Question

Which of the following functions are concerned with the plant growth regulator cytokinin? I. Chloroplast production in leaves II. Stomatal closure III. Root growth and root hair formation IV. Overcome apical dominance

• A. I and II
• B. II and III
• C. I and IV
• D. I, III and IV

Hint:

Cytokinin = Cell division and breaking apical dominance.

Answer 1

The Correct Option is C

Step 1: Understand the question.
From four listed jobs, we must pick the ones that belong to cytokinin.

Step 2: What cytokinins do.
Cytokinins are growth regulators that push cell division and keep leaves green and fresh.

Step 3: Check item I.
Cytokinins help make chloroplasts in leaves, so leaves stay green and delay ageing. So I is a cytokinin function.

Step 4: Check item IV.
Cytokinins wake up the side or lateral buds and so help overcome apical dominance. So IV is also a cytokinin function.

Step 5: Rule out II and III.
Stomatal closure (II) is the job of abscisic acid, ABA, during water stress. Root growth and root hair formation (III) is mainly promoted by auxins. So these two are not cytokinin functions.

Step 6: Conclusion.
Only I and IV fit cytokinin, so the correct answer is "I and IV". \[ \boxed{\text{I and IV}} \]