Part 6 — Post-fertilization events: development of endosperm & embryo (25 MCQs)

Q101. Primary endosperm nucleus (PEN) formed after double fertilization divides to form:

a) Endosperm tissue which nourishes embryo (may be cellular, nuclear, or helobial types)
b) Embryo directly
c) Seed coat
d) Cotyledon

Answer: a) Endosperm tissue which nourishes embryo (may be cellular, nuclear, or helobial types)

(a) Correct. PEN gives rise to endosperm, the nutritive tissue.

Q102. Types of endosperm development include:

a) Nuclear, cellular and helobial types
b) Linear, radial, circular types
c) Monocarpic & polycarpic types
d) None of the above

Answer: a) Nuclear, cellular and helobial types

(a) Correct. Classifications based on cytokinesis pattern after PEN division.

Q103. Nuclear type of endosperm development is characterised by:

a) Free nuclear divisions of PEN followed later by cell wall formation
b) Immediate cytokinesis after each nuclear division
c) No division occurs
d) Multiple pollen tubes enter ovule

Answer: a) Free nuclear divisions of PEN followed later by cell wall formation

(a) Correct. Most angiosperms exhibit nuclear endosperm (e.g., cereals).

Q104. The suspensor in plant embryo functions to:

a) Protect seed coat only
b) Push embryo into nutritive tissue and sometimes transfer nutrients from endosperm to embryo
c) Become primary root only
d) Form endosperm

Answer: b) Push embryo into nutritive tissue and sometimes transfer nutrients from endosperm to embryo

(b) Correct. Suspensor acts as anchorage and nutrient conduit, sometimes degenerates later.

Q105. First division of zygote in Arabidopsis or typical angiosperm is:

a) Symmetrical producing two equal cells only
b) Asymmetrical producing a small terminal cell and a larger basal cell, latter forming suspensor and basal part, terminal forming embryo proper
c) Produces cotyledons immediately
d) Random multinucleate cell

Answer: b) Asymmetrical producing a small terminal cell and a larger basal cell

(b) Correct. Basal cell forms suspensor; terminal forms proembryo.

Q106. Colbert: Stage when embryo shows heart shape (in dicots) is called:

a) Globular stage
b) Heart-shaped stage (due to cotyledon initiation)
c) Torpedo stage
d) Mature stage

Answer: b) Heart-shaped stage (due to cotyledon initiation)

(b) Correct. After globular stage, cotyledons initiate producing heart-shaped embryo.

Q107. The cotyledons in dicots arise from:

a) External integument
b) Embryo proper during heart stage
c) Endosperm only
d) Suspensor

Answer: b) Embryo proper during heart stage

(b) Correct. Cotyledons develop from embryo proper.

Q108. Endosperm formed before embryo development is retained as:

a) Endospermic seeds (e.g., cereals — maize, wheat) where endosperm stores reserve
b) Non-endospermic seeds (dicots) always
c) Absent in all monocots
d) Always 2n tissue

Answer: a) Endospermic seeds (e.g., cereals — maize, wheat) where endosperm stores reserve

(a) Correct. Many monocots retain endosperm. Dicots often absorb it into cotyledons (non-endospermic seeds).

Q109. In many dicots endosperm is:

a) Persistent at maturity
b) Absorbed by cotyledons and absent at maturity (non-endospermic)
c) Converted into seed coat
d) Never formed

Answer: b) Absorbed by cotyledons and absent at maturity (non-endospermic)

(b) Correct. E.g., pea, bean: endosperm used to form cotyledons.

Q110. Polyembryony refers to:

a) Single embryo formation per seed always
b) Formation of multiple embryos in a single seed (may result from cleavage of zygote, fertilization of more than one egg or from adventive embryony)
c) No embryo formation
d) Fusion of embryos

Answer: b) Formation of multiple embryos in a single seed

(b) Correct. Seen in citrus and some other plants.

Q111. In many plants embryo development progresses: globular → heart → torpedo → mature. Which feature is formed in torpedo stage?

a) Root and shoot meristem and elongation along axis producing torpedo shape; cotyledons elongated
b) Pollination occurs
c) Endosperm forms
d) Seed coat forms only

Answer: a) Root and shoot meristem and elongation along axis producing torpedo shape; cotyledons elongated

(a) Correct. Torpedo stage has elongating embryo body and more definite axis.

Q112. Suspensor usually degenerates at:

a) Early zygote stage always
b) After embryo becomes established and cotyledons develop; sometimes persists in some species
c) Never degenerates
d) Immediately after pollination

Answer: b) After embryo becomes established and cotyledons develop; sometimes persists in some species

(b) Correct. Suspensor may disintegrate after serving nutritive role.

Q113. In endosperm development, helobial type is found in:

a) Solanaceae only
b) Members of family Liliaceae only
c) Some groups like Brassicaceae? (Actually helobial in family Brassicaceae? — typical example is family Cruciferae? but standard answer: Helobial endosperm occurs in some monocots like Alismataceae and in some families)
(Hold short explanation — pick standard example)

Answer: Helobial endosperm occurs in some monocots (e.g., Alismataceae) — but because question expects classification identify helobial as one of three types

Explanation: Helobial: first division results in two unequal cells — one undergoes nuclear type divisions, the other cellular type. Not extremely common.

(Note: For exam focus remember the three main types: nuclear (most common), cellular, helobial)

Q114. Primary endosperm nucleus (PEN) typically is formed by fusion of:

a) Egg and sperm
b) Two polar nuclei and one sperm → triploid (3n) PEN
c) Two eggs
d) One egg and two sperms

Answer: b) Two polar nuclei and one sperm → triploid (3n) PEN

(b) Correct. Formation of primary endosperm nucleus.

Q115. Endosperm that is formed by fusion of diploid central cell and haploid sperm to form 2n endosperm occurs in:

a) All angiosperms always 3n PEN
b) Some special groups (rare) — e.g., family of some species exhibit diploid endosperm — but standard: in most plants PEN = 3n.
(This question is nuanced — many angiosperms are 3n but some groups like some orchids/tulips differ.)

Answer: Generally, most angiosperms form 3n endosperm (Polygonum type).

Explanation: Some exceptions exist where polar nuclei fuse before or after depending species; extreme cases have variable ploidy — NEET focuses on 3n common case.

Q116. Cotyledons are primarily:

a) Leaf-like embryonic structures that store food or transfer food to embryo in some seeds
b) Part of seed coat
c) Pollen grains
d) Only in monocots

Answer: a) Leaf-like embryonic structures that store food or transfer food to embryo in some seeds

(a) Correct. Cotyledons can store reserves (dicots) or absorb endosperm (dicots) or be single in monocots.

Q117. Hypocotyl is the embryonic part that connects:

a) Radicle and cotyledons/shoot; forms transition between root and shoot axis
b) Tip of the radicle only
c) Seed coat and endosperm
d) Ovule and ovary

Answer: a) Radicle and cotyledons/shoot; forms transition between root and shoot axis

(a) Correct. Hypocotyl is embryonic stem below cotyledons.

Q118. In a typical dicot embryo, epicotyl gives rise to:

a) Root system
b) Plumule (shoot apical meristem and young leaves)
c) Seed coat
d) Endosperm

Answer: b) Plumule (shoot apical meristem and young leaves)

(b) Correct. Epicotyl is shoot above cotyledons.

Q119. In many legumes, endosperm is entirely consumed by embryo and food is stored in:

a) Seed coat
b) Cotyledons
c) Endosperm (persisting)
d) Fruit pulp only

Answer: b) Cotyledons

(b) Correct. E.g., pea/gram: cotyledons are food reserves.

Q120. Germination-ready seed possesses which of these?

a) Fully differentiated embryo with radicle and shoot apex, stored food (endosperm or cotyledons), and intact seed coat — viability and proper dormancy conditions determine germination
b) Only endosperm, no embryo
c) Only embryo, no reserves
d) None of the above

Answer: a) Fully differentiated embryo with radicle and shoot apex, stored food (endosperm or cotyledons), and intact seed coat

(a) Correct. Seeds contain embryo + food reserves + seed coat.

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Part 6 — Post-fertilization events: development of endosperm & embryo (25 MCQs)