Sexual Reproduction in Flowering Plants Test - 60

Correct Option: B

The bulb is the modified underground stem surrounded by the fleshy leaves. It usually contains stored food like the tulip bulb. Also, a capsule is a type of simple but mostly dry and dehiscent fruit. Some examples are Cotton, Eucalyptus, Datura, Witch Hazel. Orchid seeds don’t have endosperm. Primrose is having free central placentation.

Thus, the correct answer is option D.

Ovum is female gamete in the flower. Stigma is the female part of flower, which receives pollen and style is the stalk of carpel. The male gametes of the flower are transferred on to the female reproductive organs through pollinators. The final product of this process is the formation of embryo in a seed. During polination stigma first receives the pollen. 
Thus, the correct answer is option (A), 'Stigma'.

• Adventive embryony, is also known as sporophytic apomixis, sporophytic budding, or nucellar embryony.
• In this process, megagametophyte in the ovule does not give rise to embryos rather they arise from cells of the nucellus of the integument. 
• It takes place without fertilization, therefore, egg cells are not involved.
  
  Thus, the correct answer is option A.

Correct Option: C

Microspore mother cells are diploid in nature (2n = 24). Endosperm will be triploid in nature, 3n = 36.

Cleistogamous flowers are flowers in which self pollination takes place in an unopened flower. Peanuts, peas, beans are some examples of cleistogamous flowers. Anemophilous flowers are flowers in which pollination occurs by wind. Entomophillous flowers are flowers in which pollination occurs by insects. Ornithophilous flowers are flowers in which pollination occurs by birds.

In Hyacinthus, Nemec observed 8 nucleated embryo sac type organisation in pollen grain. This is called as Nemec phenomenon.
Rarely in angiosperms, the pollen tube develops further in embryo sac. The abnormality is called as Nemec phenomenon.
Nemec phenomenon possessing pollen sacs have also been reported by Stow. The microspore here increases in size to form a sac like structure. The nucleus undergoes three mitotic divisions to form 8 nuclei. Of these, 3 lie at the end where exine is still intact, 3 at the opposite end and 2 in the middle. Stow observed that when the pollen embryo sacs were placed on an agar medium, together with some normal pollen grains of another variety, the pollen tubes from the latter coiled surround the pollen embryo sacs. 

• Stamen is the male reproductive organ that consists of a long slender filament and broad knob like anther; each anther lobes of anther contains two long and cylindrical microsporangia. Since stamen bear microsporangia in anther lobes, they are also called microsporophylls. Option A is incorrect.
• Gynoecium represents the megasporophyll as it carries megasporangia, i.e., the ovule, at the basal part of the pistil. Option B is incorrect. 
• Megaspore represents the first cell of the embryo sac/female gametophyte. Option C is incorrect. 
• The pollen grain is the first cell of the male gametophyte that divides mitotically to form a small generative cell and a large tube/vegetative cells. Pollen with small generative and large vegetative or with one vegetative cell and two male gametes is known as a mature male gametophyte.