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.322Easy
Which of the following is NOT a function of the filament in a stamen?
Answer: C
The filament supports and elevates the anther. Pollen production occurs in the anther's microsporangia, not in the filament. The filament conducts nutrients and water.
Q.323Easy
In the double fertilization process of angiosperms, one sperm nucleus fuses with the egg nucleus. What is the ploidy level of the resulting zygote?
Answer: B
When a haploid sperm (n) fuses with a haploid egg cell (n), the resulting zygote is diploid (2n), which develops into the embryo.
Q.324Medium
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.325Easy
The ovule integument develops into the seed coat. How many integuments do most dicot plants possess?
Answer: B
Most dicotyledonous plants have bitegmic ovules (two integuments), which develop into the seed coat layers.
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Q.326Medium
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.327Medium
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.328Medium
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.329Medium
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.330Medium
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.331Medium
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.332Medium
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.333Easy
Which of the following plants reproduces primarily through runners or stolons?
Answer: B
Strawberry reproduces vegetatively through runners (stolons) that produce new plants at nodes, enabling rapid vegetative propagation.
Q.334Hard
The endothecium in the anther wall is important for:
Answer: B
The endothecium contains fibrous thickenings on cell walls that help in anther dehiscence by creating tension during drying, aiding pollen dispersal.
Q.335Medium
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.336Easy
Which stage of the plant life cycle shows dominance of the diploid phase in angiosperms?
Answer: B
In angiosperms, the sporophytic phase (diploid multicellular plant body) is dominant, while the gametophytic phase is reduced and represented by pollen and embryo sac.
Q.337Hard
The phenomenon where pollen grains retain viability after being kept in dry conditions for extended periods is called:
Answer: A
Pollen dormancy refers to the reduced metabolic activity of pollen that allows it to maintain viability over extended storage periods in dry, cool conditions.
Q.338Hard
In a typical angiosperm flower, after dehiscence, the mature pollen is released at which stage?
Answer: B
Most angiosperms release pollen at the binucleate stage (containing generative and vegetative nuclei). Some release at the trinucleate stage after generative nucleus division.
Q.339Medium
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).
Q.340Hard
In orchids, the lack of endosperm development is compensated by:
Answer: B
Many orchids have seeds without endosperm (lacking nutritious reserve tissue). They require mycorrhizal fungal associations to obtain nutrients from the soil for germination and growth.
