NEET Biology Plant Growth and Development Important Questions Set 02

These Class 11 NEET Biology important questions on Plant Growth and Development give 23 questions with step-by-step answers, arranged as very short, short and long answer types, taken from a model test paper. They help NEET aspirants revise the definitions, structures, differences and key terms of the chapter.

Very Short Answer Type Questions

Question 1. Write two structures or parts of a plant which show limited growth.
Answer: Leaves, flowers and fruits. (Any two)

Question 2. Name one meristem :
(a) Responsible for primary growth.
(b) Responsible for secondary growth.
Answer: (a) Root apical meristem, shoot apical meristem and (Any one)
(b) Lateral meristem

Question 3. Which type of cell wall is known as primary in nature?
Answer: The cell wall which is thin, cellulosic and have abundant plasmodesmatal connections is known as primary cell wall

Question 4. What is formed from the cells positioned away from root apical meristem after differentiation?
Answer: Root cap

Question 5. What happens if the coleoptile tip of canary grass is removed?
Answer: There is no bending of shoot towards light because the stimulus of light will not be perceived.

Question 6. What is the use of gibberellins in conifers?
Answer: Gibberellins cause quicker early growth in conifers which is useful for obtaining early and quicker yield of economically important seeds.

Question 7. Which phytohormone works in leaves to close the stomata during dessication?
Answer: ABA

Question 8. Name the plant which shows leaves of different shapes according to its habitat.
Answer: Buttercup

Short Answer Type Questions

Question 9. Why is plant growth said to be unique?
Answer: Plant growth is said to be unique because plants have the capacity for indeterminate or unlimited growth which continues throughout their life. The growth of the plants is due to the presence of meristems.

Question 10. Write two characteristics of the cells found in meristematic phase of growth.
Answer: (i) The cells have dense protoplasm.
(ii) The cells contain large nucleus.
(iii) The cells have high respiratory rate.
(iv) The cell wall of the cells is primary in nature. (Any two)

Question 11. Mention four different structures formed on differentiation of meristems.
Answer: Aerenchyma, chlorenchyma, trichomes, collenchyma, tracheary element, root cap. (Any four)

Question 12. What happens if dedifferentiated cells loose their capacity to divide?
Answer: They form permanent tissues specialised for a particular function and this phenomenon is known as redifferentiation. Various tissues are formed due to redifferentiation process like secondary phloem, xylem phloem, cork etc.

Question 13. Name the phytohormone made up of
(a) Indole compounds
(b) Adenine derivative
Answer: (a) Auxin
(b) Cytokinin

Question 14. (a) Removal of which part of plant helps in the preparation of hedges and bushy growth?
(b) Name the synthetic hormone used as weedicide.

Answer:

(a) Apical bud

(b) 2, 4-D or 2, 4-Dichlorphenoxy acetic acid.

Question 15. Why tobacco plants do not flower in summers?
Answer: Because tobacco is a short day plant which requires low light period whereas during summers light period is long which causes the tobacco plants not to flower.

Short Answer Type Questions

Question 16. (a) Which type of growth is represented by the given expression? Lt = L₀ + rt
(b) What do Lt, L₀, r and t stands for?

Answer:

(a) Arithmetic growth

(b) Lt = length of the organ at time 't'

L₀ = length of the organ at time 'zero'

r = growth rate per unit time

t = time of growth

Question 17. Oxygen is an essential factor for growth. Explain.
Answer: All higher plants respire aerobically for which they need oxygen. The amount of oxygen available to the plants determine the amount of respiratory energy that can be utilized for biosynthetic activity i.e., anabolic activity required for growth.

Question 18. (a) From where was auxin first isolated?
(b) Which hormone promotes female flowers in cucumber?
(c) Why gardeners use auxins in their lawns?

Answer:

(a) Auxin was first isolated from human urine samples.

(b) Ethylene promotes female flowers in cucumbers thereby increasing the yield.

(c) Because they want to prepare weed-free lawns.

Question 19. (a) Name the acidic phytohormone which is used to speed up the malting process.
(b) What are climacteric fruits?

Answer:

(a) Gibberellins

(b) The climacteric fruits are fleshy fruits which shows a sudden sharp rise in the rate of respiration at the time of ripening.

Question 20. Explain with the help of an example, the role of ethylene in aquatic plants.
Answer: Both stem and petiole elongation are promoted by ethylene in submerged and partially submerged aquatic plants. For example, leaves of rice seedlings remain out of water due to ethylene where it induces rapid growth of internodes and leaf bases.

Question 21. (a) Define heterophylly.
(b) Give two examples of plants which show heterophyllous development.
Answer: (a) Heterophylly is the phenomenon of appearance of different forms of leaves on the same plant.
(b) Cotton, coriander and larkspur. (Any two)

Long Answer Type Questions

Question 22. Which one of the plant growth regulators would you use if you are asked to :
(a) Induce flowering in pineapple and litchi.
(b) Remove weeds from wheat field.
(c) Bolt a rosette plant.
(d) Increase the resistance of plants against pathogens.
(e) Quickly ripen a fruit.
Answer: (a) Auxin (NAA and 2, 4-D)
(b) 2, 4-D (Auxin)
(c) Gibberellin
(d) Cytokinin
(e) Ethylene

Question 23. Explain the germination of seed with the help of diagram.

Answer:

Epicotyl hook Seed coat

Epicotyl Cotyledons Soil line Cotyledon

Hypocotyl Hypocotyl

Germination of seed.