Question

Cytokinins are known to
A) Inhibit cytoplasmic movement
B) Help in retention of chlorophyll
C) Influence water movement
D) Promote abscission layer formation

Answer 1

Hint: Cytokinins causes re-greening of yellowing leaves.

Complete Answer:
- Cytokinins are a kind of plant hormone that mainly promotes cell division and is a purine adenine derivative.
- The roots produce them, and move up through the xylem. Farmers also use cytokinins to encourage plant growth, and are known to play an important role in plant pathogenesis. These hormones were present in all complex plants, including fungi, mosses, and bacteria. Today the botanists know over 200 different natural and synthetic cytokinins.

Now, let us find the solution from the options-
- Richmond and Lang (1957) first demonstrated that treatment with cytokinin contributes to greater retention of chlorophyll and protein in removed cocklebur plant leaves (Xanthium pennsylvanicum).
- Cytokinins are well known to have an effect on the retention of chlorophyll from higher plants.
- This cytokinin effect has now been seen in several other species, including causing yellowing leaves to re-green.
- Experimentation has led to an understanding that the increase in durability of cytokinin is unique to leaves and it could be affected by other factors such as light and sugar.

Thus, the correct answer is option (B) Help in retention of chlorophyll.

Note: Chlorophyll a and b have been affected by cytokinins. Retention of chlorophyll is only one indicator of leaf photosynthetic activity, as photosynthesis can decline far before declining chlorophyll content.