Chapter 23, Problem 5STP

Summary Introduction

Introduction:

The conifers are heterosporous. They form two spores,one develops in male and the other in the female gametophyte. The female cone has two ovules, each undergoes meiosis in the megasporangium forming four megaspores. Three of them disintegrate and the remaining megasporeundergoes mitotic division and form female gametophyte. The male cone are the pollen grains, which undergo meiosis and form micropores as they have a small reproductive scale. The pollen grains are transported to the female reproductive part through air or wind. If this pollen falls near the micropyle, that is, the opening of the ovule, it gets trapped in a sticky substance termed as pollen drop. Ones the pollen drop gets absorbed inside the ovule, the pollens is pulled close to the micropyle and there the pollen grain continues to develop.

Answer to Problem 5STP

Correct answer:

The correct answer is option (D)wind.

Explanation of Solution

Explanation/justification for the correct answer:

Option (D) wind. The male cone or the pollen grains transported to the female reproductive part through air or wind as they are very light weighted.So, the correct answer is option (D).

Explanation for incorrect answer:

Option (A) birds. The conifers like lycophytes are short heightened and the pollens are very light weighted. The birds do not pollinate for them.So, this is an incorrect option.

Option (B) insects. Sometimes insects are involved in the pollination of conifers but they are not the primary pollinator.So, this is an incorrect answer.

Option (C) water. Water is also involved in pollination but for conifers, water is not the primary pollinator.So, this is an incorrect answer.