pancreatic duct which opens into duodenum.

Functions of Liver:
Liver performs various functions.

Metabolic Function:
Liver is metabolic center and metabolic processes take place in liver.

• After absorption of glucose it reaches into liver. Insulin of pancreas converts glucose into glycogen inside liver; this glycogen is stored inside liver when body required glucose then glucagons of pancreas convert glycogen into glucose and supply it to body through liver. Liver also separates ammonia group from amino acid and converts it into urea which is eliminated through kidney.
• Liver converts fatty acid or Glycerol into Ketone Bodies which is supplied to muscles for active energy.
• Liver also converts harmful substances into useful substances which are absorbed by intestine.

Storage Function:
Liver stores various substances such as glucose, fats, minerals and vitamins.

Synthetic Function:
Liver also performs synthesis of different substances.

• It produces different vitamins for building of body.
• It produces substances which prevent the blood from clotting.

PANCREAS:
It is second largest digestive gland. It is a leaf-like transparent gland which is present parallel to duodenum. Pancreas also known as Exocrine and Endocrine gland.

Pancreas as Exocrine Gland:
As exocrine gland pancreas produce digestive juices called pancreatic juice. It is reached to duodenum through pancreatic duct. These digestive juices help in digestion of food inside duodenum.

Pancreas as Endocrine Gland:
As endocrine gland it produces two types of hormones.

• Insulin
• Glucagon

Insulin metabolizes glucose and converts it into glycogen while glucagons synthesize glucose. The deficiency of insulin causes a disease in man called diabetes mellitus.

DISORDERS OF DIGESTIVE SYSTEM:
Various types of disorders found in digestive system:

Diarrhea:
Loose motion also known as diarrhea. Rapid discharge of faecal material with water called diarrhea. There are three causes of diarrhea.

• Enteritis:
  Inflammation of large intestine due to virus and bacteria called enteritis. It also causes diarrhea.

• Cholera:
  Discharge of bicarbonates and Na ions with faecal material and water called cholera. Severe discharge caused death of man.

• Psychogenic Diarrhea:
  Rapid discharge of faecal material with water, caused by excessive impulses of brain. When brain is mentally disturbed it causes diarrhea called psychogenic diarrhea.

Dysentery:
Rapid release of faecal material with mucous and blood called dysentery. It is also type of diarrhea. Dysentery is caused by protozoa Entamoeba Histolytica and bacillary bacteria.

Constipation:
The slow movement of faecal material inside large intestine called constipation. Due to slow movement of faecal material it stays long time in large intestine and reabsorption of water is take place which results faeces becomes hard and it caused problem in defecation. Continuous constipation is a result of imbalance in bowel movement. Including fibrous food in diet controls it.

Piles:
Piles are also known as Haemorrhoids. It is the dilation of vein near the anus. Piles are found inside or outside anus. Inside anus it is open while outside the anus it is covered by skin. Piles are painful or not painful. The disease of piles is produced by continuous constipation. Due to constipation defection problem is created and it requires extra force which results veins are dilated and piles are produced.

Dyspepsia:
Discomfort of epigastric region called dyspepsia. It is characterized by flatulence, heartburn, abdominal pain, anorexia and nausea and vomiting. Dyspepsia is usually caused by peptic ulcer.

Peptic Ulcer:
Gastric ulcer and duodenal ulcer are commonly known as peptic ulcer. Inside duodenum it is occur after few cm distance of stomach. While in stomach it is occur everywhere except cardiac end. Peptic ulcer is caused by erosion of mucous in the inner wall of stomach and duodenum. It also caused by long use of spicy and oily food. Peptic ulcer is also a neurogenic and it is caused by stress.

Food Poisoning:
Food poisoning or gastroenteritis is caused by long use of infected food. Virus, bacteria or protozoa may infect food. Salmonella species are very common cause of food poisoning. Raw eggs, buffalos and frozen chicken are also caused food poisoning.

Malnutrition:
When an organism is deficient in or receives excess of one or more nutrients over a long period of time is said to have malnutrition. The deficiency is known as under-nutrition and the excess, over-nutrition. Under-nutrition is the most common problem of underdeveloped countries, whereas obesity with heart ailment and reduced life expectancy are the symptoms of over nutrition which is more common in developed countries.

Over Weight and Obesity:
The accumulation of excess fat in body called overweight and obesity. Obesity is very commonly found in developed countries. In obesity intake of energy becomes higher but the expenditure of energy becomes low. Obesity causes various diseases in human, such as blood pressure (high or low), sugar.

Anorexia Nervosa:
Loss of appetite is called anorexia nervosa. These types of disease are very common in girls and young ladies. In this type of disease loss of appetite seriously if food is not taken for a long time. Due to anorexia nervosa some time vomiting is also occurring.

Bulimia Nervosa:
Bulimia nervosa is usually found in those ladies who have anorexia nervosa. When they pass age of anorexia nervosa then feel severe appetite and they involve into bulimia nervosa. These type of ladies usually utilize binge which is consists of chocolate, cake and other dairy product.

PARASITIC NUTRITION:
Nutrition in which living organism obtain their food from other living organisms called parasitic nutrition. Living organism which provides food called host while other living organisms which obtain their food called parasite.

Types of Parasites:
There are four types of parasite found:

• Exo Parasite
• Endo Parasite
• Obligatory Parasite
• Facultative Parasite

Exo Parasite:
Those parasites which obtain their food from external surface of host called exo parasite. E.g. Mosquito, bed bug, lice, leech.

Endo Parasite:
Those parasites which obtain their food from inside the host called endo parasite. E.g. Tape worm, liver fluke and ring worm.

Obligatory Parasite:
Those parasites which are completely dependent on body of host, called obligatory parasite. E.g. Virus.

Facultative Parasite:
Those parasites which are dependent on host, after death of host they utilize organic dead matter called facultative parasite. E.g. Fungi.

ENDO PARASITES OF MAN:
Parasites have different adaptations with their host if parasite cause disease in host called Pathogenic. If parasite do not cause disease in host called non-pathogenic. Some endoparasites of man are as follows:

• Virus:
  They cause influenza, measles, rabies, polio, yellow fever, hepatitis and aids.

• Bacteria:
  Bacteria cause tuberculosis, typhoid, tetanus, plague, leprosy.

• Fungi:
  Fungi cause dermatophytes, ring worm disease in athletes, onychomycosis.

• Protozoa:
  Protozoa cause different diseases in man. Such as plasmodium cause malaria, trypanosoma cause trypanosomiasis, leishmania cause leishmaniasis and entamoeba cause entamoebiasis.

• Helminthes:
  Helminthes cause different diseases such as taenia saginata causes taeniasis. Ancylostoma, hookworm, ascaris are usually found in intestine of child. Filaria cause filariasis.

Nutrition

 Chapter # 12

NUTRITION
BOTANY PART

Q.1: What is nutrition and what are different types of nutrition?

Ans:
The process by which living organisms obtain energy to perform all their functions of life to make important materials and to maintain their structure is called nutrition.

Types Of Nutrition:
There are two types of nutrition:

Autotrophic Nutrition:
When the living organisms can manufacture their own food material, it is called autotrophic nutrition, and the living organisms are known as autotrophs. There are two types of autotrophic nutrition.

• Phototrophic Nutrition:
  In this nutrition, the living organisms manufacture their food in the presence of sunlight. This type of nutrition is found in plants and bacteria.
• Chemotrophic Nutrition:
  This type of nutrition is also common in bacteria. In this nutrition, light is not used, but certain inorganic substances are involved to produce energy by oxidation process. The bacteria use inorganic compounds as source of carbon and get energy by oxidation and reduction process. They oxidize the compounds like nitrate, sulphur, ammonia, ferrous iron, hydrogen sulphide etc.

Heterotrophic Nutrition:
When the living organisms cannot manufacture their own food and they depend upon other organisms for their food, it is called heterotrophic nutrition and the living organisms are known as heterotrophs. Heterotrophs may be parasites or saprophytes.

Q.2: What is the role of Nitrogen in plants?

Ans:
The plants absorb nitrogen in the form of nitrates and ammonium salts. It is present in the structure of protein molecules, nucleic acids, and chlorophyll.

Deficiency Symptoms:

• Chlorosis: Due to the loss of chlorophyll yellowing of leaves develops, called chlorosis.
• Process of cell division and cell elongation is stopped

Q.3: What is the role of Phosphorus in plants?

Ans:
The plants absorb phosphorus in the form of soluble phosphates such as $H_2PO_4$ and $HPO_4$. It is present in sufficient amount in the growing and storage organs such as fruits and seeds. In the body of plants, phosphorus is present in the nucleic acids, phospholipids, ATP, NAD, and NADP compounds. Phosphorus promotes healthy growth of plants and fruit ripening. The coenzymes NAD and NADP contain phosphorus. These are important in oxidation-reduction processes. These are involved in many processes like photosynthesis, respiration, nitrogen metabolism, and fatty acid synthesis.

Deficiency Symptoms:

• Dead necrotic regions: The deficiency causes dead necrotic regions on the leaves, petioles, and fruits.
• Premature leaf fall occurs.
• Cambium activity is affected.
• Dormancy is prolonged.
• Accumulation of carbohydrates occurs.
• In some plants, the leaves show dark to blue-green coloration, such as dark green in Pisum (Gram).
• Sometimes purple or red anthocyanin pigmentation takes place in leaves.

Q.4: What is the role of Potassium in plants?

Ans:
Potassium is also an important mineral. It is present in growing regions of plants. It is used in the processes of respiration, photosynthesis, chlorophyll formation, and nucleic acid synthesis. It is involved in the opening of stomata. It is also used in enzyme action required in carbohydrate metabolism and formation of peptide bonds.

Deficiency symptoms:

• Dull Or Bluish Green Leaves:
  The deficiency of Potassium causes dull or bluish-green leaves.
• Irregular Chlorosis:
  Irregular chlorosis occurs near the tips and margins of leaves.
• Stunted Growth:
  Plant is stunted in growth with short internodes.
• Tips of leaves turn downward.

Q.5: What is the role of Magnesium in plants?

Ans:
Magnesium is required by the plant for the formation of chlorophyll. Without chlorophyll, photosynthesis cannot occur. It is also an activator of certain enzymes. It acts as a phosphorus carrier in the plant. It takes part in seed formation having high oil contents. It is also required in the preparation of fats and carbohydrate metabolism.

Deficiency Symptoms:

• Chlorosis or yellowing: Chlorosis or yellowing occurs first in older leaves and then in younger leaves.
• Hard stem: Stem becomes hard and woody and yellowish green.
• Fall of leaves: Affected leaves wither and fall earlier.
• Necrotic spots are developed on leaves.

Q.6: What are the heterotrophic plants?

Ans:
Some plants are not able to manufacture their own food material due to the lack of chlorophyll or some other reason, so they completely or partially depend upon other organisms. These are called heterotrophic plants, and the nutrition is known as heterotrophic nutrition.

There are two types of heterotrophic plants:

• Parasitic Plants:
  They obtain their food from living organisms.
• Saprophytic Plants:
  They obtain their food from non-living organisms.
• Carnivorous Plants:
  These plants obtain nitrogenous compounds from insects or other small animals.

Q.7: Write a note on parasitic plants?

Ans:
Parasitic Plants:
These plants obtain their food from other living organisms. These plants are two types:

• Obligate Parasites:
  These plants entirely depend upon other living organisms for their food. They are also called total parasites.
• Partially Parasites:
  These plants partially depend upon other organisms for their food. They are also called partially parasites. The parasitic plants produce special root-like structures, called haustoria. These haustoria penetrate into the host plant body and absorb food material.

The parasitic angiospermic plants are as follows:

• Partial stem parasite
• Total stem parasite
• Partial root parasite
• Total root parasite

Partial Stem Parasite: These plants grow upon other host plants, they can manufacture some of their food due to the presence of chlorophyll, and they partially depend upon the host plant. They absorb nutrients and water from the host plant by the help of haustoria.

Examples:

• Loranthus has thick green leaves, woody stem, and haustoria. It grows up mango, Bauhinia plant, rosaceous trees, and many shrubs.
• Viscum
• Cassytha filiformis.

Total Stem Parasite: These plants completely depend upon host plants for their food. They produce haustoria into the body of the host plant and absorb food material. Ultimately the host plant may die.

Example:
Cuscuta plant (Amar bail).

Partial Root Parasite: These plants get their food partially from the roots of other plants. For example, Sandalwood tree. Its seedling does not grow independently. Its roots absorb nourishment from the roots of other plants.

Total Root Parasite: These plants obtain their food completely from the roots of neighboring plants. These plants usually attack the plants of the family Cruciferae and Solanaceae. For example, Orobanche, Cistanche, Striga. Cistanche parasites on the roots of Calotropis plant. Striga is a parasite on the roots of sugarcane, Sorghum, or Jawar.

Q.8: What are the saprophytic plants?

Ans: SAPROPHYTIC PLANTS: These are special plants, which grow upon dead organic matter. These plants do not contain chlorophyll. Their roots are without root hairs and cannot absorb nourishment from the soil. They decompose dead organic food into simpler compounds and use them for their growth and development. For example, Neothia (bird’s nest or orchid), Monotropa. Roots of these plants form an association with fungi, which helps in the absorption of food from dead bodies.

Q.9: What are Carnivorous plants? Name some carnivorous plants?

Ans: CARNIVOROUS PLANTS: Some plants use insects, so they are called carnivorous or insectivorous plants. These plants show certain modifications to capture insects. These plants contain chlorophyll and manufacture their own food, but cannot prepare nitrogenous compounds and proteins, so to get these compounds, the plants use insects. These plants usually grow in those regions where nitrogen is not sufficiently available, so they depend upon insects for nitrogen and proteins.

Some insectivorous plants are as follows:

• Pitcher plant
• Sundew plant
• Utricularia or Bladder wort
• Venus fly trap plant
• Water fly trap plant.

Q.10: Write a note on Pitcher Plant?

Ans: PITCHER PLANT:

• In this plant, leaves are modified into flask-shaped structures, called leaf pitcher. These pitchers are used to capture insects.
• The pitcher also has a lid to close its mouth.
• When insects come on its mouth, they are slipped into the pitcher.
• From the inner surface of the pitcher, digestive enzymes are secreted, which help in the digestion of insects.

Q.11: What are Sundew insectivorous plants?

Ans: SUNDEW PLANT: (DROSERA INTERMEDIA)

• It is a small herb plant with about half a dozen leaves.
• Each leaf is covered on the upper surface with many glandular hairs, called tentacles.
• The glands secrete a fluid, which glitters in the sunlight like dew, so the plant is called Sundew plant.
• The insects are attracted to the plant due to smell, these insects are captured by the tentacles, then they are digested by enzymes.

Q.12: Describe Venus fly trap plant?

Ans: VENUS FLY TRAP PLANT:

• It is a herb plant, grows in moist places.
• The leaves of the plant consist of two halves with a midrib in the centre.

Q.13: Describe Utricularia? (Bladderwort)

Ans: UTRICULARIA: (BLADDER WORT)

• It is a water-living plant, in which leaves are modified into small cup-shaped structures, called bladders.
• The bladders are used to capture the insects.
• Each bladder has a small opening, which acts as a trap-door.
• The insects enter the bladder through the trap-door. From the inner region of the bladder, enzymes are produced for the digestion of insects.

Q.14: Describe water fly trap plant?

Ans: WATER FLY TRAP PLANT: (ALDROVANDA)

• It is a water-living free-floating plant. It is rootless with whorls of leaves.
• The leaves are modified to capture the water flies. Each leaf has two lobes.
• Along the margin of leaf, teeth-like structures are present. It also has jointed hairs and stalked glands on the surface.
• When flies are captured, enzymes are secreted from glands which take part in digestion of insects.

Q.15: What is Heterotrophic nutrition in Animals?

Ans: HETEROTROPHIC NUTRITION IN ANIMALS: In heterotrophic nutrition, living organisms are not able to manufacture their own food, but they depend upon other organisms. All animals, fungi, and many bacteria are included in heterotrophic organisms. These are called heterotrophs.

In animals, there are different types of heterotrophic nutrition:

• Holozoic Nutrition: In this nutrition, the animals take solid organic food, it is digested by the action of enzymes, then it is assimilated to release energy by oxidation process.
• Saprozonic Nutrition: When the organisms take their food from dead organic substances, it is called saprozoic nutrition.
• Parasitic Nutrition: In this nutrition, the organisms obtain their food from the body of host and cause great damage to their body.

Q.16: What are different types of animals on food basis?

Ans: TYPES OF ANIMALS ON THE BASIS OF FOOD: On the basis of feeding system, the animals are of the following types.

• Detritivores: These animals take their food from organic debris (detritus). When the organic debris is decomposed, they use them as their food e.g. Earthworm.
• Predators: These animals attack other animals, kill them, and then use them as their food e.g. Lion.
• Herbivores: These animals use plants as their food e.g. Cow, Rabbit, Horse etc.
• Carnivores: These animals obtain their food from other animals e.g. Cats, Dogs.
• Omnivores: These animals use both plants and animals as their food i.e. eat meat and vegetable matter. e.g. Man, Crow, Rat etc.
• Filter feeders: These are water-living animals, in their body food enters along with water. Food particles are used by the body, water is filtered out. e.g. Sponges.

• Fluid Feeders:
  These animals take their food from other animals in the form of fluid. e.g. Mosquitoes suck blood from man.

  Microphagus Feeders:
  These animals take food in the form of small pieces.

  Macrophagus Feeders:
  These animals take food in the form of large pieces.

Q.17: What is Holozoic Nutrition?

Ans: HOLOZOIC NUTRITION:
When complex food substances are taken in, these are converted into simpler diffusible form by enzymes, absorbed by the body, and used to provide energy. This process is called holozoic nutrition.

The holozoic nutrition consists of five steps:

1. Ingestion: When complex food molecules are taken inside the body with the help of certain organs, it is called ingestion.
2. Digestion: When complex food molecules are converted into simpler and diffusible form by the action of enzymes, it is called digestion.
3. Absorption: When digested diffusible food substances diffuse into blood or body cells across the membrane of the digestive part, it is called absorption.
4. Assimilation: When the products of digestion are used to produce energy in the body, it is called assimilation.
5. Egestion: When undigested food substances are expelled out of the body, it is called egestion.

Q.18: What are extracellular and intracellular digestion?

Ans:
There are two types of digestion:

• Extracellular Digestion: When the digestion takes place outside the cells in the digestive tract, it is called extracellular digestion.
• Intracellular Digestion: When the digestion occurs inside the cells, it is called intracellular digestion.

Intracellular Digestion:
When digestion takes place inside the cells, it is called intracellular digestion.

Q.19: Describe the process of nutrition in Amoeba?

Ans: NUTRITION IN AMOEBA:
Amoeba is a unicellular freshwater organism. It is a microphagus feeder, meaning it uses small organisms as its food, such as minute food particles, bacteria, flagellates, and ciliate animals and plants.

Ingestion:
Amoeba captures food particles with the help of pseudopodia. It produces two pseudopodia at the same time, forming a cup-like structure around the food. Then the food is taken in through the surface of the body. The food is surrounded by a drop of water, which forms a food vacuole. This process is known as ingestion.

Process of Digestion:
In the digestion of food, lysosomes are involved. Some lysosomes are attached to the membrane of the food vacuole. They secrete certain enzymes like proteases, amylases, and lipases into the food vacuole. The food vacuole decreases in size as a result of water loss. Due to the enzyme activity, the food is completely digested.

Absorption of Food:
After digestion, fine canals are produced from the digestive vacuole. Along these canals, the soluble products of food pass into the surrounding cytoplasm. These food products are absorbed into the cytoplasm, where the absorbed food circulates throughout the cytoplasm.

Assimilation:
After absorption, the food is assimilated to form new cytoplasm and to produce energy.

Egestion:
Insoluble or undigested food particles are expelled out of the body by exocytosis. In Amoeba, digestion of food occurs inside the cell, so it is called intracellular digestion.

Q.20: Describe the process of nutrition in Hydra?

Ans: NUTRITION IN HYDRA:
Hydra is a water-living animal. It is a macrophagus feeder, meaning it takes large pieces of food. Hydra has an elongated tube-like body. At its upper end, the mouth is present, surrounded by finger-like projections called tentacles, which are used to capture prey.

Hydra is a diploblastic animal, meaning it consists of two layers: the outer layer is called ectoderm, and the inner is known as endoderm. Between these layers is a non-cellular sheet called mesogloea. The mouth of Hydra opens into a cavity called gastrocoel or enteron, which is closed at the lower side. Endodermal cells lie close to the enteron.

The endoderm layer contains two types of cells: glandular cells (with glands) and flagellated cells (with flagella). When food enters the enteron through the mouth, the glandular cells secrete proteolytic enzymes to digest the food. Flagellated cells and contractions of the body wall also aid in digestion, which occurs extracellularly in the enteron. After partial digestion, some of the digested food is absorbed by endodermal cells, where intracellular digestion also takes place. This dual digestion process is both extracellular and intracellular in nature. The digested food is absorbed by endodermal cells and diffused to other body regions, while undigested particles are expelled through the mouth.

Q.21: Describe the process of nutrition in Planaria?

Ans: NUTRITION IN PLANARIA:
In Planaria, an alimentary canal is present, consisting of three parts: mouth, pharynx, and intestine. The mouth is in the middle of the lower body region. When Planaria takes food from outside, it passes through the pharynx into the intestine, which divides into three branches—one central branch extending forward and two lateral branches extending backward. These branches divide into numerous branches, forming a branching system responsible for digestion, absorption, and distribution of food. This system is known as the gastrovascular system, differing from that of other animals.

The food of Planaria consists of dead aquatic animals. The food is taken in through the mouth, which opens into the pharynx and then the intestine. The enzymes act upon the food in the intestine. The digested food is absorbed by the branches of the intestine, which is distributed throughout the body by diffusion. In Planaria, the digestion is both intracellular and extracellular. The branching system of the intestine mainly helps in the supply of food throughout the body; otherwise, simple diffusion does not help in this process. This system is like the circulatory system of higher animals. The undigested food is expelled out of the body through the mouth, as the anus is absent.

Q.22: Describe the process of nutrition in Cockroach?

Ans: NUTRITION IN COCKROACH:
Cockroach is an insect; it is omnivorous, meaning it takes any kind of organic matter. It uses its antennae in the search of food. The digestive system of the cockroach consists of a tube-like alimentary canal, which extends from the mouth to the anus. The alimentary canal consists of three parts:

• Fore gut or stomodaeum
• Mid gut or mesenteron
• Hind gut or proctodaeum

Fore Gut or Stomodaeum:
It is the upper region of the alimentary canal. It consists of the mouth, buccal cavity (preoral cavity), pharynx, oesophagus, crop, and gizzard. The mouth opens into the pre-oral cavity (buccal cavity). The food is mixed with saliva, secreted by salivary glands. The saliva contains amylase enzyme, which digests carbohydrates. The mouth opens into the pharynx. It is tube-like, present up to the end of the head, then it opens into the oesophagus. The oesophagus is thin-walled and tube-like. It passes through the neck, enters the thorax, and opens into the crop. The crop is a pear-shaped sac-like large part, present in the thorax. It stores food material and leads into the gizzard. The gizzard is a small, thick-walled structure, present at the lower region of the crop. Its internal lining is raised into six teeth-like structures, which are used for the grinding of food, so the food is converted into a fine state.

Mid Gut or Mesenteron:
It is the middle part of the alimentary canal. It is a thin-walled, narrow, tube-like structure. From the upper outer surface of the mesenteron, six to eight club-shaped structures are produced, called hepatic caecae. These secrete digestive enzymes, which help in the digestion of proteins and fats. After digestion, the food is also absorbed in the mid-gut.

Hind Gut or Proctodaeum:
It is the lower region of the alimentary canal. It consists of three parts: ileum, colon, and rectum. The ileum is the upper part of the hind gut. It is thin-walled, tube-like. The mesenteron opens into the ileum. From the outer region of the ileum, fine hair-like structures are developed, called Malpighian tubules. These are excretory organs. The ileum opens into the colon. The colon is long...

Q.23: Name the different parts of alimentary canal of man?

Ans: PARTS OF ALIMENTARY CANAL:
The alimentary canal of man consists of the following parts:

• Mouth and buccal cavity
• Pharynx
• Oesophagus
• Stomach
• Small intestine: This part is further divided into (i) Duodenum, (ii) Jejunum, (iii) Ileum.
• Large intestine: This part is further divided into three portions: (i) Colon, (ii) Caecum, (iii) Rectum.

Q.24: What are the glands of digestion in man?

Ans: GLANDS:
In the body of man, three types of glands are present, which secrete digestive enzymes. These are as follows:

• Salivary glands
• Liver
• Pancreas

Q.25: Write a note on teeth of man & write down the dental formula?

Ans:
There are different types of teeth in man: incisors, canines, premolars, and molars. Incisors and canines are the anterior teeth, while premolars and molars are the posterior ones. They change the food into small particles. Man has two sets of teeth; it is called diphyodont. One set is of milk teeth, deciduous, and these are replaced by another set, permanent teeth. The teeth are of different shapes and sizes; it is called heterodont. These teeth are embedded in the gums; it is called thecodont. Man has 8 incisors, 4 canines, 8 premolars, and 12 molars. The human dental formula is
$\left(\frac{2}{2}, \frac{1}{1}, \frac{2}{2}, \frac{3}{3}\right) \times 2 = 32$

Q.26: Write a note on plaque and dental diseases of man?

Ans: PLAQUE AND DENTAL DISEASES:
When salivary material and bacteria are mixed together, it is called plaque. Many diseases and abnormalities can occur by plaque.

• Periodontal Disease:
  When plaque is accumulated, bacteria cause inflammation of the gums. By this continuous process, inflammation spreads to the roots of teeth and destroys their peridental layer, due to which the teeth become loose and fall off. It is called periodontal disease.

• Calculus:
  When plaque combines with certain chemicals in the saliva, it becomes hard and calcified. It is deposited on the teeth and cannot be removed easily; it is called calculus.

  Dental Caries:
  When the enamel part of the teeth is destroyed and dentine and pulp are attacked by bacteria, converting sugar into acid, it causes toothache and loss of teeth, which is called dental caries.

  There are many factors of dental caries:

  • Sugary foodstuffs are used, and teeth are not cleaned properly.
  • Saliva composition may be disturbed or changed.
  • Lack of oral hygiene.
  • Low level of fluoride in drinking water.
  
  

  Q.27: Describe the salivary glands of man?

  Ans: SALIVARY GLANDS AND SALIVA
  The teeth change the food into small particles. In this process, the tongue also helps. It is also used for sucking and testing the food. During this process, salivary glands are stimulated and secrete saliva, which is mixed with food.

  There are three pairs of salivary glands in the oral cavity:

  • Parotid Glands: Present below the ear pinnae.
  • Sub Lingual Glands: Present under the tongue.
  • Sub Mandibular Glands: Present at the base of jaws.

  Saliva is an alkaline fluid. It contains water and mucus, which moisten and soften the food and help in lubrication, making it easier to swallow. Saliva contains two enzymes, amylase and lysozyme. Amylase of saliva digests starch and converts it into polysaccharides, then into disaccharides. Lysozyme enzyme destroys pathogenic bacteria.

  Q.28: What are peristalsis and antiperistalsis?

  Ans: PERISTALSIS & ANTIPERISTALSIS:
  In the gut wall, contraction and expansion occur in an alternate manner. This propulsive movement is called peristalsis. For the swallowing of food and water, peristaltic movements are required.

When there is great stretching and irritation in the gastrointestinal wall, it is called antiperistalsis. It occurs at the time of vomiting. When there is contraction in the abdominal muscles and the stomach is squeezed, the gastric contents move upward through the oesophagus in the form of vomiting. In antiperistalsis, the movements are reversed. It usually occurs due to overeating or any other reason.

Q.29: Describe the process of digestion in the stomach of man?

Ans:
The stomach is a muscular sac-like part, present on the left side of the abdominal cavity below the diaphragm. The stomach performs three functions:

• Storage of food
• Mechanical digestion of food
• Chemical digestion of food by enzymes

The stomach has three regions. Its upper region is called the cardiac end. This end contains a valve called the cardiac sphincter. The middle region of the stomach is the fundus. It is the main part containing gastric glands. These glands have three types of cells:

• Mucus secreting cells
• Zymogen cells, which secrete pepsinogen enzyme
• Oxyntic cells, which secrete dilute HCl

The lower part of the stomach is called the pyloric region. It opens into the duodenum; at this region, a valve is present, called the pyloric sphincter. When food comes into the stomach, the gastric glands secrete gastric juice which is mixed with the food.

Gastric Juice contains the following compounds:

• Mucus: It protects the inner lining of the stomach from the action of enzymes.
• Water: It moistens and softens the food.

HCl:

• It stops the action of saliva and kills bacteria. It also provides an acidic medium.

Enzymes: In the gastric juice, the following enzymes are present:

• Pepsin: By the action of HCl, the pepsinogen enzyme is changed into pepsin, which converts proteins into peptones and proteoses.
• Rennin: It changes the milk into curd in young ones. In adults, this process takes place by HCl.
• Gastrin: A hormone produced in the stomach. It activates gastric glands to produce gastric juice.

The partly digested food is in the form of a paste-like substance called chyme. It comes into the duodenum.

Q.30: Describe the process of digestion in the small intestine of man?

Ans: SMALL INTESTINE: The stomach leads into the small intestine. It is about 6 meters long and 2.5 cm wide. It consists of three parts:

• Duodenum
• Jejunum
• Ileum

Duodenum: The stomach directly opens into the duodenum, which is about 30 cm long. It receives a common bile duct and a pancreatic duct through a common opening. When food comes into the duodenum, it mixes with the bile, which is secreted by the liver. Bile contains water, bile salts, and bile pigments.

Bile:

• It neutralizes the acid in the food and makes it alkaline.
• It acts upon fats and converts them into a milky suspension, i.e., emulsification takes place.

There are two bile pigments: red pigment (bilirubin) and green pigment (biliverdin). These are produced by the breakdown of hemoglobin from ruptured RBCs in the liver. Bile pigments are excretory products.

Pancreatic Juice: It is secreted by the pancreas and produced by the activity of a hormone called secretin, which is produced by the duodenum. Secretin enzyme is also produced due to HCl, which comes from the stomach along with food.

Pancreatic juice contains the following enzymes:

• Trypsin (Protease): It is an active enzyme, but it is converted into an active enzyme from the inactive enzyme trypsinogen by the activity of enterokinase enzyme. Trypsin acts upon proteins and converts them into polypeptides.
• Chymotrypsin: It converts milk protein casein into amino acids.
• Amylase: It converts starch into maltose.
• Lipase: It converts fats into fatty acids and glycerol.

Digestion In Jejunum: The duodenum opens into the jejunum, which is about 2.4 meters long. It secretes the following enzymes:

• Peptidase (Erepsin): It acts on proteoses and peptides and converts them into amino acids. These are diffusible substances.
• Maltase: It converts maltose into glucose.
• Sucrase: It converts sucrose into glucose and fructose.
• Lactase: It converts milk sugar into glucose and galactose.

In this way, starch is changed into simple sugars.

Q.31: Describe the absorption of food in man?

Ans: ABSORPTION OF FOOD: Absorption of food takes place in the ileum, which is about 3.6 meters long. It receives much diluted food, called chyle. The inner surface of the ileum has numerous finger-like projections, called villi. The villi contain smooth muscles and are supplied by blood capillaries and lacteals (lymph vessels).

As a result of digestion, carbohydrates are changed into simple sugars, and proteins are converted into amino acids. These are absorbed by the mucous membrane of the villi. The absorption of food occurs through diffusion or active transport. The simple sugars and amino acids are carried to the liver by the hepatic portal vein. Fatty acids and glycerols are absorbed by the lacteals.

epithelial cells of villi. In these cells, they are changed into simple fats, called triglycerides. The simple fats are diffused into lymph vessels, lacteals.

Some glucose is added to the blood and supplied to different parts of the body. It is used as energy. The extra amount of glucose is converted into glycogen and stored in the liver. It is used again by the body at the time of need. The amino acids cannot stay in the liver. Their large amount is diffused into the blood and used by the body. The additional amount of amino acids is either changed into glucose or into a substance called urea, which is removed from the body by the excretory system.

The fatty acids and glycerols are diffused into the lymph vessels called lacteals, where they are changed into small droplets. The lymph vessels distribute them to all cells of the body, where assimilation takes place. The short-chain fatty acids and glycerine are water-soluble; they are absorbed by the blood capillaries. The extra fats are stored in the body and are used when the body requires energy.

Q.32: Describe the large intestine of man?

Ans: THE LARGE INTESTINE: The large intestine consists of three parts:

• Colon
• Caecum
• Rectum

Colon: It consists of three portions, an ascending, a transverse, and a descending portion. It reabsorbs water and salts from the undigested food and returns them to the circulatory system. They are again used by the body. If this reabsorption of water and salts does not occur, diarrhea causes excessive loss of water and salts, which can lead to dehydration, which is very dangerous to the body.

Caecum: The part of the colon which lies below the T-like junction with the small intestine is called the caecum. It contains bacteria that take part in the digestion of cellulose. The caecum has a small finger-like projection, called the appendix. Sometimes, some food substances are diffused into the appendix and cause disturbance and infection, called appendicitis. Due to extreme pain, the appendix is removed from the body.

Rectum: It is the last part of the large intestine. It opens to the outside by the anus. When the undigested food enters the colon, it reabsorbs water and salts from it. The remaining undigested food comes into the rectum and is then discharged out of the body through the anus.

Q.33: Describe the functions of the liver?

Ans: FUNCTIONS OF LIVER:

• It produces a secretion called bile. The bile combines with the food and neutralizes its acidity. It also acts as an antiseptic. It works upon fats and changes them into a milky substance, after which the enzymes take part in further digestion of fats.
• The liver performs a metabolic function. From the ileum, the digested food is transferred to the liver by the hepatic portal vein. The liver keeps the food substances in balance.
• The liver converts an extra amount of glucose into glycogen, which is stored in the body and can be used again.
• The liver changes the amino acids into carbohydrates by removing the nitrogen. These carbohydrates are used as energy, while the nitrogenous substances are removed from the body in the form of urine.
• The liver acts upon fatty acids and stores them in the form of fats. They are again used as nutrients by the body.
• The liver converts poisonous materials into non-poisonous and harmless substances.
• It stores vitamins.
• It produces special materials to help in the clotting of blood.
• It maintains the chemical composition of blood.
• It takes part in the removal of bile particles such as biliverdin, bilirubin, and other unnecessary substances.

Q.34: Describe the functions of the pancreas?

Ans: PANCREAS: The pancreas is an important gland. It is located behind the stomach. It is an exocrine gland because it secretes pancreatic juice, which contains important enzymes for the digestion of food. The pancreas also acts as an endocrine gland by secreting a hormone called insulin. This hormone converts extra sugar into glycogen. It also secretes another hormone, glucagon, which again converts glycogen into glucose for the production of energy.

Q.35: Name the disorders of the gastrovascular tract?

Ans: DISORDERS OF THE GASTRO-INTESTINAL TRACT: In the digestive cavity of human beings, many disorders or diseases can develop. These are as follows:

• Diarrhoea
• Dysentery
• Constipation
• Piles
• Dyspepsia
• Peptic ulcer
• Food poisoning

Q.36: Write a note on Diarrhoea?

Ans: DIARRHOEA: When the undigested matter is discharged rapidly through the large intestine, it is called loose motions or diarrhoea.

There are many reasons for diarrhoea:

• Enteritis: It is an infection caused by a virus or bacteria. By their activity, the mucosa lining of the intestine is affected, causing diarrhoea.
• Cholera: It is caused by bacteria. The inner layer of the intestine is damaged, due to which water and minerals (bicarbonate ions and sodium ions) are rapidly discharged out of the body, leading to dehydration. In severe cases, death may occur.
• Psychogenic Diarrhoea: Due to certain nervous tensions, a disorder occurs in the intestine, causing diarrhoea. It is called psychogenic diarrhoea.

Q.37: Write a note on Dysentery?

Ans: DYSENTERY: When there is inflammation in the large intestine and blood and mucosa are discharged along with undigested material, it is called dysentery. Dysentery is caused by the infection of bacteria or entamoeba. The internal lining of the large intestine is damaged, resulting in the secretion of blood and mucus.

Q.38: What is Constipation?

Ans: CONSTIPATION: When the undigested matter is passed very slowly through the intestine and includes hard and dry parts, it is called constipation. It is due to the accumulation of undigested food in the large intestine for a long time, where its water is reabsorbed by the wall of the colon, causing it to become dry and hard. Another reason for constipation is habitual in certain individuals. In such conditions, the inner part of the intestine develops a tendency to prevent normal and regular discharge of undigested matter.

Q.39: What is Piles (Haemorrhoids)?

Ans: PILES (HAEMORRHOIDS): When the veins close to the anus are dilated, it is called piles or haemorrhoids. These dilated veins sometimes start bleeding at the time of discharge of undigested matter, so the patient feels a great difficulty and pain. The haemorrhoids may be just outside the anus or inside the anal opening. The main cause of piles is constipation. When the pressure is exerted for the discharge of undigested matter, it results in the dilation of veins.

There are certain methods to avoid piles:

• Constipation should be controlled.
• Hygienic conditions should be maintained.
• Soft food or laxatives may be used.
• Fiber diet should be used, because fibers help for the easier passage of undigested matter.

Q.40: What is Dyspepsia?

Ans: DYSPEPSIA: Dyspepsia is the incomplete or imperfect digestion. It may be due to peptic ulcer, more acidity in the stomach, abnormal function of stomach or intestine. In dyspepsia, there may be heartburn, flatulence, nausea (feeling of vomiting), and vomiting. Sometimes dyspepsia occurs without any proper reason. It may be due to certain disturbances in the alimentary canal.

Q.41: What is Peptic ulcer?

Ans: PEPTIC ULCER: When the mucous layer of the alimentary canal is damaged by the digestive enzymes, it is called a peptic ulcer. The ulcer may occur in the stomach, in the upper region of the duodenum, or sometimes in the lower region of the oesophagus. In severe cases of ulcers, small holes and wounds are developed by the action of acid and pepsin enzyme. The reasons for ulcers may be hereditary character, psychogenic reasons, or anxiety, i.e., uneasiness and depression.

Q.42: What is Food poisoning?

Ans: FOOD POISONING: The indigestion of food containing toxic substances causes food poisoning. Its main reasons are bacteria, viruses, protozoa, or some allergy. In human beings, it is caused by the use of contaminated food or milk. Its main symptoms are diarrhoea, vomiting, and pain in the digestive tract. Food poisoning is caused by Salmonella bacteria, which are usually present in uncooked chicken or eggs. Food poisoning mostly appears within 48 hours after using the contaminated food.

Malnutrition:

• Defined as the deficiency or excess of nutrients in the body.
• Under-nutrition is common in poorer countries due to lack of access to food, while over-nutrition is more common in developed countries, leading to obesity and other health issues.

Overweight and Obesity:

• Excessive body fat due to over-eating and low energy expenditure.
• It may have genetic links and can lead to severe health consequences, even death.

Anorexia Nervosa:

• A condition characterized by a loss of appetite, often found in young women due to psychological reasons.
• Fear of gaining weight leads to food refusal, dangerous weight loss, and potential vomiting, requiring psychiatric treatment.

Bulimia Nervosa:

• Involves binge eating followed by attempts to avoid weight gain, often through vomiting.
• Linked to nutrient deficiency and prolonged treatment.

Endoparasites of Humans:

• Viruses: Cause diseases like influenza, polio, smallpox, rabies, measles, and yellow fever.
• Bacteria: Responsible for diseases like tuberculosis, typhoid, cholera, plaque, tetanus, and leprosy.

Fungi:

• Dermatophyte fungi cause skin-related diseases in humans, such as:
• Skin diseases
• Athlete’s foot
• Ringworm disease

Protozoans:

• Protozoans are responsible for various diseases, including:
• Malaria (caused by Plasmodium)
• Amoebic dysentery (Amoebiasis, caused by Entamoeba)
• Sleeping sickness (caused by Trypanosoma, leading to Trypanosomiasis)
• Leishmaniasis (caused by Leishmania)

Helminths (Parasitic Worms):

• Flatworms and roundworms cause several diseases in humans, such as:
  • Taeniasis (caused by Taenia saginata)
  • Hookworm disease (caused by Ancylostoma)
  • Intestinal worm disease in children (caused by roundworms, specifically Ascaris)
  • Filariasis (caused by Filaria)