QUESTION BANK

Chapter 1: Reproduction in Lower and Higher Plants

1. Write any three methods of Asexual reproduction in lower organisms. (3 M)

Answer:

 Budding: Formation of a new organism from a bud on the parent, as seen in Hydra.

 Fragmentation: The body of the organism breaks into parts, each developing into a
new individual, e.g., sponges.

 Vegetative Propagation: New plants grow from parts like roots, stems, or leaves,
e.g., in algae and some fungi.

2. Define: a. Scion: A detached shoot or branch of a plant grafted onto a stock to grow
together. b. Stock: The rooted part of a plant onto which a scion is grafted. c. Grafting: A
horticultural technique of joining the tissues of two plants so that they unite. d.
Microsporogenesis: The process of formation of microspores (pollen grains) in anthers
during male gametophyte development.

3. Explain in detail the structure of pollen grain with a neat labelled diagram. (3 M)
Answer: A pollen grain is a male gametophyte. It consists of:

 Exine: The outer tough layer made of sporopollenin, providing protection.

 Intine: Vegetative cell wall beneath exine.

 Generative Cell: Divides to form two sperm cells.

 Vegetative (Tube) Cell: Controls pollen tube formation. Diagram (sketch): Show
outer exine, inner intine, and within, the generative and tube cells.
4. With a neat and labelled diagram explain the T.S. of anther. (4 M) Answer: The
transverse section (T.S.) of an anther shows:

 Anther Wall: Comprising epidermis, developing endothecium, middle layers, and

tapetum.

 Pollen sacs (microsporangia): Contain microspore mother cells.

 Microspores: Develop into pollen grains.

(Diagram not printable here but should label layers and microsporangia.)

Chapter 4: Molecular Basis of Inheritance

5. Write a note on Friedrich Miescher's experiment regarding DNA discovery. (3 M)

Answer: Friedrich Miescher isolated a substance from the nuclei of white blood cells, which
he called nuclein. This substance was rich in phosphorus, differing from proteins, and is now
known as DNA. His discovery marked the first identification of DNA as a distinct nucleic
acid.

6. In the light of Griffith's experiment explain the action of two strains of

Streptococcus pneumoniae and give his conclusion. (4 M) Answer: Griffith used smooth
(S) and rough (R) strains of bacteria in mice.

 S strain (virulent) caused pneumonia; R strain (non-virulent) did not.

 Heat-killed S bacteria alone did not cause disease.

 However, when live R bacteria were injected with heat-killed S bacteria, mice died,
and live S bacteria were recovered. Conclusion: A ‘transforming principle’ from
heat-killed S bacteria transformed R bacteria into virulent S bacteria, demonstrating
genetic material transfer.

7. Explain the experiment performed by Avery, MacLeod, and McCarty to prove that
‘transforming principle is DNA’. (2 M) Answer: They extracted material from heat-killed
S bacteria and treated it with enzymes:

 Protease: No effect; transformation continued.

 RNAase: No effect; transformation continued.

 DNAase: Inhibited transformation, indicating DNA was the genetic material

responsible for transformation.
8. Describe the experiment of Hershey and Chase to prove that DNA is the genetic
material. (4 M) Answer: They used radioactive isotopes:

 Phosphorus-32 (^32P) to label DNA.

 Sulfur-35 (^35S) to label proteins. They infected bacteria with bacteriophages

labeled with these isotopes. After infection, only ^32P entered bacterial cells,
showing DNA, not protein, was the hereditary material.

Chapter 8: Respiration and Circulation

9. Write the important features of respiratory surface for efficient gaseous exchange.
(2 M) Answer: Features include:

 Thin and moist to facilitate diffusion.

 Large surface area for increased gaseous exchange.

 Rich blood supply to transport gases rapidly.

 Close contact with the circulatory system.

10. With a neat and labelled diagram, describe the human respiratory organ. (4 M)
Answer: The human respiratory organ is the lungs, which have:

 Trachea dividing into bronchi, further branch into bronchioles.

 Alveoli: tiny air sacs where gas exchange occurs. (Diagram should illustrate trachea,
bronchi, bronchioles, alveoli with labels.)

11. Give the functions of: a. Vestibule: The passage that conducts air from nose to
pharynx with cilia trapping dust. b. Epiglottis: Flap that covers the larynx during
swallowing to prevent food entry. c. Olfactory or sensory chamber: Contains receptors for
smell. d. Tonsils: Lymphatic tissue that traps ingested or inhaled pathogens.

12. Write a note on Trachea. (2 M) Answer: The trachea is a tube reinforced with
cartilage rings that connects larynx to bronchi, conducting air to the lungs. It is lined with
ciliates mucous membrane trapping dust and microbes.
13. What is the common passage for food and air called? (1 M) Answer: Pharynx.

Chapter 10: Human Health and Diseases

14. Describe the Mechanism of Breathing. (3 M) Answer: Breathing involves inspiration

and expiration:

 Inspiration: Diaphragm contracts and moves downward, intercostal muscles

expand chest cavity, creating negative pressure. Air enters the lungs.

 Expiration: Diaphragm relaxes and moves up, chest contracts, expelling air due to
positive pressure.

15. Explain with a neat and labelled diagram the Human Respiratory System. (4 M)
(Refer to answer 10 above for diagram and label. Text explanation:) The system includes
nose, pharynx, larynx, trachea, bronchi, bronchioles, and alveoli where gas exchange occurs.

16. Compare the changes that occur in the diaphragm during inspiration and
expiration. (2 M) Answer:

 Inspiration: Diaphragm contracts and flattens downward.

 Expiration: Diaphragm relaxes and curves upward, pushing air out.

17. Why is it advantageous to breathe through the nose rather than through the
mouth? (2 M) Answer: Nose filters, warms, and humidifies air, trapping dust and microbes,
reducing infection risk, and ensures better oxygen absorption.

18. Match the following:

Respiratory Surface Organism

i) Book gills b) Limulus

ii) Cloaca d) Turtle

iii) Lungs a) Mammals

Respiratory Surface Organism

iv) Plasma membrane c) Amoeba

19. State the significance of mother’s milk to a newborn infant. (2 M) Answer:

Provides essential nutrients, antibodies, and immune factors, promoting immunity and
growth.

20. Define Antigens and Antibodies. (2 M) Answer:

 Antigens: Foreign substances that induce an immune response.

 Antibodies: Proteins produced by immune cells that recognize and bind antigens.

21. What is immunity? (1 M) Answer: The body's ability to resist infections and eliminate
pathogens.

22. What are different types of immunity? (1 M) Answer:

 Innate immunity: Present at birth.

 Acquired immunity: Develops after exposure to pathogens.

23. What do you mean by immunology? (1 M) Answer: The branch of biology studying
immune responses and immune system functions.

24. What is the role of fever in innate immunity? (2 M) Answer: Fever inhibits pathogen
growth, enhances immune activity, and accelerates tissue repair.

25. Differentiate between innate immunity and acquired immunity. (3 M)

Aspect Innate Immunity Acquired Immunity

Entry Present from birth Develops after exposure

Aspect Innate Immunity Acquired Immunity

Specificity Non-specific Specific to particular pathogens

Memory No memory Has memory, faster on second exposure

Certainly! Continuing from question 26:

26. Write the unique features of Adaptive immunity. (2 M)

Adaptive immunity is characterized by its ability to recognize specific pathogens and

develop a memory response, leading to long-term protection. Its unique features include:

 Specificity: It targets particular antigens present on pathogens.

 Memory: It retains a memory of past infections, allowing a faster and stronger

response upon re-exposure.

27. Enlist the various types of barriers which prevent entry of foreign agents into the
body. (2 M)

Barriers that prevent pathogen entry include:

 Physical barriers: Skin and mucous membranes.

 Chemical barriers: Lysozymes in saliva and tears.

 Biological barriers: Normal microbiota that compete with pathogens.

28. Write the examples of: (2 M)

a. Natural Acquired Active immunity: Immunity acquired after recovering from disease, e.g.,
chickenpox.

b. Artificial Acquired Active immunity: Immunity obtained through vaccination, e.g., measles
vaccine.

Q29. State the Adaptations shown by Maize Plants for pollination by Wind.

Adaptations in Maize for wind pollination (Anemophily) include:

1. Lightweight and dry pollen grains – Easily carried by wind over long distances.
 2. Well-exposed stamens and feathery stigmas – Stamens hang out of the flower to
release pollen; stigmas are long and brush-like to capture pollen.

3. Unisexual flowers (monoecious plant) – Male (tassel) and female (ear) flowers are
separate, which promotes cross-pollination.

4. Production of large quantities of pollen – Increases chances of successful pollination.

Q30. State the Adaptations shown by Salvia flowers for pollination by Insects.

Adaptations in Salvia for insect pollination (Entomophily) include:

1. Brightly coloured and attractive flowers – Attract pollinating insects like bees.

2. Presence of nectar – Rewards insects, encouraging visits.

3. Special lever mechanism – When an insect enters the flower, it triggers the stamens
to deposit pollen on the insect’s body.

4. Fragrance and structure – Helps guide insects to the reproductive parts.

Q31a. Study of Imbibition using Raisins – Observations and Conclusions

 Observation: Raisins swell up and increase in size when soaked in water for a few
hours.

 Conclusion: This demonstrates imbibition, a process where dry plant materials

absorb water and swell due to capillary forces. It is a passive type of water
absorption.

Q31b. Separation of Plant Pigments Using Paper Chromatography – Observations and

Conclusions

 Observation: Different coloured bands (green, yellow, orange) appear on the paper
strip, each at a different level.

 Conclusion: This shows that plant pigments (like chlorophyll a, chlorophyll b,

carotenoids, and xanthophylls) can be separated based on their solubility in the
solvent and their molecular size using paper chromatography.