Botany MCQs for NEET — Practice Questions with Answers

In apple, the fruit is called a pome. It is a fleshy false fruit which develops from fleshy thalamus. The true fruit containing seeds remains inside. The edible part is the fleshy thalamus. 

Cross pollination involves transfer of pollen grains from the flower of one plant to the stigma of the flower of another plant. It is also called xenogamy or allogamy. Autogamy is self fertilization. Cleistogamy is the process of pollination and fertilization which takes place before the flower has opened. Geiotonogamy is the cross pollination between two flowers on the same plant. 

The seeds of castor (Ricinus communis) is often referred to as castor bean, exhibits a great range of variations in size and colour and shows great resemblance to a tick or beetle in having a slick mottled testa. The seed contains a tiny embryo with a distinct radicle, an undifferentiated plumule and 2 flat thin papery cotyledons embedded in the endosperm. Castor bean seeds (malphghiales) are a classical seed system to study endosperm reserve breakdown.

The ubisch bodies are spheroidal structures only a few microns in diameter. they are produced by the glandular tapetum and are involved in the external thickening of the xine, whose pattern is laid down by the spore cytoplasm in the tetrad stage.

In cereals, one or few outer layers of endosperm are thick walled with dense cytoplasm having pits. These are manly filled with aleurone grains hence calld aleurone tissue. These layers secret some hycrolytic enzymes like amylases and proteases which break down starch and protein during seed germiation. Since this layer is formed from endosperm it is triploid in nature.

Apple is false fruit as the ovary does not form the fruit but the fleshy thalamus modifies into fruit which is edible.

Pollination by bat is called chiropteriphily.

The direct or indirect effet of male parent (pollen grain) on structures inside embryo sac except embryo has been termed by Focke, 1881 as xenia. this phenomenon is limited to endosperm part only and seen in Zea mays. Metaxenia may be defined as the effect of pollen on the sead coat or pericarp lying outside the embryo sac. In Phoenix dactylifera, the size and time of maturity of fruits depend on the type of pollen grains fertilizing the ovules. There is secretion of certian hormones or similar substances by endosperm or embryo or both which diffuse out into the wall of the sed and fruit and exer specific effect. the secretion of these substances, in turn, is influenced by the pollen grains whcih fertilise the ovules.

Exine is outer layer of pollen grain which is acetolysis resistant layer. It is also resistant to physical and biological degradation. Because of this property of exine, pollen grains are found well preserved for long periods in fossil deposits.

After entering the wall of the embryo sac the pollen tube during its entry into the embryo sac passes through the nucellar cells and the synergids, e.g. Fagopyrum. The pollen tubes passes between the egg and one synergid. In Cardiospermum, it passes between embryo sac wall and synegid. In Oxalis, it passes directly through a synergid. In Viola, it enters a synergid and makes its way thorough the base of the synergid. In normal cases only one synergid destroys by the impact of the pollen tube and the other remains intact until sometimes afterwards.