BIOLOGICAL MOLECULES

 BIOLOGICAL MOLECULES

BIOCHEMISTRY:
The branch of biology which explains the biochemical basis of life is called biochemistry.

Importance Of Biochemistry:

• It provides information about all the processes carried out in the living organism.
• It helps us to understand abnormal mechanisms which lead to disease and development of medicines and equipment for the treatment of diseases.
• It also provides information on cell differentiation.
• It also explains about growth of cells.
• It has enabled us to understand the mechanism of memory.

CHEMICAL COMPOSITION OF CELL:
All living organisms are composed of cells and living cells contain a living material called protoplasm which chemically contains 70 to 90% of water. Besides water, organic molecules and biochemicals are the main constituent of protoplasm.

BIOCHEMICAL’S:
The compounds produced by living organisms are called biochemicals. Only six elements—carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur—form 98% of the biochemical and body weight of organisms.

Types Of Biochemical’s:

• Proteins
• Carbohydrates
• Lipids
• Nucleic acids
• Conjugated molecules

WATER:
Water is the most abundant component of organisms. Its amount in living cells varies from 70% to 90%. Water provides the medium in which all biochemical reactions take place and has played a major role in the evolution of biological systems. Water is a polar molecule. The oxygen part of the molecule has a net negative charge, and the hydrogen part has a net positive charge. Thus the molecule as a whole shows polarity.

Biologically Important Properties Of Water:
Some biologically important properties of water are given below:

• Behave As Best Solvent:
  Water properties as a solvent depend on the fact that it is a polar molecule. Water effectively weakens the attraction between ions of opposite charge. Water is therefore a good solvent, ionic solids, and polar molecules readily dissolving in it. It also acts as a solvent to many non-polar substances. This is of great biological importance because all the chemical reactions that take place in cells do so in aqueous solutions.

• Slow To Absorb And Release Heat (High Specific Heat Capacity):
  Water has a very high heat capacity. This means that water is good at maintaining its temperature. This thermal stability makes it the most suitable medium for cells.

• High Heat Of Vaporization And Low Freezing Point:
  It is also an important thermal property of water. Water requires a higher amount of heat energy to change into vapors and also requires to lose a lot of heat to freeze. Thus in the presence of water, protoplasm is not at the risk of boiling or freezing except in drastic conditions.

• An Amphoteric Molecule:
  Water molecules are amphoteric because they act both as an acid and a base. Therefore, it is a perfect medium for the biochemical reactions occurring in cells. It acts as a buffer and helps to prevent changes in the pH of cells, which reduces the chance of any interference in the metabolism of the cell.

• Cohesive Force In Water Molecules:
  Due to cohesive forces, water molecules do not break apart, which helps it flow freely. The strong cohesion forces that exist between water molecules play an important part in the movement of water up the capillary-like vessels and tracheids in the stems of plants.

• Organic Molecules:
  The modern definition of organic molecules is modified as the molecules containing carbon as the basic element bonded covalently with a hydrogen atom.

Synthesis Of Large Molecules By Condensation:
Large molecules or macromolecules are huge and highly organized molecules that form the structure and carry out the activities of cells. Macromolecules are constructed from monomers by a process called condensation. This type of condensation is called dehydration synthesis because two monomers join together when water is removed and a bond is made.

Breaking Of Large Molecules By Hydrolysis:
A process during which polymers are broken down into their subunits (monomers) by the addition of H₂O is called hydrolysis. During this process, a water molecule breaks into H⁺ and OH⁻ ions. -OH group attaches to one monomer, and H attaches to the other.

Carbon: Organic chemistry is the chemistry of carbon of the living world. Carbon very widely in their properties and adaptations. Carbon is a tetravalent element. It forms four covalent bonds with other atoms.

Biological Molecules:

Proteins:

Introduction: Proteins play a vital role in the formation of structure in organisms. The dry weight of the cell contains about 50% of proteins. The name protein was suggested by Berzelius in 1838 and in 1883 G.J. Murdler recognized the importance of protein.

Definition: Proteins can be defined as the polymers of amino acids, where specific amino acids link together in a definite manner to perform a particular function of protein.

Structure Composition Of Protein: Proteins are complex organic compounds having C, H, O, and N as elements but sometimes they contain P and S also.

Synthesis Of Protein Molecule: Amino acid as a building block of protein. Proteins are macromolecules or polymers of amino acid monomers. These amino acids are linked together by a specialized bond or linkage called peptide linkage.

During protein synthesis through condensation, each amino acid becomes joined to other amino acids forming a long continuous unbranched polymer called polypeptide. The sequence of amino acids in the peptide chain is specific for each protein.

Structure Of Protein: These are four basic structural levels of proteins.

• Primary Structure: Polypeptide chain containing a linear sequence of amino acids e.g., insulin.
• Secondary Structure: Polypeptide chains twisted or spirally coiled e.g., keratin.
• Tertiary Structure: The arrangement of secondary structure into the three-dimensional (fold or super fold) structure having peptide, hydrogen, ionic, and disulphide bonds e.g., lysozyme.
• Quaternary Structure: It is the arrangement formed by the union of two or more polypeptide chains e.g., hemoglobin.

Functions Of Protein:

• Proteins are a rich source of energy.
• Proteins, along with lipids, are used in the formation of plasma membranes and other membranes of the cell.
• Muscles are made up of two contractile proteins named Actin and Myosin.
• Contraction and relaxation of these muscle proteins are responsible for locomotion.
• The shape of the protein molecule is directly related to its function. In general, proteins fall into two groups.

Globular And Fibrous:

• Keratin is a fibrous protein. It is used in the formation of hair, nails, and is also found in the skin.
• Hemoglobin is the protein present in red blood cells and is responsible for the transport and supply of oxygen to body cells.
• All enzymes present in the body cells of animals and plants are proteins. They control all types of biochemical reactions occurring within cells.
• Proteins are stored food substances in plants. Stored food in seeds is used for the germination and development of seeds into young plants.

Carbohydrates: Carbohydrates are organic compounds present in all living organisms. The group contains carbon, oxygen, and hydrogen. Carbohydrates are called hydrated carbons because the hydrogen and oxygen are mostly found in the same ratio as in water, i.e., 2:1. Examples include sugar, starch, glycogen, and cellulose. Carbohydrates are divided into three classes.

Types of Carbohydrates:

1. Monosaccharides:

   • Simple sugars that cannot be hydrolyzed into smaller sugars.
   • General formula: $\text{C}_n\text{H}_{2n}\text{O}_n$.
   • Usually sweet, crystalline solids that dissolve in water.
   • Classified based on the number of carbon atoms (e.g., triose, tetrose, pentose, hexose).
   • Common examples: Glucose (found in fruits, sweet corn, honey), Fructose (found in sugarcane), Galactose (found in milk as part of lactose).

2. Oligosaccharides:

   • Composed of 2 to 10 monosaccharides.
   • Disaccharides (two monosaccharides) are the most common type, e.g., sucrose (table sugar), lactose (milk sugar), and maltose.
   • Oligosaccharides with 3 to 10 monosaccharides include substances like Dextrin.

3. Polysaccharides:

   • Made up of hundreds or thousands of monosaccharides linked by glycosidic bonds.
   • Common examples: Starch, Glycogen, Cellulose.
   • General formula: $(\text{C}_6\text{H}_{10}\text{O}_5)_n$.

Specific Polysaccharides:

• Starch: A storage carbohydrate in plants; consists of chains of glucose molecules in forms like amylose and amylopectin. Found in cereals, legumes, potatoes.
• Cellulose: Found in plant cell walls, made of long straight chains of glucose. It is hydrophilic and provides structural support.
• Glycogen: Known as "animal starch," it is a storage carbohydrate in animals, highly branched and stored in the liver, muscles, and other tissues.

Functions of Carbohydrates:

• Energy Source: Carbohydrates are a primary energy source for metabolism in the body.

These summaries cover the basic structure, types, and functions of carbohydrates. Let me know if you need further assistance or clarification on any specific topic.

Carbohydrates (Additional Functions):

• Storage Food Molecules: In plants, excess glucose is stored as starch, and in animals as glycogen.
• Structural Role: Carbohydrates serve as building blocks, with cellulose forming plant cell walls and chitin providing support in animal exoskeletons (like arthropods).
• Complex Molecules: They form complex conjugated molecules, including glycolipids and glycoproteins.

Lipids:

• Definition: Lipids are organic compounds insoluble in water but soluble in organic solvents. They have less oxygen compared to carbohydrates and are primarily composed of fatty acids and glycerol.

Types of Lipids:

1. Acylglycerol (Fats and Oils):

   • Made of glycerol and fatty acids.
   • Provide energy and are divided into:
     • Saturated Fats: Found in animals, solid at room temperature (e.g., stearin).
     • Unsaturated Oils: Found in plants, liquid at room temperature (e.g., linoleic acid in cottonseed oil).

2. Waxes:

   • Simple lipids formed from fatty acids and long-chain alcohols.
   • Water-repellent and used for protection in plants and animals.

3. Phospholipids:

   • Key components of biological membranes, consisting of a hydrophobic and a hydrophilic end.
   • Vital for cell membrane permeability and transport functions.

4. Terpenoids:

   • Based on isoprenoid units, include classes like terpenes, steroids, and carotenoids.
     • Terpenes: Volatile, used in essential oils (e.g., menthol, camphor).
     • Steroids: Includes compounds like cholesterol.
     • Carotenoids: Pigments found in plants, aiding in photosynthesis (e.g., carotene).

Nucleic Acids:

• Discovery: Isolated by Friedrich Miescher from the nuclei of pus cells, named "nuclein," later renamed nucleic acid due to its acidic nature.
• Types:
• DNA (Deoxyribonucleic Acid): Confined to the nucleus.
• RNA (Ribonucleic Acid): Mostly found in the cytoplasm.

Nucleic Acids as Informational Macromolecules:

• DNA and RNA: Both are types of nucleic acids involved in storing and transferring genetic information. DNA encodes genetic instructions, while RNA assists in protein synthesis.

DNA as Hereditary Material:

• Early experiments, including Griffith’s transformation experiment and later confirmation by Hershey and Chase, established DNA as the genetic material.
• Genetic Code: DNA consists of specific sequences of nitrogenous bases, encoding vast amounts of information.

RNA as a Carrier of Information:

• Location: DNA remains in the nucleus, while RNA serves as an intermediary, carrying genetic instructions to the cytoplasm.
• Protein Synthesis: Genetic information flows from DNA to mRNA (messenger RNA) in two main steps:
  1. Transcription: DNA information is transcribed to mRNA, which then moves to the cytoplasm.
  2. Translation: tRNA (transfer RNA) and rRNA (ribosomal RNA) help translate the mRNA code into a specific sequence of amino acids, forming proteins.

The page also includes diagrams illustrating the transcription process in detail.

Conjugated Molecules:

Conjugated molecules are formed when biomolecules of two different types combine, functioning as a unit.

Types of Conjugated Molecules:

1. Glycolipids or Cerebrosides:

   • Formed when carbohydrates combine with lipids, producing glycolipids.
   • Important for brain function and are constituents of the nervous system. Examples include galactolipids and sulfolipids in chloroplasts.

2. Glycoproteins or Mucoproteins:

   • Produced when proteins conjugate with carbohydrates.
   • The protein forms the core structure, and the carbohydrate part extends as a branched chain.
   • Found in mucus, synovial fluid (as lubricants), connective tissue matrix, and cell membranes. Egg albumin and certain hormones like gonadotropins are also glycoproteins.

3. Nucleoproteins:

   • Nucleic acids conjugated with proteins.
   • Found in the nucleus, weakly acidic, and soluble in water.

4. Lipoproteins:

   • Formed by conjugating lipids with proteins.
   • Assist in lipid transport in the blood plasma.
   • Found in cell membranes, mitochondria, endoplasmic reticulum, and other cellular structures.

These conjugated molecules play various roles in biological systems, from structural functions to biochemical transport. Let me know if you need any more details on these or any other topics covered.

Nucleotide Structure:

• Components:
  • Pentose Sugar: Ribose in RNA, deoxyribose in DNA.
  • Phosphoric Acid: Attached to the fifth carbon of the sugar.
  • Nitrogenous Base: The organic base of the nucleotide.

These points offer a concise overview of carbohydrates, lipids, and nucleic acids in biological systems. Let me know if you'd like more details on any specific part.

THE BIOLOGY

Chapter # 01

Theory & Question Answers
Section I - Introduction

THE BIOLOGY

BIOLOGY:
Biology is the study of life and living organisms, defined as "the branch of natural science that deals with organisms and different phenomenon of life." Formerly, living organisms were classified into two kingdoms, i.e., plant kingdom and animal kingdom.

SUBDIVISION OF BIOLOGY:

• Botany:
  Botany is the subdivision of biology that deals with the scientific study of plants.

• Zoology:
  Zoology is the subdivision of biology that deals with the scientific study of animals.

Five Kingdom System:
According to the modern system of taxonomy, living organisms have been classified into the following five kingdoms.

• Kingdom Prokaryotae (Monera):
  It includes almost all the prokaryotes, e.g., bacteria and cyanobacteria.

• Kingdom Protictista (Protista):
  It includes all the unicellular eukaryotic organisms, which are no longer classified as animals, plants, or fungi, e.g., Euglena, Paramecium, Chlamydomonas, Plasmodium, etc. Multicellular algae and primitive fungi have also been included.

• Kingdom Fungi:
  It includes non-chlorophyllous, multicellular (except yeast) organisms having chitinous cell walls and a coenocytic body called mycelium, e.g., Agaricus (mushroom), yeast, etc. They are absorptive heterotrophs.

• Kingdom Plantae:
  It includes all the eukaryotic, multicellular, chlorophyllous, photosynthetic autotrophs with cell walls made primarily of cellulose, zygote retained to become an embryo, and exhibiting heteromorphic alternation of generations, e.g., Moss, Fern, Pines, Apples, etc.

• Kingdom Animalia:
  It includes all eukaryotic, non-chlorophyllous, multicellular, ingestive heterotrophs with no cell wall, e.g., Hydra, Earthworm, Human beings, etc.

Scientists have discovered and named more than one and a half million species of living organisms which exist in a great variety of forms - shapes and sizes. For example, the smallest microscopic ones, bacteria which may measure no more than 0.0001 mm to probably the largest animal, whale, in the world, which may measure up to 40 meters in length and weigh 150 tons and trees, redwood tree, measuring over 300 feet in height.

Modern biology does not only concern with the recognition and classification of these species but also deals with their vital structural and functional aspects.

MAJOR BRANCHES OR FIELDS & SPECIALIZATION IN BIOLOGY:
Some of the major branches or fields of specialization in biology are defined below.

• Molecular Biology:
  It is a recent branch of biological science that deals with the structure and function of the molecules which form the structure of the cell and its organelles that take part in the biological process of a living organism (Nucleic acids – Protein molecule).

• Microbiology: (Micro = Very Small)
  It deals with the study of microorganisms (viruses, bacteria, protozoans, and pathogenic fungi), which can only be seen under a microscope.

• Environmental Biology:
  It deals with the study of environment and its effects on organisms. Previously it was known as ecology.

• Marine Biology:
  It deals with the study of organisms inhabiting the sea and ocean, and the physical and chemical characteristics of their environment.

• Fresh Water Biology:
  It deals with the life dwelling in freshwater bodies, their physical and chemical characteristics affecting it.

• Parasitology: (Para = Beside, Sitos = Foode, Logs = Science/Study)
  It deals with the study of parasitic organisms, their life cycles, mode of transmission, and interaction with their hosts.

• Human Biology:
  This branch of biology deals with all biological aspects of man regarding evolution, anatomy, physiology, health, inheritance, etc.

• Social Biology: (Sociare = Companion)
  Social biology is concerned with the social interactions within a population of a given animal species, especially in human beings, focuses on such issues as whether certain behavior is inherited or culturally induced.

Biotechnology: (Bio = life, Technologia = systematic treatment)
This is a very recent branch introduced in biological sciences. It deals with the use of the data and techniques of engineering and technology for the study and solution of problems concerning living organisms, particularly human beings.

LEVELS OF BIOLOGICAL ORGANIZATION:
Life is built on a chemical foundation. This foundation is based on elements. Atom is the smallest possible unit of an element, which retains all the properties of that element.

• Molecules:
  Atoms may combine in a specific way to form molecules.

• Organic Molecules:
  The molecules of living matter containing carbon as a basic element bonded covalently with a hydrogen atom. The simple organic molecules are sugar, glycerol, fatty acids, amino acids, purine, and pyrimidines.

• Macromolecules:
  In the bodies of living organisms, simple organic molecules are converted into more complex organic molecules called macromolecules and recognized as nutrients carbohydrates, lipids, and proteins.

• Cell:
  By various chemical arrangements and formulation of complex molecules, life emerges on the level of a cell. A cell is the smallest unit of life. All cells contain genes, which are functional units of DNA. Inside the cell, sub-cellular structures called organelles are present.

• Tissues:
  The cellular fabric of many varieties, of which organisms are made, is a cell tissue group of cells that perform a particular function, e.g., nervous tissues, xylem, etc.

• Organ:
  Various tissue types combine to make up an organ, e.g., the brain.

• Organ System:
  Several organs that collectively perform a single function form an organ system, e.g., the nervous system consists of the brain, spinal cord, sense organs, and nerves.

• Individual Whole Organism:
  Different organ systems functioning altogether in a highly advanced coordination and cooperation make up an individual whole organism.

Biotechnology: (Bio = life, Technologia = systematic treatment)
This is a very recent branch introduced in biological sciences. It deals with the use of the data and techniques of engineering and technology for the study and solution of problems concerning living organisms, particularly human beings.

LEVELS OF BIOLOGICAL ORGANIZATION:
Life is built on a chemical foundation. This foundation is based on elements. Atom is the smallest possible unit of an element, which retains all the properties of that element.

• Molecules:
  Atoms may combine in a specific way to form molecules.

• Organic Molecules:
  The molecules of living matter containing carbon as a basic element bonded covalently with a hydrogen atom. The simple organic molecules are sugar, glycerol, fatty acids, amino acids, purine, and pyrimidines.

• Macromolecules:
  In the bodies of living organisms, simple organic molecules are converted into more complex organic molecules called macromolecules and recognized as nutrients carbohydrates, lipids, and proteins.

• Cell:
  By various chemical arrangements and formulation of complex molecules, life emerges on the level of a cell. A cell is the smallest unit of life. All cells contain genes, which are functional units of DNA. Inside the cell, sub-cellular structures called organelles are present.

• Tissues:
  The cellular fabric of many varieties, of which organisms are made, is a cell tissue group of cells that perform a particular function, e.g., nervous tissues, xylem, etc.

• Organ:
  Various tissue types combine to make up an organ, e.g., the brain.

• Organ System:
  Several organs that collectively perform a single function form an organ system, e.g., the nervous system consists of the brain, spinal cord, sense organs, and nerves.

• Individual Whole Organism:
  Different organ systems functioning altogether in a highly advanced coordination and cooperation make up an individual whole organism.

BROADER LEVEL OF ORGANIZATION:
A group of very similar interbreeding organisms which produce fertile and viable offspring. The members of a species have the same number of chromosomes. It is the basic unit of biological classification.

Population:
Members of the same species living in close association in a given area are considered a population.

Community:
Two or more populations of different species living and interacting in the same area.

Ecosystem:
A community with its environment, including land, water, and atmosphere, constitutes an ecosystem. A community together with its non-living surroundings.

Biosphere:
The entire surface region of the earth inhabited by living things is called the biosphere.

Phyletic lineage:
It’s an ancestor to descendant link which shows the common origin of species.

BIOLOGICAL METHODS:
A scientific method which is used to resolve a biological problem related to or produced by living organisms is called a biological method.

Steps Of Biological Methods:
It consists of the following steps:

• Observation:
  Scientists make keen observations and collect the facts already reported by other scientists.

• Hypothesis:
  Intelligent guess in the form of a statement on the basis of observed facts or available information is called hypothesis. This part involves inductive reasoning where scientists use isolated facts to reach a general idea that explains a phenomenon.

• Deductive Reasoning:
  The logical test or logical explanation of the hypothesis is called deduction. A deduction is a statement which further leads to an experiment, and it often involves "if" and "then."

• Experiment:
  Practicals are conducted to test the hypothesis. It is based on deduction.

• Conclusions:
  Based on the results of accurate experimentation, conclusions are drawn. The conclusion either proves or rejects the hypothesis.

THEORY:
If more and more evidence comes to hand in the favor of a hypothesis, the hypothesis gains acceptance and eventually is promoted to the rank of a theory. A theory is a set of scientific assumptions consistent with one another and supported by evidence.

LAW:
If a theory is found to be true in all tested circumstances, it is accepted as a law.

APPLICATIONS OF BIOLOGY FOR THE WELFARE OF MANKIND:
Biology has made an enormous impact on human welfare and in improving quality of life. The practical contribution of biology creates importance among the people. Knowledge of biology ensures a higher standard of living and helps us:

• To promote better health.
• Protection and conservation of the environment.
• In the field of agriculture and medical science.

IMMUNIZATION BY VACCINATION:
Vaccination involves the inoculation of a pathogen in an inactive form in hosts’ bodies to induce immunity in the host. It was first introduced by Edward Jenner in 1795. Vaccination enhances and produces immunity against the various pathogens in the body process called immunization. In the vaccination process, vaccines are introduced in animals and humans to prevent them from infectious diseases such as Polio, Smallpox, and Hepatitis, etc. Vaccine reduces the children's mortality rate.

ANTIBIOTICS:
These are the chemical substances produced by some microorganisms which are in low concentration inhibit the growth or even kill other microorganisms. The first antibiotic to be discovered was penicillin. It was derived from the fungus Penicillium notatum. Fleming, Florey, and Chain received the Nobel Prize jointly in 1945 for this path-breaking discovery. The antibiotics used to control critical diseases like T.B, Leprosy, Typhoid, Cholera, and Anthrax.

RADIOTHERAPY:
Another achievement of biological research is radioactive rays (X – rays) has been used in the medical sciences for the diagnosis and treatment of human diseases. In recent medical technology, radioactive rays are successfully used to treat cancer or tumors; ultrasonic or shock waves are used to cure kidney stones. In advanced medical science, biologists are busy developing new medicines to tackle the problem related to health. These days treatment of diseases that previously uncovered with the help of certain chemical substances has proved to be successful, e.g. some anticarcinogenic chemicals are given to cancer patients.

HYDROPONICS:
It is an effective agricultural technique to tackle the problem of food deficiency and produce better quality crops. Hydroponics is the science of growing terrestrial plants in an aerated solution. It is also known as soilless or water culture. Hydroponics is basically a cultivation through micronutrients.

Advantages:

• It controls weeds and soil disease problems.
• It requires a very small area for cultivation.
• Plants can be grown in arid areas.
• It is used to determine which of the mineral elements are essential.

CLONING:
It is the production of identical duplicate copies of genetic material; either cell or organ or entire multicellular organism. A duplicate copy is known as a clone.

Types of Cloning:

Natural Cloning:
It occurs naturally in plants and animals. Some common examples include identical twins or triplets in humans, asexual reproduction in plants and animals, regeneration, and the development of tumors and cancers.

Artificial Cloning:
Artificial cloning has long been a focus of attention in biological sciences. The first cloned mammal was Dolly, a sheep, successfully developed in 1997.

Advantages:
Cloning of human cells such as liver cells, skin cells, and blood cells has been very promising for transplantation. Vegetative reproduction of fruits and nuts by grafting helps to overcome food shortages. Through this technology, the production of medically significant substances such as insulin, growth hormones, interferon, and anti-thrombin has been achieved.

PROTECTION AND CONSERVATION OF ENVIRONMENT:
Our environment faces a great threat from pollution. Acid rain, stone cancer, and greenhouse effects have increased with the rise in human population and industrialization. Many toxic wastes produced by industries, deforestation, and industrialization have disturbed the balance of nature with catastrophic results. The study of biology provides the knowledge to maintain a stable and balanced ecosystem, to conserve and protect our environment by growing plants, and reduce pollution from industries.

CONCEPT OF BIOLOGICAL CONTROL AND INTEGRATED DISEASE MANAGEMENT:
In disease management, the use of natural processes to combat pathogens is very helpful. It involves the following methods:

Introduction of Natural Enemies:
Biological pest control involves exposing them to parasites and predation. If small fishes are introduced in ponds and ditches of stagnant water, they feed on mosquito larvae. Thus, malaria is controlled naturally.

Inter Planting:
Growing plants in climates that are unstable for the pathogen can control plant diseases. Interplanting stimulates conditions in the natural ecosystem by limiting the spread of infectious diseases and can also control.

Crop Rotation:
It involves the cultivation of different crops alternatively in the same field. It doesn’t only avoid the risk of the same pathogen in the next year, but also controls the growth of parasitic weeds.

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.