Chapter 2: Sexual Reproduction in Flowering Plants

Ans: Correct Ans is a.

Cleistogamous flowers, otherwise known as closed flowers are the ones which do not open during any phase. In these flowers, autogamy i.e., fertilization by pollen and egg of the same flower is the only option. Chasmogamous flowers i.e., the flowers which have exposed stamens and anthers exhibit autogamy only under certain conditions. Geitonogamy means that the pollen grain of the flower fertilizes the egg of another flower but on the same plant. This can also occur in chasmogamous flowers as the reproductive structures are exposed. According to this, the correct option would be a.

Ans: Correct Ans is c.

The characteristics light, non-sticky and large in amount in a pollen grain are particularly present in anemophily i.e., pollination by wind. This helps in efficient dispersal of pollen grains by the aid of wind. Stigmas in these kinds of plants are long and feathery to ensure easy trapping of airborne pollen grains as they move with the wind. Stamens in these plants usually are well exposed to help in dispersal of the pollen grains as they wave in the wind currents. This kind of pollination can be seen in wheat, corn, rice, etc. 

Ans: Correct Ans is b.

Autogamy refers to fertilization of an egg by the pollen of the same flower while geitonogamy implies fertilization of an egg by the pollen of a different flower of the same plant. Now, dioecious plants are those that have either the male flower containing only stamens or the female flower containing only pistils while the monoecious plants are those bearing both male and female parts in a flower. Therefore, a dioecious plant bearing either male or female flowers can cause neither autogamy nor geitonogamy but xenogamy (fertilization of an egg by pollen of a different plant) is present in them. This is seen in onions.

Ans: Correct Ans is a.

Synergids are the cells which lie within the egg apparatus along with the egg nucleus and are haploid cells. Zygote is a diploid cell formed by the union of egg nucleus and sperm nucleus. Primary endosperm nucleus which is formed by the polar nuclei and sperm nuclei.  

Ans: Correct Ans is b.

Synergid cells are two specialized cells that lie adjacent to the egg cell in the female gametophyte. In an embryo sac, the synergids are located at the micropylar end while the antipodal cells are located at the chalaza end. When zygote is formed, these cells get degenerated. 

Ans: Correct Ans is c.

Crop improvement is the process of enhancing crop production and quality in agriculture.

Artificial hybridization is a method used to selectively increase desired traits in plants. In artificial hybridization, the pollen grains which are highly probable to contain genes of the desired trait are allowed to pollinate and fertilize female flowers. This is ensured by bagging of female flowers, and the extraction of anthers from monoecious flowers to prevent self-pollination (emasculation). This is irrelevant in dioecious plants

Ans: Correct Ans is c.

When different structures have similar functions, they are known as homologous structures. Cotyledons are utilitarian in storing food in dicot plants while in monocots, one cotyledon is used for storing food (which is known as Scutellum), while the other cotyledon is reduced to a structure called epiblast.

So, the correct Ans is ‘C’

Ans: Correct Ans is b.

When the embryo is formed with the use of sexual parts only and no fertilization has taken place, the phenomenon is known as apomixis. Parthenocarpy is also the absence of fertilization but in parthenocarpy, seedless fruits develop, and sexual parts are not involved in vegetative propagation.

Ans: Correct Ans is a.

Mitosis and meiosis are the two pathways in which a cell can divide to give rise to new cells or daughter cells which are diploid and haploid respectively. In mitosis, the ploidy of the cell doesn’t change as there is the multiplication of genetic material midway through the process. In meiosis, the ploidy of the daughter cells gets halved. That’s why its known as the reduction division. In angiosperms, a megaspore mother cell after forming a megaspore forms an embryo sac via meiosis which leads to the formation of a haploid gamete or cell.

Ans: Correct Ans is a.

The fruit is formed from an ovary in angiosperms, usually, after fertilization i.e., the union of pollen and egg. However, in some cases, the fruit may develop from the ovary without any kind of fertilization. This process is called parthenocarpy in which mitosis leads to the formation of fruit. The fruit thus formed is a parthenocarpic fruit for e.g., banana.