Which of the following represents the correct sequence of events in double fertilization?
Answer: A
In double fertilization, one sperm fuses with the egg to form zygote, and the other fuses with two polar nuclei to form primary endosperm nucleus.
Q.2Medium
The embryo sac in flowering plants develops from:
Answer: C
The functional megaspore undergoes mitotic divisions to develop into the embryo sac (female gametophyte).
Q.3Medium
In a typical angiosperm, how many mitotic divisions occur in the male gametophyte after meiosis?
Answer: A
After meiosis produces microspores, one mitotic division produces a two-celled pollen grain (mature male gametophyte).
Q.4Medium
Which of the following is NOT a method of vegetative propagation?
Answer: C
Pollination is part of sexual reproduction, not vegetative propagation. It involves transfer of pollen.
Q.5Medium
The endosperm in angiosperms is:
Answer: C
Endosperm is triploid (3n), formed by fusion of one sperm nucleus (n) with two polar nuclei (2n).
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Q.6Medium
Which stage represents the gametophytic phase in the life cycle of angiosperms?
Answer: B
Pollen grain (male gametophyte) and embryo sac (female gametophyte) represent the gametophytic phase in angiosperms.
Q.7Medium
The synergid cells in the embryo sac function to:
Answer: B
Synergids guide the pollen tube towards the egg apparatus and help in pollen tube entry through the filiform apparatus.
Q.8Medium
Which of the following correctly describes the ploidy level changes during sexual reproduction?
Answer: B
Meiosis reduces ploidy from diploid (2n) to haploid (n), while fertilization restores diploid (2n) condition.
Q.9Medium
The primary endosperm nucleus in angiosperms is formed by:
Answer: B
The primary endosperm nucleus is formed by the fusion of one sperm cell with the two polar nuclei (or secondary nucleus), making it triploid.
Q.10Medium
During megasporogenesis in angiosperms, a megaspore mother cell undergoes meiosis to produce four megaspores. In most flowering plants, how many of these megaspores degenerate?
Answer: C
In typical monosporic development, the megaspore mother cell produces four megaspores through meiosis, but only one (usually the chalazal megaspore) survives and develops into the female gametophyte. The other three degenerate.
Q.11Medium
Identify the correct sequence: Microspore → ? → Pollen grain → Male gametophyte
Answer: D
A microspore undergoes mitosis to form the male gametophyte (2-celled or 3-celled pollen grain consisting of generative and vegetative cells). The pollen grain itself is the male gametophyte.
Q.12Medium
In the mature female gametophyte (embryo sac) of angiosperms, how many nuclei are present at maturity?
Answer: D
The mature female gametophyte (7-celled, 8-nucleate) contains: 1 egg cell, 2 synergids, 2 polar nuclei (in central cell), and 3 antipodal cells = 8 nuclei total.
Q.13Medium
The phenomenon of vegetative reproduction in bryophyllum (Kalanchoe) by leaf margins is an example of:
Answer: C
In Bryophyllum, small adventitious buds form at the margins of leaves, which can develop into new plants when they fall to the soil.
Q.14Medium
Microsporogenesis differs from megasporogenesis in flowering plants primarily in that:
Answer: A
In microsporogenesis, all four microspores produced from meiosis are typically functional. In megasporogenesis, usually three of the four megaspores degenerate, leaving only one functional megaspore.
Q.15Medium
The tapetum in the anther is primarily involved in:
Answer: B
The tapetum is a nutritive tissue layer that provides nutrients to developing microspores and pollen grains through absorption and transfer.
Q.16Medium
In apomixis, the embryo develops from:
Answer: B
Apomixis is asexual reproduction through seeds where the embryo develops from an unfertilized egg cell (apomeiotic parthenogenesis) or other cells without meiosis or fertilization.
Q.17Medium
The nucellus in an ovule functions primarily to:
Answer: C
The nucellus is the nutritive tissue surrounding the megasporangium that provides nutrients to the developing megaspore and female gametophyte.
Q.18Medium
The polar nuclei in the central cell of the embryo sac fuse with the second sperm nucleus to form the:
Answer: A
The fusion of two polar nuclei (2n) with one sperm nucleus (n) produces the primary endosperm nucleus (3n), which develops into the endosperm tissue.
Q.19Medium
In the pollen grain, the generative nucleus is located in the:
Answer: C
The generative nucleus lies within the vegetative (or tube) cell in mature pollen. The vegetative cell also contains a large vacuole.
Q.20Medium
The ploidy level of the endosperm in a typical angiosperm is:
Answer: C
The endosperm is triploid (3n) because it develops from the primary endosperm nucleus, which is formed by fusion of two polar nuclei (2n) and one sperm nucleus (n).
