Question 1

The response of plants to the relative lengths of day and night (which affects flowering) is called:

Accepted Answer

Photoperiodism. Photoperiodism is the dependence of flowering on the duration of light/dark periods.

Question 2

The promotion of flowering by a period of low temperature (cold treatment) is called:

Accepted Answer

Vernalisation. Vernalisation is the low-temperature requirement for flowering in some plants (e.g. winter wheat).

Question 3

Short-day plants flower when the ______ exceeds a critical length:

Accepted Answer

Continuous dark period (night). It is actually the uninterrupted dark period that matters — short-day plants need a long enough continuous night.

Question 4

The site of perception of the photoperiodic (light/dark) stimulus is the ______, though flowering occurs at the ______:

Accepted Answer

Leaves; shoot apex. Leaves perceive the photoperiod and produce a hormonal signal (florigen) that induces flowering at the shoot apex.

Question 5

Interrupting the long dark period of a short-day plant with a flash of light will:

Accepted Answer

Prevent flowering. A light break during the critical dark period stops flowering in short-day plants — confirming the dark period is decisive.

Question 6

Vernalisation prevents precocious flowering and allows plants like winter varieties of wheat to flower in ______ by ______:

Accepted Answer

Spring; exposing seedlings/seeds to a period of low temperature. Cold treatment of germinating seeds/seedlings (vernalisation) enables winter varieties to flower in the next spring/summer.

Photoperiodism & Vernalisation — NEET Biology MCQs with Solutions

Questions with solutions