Question

At what stage does the diploid zygote form?

a. when the female cone begins to bud from the tree

b. at fertilization

c. when the seeds drop from the tree

d. when the pollen tube begins to grow

Short answer

The correct option is (b). at fertilization.

Step-by-step solution

Step 1. Introduction

Fertilization is the fusion of sperm nucleus and female nucleus takes place to form a diploid zygote.

Step 2. Reason for incorrect option

• The female cone grows as the seeds mature, getting larger and browner.
• When the seeds drop from the tree diploidzygote doesn't form.
• Pollen tube growth isinfluenced by the interaction between the stigma-style and the pollen grain.

Step 3. Reason for correct option

• Upon fertilization, a diploid zygote forms.
• The diploid zygote forms after the pollen tube has finished forming so that the male generative nucleus (sperm) can fuse with the female egg.