Plant Growth and Development Mock Test – Class 11 Biology

1. A root cell formed near the apex begins vacuolar enlargement, but its wall becomes rigid and heavily reinforced before the cell reaches its normal maximum length. Apical meristematic division continues. Which outcome is most likely?

2. A plant produces one characteristic leaf form during its juvenile phase and a distinctly different form after reaching the adult phase. Both forms develop under similar external conditions. This observation is best interpreted as:

3. A cultured plant tissue is required to produce new shoots from locations where shoots do not normally arise. Which cytokinin-related response is most relevant?

4. Equal dormant seeds receive adequate water, oxygen and suitable temperature.

Which conclusion best integrates the results?

5. Equal dormant peanut seeds receive sufficient water, oxygen and suitable temperature. Group P receives no ethylene, while Group Q receives ethylene and begins germinating earlier. The strongest conclusion is:

6. An untreated sugarcane field yields . Under conditions giving the maximum stated gibberellin-related increase of , the expected yield is:

7. Evaluate the following statements about ethylene.
I. It promotes senescence in plant organs.
II. It promotes abscission, especially of leaves and flowers.
III. It permanently prevents separation of every mature organ.
IV. It may shorten the functional life of responsive tissues.

8. A spatial arrangement is described below. Position P is the shoot apex, Q is the root apex, R is an intercalary meristem near the base of a grass internode, and S is a cylindrical vascular-cambium ring in a woody stem. Which assignment of growth directions is correct?

9. Equal transverse marks are placed along a young root and remeasured after .

The principal zone of root elongation lies in:

10. In a lineage showing arithmetic growth, a mutation causes both daughters of every division to retain mitotic capacity. If resources remain sufficient, the most likely change is:

11. A biomass-versus-time curve is horizontal throughout a measured stationary-phase interval. Biomass is at the beginning and remains at the end. What are the net absolute and initial-size-normalised relative growth rates over that interval?

12. Assess the following statements concerning environmental effects mediated through plant growth regulators.
I. Light and temperature can influence developmental events partly through changes in PGR activity.
II. Environmental influence does not eliminate genomic control or tissue responsiveness.
III. Every light- or temperature-controlled event is explained completely by one PGR.
IV. An environmental cue may alter PGR activity without itself becoming a plant growth regulator.

13. Assertion: Sterile filtrate from a culture of Gibberella fujikuroi can reproduce bakanae-like elongation in rice seedlings.
Reason: The elongation-promoting effect depends exclusively on living fungal cells remaining inside the treated seedlings.

14. A developing stem region shows normal water and mineral supply but greatly reduced auxin activity. Compared with an untreated region, it produces fewer new cells and forms poorly organised xylem. The observations support the conclusion that auxin:

15. Use the horticultural arrangements described below.
Site P: An intact shoot apex suppresses axillary buds.
Site Q: The shoot apex is removed and lateral branches develop.
Site R: An unrooted stem cutting receives auxin at its cut base and forms roots.
Site S: An unfertilised tomato ovary receives auxin and develops into a seedless fruit.
Which pair represents direct horticultural auxin applications rather than manipulation of the plant's existing apical dominance?

16. Four leaves are measured over different intervals.

The highest absolute growth rate is shown by:

17. A treatment prevents developing apple fruits from responding to gibberellin but does not directly interfere with fertilisation or water supply. Compared with responsive fruits receiving the same regulator, the treated fruits are most likely to show:

18. A leaf reaches its mature size, its cells complete expansion and differentiation, and no further enlargement occurs. At the same time, the shoot apex continues forming new leaves. This pattern shows that:

19. Living shoot tips are divided into two hydrated groups supplied with equal nutrients and suitable temperature. Group P receives adequate oxygen, while Group Q is kept oxygen-limited. Group P shows much greater permanent enlargement. The result most strongly supports the view that:

20. Rising water gradually submerges most of a deep-water rice plant. Its internodes and petioles then elongate rapidly, keeping several leaves above the surface. The response is best interpreted as:

21. Assertion: Auxin may prevent premature fruit drop and also promote abscission in another situation.
Reason: The effect of auxin can depend on the age and developmental state of the responding organ.

22. Which of the following statements about modes of plant growth regulator interaction are valid?
I. Complementary regulators may contribute different parts of one developmental outcome.
II. Synergistic regulators may produce an enhanced combined effect.
III. Antagonistic regulators exert opposing influences on a response.
IV. One regulator must use the same interaction mode in every tissue.

23. Study the spatial arrangement below. Apple P develops with a relatively rounded outline. Apple Q receives a gibberellin treatment during development and becomes more elongated along its main axis, producing an improved shape. The principal effect represented is:

24. Tea plants are repeatedly pruned by removing growing shoot tips. Compared with unpruned plants, they develop a bushier form with more lateral branches. The practice is effective since it:

25. A propagation laboratory first needs shoots to arise from callus at positions where shoots do not normally form. The resulting shoots must then develop roots before transfer to soil. Which staged regulator logic is most appropriate?

26. Four plots containing mature grass and young dicot weeds receive different treatments.

What is the strongest inference from the complete comparison?

27. During a dry period, a plant shows increased ABA activity, reduced shoot growth, narrower stomatal pores and improved survival compared with an ABA-insensitive plant. Which interpretation best integrates these observations?

28. Two growth-rate curves are plotted against temperature. Under normal oxygen, the curve peaks at . Under oxygen limitation, the curve has a similar optimum position but remains lower at every temperature. Which conclusion best fits the pattern?

29. Assertion: Cytokinin treatment may keep a detached leaf green for longer.
Reason: Cytokinin can promote nutrient mobilisation toward the treated tissue and delay senescence.

30. Use the four arrangements described below.
Panel P: A coleoptile tip is covered and normal bending is lost.
Panel Q: A lower coleoptile region is covered while the exposed tip still controls bending.
Panel R: Rice seedlings elongate after receiving sterile fungal filtrate.
Panel S: Bananas ripen faster when exposed to air from ripe oranges.
Which pair most directly demonstrates that an influence can act after separation from the living source that produced it?

31. A rosette plant and a deep-water rice plant are treated with regulators under their appropriate conditions.

Which interpretation best compares the responses?

32. Assertion: Synthetic NAA may be used to promote rooting in stem cuttings.
Reason: Classification as synthetic refers to the origin of NAA and does not prevent it from producing an auxin response.

33. Ethephon application to cucumber plants is commonly used to:

34. Consider the following sites in a plant.
I. Root apex
II. Developing shoot bud
III. Young fruit
IV. Fully dead mature xylem element
Natural cytokinins are most characteristically produced in:

35. A grower must choose among ethephon applications.

Which statement correctly relates the situations?

36. Stem cuttings are evaluated after transfer to soil.

Which interpretation best integrates the observations?

37. Root systems are compared after equal ethylene exposure.

Which interpretation best fits the data?

38. Arrange the events by which ethephon can assist thinning in a responsive crop.
P. Excess reproductive structures separate from the plant.
Q. Ethephon is absorbed.
R. Ethylene is released within the plant.
S. Abscission is accelerated.

39. Assertion: A mature tracheary element may remain a highly specialised differentiated cell even after losing its protoplasm.
Reason: Differentiation always preserves living protoplasm in every mature plant cell.

40. A graph plots root length against time. Root P starts at and grows as a straight line with slope . Root Q starts at with slope . The lines meet after . Which interpretation is correct?

41. A lawn consists mainly of mature grasses but contains numerous actively growing broad-leaved weeds. The manager wants to suppress the weeds while retaining the established grass cover. The most appropriate auxin-related treatment is:

42. Two identical shoots are decapitated and receive equal cytokinin applications on their axillary buds. Buds of Shoot P respond normally to cytokinin, whereas buds of Shoot Q are cytokinin-insensitive. P develops many lateral branches, but Q shows weak outgrowth. Which inference is strongest?

43. Which of the following statements about the broad promoter group of plant growth regulators are valid?
I. Auxins, gibberellins and cytokinins are commonly placed in this group.
II. Their effects may include cell division, enlargement, pattern formation, flowering or fruit development.
III. The grouping is broad and does not mean that each regulator promotes every process in every tissue.
IV. ABA is the principal member of this promotory group.

44. A submerged buttercup shoot is transferred to conditions in which its growing apex remains above water. Existing submerged leaves retain their form, but later leaves resemble the aerial form. The strongest inference is:

45. A graph plots the size of a developing plant organ on the y-axis against time on the x-axis. The curve begins gradually, rises steeply and later approaches a plateau. Why is this record sigmoid rather than indefinitely exponential?

46. Arrange the events linking daughter-cell fate with geometric growth.
P. Both daughters retain division capacity.
Q. A dividing cell undergoes mitosis.
R. The number of dividing cells increases multiplicatively.
S. The total growth curve becomes progressively steeper under unrestricted conditions.

47. A researcher wants to determine whether enlargement of a plant-derived sample is true growth or reversible swelling. Which additional observation would provide the most decisive test?

48. A treatment applied just behind a root meristem strongly suppresses vacuole enlargement and deposition of new wall material but does not immediately block mitosis at the apex. Which effect is most likely?

49. A fruit produces ethylene normally but carries a defect that prevents its ripening tissues from responding to the gas. Compared with a responsive fruit at the same stage, it is most likely to show:

50. A naturally occurring cytokinin is isolated independently from corn kernels and coconut milk. Which compound best fits the evidence?