Part 3 — Megasporogenesis & female gametophyte (embryo sac) (25 MCQs)

Q46. Megasporogenesis occurs in:

a) Anther locule
b) Ovule (megasporangium) within ovary
c) Style
d) Sepal

Answer: b) Ovule (megasporangium) within ovary

(b) Correct. Megasporocyte in ovule undergoes meiosis to produce megaspores.
Others incorrect.

Q47. In typical angiosperm (Polygonum type), megaspore mother cell undergoes meiosis to produce:

a) Four functional megaspores that all develop
b) Four megaspores; three degenerate, one functional near chalaza (or micropylar depending on species)
c) Two megaspores only
d) Many megaspores by mitosis

Answer: b) Four megaspores; three degenerate, one functional near chalaza (or micropylar depending on species)

(b) Correct. Polygonum type: one functional megaspore (usually chalazal-most) gives embryo sac.
Others incorrect.

Q48. The functional megaspore gives rise to a:

a) Male gametophyte
b) Female gametophyte (embryo sac) through three mitotic divisions
c) Endosperm directly
d) Pollen tube

Answer: b) Female gametophyte (embryo sac) through three mitotic divisions

(b) Correct. One megaspore undergoes three mitoses to form 8-nucleate embryo sac.
Others incorrect.

Q49. A mature Polygonum-type embryo sac typically contains:

a) 4 nuclei only
b) 8 nuclei — arranged as 1 egg, 2 synergids, 3 antipodals, 2 polar nuclei (central cell)
c) 6 nuclei always
d) 3 nuclei only

Answer: b) 8 nuclei — arranged as 1 egg, 2 synergids, 3 antipodals, 2 polar nuclei (central cell)

(b) Correct. Classic 8-nucleate, 7-celled structure (central cell has 2 polar nuclei).
Others incorrect.

Q50. The two nuclei in the central cell of embryo sac are called:

a) Egg and synergid
b) Polar nuclei
c) Antipodal nuclei
d) Pollen nuclei

Answer: b) Polar nuclei

(b) Correct. Two polar nuclei fuse with one male gamete to form primary endosperm nucleus (PEN) during double fertilization.
Others wrong.

Q51. Synergids function to:

a) Nourish embryo after fertilization only
b) Attract and guide pollen tube and often degenerate, facilitating fertilization
c) Protect ovule physically only
d) Form endosperm

Answer: b) Attract and guide pollen tube and often degenerate, facilitating fertilization

(b) Correct. Synergids help pollen tube entry and orientation.
Others incorrect.

Q52. Antipodal cells are located:

a) Near micropyle
b) At chalazal end of embryo sac
c) Within integuments
d) Outside ovule

Answer: b) At chalazal end of embryo sac

(b) Correct. Antipodals are at opposite end to micropyle.
Others incorrect.

Q53. The egg apparatus includes:

a) Egg cell + two synergids + one polar nucleus
b) Egg + two synergids (forming egg apparatus)
c) Egg only
d) Antipodals only

Answer: b) Egg + two synergids (forming egg apparatus)

(b) Correct. Egg apparatus = egg cell + two synergids (near micropyle).
Polar nuclei are central cell components.

Q54. Integuments of ovule develop into:

a) Embryo
b) Seed coat (testa and tegmen) after fertilization
c) Endosperm
d) Flower petals

Answer: b) Seed coat (testa and tegmen) after fertilization

(b) Correct. Integuments form seed coat layers after fertilization.
(a,c,d) Incorrect.

Q55. The micropyle in mature seed allows:

a) Entry of pollen directly during anthesis
b) Passage for pollen tube during fertilization and later the radicle emergence during germination
c) Protection only
d) Formation of endosperm

Answer: b) Passage for pollen tube during fertilization and later the radicle emergence during germination

(b) Correct. Micropyle is small opening at seed surface.

Q56. Gymnosperm ovules commonly have:

a) Two integuments
b) One integument (unitegmic)
c) No integuments
d) Multiple micropyles only

Answer: b) One integument (unitegmic)

(b) Correct. Gymnosperms typically unitegmic; angiosperms bitegmic.
(a) Angiosperms usually bitegmic.

Q57. Which cell(s) of the embryo sac fuse with the two male gametes during double fertilization?

a) Egg and one synergid
b) Egg and central cell polar nuclei (forming zygote and PEN)
c) Two antipodals
d) Synergids only

Answer: b) Egg and central cell polar nuclei (forming zygote and PEN)

(b) Correct. One sperm fertilizes egg → zygote; other fuses with polar nuclei → primary endosperm nucleus.

Q58. Which of the following embryo sac development types is the most common in angiosperms?

a) Polygonum type (monosporic)
b) Oenothera type (cellular)
c) Allium type (bisporic)
d) Peperomia type (tetrasporic)

Answer: a) Polygonum type (monosporic)

(a) Correct. Polygonum monosporic 8-nucleate type is most common.
Others less common.

Q59. A bitegmic ovule means:

a) Ovule with two carpels
b) Ovule having two integuments
c) Two ovules fused
d) Two micropyles present

Answer: b) Ovule having two integuments

(b) Correct. Bitegmic = two integuments.
Others wrong.

Q60. The megaspore mother cell is:

a) Diploid (2n) and undergoes meiosis
b) Haploid and undergoes mitosis
c) Triploid
d) Multinucleate syncytium

Answer: a) Diploid (2n) and undergoes meiosis

(a) Correct. Megasporocyte is 2n and undergoes meiosis to produce megaspores.

Q61. In angiosperm embryo sac, the two nuclei that fuse with one sperm are located in:

a) Egg cell
b) Central cell (polar nuclei)
c) Synergids
d) Antipodals

Answer: b) Central cell (polar nuclei)

(b) Correct. Fusion yields triploid primary endosperm nucleus.

Q62. Which structure secretes substances to guide the pollen tube to micropyle?

a) Nucellus
b) Synergids (one degenerate as pollen tube enters)
c) Antipodals
d) Outer integument

Answer: b) Synergids (one degenerate as pollen tube enters)

(b) Correct. Synergids secrete attractants; one often degenerates on pollen tube reception.

Q63. The chalaza is:

a) Micropylar end of ovule
b) Opposite end of micropyle, where nucellus and integuments join
c) A type of embryo sac
d) Pollen tube pathway

Answer: b) Opposite end of micropyle, where nucellus and integuments join

(b) Correct. Chalazal end anchors ovule.

Q64. When a functional megaspore is the one near micropyle (rather than chalaza), it’s called:

a) Basal functional megaspore (chalazal)
b) Micropylar functional megaspore — leading to Allium-type embryo sac (bisporic/trisporic variations)
c) Antipodal megaspore
d) None of the above

Answer: b) Micropylar functional megaspore — leading to Allium-type embryo sac

(b) Correct. There are variations — functional megaspore position differs across types.

Q65. An embryo sac that develops from all four megaspore nuclei without typical degeneration is called:

a) Monosporic
b) Bisporic
c) Tetrasporic (polysporic)
d) Aposporous

Answer: c) Tetrasporic (polysporic)

(c) Correct. Tetrasporic embryo sacs involve all nuclei (e.g., Fritillaria).

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Part 3 — Megasporogenesis & female gametophyte (embryo sac) (25 MCQs)