ICSE Class 10

General instructions: Answer all questions. Marks are shown in brackets [ ].

Objective

1. 1.
   The growth of plants in the direction of light is called

   1. A. phototropism
   2. B. geotropism
   3. C. chemotropism
   4. D. hydrotropism
   [1]
2. 2.
   Growth of pollen tube towards the ovule is an example of _______.

   1. A. phototropism
   2. B. geotropism
   3. C. hydrotropism
   4. D. chemotropism
   [1]
3. 3.
   Auxins were discovered by:

   1. A. Darwin
   2. B. F.W.Went
   3. C. Boysen - Jensen
   4. D. None of these
   [1]
4. 4.
   A sunflower plant bends towards the sun. It is ________response.

   1. A. Thigmonastic
   2. B. Photonastic
   3. C. Thermonastic
   4. D. Seismonastic
   [1]
5. 5.
   During his biology class, Anil was learning about different hormones in plants and animals. He wanted to identify which of the following is specifically a plant hormone. Which of the following is a plant hormone?

   1. A. Adrenaline
   2. B. Glucagon
   3. C. Cytokinin
   4. D. Oxytocin
   [1]
6. 6.
   Which plant hormone is primarily located at the apical meristem of plants?

   1. A. Gibberellin
   2. B. Auxin
   3. C. Ethylene
   4. D. Abscisic acid
   [1]
7. 7.
   When roots of a plant always move towards water, even if it means going against the pull of gravity. This indicates

   1. A. hydrotropism
   2. B. negative geotropism
   3. C. geotropism
   4. D. positive geotropism
   [1]
8. 8.
   Why are hormones referred to as 'chemical messengers'?

   1. A. They transmit electrical signals between neurons.
   2. B. They are released into ducts and transported to target organs.
   3. C. They are chemicals poured into the bloodstream to regulate body functions.
   4. D. They break down food molecules during digestion.
   [1]
9. 9.
   Auxanometer is used to measure the growth in length of a plant organ. Which of the following is correct about auxanometers?

   1. A. It measures only temperature-induced growth.
   2. B. It measures only sunlight-induced growth.
   3. C. It can measure plant growth in response to temperature, sunlight, and water conditions.
   4. D. It is used to measure root pressure.
   [1]
10. 10.
    Which effect is associated with cytokinin but NOT with auxin?

    1. A. Stimulates cell division and seed germination.
    2. B. Promotes stem elongation and phototropism.
    3. C. Accelerates root growth and fruit development.
    4. D. Inhibits leaf senescence and delays aging.
    [1]
11. 11.
    Why does the stem of a plant grow toward light?

    1. A. Light destroys auxin on the illuminated side, causing uneven growth.
    2. B. Auxin accumulates on the shaded side, promoting growth and curvature toward light.
    3. C. Roots secrete a hormone that pulls the stem toward light.
    4. D. Light directly stimulates cell division on the illuminated side.
    [1]
12. 12.
    Which of the following is an advantage of senescence in plants?

    1. A. Old and inefficient organs are replaced by young and developing leaves, buds, flowers, and fruits.
    2. B. Senescence increases the rate of photosynthesis in older leaves.
    3. C. It prevents the formation of new roots and shoots.
    4. D. Senescence reduces the plant's ability to absorb water and nutrients.
    [1]
13. 13.
    A plant hormone related with inhibition of senescence is :

    1. A. Ethylene
    2. B. GA
    3. C. Bromic acid
    4. D. ABA
    [1]
14. 14.
    What causes the sunflower head to point toward the sun?

    1. A. Auxin accumulates on the shaded side, causing faster growth and curvature toward light.
    2. B. The sunflower stem hardens on the sunlit side, forcing the head to bend.
    3. C. The sunflower head is pulled by magnetic forces from the sun.
    4. D. The roots grow toward the sun, tilting the entire plant.
    [1]
15. 15.
    A biology teacher asked students to name two phytohormones responsible for inducing fruit ripening. Raj said: Ethylene and Cytokinins Sonu said: Ethylene and Gibberellins Lata said: Ethylene and Auxins Abhay said: Auxins and Gibberellins Who were correct?

    1. a. Raj and Lata
    2. b. Sonu and Raj
    3. c. Lata and Sonu
    4. d. Abhay and Lata
    [1]
16. 16.
    Both ethylene and ABA are responsible for

    1. A. inducing dormancy of seeds
    2. B. stimulation of apical dominance
    3. C. ripening of fruits
    4. D. promoting abscission of leaves and fruits
    [1]
17. 17.
    A high auxin to cytokinin ratio favours the:

    1. A. Shoot development
    2. B. Formation of undifferentiated cells
    3. C. Root development
    4. D. None of the above
    [1]
18. 18.
    Which of the following setups correctly demonstrates hydrotropism in germinated bean seeds?

    1. A. Placing seeds on dry wire mesh above water in a conical flask and observing root growth.
    2. B. Keeping seeds in a closed box with no light and observing root direction.
    3. C. Placing seeds on moist soil in a pot and exposing to uniform light.
    4. D. Suspending seeds in air with water droplets and observing root curvature.
    [1]
19. 19.
    Which hormone controls the phenomenon where the growth of apical buds suppresses the growth of lower axillary buds?

    1. A. Auxin
    2. B. Gibberellin
    3. C. Cytokinin
    4. D. Abscisic acid
    [1]
20. 20.
    Why can one rotten orange spoil an entire basket of oranges?

    1. A. The rotten orange releases ethylene gas, which diffuses and accelerates ripening in others.
    2. B. The rotten orange attracts insects that spread decay to nearby oranges.
    3. C. The rotten orange absorbs nutrients from surrounding oranges, causing them to spoil.
    4. D. The rotten orange releases a toxic liquid that contaminates the basket.
    [1]