Test: Post-Fertilization (Structures & Events) - NEET MCQ

In coconut (Cocos nucifera), the surrounding white kernel called coconut meal is cellular endosperm and the coconut water (also called coconut milk) in the centre is free nuclear endosperm made up of thousands of nuclei.

Topic in NCERT: Endosperm Development

Line in NCERT: "The coconut water from tender coconut that you are familiar with, is nothing but free-nuclear endosperm (made up of thousands of nuclei) and the surrounding white kernel is the cellular endosperm."

∗ In the most common type of endosperm development, the PEN undergoes successive nuclear division to give rise to free nuclei.
∗ Embryo develops at the micropylar end of the embryo sac where zygote is situated.
Topic in NCERT: Endosperm
Line in NCERT: "In the most common type of endosperm development, the PEN undergoes successive nuclear divisions to give rise to free nuclei.
 Embryo develops at the micropylar end of the embryo sac where the zygote is situated.

• Endosperm is formed during double fertilization.
• It is triploid because it is formed when one of the two sperm that is haploid enters inside the embryo sac & fuses with two polar nuclei (each polar nuclei is haploid).
• So the endosperm formed is triploid.

Hence, the correct option is B.
Topic in NCERT: Endosperm
Line in NCERT: "The primary endosperm cell divides repeatedly and forms a triploid endosperm tissue."

• Endosperm can be classified into two types according on how it is consumed during development: endospermic and non-endospermic.
• If the endosperm is consumed by the growing embryo, it is said to be non-endospermic.
• In some plants, the endosperm is completely absorbed by the embryo, some of the examples are peas, beans, and green gram, in this type of food is stored in dicot seeds.
• Whereas in some dicots, food is stored in endosperm examples are castor, maize, etc.
• In the case of coconut, the endosperm is present in the liquid form and it is stored.

Hence, The correct answer is option (C).

Topic in NCERT: Endosperm

Line in NCERT: "Endosperm may either be completely consumed by the developing embryo (e.g., pea, groundnut, beans) before seed maturation or it may persist in the mature seed (e.g. castor and coconut) and be used up during seed germination."

After fertilisation, the integuments of the ovule form the protective coats (seed coats). Outer integument develops into testa and the inner one develops into tegmen.

Topic in NCERT: The development of fruit from the ovary

Line in NCERT: "The wall of the ovary develops into the wall of fruit called pericarp."

• The epicotyl bearing shoot apex and leaf primordia are enclosed in a foliar structure called coleoptile. It protects the plumule during emergence from the soil.
• The radicle is protected in a sheath called coleorhiza. It protects the radicle during its passage into the soil.
• So, the correct answer is " radicle, plumule ".

Topic in NCERT: Embryo

Line in NCERT: "At its lower end, the embryonal axis has the radical and root cap enclosed in an undifferentiated sheath called coleorrhiza. The portion of the embryonal axis above the level of attachment of scutellum is the epicotyl."

Given figure represents the monocotyledonous embryo of a grass.

Topic in NCERT: Embryo

Line in NCERT: "The cotyledon is called scutellum that is situated towards one side (lateral) of the embryonal axis. At its lower end, the embryonal axis has the radical and root cap enclosed in an undifferentiated sheath called coleorrhiza. The portion of the embryonal axis above the level of attachment of scutellum is the epicotyl. Epicotyl has a shoot apex and a few leaf primordia enclosed in a hollow foliar structure, the coleoptile."

In the most common type of endosperm development:
- The PEN undergoes successive nuclear divisions to give rise to free nuclei.
- Subsequently, cell wall formation occurs.
This process implies that the initial divisions of the PEN do not involve cell wall formation; instead, the formation of free nuclei precedes cell wall development. This sequence is a fundamental aspect of endosperm development, ensuring the creation of a structured cellular framework during this critical stage of plant growth.
Topic in NCERT: Endosperm"
Line in NCERT: "In the most common type of endosperm development, the PEN undergoes successive nuclear divisions to give rise to free nuclei. This stage of endosperm development is called free-nuclear endosperm."

(B) The correct answer is B: Globular embryo, Heart-shaped embryo, Mature Embryo.
- Globular embryo: At this stage, the embryo is spherical in shape.
- Heart-shaped embryo: The embryo develops into a heart shape as it matures.
- Mature Embryo: This is the final stage where the embryo is fully developed and ready for seed formation.
Understanding these stages helps track the growth of a dicot embryo from its early spherical form to its mature, seed-forming stage.Globular embryo, Heart shaped embryo, Mature Embryo
Topic in NCERT: Embryo
Line in NCERT: "The developing embryo passes through different stages such as the proembryo, globular and heart-shaped stages before maturation."

In angiosperms, endosperm is a triploid structure.
∴ 3n = 24 (given), then n = 8
As gametes are haploid structures, therefore number of chromosomes in gametes is 8

Correct option is D. A-Seed coat, B-Endosperm, C-Cotyledon, D-Hypocotyl

In some seeds, remains of nucellus persist. This residual nucellus which persists in the seed is called perisperm, e.g., black pepper, coffee, castor, cardamum, Nymphaea.

Topic in NCERT: Seed

Line in NCERT: "Occasionally, in some seeds such as black pepper and beet, remnants of nucellus are also persistent. This residual, persistent nucellus is the perisperm."

Endosperm development precedes embryo development because the endosperm provides nutrients to the developing embryo: 

• Endosperm formation

  During double fertilization, one sperm nucleus enters the embryo sac and fuses with two polar nuclei to create the endosperm. 

• Endosperm function

  The endosperm provides nutrients to the embryo, protects it, and controls its growth. In mature albuminous seeds, the endosperm stores starch and fat.

Topic in NCERT: Endosperm

Line in NCERT: "Endosperm development precedes embryo development."

Nuclear endosperm (X) is the most common type of endosperm. It is named so because it contains free nuclei in the beginning. The primary endosperm nucleus divides of free nuclei. Meanwhile central vacuole appears in the central cell and pushes the cytoplasm containing the nuclei to the periphery. The cytoplasm thickens so that the vacuole decreases in size. It ultimately disappears with the exception of a few cases. The multinucleate cytoplasm undergoes cleavage and gives rise to a multicellular tissue, e.g., maize, wheat, rice, sunflower, Capsella bursa-pastoris.

Topic in NCERT: Endosperm

Line in NCERT: "Endosperm development is called free-nuclear endosperm."

- A: Plumule
- Function: Develops into the shoot system, including stems and leaves. It is the embryonic shoot.
- B: Cotyledons
- Function: Seed leaves that store nutrients for the embryo. In dicots, they typically store food to support the seedling's growth.
- C: Radicle
- Function: Develops into the root system. It is the first part of the embryo to emerge during germination.
These components collectively form the embryonal axis of a dicotyledonous embryo.

Topic in NCERT: Embryo
Line in NCERT: "A typical dicotyledonous embryo (Figure 1.14a), consists of an embryonal axis and two cotyledons."