Question

Seedlings grown in the dark are
a.Similar to those grown in the light.
b.Taller than those grown in the light.
c.Shorter than those grown in the light.
d.Not able to grow.

Answer 1

Hint: Seedling is referred to as a young plant sporophyte. It develops out of a plant embryo from a seed. A typical seedling has three parts - embryonic root or radicle, embryonic shoot or hypocotyl and seed leaves or cotyledons.

Complete Answer:
It is a well-known fact that plants require an adequate amount of water, nutrients, and sunlight for their proper growth and development. When plants do not receive enough sunlight or are grown in areas of darkness, branches and stems of such plants tend to bend towards the source of light. This is one of the tropic movements of plants. Because of this curvature and bending, it appears that plants that grow in darkness are taller.

The reason behind the seedlings which are grown in darkness is taller compared to the seedlings which are grown in the light is that the production of the photosensitive phytohormone auxin occurs. This causes an increase in the height of the plants. This hormone is destroyed in the presence of light and so the plants which are grown in light are comparatively shorter.

Thus, the correct option is b) Taller than those grown in the light.

Note: The growth of seedling is also affected by the colour of light. When the seedling is exposed to red and blue light it was seen that there was an effective plant growth. Red light helps by stimulating vegetative growth and flowering while blue light regulates plant growth. It is to be noted that the amount of light given to the plant should be controlled as too much exposure is also not good.