Class 10 Board Examination — Biological Science Mock Test Paper Time: 3 Hours | Maximum Marks: 60
General Instructions: 1. Section A contains MCQs (1 mark each) 2. Section B contains Short Answer questions (2 marks each) 3. All questions are compulsory 4. Draw neat diagrams wherever necessary
SECTION A — Multiple Choice Questions
(1 Mark Each | 10 × 1 = 10 Marks)
Q1. Which of the following is the correct sequence of events in photosynthesis? (a) Light reaction → Calvin cycle → Glucose formation (b) Calvin cycle → Light reaction → Glucose formation (c) Glucose formation → Light reaction → Calvin cycle (d) Light reaction → Glucose formation → Calvin cycle
Q2. The enzyme that breaks down starch in the mouth is: (a) Pepsin (b) Trypsin (c) Salivary amylase (d) Lipase
Q3. Which blood group is called the universal donor? (a) A (b) B (c) AB (d) O
Q4. The functional unit of the kidney is: (a) Neuron (b) Nephron (c) Alveolus (d) Villus
Q5. Which part of the brain controls balance and posture? (a) Cerebrum (b) Cerebellum (c) Medulla oblongata (d) Hypothalamus
Q6. The hormone responsible for the fight or flight response is: (a) Insulin (b) Thyroxine (c) Adrenaline (d) Estrogen
Q7. In which type of reproduction does the offspring have the same genetic material as the parent? (a) Sexual reproduction (b) Asexual reproduction (c) Cross-pollination (d) Fertilisation
Q8. Mendel's Law of Segregation states that: (a) Two traits are inherited together (b) Alleles separate during gamete formation (c) Dominant traits always appear in F1 (d) Recessive traits disappear permanently
Q9. Which of the following is a non-biodegradable pollutant? (a) Vegetable peels (b) Paper (c) DDT (d) Cotton
Q10. The process by which organisms best suited to their environment survive and reproduce is called: (a) Mutation (b) Adaptation (c) Natural selection (d) Speciation
SECTION B — Short Answer Questions
(2 Marks Each | 15 × 2 = 30 Marks)
Q11. What is photosynthesis? Write the overall chemical equation for photosynthesis.
Q12. Differentiate between aerobic and anaerobic respiration. Give one example of each.
Q13. What is the role of the following in the human digestive system: (i) Bile juice (ii) Villi
Q14. Describe the structure and function of the human heart in brief.
Q15. What is transpiration? State any two significance of transpiration in plants.
Q16. Differentiate between the central nervous system (CNS) and the peripheral nervous system (PNS).
Q17. What are plant hormones? Name any four plant hormones and state one function of each.
Q18. Define the following terms: (i) Pollination (ii) Fertilisation
Q19. Explain Mendel's Law of Dominance with a suitable example.
Q20. What is the difference between acquired traits and inherited traits? Give one example of each.
Q21. What is speciation? State any two factors that may lead to speciation.
Q22. What are the different methods of contraception? Name and explain any two methods.
Q23. Define ecosystem. What are its two main components? Give one example of a natural ecosystem.
Q24. What is the 10% law of energy flow in an ecosystem? Explain with an example.
Q25. State any four measures to conserve the environment and protect biodiversity.
ANSWERS
Section A — Answers
A1. (a) Light reaction → Calvin cycle → Glucose formation
A2. (c) Salivary amylase
A3. (d) O
A4. (b) Nephron
A5. (b) Cerebellum
A6. (c) Adrenaline
A7. (b) Asexual reproduction
A8. (b) Alleles separate during gamete formation
A9. (c) DDT
A10. (c) Natural selection
Section B — Answers
A11. Photosynthesis is the process by which green plants manufacture their own food using sunlight, carbon dioxide, and water in the presence of chlorophyll.
Overall chemical equation: 6CO₂ + 6H₂O → (sunlight/chlorophyll) → C₆H₁₂O₆ + 6O₂
Carbon dioxide and water are converted into glucose and oxygen using light energy absorbed by chlorophyll.
A12.
| Aerobic Respiration | Anaerobic Respiration | |
|---|---|---|
| Oxygen | Requires oxygen | Does not require oxygen |
| End products | CO₂ + H₂O + Energy | Lactic acid / Ethanol + CO₂ + Energy |
| Energy released | 38 ATP (large amount) | 2 ATP (small amount) |
Example of aerobic respiration: Respiration in humans Example of anaerobic respiration: Fermentation by yeast
A13. (i) Bile juice: Secreted by the liver and stored in the gall bladder. It does not contain enzymes but it makes the acidic food coming from the stomach alkaline so that pancreatic enzymes can act on it. It also emulsifies fats, breaking large fat droplets into smaller ones for easier digestion.
(ii) Villi: Finger-like projections on the inner wall of the small intestine. They increase the surface area for absorption of digested food. Each villus contains blood capillaries and lacteals that absorb nutrients into the bloodstream.
A14. Structure: The human heart is a muscular organ divided into four chambers — two upper chambers called atria (right atrium and left atrium) and two lower chambers called ventricles (right ventricle and left ventricle). Valves between chambers prevent backflow of blood.
Function: The heart acts as a double pump. The right side pumps deoxygenated blood to the lungs (pulmonary circulation), while the left side pumps oxygenated blood to all parts of the body (systemic circulation). It beats about 72 times per minute to maintain continuous blood circulation.
A15. Transpiration is the process of loss of water in the form of water vapour through the stomata of leaves and other aerial parts of plants.
Two significances of transpiration:
- It helps in the upward movement of water and dissolved minerals from roots to leaves (ascent of sap).
- It cools the plant surface by losing excess water, thereby regulating the temperature of the plant.
A16.
| CNS | PNS | |
|---|---|---|
| Components | Brain and spinal cord | All nerves outside the brain and spinal cord |
| Function | Processes and integrates information | Carries impulses to and from the CNS |
| Location | Enclosed in skull and vertebral column | Distributed throughout the body |
The CNS acts as the control centre while the PNS connects the CNS to organs, muscles, and sense organs.
A17. Plant hormones (phytohormones) are chemical substances produced in small quantities in plants that regulate and coordinate growth and other physiological activities.
Four plant hormones and their functions:
- Auxin — Promotes cell elongation and controls phototropism (bending of plant towards light).
- Gibberellin — Promotes stem elongation and helps in seed germination.
- Cytokinin — Promotes cell division and delays ageing (senescence) of leaves.
- Abscisic acid — Inhibits growth, promotes leaf fall (abscission), and helps plants withstand drought by closing stomata.
A18. (i) Pollination: The transfer of pollen grains from the anther of a flower to the stigma of the same or another flower of the same species is called pollination. It can be self-pollination (within the same flower) or cross-pollination (between different flowers).
(ii) Fertilisation: The process of fusion of the male gamete (from pollen) with the female gamete (egg cell) present in the ovule to form a zygote is called fertilisation. In plants, this process is called double fertilisation.
A19. Mendel's Law of Dominance: When two parents with contrasting traits are crossed, only one trait (the dominant trait) appears in the F1 generation. The other trait (the recessive trait) is suppressed but not lost.
Example: When Mendel crossed a tall pea plant (TT) with a dwarf pea plant (tt), all F1 offspring were tall (Tt). Tallness (T) is the dominant trait and dwarfism (t) is the recessive trait. The recessive trait reappears in the F2 generation in a 3:1 ratio when F1 plants are self-pollinated.
A20. Acquired traits: Characteristics that an organism develops during its lifetime due to the environment or use of body parts. These are not passed on to the next generation. Example: A bodybuilder's muscular body developed through exercise.
Inherited traits: Characteristics that are genetically passed from parents to offspring through genes. Example: Eye colour, blood group, and height in humans.
A21. Speciation is the process by which new species are formed from existing species over a long period of time due to evolution.
Two factors that may lead to speciation:
- Geographical isolation: When populations of the same species are separated by physical barriers like mountains, rivers, or oceans, they evolve independently over time and may become separate species.
- Genetic drift: Random changes in gene frequency in small isolated populations over many generations can lead to the formation of new species.
A22. Contraception refers to the methods used to prevent unwanted pregnancy.
Two methods:
- Barrier method: Physical barriers like condoms (for males) and diaphragms (for females) prevent the sperm from reaching the egg. Condoms also protect against sexually transmitted infections (STIs).
- Hormonal method: Oral contraceptive pills containing hormones (estrogen and progesterone) are taken by females to prevent ovulation. They regulate the menstrual cycle and prevent the release of eggs, thus preventing fertilisation.
A23. Ecosystem is a self-sustaining unit of the environment in which living organisms (biotic components) interact with each other and with their non-living surroundings (abiotic components).
Two main components:
- Biotic components — All living organisms such as producers, consumers, and decomposers.
- Abiotic components — Non-living factors such as sunlight, temperature, water, soil, and air.
Example of a natural ecosystem: A pond ecosystem or a forest ecosystem.
A24. The 10% Law (given by Lindeman, 1942) states that only 10% of the energy available at one trophic level is transferred to the next trophic level. The remaining 90% is lost as heat during metabolic activities.
Example: Producers (Plants) → 10,000 J Primary consumers (Grasshoppers) → 1,000 J (10% of 10,000) Secondary consumers (Frogs) → 100 J (10% of 1,000) Tertiary consumers (Snakes) → 10 J (10% of 100)
This shows why food chains are generally limited to 3–4 trophic levels.
A25. Four measures to conserve the environment and protect biodiversity:
- Afforestation: Planting more trees and protecting existing forests to maintain habitat for wildlife and reduce deforestation.
- Reduce, Reuse, Recycle (3R): Minimising waste generation, reusing materials, and recycling products to reduce pollution and conserve natural resources.
- Protection of wildlife: Establishing wildlife sanctuaries, national parks, and biosphere reserves to protect endangered species from extinction.
- Controlling pollution: Reducing the use of chemical pesticides and fertilisers, treating industrial waste before disposal, and promoting the use of renewable energy sources to reduce air, water, and soil pollution.
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