Sexual reproduction in flowering plants practice · Mixed difficulty

Option D (Two polar nuclei) is correct because in angiosperms, triple fusion involves the fusion of a second sperm with two polar nuclei to form the endosperm.

Option D (Both (A) and (R) are false) is correct because insects visit flowers for both nectar and pollen, not just honey, and the attraction of flowers doesn't necessarily prevent them from damaging other parts of the plant.

Option A (TRUE) is correct because in coconut, the cellular endosperm does indeed surround the nuclear endosperm.

Option C (Nourish the developing pollen grains) is correct because the tapetum is the innermost layer of the anther and provides nutrients to the developing pollen grains.

Option D (Generative cell) is correct because in angiosperms, the generative cell divides to form two male gametes.

Option D (Asexual reproduction) is correct because apomixis is a form of asexual reproduction that mimics sexual reproduction.

Option D (16) is correct because each anther typically has four microsporangia (pollen sacs), and each microspore mother cell within these sacs undergoes meiosis to produce four pollen grains. If there are four cells in an anther, and each cell is a microspore mother cell, then 4 cells * 4 pollen grains/cell = 16 pollen grains.

Option A (I, II & III are correct) is correct because hydrophily is rare, pollen grains are protected by mucilage, and some plants release pollen inside the water.

Option B (Both A and R are true and R is not the correct explanation of A) is correct because both the assertion and reason are true statements, but the reason doesn't explain the assertion.

Option B (Elephant) is correct because elephants are known to disperse the seeds of Rafflesia by consuming the fruits and excreting the seeds in different locations.

The correct answer is B (Homozygosity) because repeated selfing, or self-fertilization, leads to an increase in homozygosity as the same alleles are combined over generations.

The correct answer is A (Fusion of male gamete with diploid secondary nucleus) because vegetative fertilization in angiosperms refers to the fusion of a sperm cell with the secondary nucleus to form the triploid endosperm.

Option C (Both (a) and (b)) is correct because both vegetative/asexual reproduction and apomixis involve a type of cell division that doesn't involve meiosis and result in offspring that are clones of the parent.

Option B (24) is correct because the aleurone layer is triploid (3n), and if synergids (n) have 8 chromosomes, then the aleurone layer has 3 * 8 = 24 chromosomes.

Option D (30 min) is correct because rice and wheat pollen grains lose viability within 30 minutes of their release.

The correct answer is B (Large, colourful, fragrant and rich in nectar) because insect-pollinated flowers typically have these characteristics to attract insects for pollination.

Option A (Both S-I and S-II are correct) is correct because unisexual flowers indeed have separate male and female reproductive organs, and both monoecious and dioecious plants bear such flowers.

Option C (Develops from unfertilized ovary) is correct because parthenocarpic fruits develop without fertilization, resulting in seedless fruits.

Option B (Has three celled egg apparatus) is correct because the egg apparatus consists of the egg cell and two synergid cells.

Option C (100) is correct because each pollen mother cell produces 4 pollen grains, and each seed requires one pollen grain. Therefore, 400 seeds require 400 pollen grains, which are produced by 100 pollen mother cells.

Option A (Never open) is correct because cleistogamous flowers are characterized by remaining closed, ensuring self-pollination.

Option A ($4 n$ and $3 n$) is correct because the PEN is formed by the fusion of two polar nuclei (2n+2n) from the female and one sperm (4n/2 = 2n) from the male, resulting in 4n, and the zygote is formed by the fusion of one egg (2n) and one sperm (2n) resulting in 4n/2 + 2n = 3n.

Option D (16) is correct because each microsporocyte undergoes meiosis to produce 4 pollen grains. Therefore, 4 microsporocytes will produce 4 x 4 = 16 pollen grains.

Option A (Dioecy) is correct because dioecy, the condition of having separate male and female plants, strictly prevents autogamy and geitonogamy, thus promoting xenogamy.

Option C (Dry and edible pollen grains) is correct because anemophilous and hydrophilous flowers typically have non-edible pollen grains, as they are not meant to attract pollinators for food. They are also dry to facilitate wind dispersal.

Option D (Animals for pollination) is the correct answer because the majority of plants rely on animals as biotic agents for pollination.

The correct answer is C (Both (a) and (b)) because parthenocarpic fruits are indeed seedless, and parthenocarpy can be induced by hormones.

Option B (Cladophora) is correct because Cladophora involves the fusion of morphologically similar gametes (isogametes).

Option A (Carion flies) is correct because Rafflesia, known for its carrion-like odor, attracts carrion flies for pollination.

Option A (Vegetative cell is not damaged) is correct because the vegetative cell controls pollen tube growth, and if it remains intact, the pollen tube can still form despite the generative cell being destroyed.