Transportation

 Biology XI Notes - Transportation - Short Questions Answers

Q.1: Write a note on Diffusion?

Ans: Diffusion:

• The movement of ions or molecules from an area of higher concentration to an area of lower concentration.

Example:

• Dropping crystals of KMnO₄ or copper sulfate in water causes them to dissolve and spread, coloring the water.

Factors Affecting Diffusion:

• Size and nature of molecules
• Temperature
• Concentration gradient

Importance of Diffusion:

• Assists in water absorption from soil.
• Aids in water movement between plant cells.
• Plays a role in transpiration, photosynthesis, and respiration.

Q.2: What is facilitated diffusion?

Ans: Facilitated Diffusion:

• Involves the movement of ions or molecules with the help of carrier proteins in the cell membrane.
• Carrier proteins create water-filled pores for transporting water-soluble substances across the membrane.
• This process does not require energy.

Q.3: Write a note on Osmosis?

Ans: Osmosis:

• Defined as the movement of water from an area of higher concentration to an area of lower concentration through a semi-permeable membrane.
• Discovered by Nullet in 1746.

Experiment:

• In a U-shaped tube with a semi-permeable membrane, one side (A) contains pure water, and the other side (B) has a 20% sugar solution.
• Water moves from A to B faster due to concentration differences, causing the level in side B to rise, demonstrating osmosis.

Importance of Osmosis in Plants:

• Essential for water absorption through root hairs.
• Facilitates water movement between cells.
• Helps in mineral salt absorption and transport of food.
• Maintains turgidity (strength) in plant tissues, helping them retain shape.
• Controls the opening of stomata by maintaining guard cell turgidity.

Q.4: What is Active Transport?

Ans: Active Transport:

• Opposite to diffusion, active transport moves molecules or ions across the cell membrane from lower to higher concentration using the cell's metabolic energy (ATP).
• Cells with active transport processes contain numerous mitochondria and high ATP levels.

Examples:

• Sodium and Potassium Transport in Nerve Cells: Potassium (K) concentration is higher inside the cell, while sodium (Na) is higher outside. Nerve cells pump Na out and K in through active transport.
• Glucose Transport in Intestines: Glucose is transported from low concentration in the intestine to high concentration in the blood.
• Food Transport in Phloem: In plants, food is transported from mesophyll cells (low sucrose concentration) to phloem (high sucrose concentration).

Importance of Active Transport:

• Essential for nutrient intake and waste expulsion against the concentration gradient.

Q.5: Write a note on Imbibitions?

Ans: Imbibitions:

• The absorption of water by hydrophilic substances, causing them to swell and increase in volume.
• Common in materials like proteins, starch, and cellulose, and can be observed in phenomena such as swollen wooden doors during rainy seasons.
• Imbibition generates heat and increases temperature when water is absorbed, and is affected by temperature.

Importance of Imbibition:

• Cell walls and protoplasm absorb water through imbibition, essential for plant physiological processes.

Q.6: Write a note on Water Potential?

Ans: Water Potential:

• Water molecules possess kinetic energy; the difference in energy between pure water and water in a solution is called water potential.
• Represented by the Greek letter Ψ (Psi), measured in bars. Pure water has a potential of zero, while solutions have negative water potential.

Uses of Water Potential:

• Controls water flow direction across cell membranes.
• Important for water transport by osmosis and measuring plant water status.

Q.7: Write a note on Osmotic Potential (Solute Potential)?

Ans: Osmotic Potential:

• Pressure exerted to prevent solvent passage into a solution separated from pure water by a membrane.
• Always negative, with lower potential indicating higher solute concentration.

Q.8: Describe the water relations of plant cells?

Ans: Water Relations of Plant Cells:

• Solute potential (Ψs) refers to the concentration of solute particles in cell sap, which lowers the cell's water potential. Higher solute concentration results in more negative water potential.

• When a cell is placed in pure water or a solution with higher water potential, water enters the cell via osmosis, creating pressure and making the cell turgid. This increases the pressure potential. The total water potential formula is:

• Water Potential (Ψ) = Solute Potential (Ψs) + Pressure Potential (Ψp)
• In a fully turgid cell, Ψ = 0, as Ψp and Ψs are equal and opposite.

Q.9: What are plasmolysis and deplasmolysis?

Ans: Plasmolysis:

• Plasmolysis occurs when a cell loses water due to exosmosis in a hypertonic solution, causing the protoplasm to shrink and form an oval shape at the cell's center.
• Incipient Plasmolysis: When protoplasm begins to separate from the cell wall.
• Full Plasmolysis: Complete detachment of protoplasm from the cell wall.

Deplasmolysis:

• The reverse process, occurring in a hypotonic solution where water enters the cell, restoring the protoplasm to its original position.

Q.10: Describe the water and mineral uptake by roots?

Ans: Water and Minerals Uptake by Roots:

• Water and salts are absorbed from the soil through three pathways:
• Cell-to-Cell Pathway: Water moves from root hairs into epidermal cells and then cell to cell until it reaches the xylem.
• Symplast Pathway: Water moves through the cytoplasm and plasmodesmata connecting root cells.
• Apoplast Pathway: Water flows through the cell walls and intercellular spaces, facilitated by hydrophilic cell walls.

• Apoplast Pathway:

• Water flows freely through the hydrophilic cell walls of epidermal and cortical cells. The Casparian strip in endodermis acts as a checkpoint, preventing entry into the xylem via apoplast

Q.11: What is the Ascent of Sap and its pathway?

Ans: Ascent of Sap:

• The upward movement of water from roots to leaves, countering gravity, is called ascent of sap.
• Path of Ascent of Sap: Conducted by xylem tissue, specifically tracheae (vessels) and tracheids.

Q.12: What is the Root Pressure Theory of Ascent of Sap?

Ans: Root Pressure Theory:

• Root pressure is a force generated by the alternate expansion and contraction of root cortical cells, creating a pumping effect for water movement.

Root Pressure Theory (continued):

• Objections on Root Pressure Theory:
  • It does not fully explain the ascent of sap as it only raises water a few meters.
  • Tall trees often lack root pressure, yet sap still ascends.

Q.13: What is Guttation?

Ans: Guttation:

• Small droplets of water appear on the tips of grass leaves in the early morning. This process, called guttation, occurs from specialized structures called hydathodes at the leaf tips or margins. It was termed by Burgerstein.

Q.14: Describe the Dixon Theory about Ascent of Sap?

Ans: Transpiration Pull and Adhesion-Cohesion Theory (Dixon Theory):

• This theory attributes the ascent of sap to:
• Transpiration Pull: Water loss from mesophyll cells reduces water content, creating tension that pulls water up from the roots.
• Adhesion Force: Attraction between water molecules and xylem walls.
• Cohesion Force: Attraction among water molecules, forming a continuous column of water from roots to leaves.

Dixon Theory (continued):

• Transpiration pull, adhesion, and cohesion forces work together to move water up the plant, even to great heights. This process is considered solar-powered, relying on sunlight rather than metabolic energy.

Q.15: What is Transpiration? What are the Types of Transpiration?

Ans: Transpiration:

• The loss of water vapor from aerial parts of plants into the atmosphere.

Types of Transpiration:

• Cuticular Transpiration: Water loss through the cuticle on the epidermis.
• Lenticular Transpiration: Water loss through lenticels in woody plants.
• Stomatal Transpiration: Major form, occurring through stomata on leaves.

Lenticular Transpiration:

• Lenticels are natural openings in the epidermis that allow gas exchange due to secondary growth. Water loss through these lenticels is termed lenticular transpiration.

Stomatal Transpiration:

• Stomata in the leaf epidermis facilitate maximum water evaporation due to their minimal resistance.

Q.16: Describe the mechanism of Transpiration?

Ans: Mechanism of Transpiration:

• Transpiration involves water evaporation from mesophyll cell walls into intercellular spaces, followed by diffusion into the atmosphere.
• Relative Humidity: High relative humidity decreases water loss, as the dry air promotes higher diffusion pressure, aiding in water vapor diffusion through stomata from high to low vapor pressure.

Q.17: Describe the structure and opening of stomata?

Ans: Structure of Stomata:

• Stomata are tiny pores in the epidermis with kidney-shaped guard cells that regulate opening and closing based on their turgidity. When guard cells become flaccid, stomata close, and when turgid, stomata open.

Factors Influencing Stomatal Opening and Closing:

• Light: Stomata open in light due to the formation of sugars, which increases osmotic pressure in guard cells, leading to water intake by endosmosis. In darkness, carbohydrates are consumed, lowering osmotic pressure, causing guard cells to lose water and close stomata.
• Potassium (K⁺) Ions: In some plants, guard cell turgidity is regulated by K⁺ ions. Accumulation of K⁺ in guard cells during the day lowers osmotic potential, drawing water in and opening stomata. Lower K⁺ concentration leads to closing.

Q.18: What are the factors which influence the opening and closing of stomata?

Ans: FACTORS INFLUENCE THE OPENING AND CLOSING OF STOMATA:
There are two factors which influence the opening and closing of stomata.

• Light
• Concentration of K⁺ ions

Light:
Light plays an important role in the opening and closing of stomata. The stomata open in light and close in the night. The guard cells contain Chlorophyll, they manufacture carbohydrates during sunlight. By the formation of sugars the osmotic pressure of guard cells increases, so water enters the guard cells due to endosmosis from the neighboring cells of epidermis. It increases the turgidity of guard cells which open stomata.

In the darkness, carbohydrates are consumed in the guard cells or these are transferred into other cells. It decreases the osmotic pressure of guard cells; due to this process exosmosis takes place, guard cells become flaccid and stomata are closed.

Concentration Of K⁺ Ions:
In some plants the turgidity of guard cells is regulated by K⁺ ion concentration. During the day time the guard cells get K⁺ ions from neighboring cells, due to their accumulation the osmotic potential of guard cells is lowered and they get water from epidermal cells, so guard cells become turgid and stomata are opened. Less concentration of K⁺ ions results in the closing of stomata.

Q.19: What are the Factors of Transpiration?

Ans: Factors Affecting Transpiration:

• Light: Controls stomatal opening, indirectly affecting transpiration rate.
• Temperature: Increases leaf temperature, raising transpiration.
• Humidity: Lower humidity increases water loss.
• Wind: Promotes transpiration by moving water vapor away.
• Soil Water: Availability of soil water impacts transpiration rate.

Factors Affecting Transpiration:

• Temperature: Higher temperatures increase the rate of transpiration.
• Humidity: Lower humidity results in increased transpiration, while higher humidity reduces it.
• Wind Velocity: Wind replaces humid air with dry air, increasing transpiration.
• Soil Water: More water in soil leads to faster transpiration.

Q.20: What is the Importance of Transpiration?

Ans: Importance of Transpiration:

• Advantages:
  • Links water absorption to transpiration.
  • Removes excess water from the plant, preventing cell rupture.
  • Facilitates mineral salt intake by roots.
  • Helps regulate plant temperature by cooling through evaporation.
• Disadvantages:
• Requires significant energy for water evaporation.
• Excessive water loss can lead to plant stress or death.
• Some plants adapt by losing leaves or modifying them to reduce transpiration.

Q.21: Describe Briefly the Translocation of Food?

Ans: Translocation:

• The movement of materials within the plant, mainly from sources (leaves) to sinks (storage areas), via the phloem.

Path of Translocation:

• Known as source-to-sink movement.

Mechanism of Phloem Translocation:

• Pressure Flow or Mass Flow Hypothesis (Münch Theory): Proposed in 1930, this theory explains translocation as a flow of solution due to an osmotic pressure gradient. Water moves from high turgor pressure areas (source) to low turgor pressure areas (sink) through plasmodesmata in the phloem.

Q.22: Describe Transportation in Hydra and Planaria?

Ans: Transportation in Hydra:

• Hydra, a diploblastic animal, has two body layers: ectoderm (outer) and endoderm (inner). Oxygen enters through the body surface via diffusion and is distributed to all parts. Food is digested in the body cavity and transported by diffusion.

Transportation in Planaria:

• In Planaria, both oxygen and food transport occurs via diffusion. Food is moved to various parts of the body through branches of the intestine, facilitated by muscle contractions.

Q.23: What are Open and Closed Types of Circulatory System?

Ans: Open Type Circulatory System:

• In open systems, blood does not flow within vessels but directly in the body cavity (haemocoel), where it contacts tissues. This system, common in arthropods and mollusks, has low pressure and the blood is called haemolymph.

Closed Type Circulatory System:

• Blood flows through vessels, distributing it to organs under higher pressure, which allows better control and is found in more active animals.

Q.24: What are the Single Circuit and Double Circuit Plans?

Ans: Single Circuit Plan (e.g., in Fish):

• Fish have a single circuit where blood flows in one direction. Their two-chambered heart (one atrium, one ventricle) pumps deoxygenated blood to the gills for oxygenation, and the oxygenated blood flows to the body.

Double Circuit Plan (e.g., in Amphibians, Reptiles, Birds, Mammals):

• Double circulation includes two circuits: systemic (to the body) and pulmonary (to the lungs). This system allows oxygenated blood to be separated from deoxygenated blood, enhancing efficiency.

• Incomplete Double Circulation: In amphibians and reptiles, the three-chambered heart partially mixes oxygenated and deoxygenated blood in a single ventricle.

• Complete Double Circulation: In birds and mammals, the four-chambered heart completely separates oxygenated and deoxygenated blood.

Q.25: What is the Evolution of Heart in Vertebrates?

Ans: Evolution of Heart in Vertebrates:

• The heart has undergone significant changes from fishes to mammals.

Heart of Fishes:

• Fish have a two-chambered, S-shaped heart with one atrium and one ventricle. Deoxygenated blood flows from the body into the atrium, then into the ventricle, which pumps it to the gills for oxygenation. The heart itself does not receive oxygenated blood.

Heart of Amphibians:

• Amphibians have a three-chambered heart with two atria and one ventricle. The left atrium receives oxygenated blood from the lungs, and the right atrium receives deoxygenated blood from the body. These blood types partially mix in the single ventricle before being pumped to the body.

Heart of Reptiles:

• Reptiles have a partially divided ventricle, with two atria. In most reptiles, oxygenated and deoxygenated blood partially mix in the ventricle. However, in crocodiles, the ventricle is fully divided, allowing complete separation of blood types, with oxygenated blood being supplied to body organs.

Heart of Birds and Mammals:

• Birds and mammals have a four-chambered heart with two atria and two ventricles, allowing complete separation of oxygenated and deoxygenated blood, ensuring that only oxygenated blood is supplied to all parts of the body.

Q.26: Write a Note on Blood?

Ans: Blood:

• Blood is a red-colored fluid that functions as connective tissue in the body of humans and other animals. It consists of two main components:
  • Plasma
  • Blood Corpuscles

Plasma:

• The liquid part of blood, constituting 55% of its volume. It is non-living, with 90% water and 10% dissolved substances (inorganic salts, blood proteins, glucose, amino acids, triglycerides, urea, hormones, enzymes, and autotoxins). Plasma also contains antibodies for disease immunity.

Blood Corpuscles:

• Comprising 40% of blood, corpuscles are of two types:
• Red Blood Corpuscles (RBCs):
• Also called erythrocytes, these are circular, oval-shaped, biconcave, and lack a nucleus. They contain hemoglobin, an iron-based pigment that absorbs oxygen and transports it to all body cells, forming bright red oxy-hemoglobin.

White Blood Corpuscles (WBCs):

• Also called leucocytes, they are colorless, irregularly shaped cells with a nucleus and are generally larger than RBCs but fewer in number. Produced in bone marrow, spleen, and lymph vessels, they have a short life span of 20-30 hours and are classified into:
  • Granulocytes: Contain fine granules in their cytoplasm, including neutrophils, eosinophils, and basophils.
  • Agranulocytes: Have clear cytoplasm without granules, such as lymphocytes and monocytes, which produce antitoxins and absorb bacteria.

Function of White Blood Corpuscles:

• WBCs destroy bacteria and protect the body. Neutrophils and monocytes are phagocytic, engulfing bacteria and foreign particles, while lymphocytes produce antitoxins.

Blood Platelets:

• Small, oval, colorless, biconvex, non-nucleated cells. They are fragments of bone marrow cells and assist in blood clotting.

Q.27: What are the Functions of Blood?

Ans: Functions of Blood:

• Functions of Plasma:
• Transport of Nutrition: Blood transports food, water, and other nutrients from the alimentary canal to various body parts for storage, oxidation, and assimilation.
• Transport of Waste Substances: Blood carries waste from body tissues to excretory organs for removal.

Functions of Blood Components:

• Transport of Metabolic By-Products: Blood transports by-products from metabolism to other parts of the body.
• Transport of Hormones: Blood transfers hormones from endocrine glands to target areas.
• Distribution of Body Heat: Circulates heat throughout the body to maintain a constant temperature.

Functions of RBCs:

• Transport of O₂ and CO₂: Carries oxygen from lungs to the body and CO₂ back to the lungs.

Functions of WBCs:

• Defense Against Diseases: Destroys germs, producing antibodies and antitoxins.

Functions of Platelets:

• Assists in blood clotting after injuries.

Q.28: Describe the Heart of Man Briefly:

Ans: Heart of Man:

• The heart consists of four chambers:

  • Right and Left Atria (Auricles)
  • Right and Left Ventricles

• The atria are separated by the inter-atrial septum, where deoxygenated blood enters the right atrium, and oxygenated blood from the lungs enters the left atrium.

• Ventricles: Form the posterior part of the heart, separated by the inter-ventricular septum. Right atrium opens into the right ventricle, guarded by a tricuspid valve, preventing backward flow. The left atrium opens into the left ventricle, guarded by a bicuspid valve.

Q.29: Describe the Cardiac Cycle (Action of Heart):

Ans: Cardiac Cycle (Action of Heart):

• The heart operates systematically, with myogenic muscles (self-contracting). The cycle of one heartbeat involves:
• Systole (contraction) and Diastole (relaxation).
• During diastole, the atria receive blood (deoxygenated in the right, oxygenated in the left).
• Atrial Systole transfers blood into ventricles.
• Ventricular Systole then sends blood to the lungs (right ventricle) and body (left ventricle).

Q.30: Write a note on Heart beat?

Ans:
Heart BEATS:
When chambers of the heart contract in a systematic and regular manner, it is called a heartbeat. A normal heart shows 72 beats per minute. Heartbeats are also known as heart sounds, which can be listened to easily. Heartbeat begins before birth and continues until death.

During a heartbeat, when the ventricles contract (systole), blood is pushed against the closed atrioventricular (AV) valves, producing the first sound ("LUB"). Following systole, the ventricles relax (diastole), and high pressure in the aorta forces some blood back toward the ventricles, closing the aortic valves, producing the second sound ("DUP"). Each heartbeat cycle includes one systole and one diastole, taking about 0.8 seconds. When there is a defect in one or more valves, it may cause a "heart murmur," detectable as a hissing sound.

Q.31: What is Sino-atrial node (S-A Node)?

Ans:
SINO-ATRIAL NODE (S-A NODE):
The sino-atrial node, located at the top of the right atrium near the superior vena cava, generates electrical impulses and initiates heart contractions, earning it the nickname "pacemaker." It comprises cardiac muscle fibers with few nerve endings from the autonomic nervous system.

Q.32: What is Atrio-ventricular node (A-V Node)?

Ans:
ATRIO-VENTRICULAR NODE (A-V NODE):
Located below the S-A node in the right atrium, the A-V node transfers excitation to all parts of the ventricles through muscle fiber bundles. It includes fibers of the bundle of His and Purkinje fibers, which propagate impulses throughout the ventricular walls. A delay of 0.15 seconds occurs between the S-A and A-V nodes to complete atrial systole before ventricular systole.

Q.33: Describe different blood diseases of man?

Ans:
DISEASES OF BLOOD:

• Leukaemia:
  A blood cancer caused by the uncontrolled production of white blood cells (WBCs), leading to their increase. Bone marrow cells spread through the body, disrupting normal WBC formation. Symptoms include frequent bleeding, and treatment options include bone marrow transplantation, although this is expensive.

• Thalassemia:
  A genetic disorder causing reduced hemoglobin production. In severe cases, patients need regular blood replacement. Children with thalassemia may have an enlarged spleen and kidneys.

Q.34: What is artificial pacemaker?

Ans:
ARTIFICIAL PACEMAKER:
When the natural pacemaker (S-A node) fails, an artificial pacemaker, which supplies electrical impulses to maintain a regular heartbeat, is implanted under the chest skin, powered by battery or electrical wires.

Q.35: What are blue babies?

Ans:
BLUE BABIES:
A condition in newborns characterized by blue skin (cyanosis) due to oxygenated and deoxygenated blood mixing, often caused by defects in the heart's septum.

Q.36: Describe different kinds of blood vessels?

Ans:
BLOOD VESSELS:
The vessels through which blood flows are called blood vessels. These vessels carry blood from the heart to body organs and bring back the blood from body parts to the heart.

The blood vessels are of two types:

• Arteries
• Veins

ARTERIES:
Arteries are the blood vessels which carry the blood from the heart to different parts of the body. Their walls are composed of three layers.

• Tunica externa: outer layer
• Tunica media: middle layer
• Tunica interna: inner layer

Outer Layer:
It is composed of connective tissues which are hard and fibrous, called collagen fibers. They can resist the internal blood pressure.

Middle Layer:
It consists of smooth muscles which are elastic. By their contraction and relaxation, their cavity (lumen) can be decreased or increased. They also control the amount of blood. The cavity of arteries is smaller than veins.

Inner Layer:
It is made up of an endothelial layer. The smallest arteries are called arterioles which control the flow of blood into the capillaries. The arterioles contain valves (sphincters) at their capillary ends, which control the blood flow into capillaries. The arteries carry oxygenated blood from the heart to different parts of the body, but in pulmonary arteries, deoxygenated blood is present, which is carried to the lungs.

VEINS:
The blood vessels which carry the blood from various parts of the body back to the heart are called veins. They are thin-walled vessels. Their walls are composed of three layers.

Outer Layer:
It is made up of hard and fibrous connective tissues, known as collagen fibers.

Middle Layer:
It has smooth elastic muscles.

Inner Layer:
It consists of endothelial layer.

The inner cavity (lumen) of veins is much larger than arteries. The veins have valves which prevent the backward flow of blood. Due to the larger diameter of veins, there is less resistance in the flow of blood, and it can flow in large volume. The smallest veins are called venules which obtain blood from capillaries. The largest vein is termed as caval vein which enters the heart. The veins contain deoxygenated blood except pulmonary veins, which bring blood from lungs to the heart.

Capillaries:
In the transport system, the function of blood circulation is to supply the important materials from one part to another. In this way, a close contact is necessary between circulation and tissues. This contact is in the form of blood capillaries. These are very fine blood vessels which are thin-walled and narrower than arteries and veins. Their diameter is about 7-10.

The wall of capillaries consists of a single layer, called endothelium, through which the diffusion of substances occurs easily. The capillaries are connected to the cells and tissues, so the exchange of important materials between tissue fluid and blood of capillaries takes place by diffusion or active transport. From the blood, $O_2$ is diffused out into body tissues and $CO_2$ of tissues is diffused into the blood. Blood capillaries also help to filter the harmful nitrogenous substances into the excretory organs for their excretion.

Q.37: Write a note on blood pressure?

Ans: BLOOD PRESSURE:
The hydrostatic force exerted by the blood against the walls of blood vessels is called blood pressure. This pressure is produced by the ventricle systole i.e. contraction of ventricles. It helps in the flow of blood from the heart to all parts of the body. When blood flows in the arteries, their walls are stretched due to elasticity, it is called pulse. This pulsation can be felt easily.

Blood pressure is measured in millimeters of Hg (Mercury). Mercury manometer is widely used throughout the world, called sphygmomanometer. The blood pressure is determined by cardiac output and by the diameter of arterioles. When constriction takes place in the walls of arterioles, it is called vasoconstriction. It rises the blood pressure and when walls of arterioles are dilated, it is called vasodilatation, it falls the blood pressure. The smooth muscles of arterioles help in constriction and relation of arterioles and these muscles are controlled by nerve impulses and hormones.

In a normal healthy person the blood pressure during systole is about 120mm high, visible in the glass tube of monometer and during diastole of ventricles is about 80mm high. It is expressed as Blood Pressure (B.P) of 120/80. The difference between systolic and diastolic pressure is called pulse pressure.

Blood Flow:
The flow of blood is very fast in larger arteries. It is highest in aorta, and then gradually reduces in arteries and much slower in capillaries. The total diameter of capillaries is greater than arteries, so the blood flows slowly in capillaries. It helps in the exchange of materials between blood and interstitial tissues.

• Drainage System:
  The lymphatic vessels take part in the returning of water and plasma proteins back to the bloodstream, which have leaked away from blood. Otherwise, death may occur in 24 hours.

• Defence Of The Body:
  The lymphatic system helps to maintain body resistance. The microorganisms, foreign bodies, and broken cells are removed by macrophages found in the lymphatic nodes.

• Absorption And Delivery Of Fats:
  The lacteals of villi absorb digested fats, which are changed into droplets. After that, these fats are returned back to the blood.

• Bathing Of Tissues:
  The lymphatic vessels bathe the tissues and keep them moist.

(Image of the Lymphatic System of Man)

Q.38: Describe Lymphatic System in the body of man?

Ans: LYMPHATIC SYSTEM:
Lymph is a tissue fluid, passes out from the walls of capillaries into the space surrounding the cells. It is actually obtained from the blood-plasma. It is colorless and without proteins. It is involved in osmotic changes between cell-protoplasm and blood.

The lymph passes through vessels, called lymphatic vessels. They form a separate network and constitute the lymphatic system. These vessels carry the fluid to the heart and blood. These vessels also contain valves due to which the backward flow is prevented. In addition to lymphatic vessels and lymph, this system also consists of lymph nodes, spleen, thymus, tonsils and some patches of tissues in appendix and small intestine.

Lymph Capillaries:
The lymph vessels produce lymph capillaries, which form a network in every organ except the nervous system. The lymph capillaries unite together to form larger lymphatic vessels; these are connected with subclavia vein.

Lacteals:
Within the villi of intestine, the lymph vessels are called Lacteals. The lymph circulates through the lymph vessels by the contraction of skeletal muscles in one direction i.e. to the heart. These vessels form collecting ducts, which are connected with veins in the lower neck.

Lymphatic Nodes:
At certain points, the lymph vessels contain special masses of connective tissues, called lymph nodes. In these nodes, lymphocytes are present. Lymphocytes are the cells of the immune system. Through lymph nodes, lymph is filtered. The lymph nodes are of different size, from microscopic size to one inch. Many lymphatic vessels carry the lymph into the lymphatic node, but from this node, a single large vessel comes out. When lymph is filtered through the lymph nodes, the lymphocytes and macrophages present here neutralize it and kill the microorganisms.

Functions Of Lymphatic System:
The lymphatic system performs the following functions:

Q.39: Write a note on Edema?

Ans: EDEMA:
Edema is an "Abnormal condition" caused by lymphatic system when it is not functioning normally. When tissue fluid is not returning into the blood by lymphatic system and it is accumulated in the body tissues and it causes swelling, it is called edema. The excess fluid may be in the cells or outside the cells. Edema results in high blood pressure, kidney failure and heart failure etc.

Causes Of Edema:

• Protein deficiency causes edema. When proteins are not used in food, the body consumes its own blood proteins, so blood cannot absorb tissue fluid, it is accumulated in the body tissues. It causes edema.
• Lymphatic system becomes fail to return fluid due to any obstruction, it results edema.
• When renal system retains salts and water, it causes edema.
• Filariasis is also a cause of edema. It is a disease due to nematodes.
• Due to burns or allergic reactions permeability of capillaries is increased, It causes edema.

Q.40: Name the various cardiovascular diseases?

Ans: CARDIOVASCULAR DISORDERS (CVD):
Diseases of heart, blood vessels and blood circulation are known as cardiovascular disorders (CVD). Some of these disorders are as follows:

• Atherosclerosis
• Hypertension
• Thrombus formation
• Coronary thrombosis
• Myocardial infarction (Heart attack)
• Stroke
• Haemorrhage

Q.41: Write a note on Atherosclerosis?

Ans: ATHEROSCLEROSIS:
Atherosclerosis is the disorder of blood vessels, in which arteries become harden. The inner walls of arteries become narrow, lose their elasticity, due to the formation of raised patches of fats in their inner lining, called athermanous plaques. In such condition flow of blood is disturbed. These raised patches consist of low density lipoprotein (LDL) i.e. cholesterol and proteins, fibrous tissues, decaying muscle cells, clusters of blood platelets or calcium.

Causes:
The causes of atherosclerosis are:

• Smoking

Q.42: What is Hypertension?

Ans: HYPERTENSION:
When the blood pressure is higher than the normal blood pressure, it is called hypertension and the person is called hypertensive. When under resting condition the mean arterial pressure is greater than 110 mmHg, it is considered as high blood pressure and hypertension. It takes place when diastolic blood pressure is greater than 90mmHg and systolic blood pressure is greater than 135-140 mmHg.

Causes:
The causes of high blood pressure hypertension are:

• Use of higher amount of salts in food
• Hereditary factor
• Smoking
• Obesity (Fatness)
• Disorders of kidneys or adrenal glands

Effects:

• Continuous high blood pressure damages the lining of blood vessels, so heart muscles become weak, and its pumping function is affected.
• It causes stroke or heart attack, even no symptom earlier, so it is called silent killer.
• It promotes atherosclerosis.
• Heart may be enlarged.

Q.43: What Is Thrombus formation?

Ans: THROMBUS FORMATION:
The clotting of blood in the blood vessels is called thrombus formation. The main cause of thrombus is atherosclerotic plaques i.e. patches of fats in the blood vessels. These patches damage the inner layer endothelium of blood vessels, then in the damaged regions platelets are deposited, it results blood clotting. By the continuous process the inner cavity lumen of arteries becomes narrow or blocked. it reduces or stops the blood supply.

Q.44: What is Coronary Thrombosis?

Ans: CORONARY THROMBOSIS:
When thrombus i.e. blood clot occurs in coronary arteries (arteries which supply blood to heart muscles) and these arteries are narrowed or blocked, it is called coronary thrombosis. Due to thrombosis O₂ is not supplied to any part of heart, so it becomes inactive or dead. It causes coronary heart disease. By thrombosis heart attack may occur.

Q.45: Write a note on myocardial infarction (Heart attack)?

Ans: MYOCARDIAL INFARCTION (HEART ATTACK):
When the blood vessels of heart are blocked either by thrombus (clotting of blood) or embolus (clotted blood comes into serum), it causes death of the part of heart and continuous chest pain, it is called myocardial infarction, commonly it is known as heart attack.

When the coronary arteries of heart are blocked and they do not supply O₂ to particular organs, that heart muscle does not work properly and gradually become dead. Such muscles of heart are called infracted and the mechanism is known as myocardial infarction. When a small part of heart is damaged, the person may recover from heart attack, but when large part is damaged, it may cause death of person.

Precautions:

• Persons should not use fatty food, rich with cholesterol.
• Body should not be over-weight.
• Blood pressure should be maintained normal by exercise.
• Smoking should be avoided.

Q.46: Write a note on stroke?

Ans: STROKE:
When any blood vessel in the brain is blocked by blood clotting (thrombus) or embolus (transfer of clotted blood in serum) and there is no proper supply of blood to the brain or sometime there is leakage of blood from blood vessels, it causes a stroke. As a result of stroke the parts of the body are paralyzed which are controlled by damaged part. The sensation, movement or function of these parts is badly affected. When any one cerebral hemisphere is damaged, it causes weakness or paralysis of one side of the body, it is called hemiplegia.

Q.47: What is Hemorrhage?

Ans: HEMORRHAGE:
When there is leakage or discharge of blood from blood vessels, it is called hemorrhage. When any blood vessel in the brain is ruptured, it causes brain hemorrhage. It is very serious and dangerous. The main cause of brain hemorrhage is hypertension. The massive accumulation of blood within the tissue is called hematoma.

Q.48: What is immune system? What are the types of immune system?

Ans: THE IMMUNE SYSTEM:
The ability of a living organism to resist the infection by parasitic microorganisms, their toxins, foreign cells or abnormal cells of the body is called immunity, and the system which shows response to the infection is known as immune system. Immunity is an essential requirement for survival, since the body of man and animals is attacked by viruses, bacteria, fungi, and parasitic animals.

Types Of Immune System:
There are two types of immune system.

• Innate immune system
• Adaptive immune system

Q.49: Describe the innate immune system?

Ans: INNATE IMMUNE SYSTEM (NON-SPECIFIC IMMUNE SYSTEM)
It is the natural immune system and non-specific, i.e., this immunity prevents the infection of all microorganisms. This system is responsible to control the activity of microorganisms. In innate immune system there are two systems of defense.

• Physical body organs (First line of defence)
• Internal body system (Second line of defence)

Physical Body Organs: (First Line Of Defence)

Skin and mucous membrane are very important organs, which act as the first line of defence i.e., prevent the attack of microorganisms. Skin does not allow the entry of infectious agents. Mucous membrane is present along the lining of digestive, respiratory, and urogenital tracts. Through the mucous membrane, microorganisms can enter the body, but mucus and certain secretions destroy these microorganisms.

Internal Body System: (Second Line Of Defence)
When due to certain reasons microorganisms enter the body, there is another line of defence for the protection of the body from microorganisms. These are:

• Phagocytes
• Antimicrobial proteins
• Inflammatory response

Phagocytes:
These are a type of W.B.C. These cells destroy microorganisms and other particles.

Antimicrobial Proteins:
In the body, certain proteins are produced which destroy infectious microorganisms; these are called antimicrobial proteins.

Inflammatory Response:
It is the condition of fire in any certain part of the body due to any injury or infection of microorganisms. In such a condition, the infected part becomes swollen, reddish, and feels heat and pain.

By infection and inflammation, fever is caused in warm-blooded animals. It is due to the release of a substance by certain W.B.C.s, called pyrogen. It increases the body temperature. Moderate fever is useful to the body because it prevents the growth of microorganisms.

Q.50: Describe the adaptive immune system?

Ans: ADAPTIVE IMMUNE SYSTEM: (SPECIFIC IMMUNE SYSTEM)
It is the specific immune response against specific microorganisms, which is developed in the body specifically against many organisms, tumor cells, transplanted tissues, and toxins. It is considered as third line defence and works with the second line defence system. It is also called specific immune response system. In adaptive immune system, special types of lymphocytes play an important role, called B-cells and T-cells. These cells are produced in bone marrow or thymus.

In adaptive immune system, two types of immunity are developed.

• Humoral immunity: (HI)
  Immunity develops due to B-cells against bacteria.
• Cell mediated Immunity: (CMI)

Q.51: What are the hormones of immune system?

Ans: HORMONES OF IMMUNE SYSTEM (CYTOKINES OR LYMPHOKINES):
The hormones of the immune system are called cytokines or lymphokines. These are protein molecules. These hormones regulate the immune responses. There are many hormones, such as interleukins (IL), interferons. Interferon's are used in response to viral infection and other stimuli. They control the growth of viruses and increase the activity of natural killer cells (NK cells).

Q.52: Describe primary and secondary immune responses?

Ans: PRIMARY & SECONDARY IMMUNE RESPONSES:
When there is the first entry of an antigen to form effect or cells, there is a response in the immunity system, it is called primary immune response. From the time of infection to the formation of maximum effect or cells 5 to 10 days are required. When there is a second infection by the same pathogen, the response takes place more quickly and rapidly by the immune system, it is called secondary immune response. The time for this response is 3 to 5 days. This quicker response is due to immunological memory of the immune system. During the primary immune response, some memory cells are formed. These cells play a role in the quicker secondary response, and also help in lifelong protection against some dangerous diseases like chicken pox.

Q.53: Describe active and passive immunity?

Ans: ACTIVE & PASSIVE IMMUNITY:
According to the function, there are two types of immunity:

• Active immunity
• Passive immunity

Active Immunity:
The immunity develops by the response of the own immune system of the body, it is called active immunity. It is of two types:

1. Natural Active Immunity:
   When the immune system is developed in the body by its own response in a natural way, it is called natural active immunity.
2. Artificial Active Immunity:
   Active immunity can be developed artificially by vaccination; it is called artificial active immunity. By vaccination, long-life protection is provided, for example, chicken pox.

Passive Immunity:
When antibodies are introduced into the body from another person or an animal, it is called passive immunity. This immunity may be natural or artificial.

• Natural Passive Immunity:
  In natural passive immunity, the antibodies are transferred from the body of a person to another person of the same species. For example, antibodies from the mother are transferred into the body of a newborn baby through the placenta.

• Artificial Passive Immunity:
  In artificial passive immunity, antibodies are obtained from the body of animals or human beings who are already immune to that disease, and these are transferred into another person. For example, antibodies for rabies are obtained from already vaccinated persons and then introduced into the body of an affected person. It is a rapid process of immunity, but it is also short-lived.

Q.54: What is immunization?

Ans: IMMUNIZATION:
Immunization is the resistance against diseases, carried out by vaccination. By effective vaccination, many dangerous diseases have been controlled properly throughout the world, such as diphtheria, measles, polio, smallpox, and hepatitis. Immunization was first introduced by the scientist Edward Jenner.

Gaseous Exchange

 Gaseous Exchange - Short Questions Answers Biology - XI

Chapter # 13 Short Questions Answers

Section IV - Functional Biology

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BOTANY PART

Q.1: Describe Photorespiration in Plants?

Ans: Photorespiration in Plants:

• When plants use oxygen and release CO₂ during day time, in the presence of sunlight, it is called photorespiration.
• Photorespiration occurs in special plants during hot and dry days, such plants are called C₃ plants, for example wheat, rice, sugarcane.

When the weather is hot and dry during the day, the stomata are closed to prevent the loss of water. Photosynthesis takes place, in which O₂ is released. Due to the increase of O₂ than the amount of CO₂, the oxygen combines with an enzyme, called ribulose bisphosphate carboxylase/oxygenase or Rubisco. This enzyme takes part to catalyze the process of carbon dioxide fixation, ribulose bisphosphate combines oxygen instead of CO₂. By the combination of O₂, RuBP compound divides into two compounds.

• Phosphoglyceric acid (PGA)
• Phosphoglycolate

Phosphoglycolate compound forms Serine and CO₂. The process can be shown in the following way.

• Ribulose bisphosphate (RuBP) → PGA + phosphoglycolate
• Phosphoglycolate → Serine + CO₂

By the process it is indicated that photorespiration is similar to respiration, because in this process O₂ is used and CO₂ is released, it is an oxidation process. In photorespiration energy rich compounds ATP are not formed, in this way energy is not produced, so this process is not useful for plants, it is wasteful and without any benefit. It also reduces photosynthesis as a result of which crop production may be reduced.

Q.2: Describe the respiratory system of Cockroach?

Ans: Respiratory Organs of Cockroach:

In cockroach respiratory organs are tube like structures, called trachea. They are present throughout its body in the form of a network. In this way the oxygen is supplied to all.

Continuation of Cockroach Respiration:

The tracheae open to the outside through ten pairs of spiracles (two in the thorax and eight in the abdomen). Valves in spiracles allow abdominal spiracles to open inward for air intake, while thoracic spiracles open outward to release CO₂.

The tracheae branch into smaller tubes, called tracheoles, that penetrate body tissues. The cockroach’s abdomen contracts and expands, facilitating airflow. During expansion, abdominal spiracles open, letting air rush in, filling tracheae and tracheoles. Oxygen diffuses slowly, while CO₂ mixes with air. During contraction, air is expelled through thoracic spiracles.

Q.3: Describe the respiratory system of Fish?

Ans: Respiratory System of Fish:

In fish, the respiratory organs are called gills. These gills arise from the pharynx and open to the outside by gill slits. The water enters through the mouth, passes over the gills, and is then excreted out through gill slits.

Structure of Gills: Each gill consists of rows of numerous structures called filaments, which are arranged in a V-shaped manner. These are supported by a curved bone, called gill bar or gill arch. Each filament contains many plate-like structures known as lamellae. These lamellae contain a network of blood capillaries to absorb oxygen from water.

Mechanism of Respiration: In fish, the blood which is supplied from the heart to the gills is deoxygenated. Gill lamellae allow blood to flow in a direction opposite to the flow of water; this is called counter-current flow. In fish, the water enters through the mouth. This oxygenated water passes over the gills. The blood which enters the gills from the body has a low concentration of O₂ and a high concentration of CO₂. The oxygen of water diffuses into the blood, and CO₂ moves from blood into the water. This exchange is helped by counter-current flow because blood and water move in opposite directions. The water with CO₂ leaves out through the gill slits on the sides of the pharynx.

This counter-current flow is very useful in fishes, allowing them to obtain 80% - 90% of the oxygen from the water flowing over the gills.

Q.4: Describe the respiratory system of Frog?

Ans: Respiratory Organs of Frog:

Frogs are amphibians and have three types of respiration:

• Cutaneous respiration - through the skin.
• Bucco-pharyngeal respiration - through the buccal cavity.
• Pulmonary respiration - through the lungs.

Cutaneous Respiration: Occurs through the skin when the frog is in water or during hibernation.

Bucco-Pharyngeal Respiration: Occurs in the buccal cavity, which has blood capillaries to facilitate gas exchange.

Pulmonary Respiration: Occurs through the lungs, involving:

• External nares (nostrils)
• Internal nares (nostrils)
• Buccal cavity (bucco-pharyngeal part)

Continuation of Frog Respiration:

• Pharynx (bucco-pharyngeal part)
• Larynx (or laryngo-tracheal chamber)
• Bronchi
• Lungs

The nostrils open into the buccal cavity, which has an opening called the glottis leading to the larynx (sound box). The larynx splits into bronchi that open into simple, elastic, spongy sac-like lungs divided into alveoli with capillaries for gas exchange.

Mechanism of Respiration:

1. Inspiration:

   • Air enters through nostrils; the bucco-pharyngeal floor lowers, closing the mouth and glottis.
   • When nostrils close and glottis opens, the floor rises, pushing air into the lungs.
   • Incomplete ventilation occurs as the lungs are not fully emptied or refilled.

2. Expiration:

   • Gas exchange occurs in the alveoli.
   • After exchange, the bucco-pharyngeal floor lowers, transferring air from lungs to the buccal cavity.
   • When the floor moves up, air exits through the nostrils.

Q.5: Describe the respiratory system of Birds.

Ans: Respiratory System of Birds: Respiration occurs through the lungs in birds, known as pulmonary respiration. Respiratory organs include nostrils, nasal passage, larynx, trachea, syrinx (voice box), bronchi, and lungs.

Respiratory System of Birds:

• External Nostrils: Small openings where fresh air enters the nasal cavity, leading to the pharynx.
• Pharynx: Contains a small opening called the glottis, which allows air to pass into the larynx, then into the trachea.
• Syrinx: Located where the bronchi split; produces sound in birds (larynx does not produce sound in birds).
• Lungs & Air Sacs:
  • Birds have compact, reddish, spongy lungs with 8-9 thin-walled air sacs located in the abdomen, neck, and wings.
  • Bronchi pass through the lungs, forming secondary bronchi and parabronchi, which connect to air sacs for constant ventilation.
  • Air sacs work like bellows, pushing air through parabronchi in one direction for efficient oxygen exchange.

Mechanism of Respiration:

• Inspiration: Air enters nasal cavity, moves through glottis, trachea, bronchi, secondary bronchi, and air capillaries for gas exchange, with air stored in air sacs.
• Expiration: Compression of air sacs pushes air through bronchi and out through nostrils. Birds take two breaths per respiration cycle, supporting efficient oxygen supply for high-altitude flight.

Q.6: What are the different organs of respiration in humans?

Ans: Organs of Respiration:

• External Nostrils
• Nasal Cavities
• Internal Nostrils
• Pharynx
• Larynx
• Trachea
• Bronchi
• Lungs

Description:

• External Nostrils & Nasal Cavities: Openings that lead to nasal cavities, which keep air moist and warm before it enters the pharynx.
• Pharynx: Contains the glottis, leading to the larynx. The epiglottis prevents food from entering the glottis.
• Larynx: Known as the voice box, containing vocal cords that produce sound.
• Trachea: A windpipe with ring-like structures to prevent collapse, allowing easy airflow.
• Bronchi & Bronchioles:
  • The trachea splits into bronchi that enter each lung, further branching into smaller bronchi and bronchioles.
  • Bronchioles end in alveoli, small sacs rich in blood capillaries for gas exchange.

Alveoli: Considered the main site for gas exchange, with a thin fluid layer aiding oxygen absorption by the blood.

Lungs: The lungs are two pink, spongy organs located in the thoracic cavity, surrounded by ribs and intercostal muscles. Each lung is encased in a thin membrane called pleura, and the space they occupy is known as the pleural cavity. The diaphragm, a thin muscular wall, separates the thorax from the abdomen. Lungs expand and contract through systematic diaphragm movements and rib adjustments driven by intercostal muscles.

Q.7: Describe the mechanism of breathing?

Ans: Mechanism of Breathing: Breathing involves two main steps:

• Inspiration (Inhalation)
• Expiration (Exhalation)

During breathing, air is taken in due to negative pressure in the thoracic cavity, where pressure is lower than atmospheric pressure (negative pressure breathing).

Inspiration (Inhalation):

• The diaphragm moves downward, and intercostal muscles push ribs forward, enlarging the pleural cavity.
• This expansion allows air to flow through the nasal cavity, pharynx, larynx, trachea, and bronchi into the alveoli of the lungs.
• Oxygen diffuses into the blood in alveolar capillaries, where it binds with hemoglobin, while CO₂ diffuses into the air.

Expiration (Exhalation):

• After gas exchange, the diaphragm rises, and ribs move inward due to intercostal muscle relaxation.
• This reduces thoracic cavity volume, compressing the lungs and forcing air out through the bronchi, trachea, and nasal cavity.

Q.8: Write a note on rate of breathing in man?

Ans: Rate of Breathing: Humans have two types of breathing:

• Voluntary Control Breathing: Involves conscious control, allowing brief breath-holding or adjusted breathing as needed.
• Involuntary Control Breathing: Automatic and managed by respiratory and cardiovascular coordination. CO₂ and H⁺ levels in blood influence breathing rate, detected by chemoreceptors (aortic and carotid bodies). The medulla oblongata in the brain regulates breathing rate based on these concentrations.

Q.9: Describe the different disorders of respiration in man?

Ans: Disorders of Respiratory Tract: Some common respiratory disorders include:

• Lung Cancer: Caused primarily by smoking; substances like nicotine and SO₂ damage respiratory tract cells, removing cilia, allowing dust and germs to enter. Abnormal cell growth damages the lung lining.

Respiratory Disorders (continued):

• Emphysema:

  • A disorder where alveoli are damaged and lose elasticity, often due to pollutants like nitrogen oxide (NO) and sulfur dioxide (SO₂).
  • Damaged alveoli reduce oxygen supply to body parts, causing breathing difficulties, lethargy, and irritability.
  • Precaution & Control:
    • Maintain a pollution-free environment.
    • Use effective medications.

• Asthma:

  • A respiratory disease marked by recurrent difficulty in breathing, often triggered by allergens like dust, pollen, or animal fur.
  • Asthma can lead to bronchiole contraction, posing risks to patients.
  • Precaution & Treatment:
    • Use effective medication and ensure a pollution-free environment.

• Tuberculosis:

• A serious lung disease caused by Mycobacterium tuberculosis, with symptoms like persistent cough, chest pain, and fever.
• It is contagious and spreads through respiratory droplets.
• Precaution & Treatment:
• Isolate patients, avoid sharing personal items, and use antibiotics.

Q.10: Write a note on Lung capacities?

Ans: Lung Capacities:

• Tidal Volume: Approximately 500 ml of air taken in and out during normal breathing (10% of lung capacity).
• Vital Capacity: Maximum air volume during deep breaths, around 4 liters.
• Residual Volume: Remaining air in the lungs after exhalation, ensuring they do not collapse.

Q.11: Describe the role of Hemoglobin (Transport of O₂)

Ans: Role of Hemoglobin:

• Hemoglobin is a red, iron-containing protein in red blood cells (RBCs) that binds with oxygen.
• Each hemoglobin molecule can carry four oxygen molecules, with each RBC containing millions of hemoglobin molecules.
• Oxygen binds to hemoglobin to form oxyhemoglobin, which transports oxygen throughout the body and releases it to tissues.

Q.12: Describe the transport of CO₂ in the body of man?

Ans: Transport of CO₂:

• CO₂ is transported from tissues to the lungs by:
• Hemoglobin: Carries approximately 35% of CO₂.
• Plasma: Dissolves CO₂ in water of plasma for transport.

Transport of CO₂ (continued):

• Carbaminohemoglobin Formation: CO₂ combines with hemoglobin to form carbaminohemoglobin, which breaks down in alveoli, releasing CO₂.
• Water of RBCs: 60% of CO₂ is transported in the water of RBCs through reactions that form compounds like carbonic acid and bicarbonate.
  • Reactions include:
    • $\text{CO₂ + H₂O} \leftrightarrow \text{H₂CO₃ (Carbonic acid)}$
    • $\text{H₂CO₃} \leftrightarrow \text{H⁺ + HCO₃⁻ (Bicarbonate)}$
    • $\text{H⁺ + NH₃} \leftrightarrow \text{NH₄⁺ (Ammonium)}$
• Water of Plasma: 5% of CO₂ is transported in plasma as potassium bicarbonate.
  • Reactions include:
    • $\text{CO₂ + H₂O} \leftrightarrow \text{H₂CO₃}$
    • $\text{H₂CO₃} \leftrightarrow \text{H⁺ + HCO₃⁻}$

Q.13: What is the role of Myoglobin?

• Role of Myoglobin: Myoglobin, smaller than hemoglobin, also absorbs oxygen and provides red color to muscles due to its strong oxygen-binding ability.

Q.14: Differentiate between Positive Pressure Breathing & Negative Pressure Breathing:

• Positive Pressure Breathing: Involves more body pressure relative to atmospheric pressure, occurring during expiration, where CO₂ is expelled.
• Negative Pressure Breathing: Involves less pressure in the thoracic cavity compared to atmospheric pressure, occurring during inspiration, where oxygen is inhaled.

Inspiration and Expiration (Comparison):

Inspiration	Expiration
Oxygen is taken in, fresh air enters.	CO₂ is expelled, air is not fresh.
Decreased thoracic cavity pressure.	Increased thoracic cavity pressure.
Ribs move outward, enlarging thoracic cavity.	Ribs move inward, reducing thoracic cavity.
Energy-consuming process.	Not an energy-consuming process.

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)