Practicing Success

Target Exam

CUET

Subject

Biology

Chapter

Sexual Reproduction in Flowering Plants

Question:

Arrange the following stages of development of a dicot embryo in the order of their occurrence:

(A) Formation of heart-shaped embryo

(B) Formation of typical dicot embryo

(C) Formation of zygote

(D) Formation of globular embryo

Choose the correct answer from the options given below:

Options:

(A), (B), (C), (D)

(C), (D), (A), (B)

(C), (A), (B), (D)

(D), (A), (B), (C)

Correct Answer:

(C), (D), (A), (B)

Explanation:

The correct answer is Option (2): (C), (D), (A), (B)

(C) Formation of zygote

(D) Formation of globular embryo

(A) Formation of heart-shaped embryo

(B) Formation of typical dicot embryo

Embryo develops at the micropylar end of the embryo sac where the zygote is situated. Most zygotes divide only after certain amount of endosperm is formed. This is an adaptation to provide assured nutrition to the developing embryo. Though the seeds differ greatly, the early stages of embryo development (embryogeny) are similar in both monocotyledons and dicotyledons. 

The zygote gives rise to the proembryo and subsequently to the globular, after that heart-shaped and mature embryo.

A typical dicotyledonous embryo consists of an embryonal axis and two cotyledons. The portion of embryonal axis above the level of cotyledons is the epicotyl, which terminates with the plumule or stem tip. The cylindrical portion below the level of cotyledons is hypocotyl that terminates at its lower end in the radicle or root tip. The root tip is covered with a root cap.