FREE NEET Biology Practice MCQ Test: Plant Growth And Development Exercise 2 Questions Answers With Detailed Explanations [PDF]

Answer: (d)

Parthenocarpy refers the development of fruits without fertilization. Such fruits are seedless but otherwise normal in appearance, e.g. banana, pineapple etc. The auxins (IAA, IBA, 2, 4-D) are applied in low concentration in a lanolin paste to the stigma of flower to induce parthenocarpy.

Answer: (a)

Dwarf strains were genetically unable to produce gibberellin, so additional fertilizers would have no effect.

Answer: (d)

Answer: (d)

Answer: (b)

Cytokinins are growth promoting phyto- hormones. Cytokinin plays an important part in organ formation (morphogenesis) with auxin. Different auxin/cytokinin ratio decides the development of root shoot ratio. The major physiological function of cytokinins is to enhance cell division. If cytokinin to auxin ratio is low, then root formation takes place but if the ratio of cytokinin to auxin is high, then, there is formation of meristematic cells in the callus.

Answer: (a)

Synergistic effect means when two hormones work together, they increase the effect or functioning of each other thus, there will be enhanced effect of both the hormones.

Answer: (a)

Answer: (b)

In the given graph of growth versus time, the phases marked as A, B and C are respectively stationary phase, lag phase and log phase. In lag phase, the growth is slow, the growth increases during log phase and becomes steady in the stationary phase.

Answer: (a)

Answer: (d)

Answer: (b)

Answer: (c)

2, 4-Dichlorophenoxy acetic acid is used for causing defoliation of forest trees. 2, 4-D or 2, 4 dichlorophenoxy acetic acid is an auxin hormone. It stimulates the growth activities of the cells of the root due to which roots get destroyed and thus plants finally destroys. 2, 4-D is used as a defoliant for broad leaved dicots.

Answer: (a)

Experiment done by Charles Darwin and his son on plant phototropism shows that the tip of the coleoptile is the light receptor of the plant that caused the bending of the entire coleoptile towards the light source.

Answer: (b)

Bolting of cabbage can be induced artificially by the application of gibberellin under conditions that would normally maintain the rosette form.

Answer: (c)

Nyctinastic leaf movement is not related to auxin level. It is a movement of leaves of many species from nearly horizontal leaves during the day and nearly vertical at night. This movement are controlled by biological clock, while the bending of shoot towards light, movement of root towards soil and movement of sunflower head tracking the sun are the conditions related to auxins.

Answer: (a)

Answer: (a)

Absolute growth rate is defined as the measurement and the comparison of total growth per unit time.

Answer: (b)

Answer: (d)

Auxin concentration increases in shaded area, i.e., auxins are collected in the opposite side of light. Increased concentration of auxin is stimulatory for shoot growth and for this reason, shaded side shows more growth than lighted side. Hence, bending of shoot takes place towards light.

Answer: (b)