Biology

Plant Growth and Hormones

695 Questions

Plant growth and hormones is a vital topic in biology that covers the physiological effects of different plant regulators like auxins, gibberellins, and cytokinins. These concepts are frequently tested in various general science sections of competitive exams. Practicing these questions helps clarify complex mechanisms like vernalisation, senescence, and tropism for test takers.

Abscisic acid effectsCytokinin functionsAuxins and tropismPlant tissue cultureSenescence in plantsNatural plant hormones

Plant Growth and Hormones Questions

Multiple choice

Which of these phases of growth is not related to plant growth curve?

  1. Formative phase

  2. Maturation phase

  3. Survival phase

  4. Exponential phase

  5. Senescence phase
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This growth phase is seen in bacteria, not in plants. In this phase, only some bacteria which can tolerate or resist unfavourable conditions will survive in the environment by producing endospores.

Multiple choice

Which of the following plant hormones is/are activated in leaves by the process of vernalisation?

  1. Morphactin

  2. Florigen

  3. Jasmonates

  4. Karrikins

  5. Brassinosteroids
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Vernalisation is the acquisition of a plant's ability to flower or germinate in the spring by exposure to the prolonged cold of winter. Vernalisation activates a plant hormone called florigen present in the leaves, which induces flowering at the end of the chilling treatment. Florigen or flowering hormone is the hypothesised hormone-like molecules responsible for controlling and/or triggering flowering in plants. Florigen is produced in the leaves and acts in the shoot apical meristem of buds and growing tips.

Multiple choice

Which of the following are examples of natural plant growth regulators? i. IAA ii. GA3 iii. Zeatin iv. 2,4-D v. IBA

  1. i, ii and iii only

  2. i, iv and v only

  3. ii and iv only

  4. iii and v only

  5. iii, iv and v only
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

All are natural plant growth regulators. Indole-3-acetic acid (IAA) is the most common, naturally-occurring, natural plant growth regulator hormone of the auxin class. Gibberellic Acid (GA3) is an important natural plant growth regulator that is used commercially to increase plant growth and crop yields. Zeatin is a member of the plant growth regulator hormone family known as cytokinins. 

Multiple choice senescence senescence and death plant growth plant growth and development biology

Senescense in plants leads into .......... of cells.

  1. Increase in size

  2. Increase in number

  3. Death

  4. Differentiation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Senescence also known as aging refers to the decrease in the functional capacity of an organism. This results in a cellular breakdown followed by metabolic failure. The death of cells followed by the death of plant is seen in senescence. Thus the correct answer is option C.