Question

Name a hormone which

a. is gaseous in nature

b. is responsible for phototropism

c. induces femaleness in flowers of cucumber

d. is used for killing weeds (dicots)

e. induces flowering in long day plants

Answer 1

a. Gaseous hormone:

H. H. Cousins confirmed that unripe bananas transported with ripened oranges ripened fast. The spoiled oranges were observed to release a volatile substance. The volatile substance was later found to be ethylene.


Final answer: Ethylene.

b. Hormone responsible for phototropism:

The response of plants toward light is called phototropism. In response to light, the following events take place:-

• Auxins move toward the shady regions forming a concentration gradient. Auxins cause the cells of the shady region to elongate.
• There is more growth in this shady region compared to the region exposed to light.
• This results in the bending of the tip towards the light.

Final answer: Auxin.

c. Hormone inducing femaleness in flowers of cucumber:

Ethylene is a gaseous phytohormone. It plays several important roles, one of which is the promotion of female flower formation in genetically male plants, for example, in cucumber.

Final answer: Ethylene.

d. Hormone as weedicides:

2,4-D (2,4-dichlorophenoxyacetic acid), a synthetic auxin, in excess acts as a weedicide specifically killing the dicotyledonous weeds and not monocots like grass.

Final answer: Auxin.

e. Hormone inducing flowering in Long day plants:

The long day plants are those plants that require a photoperiod longer than the critical photoperiod for flowering.

When long day plants do not receive sufficient light, gibberellins can be sprayed onto them to initiate flowering.

Final answer: Gibberellins.