Botany MCQs for NEET — Practice Questions with Answers

The NCERT exercise question 'Why do you think the zygote is dormant for sometime in a fertilised ovule?' directly points to this concept. Zygote dormancy is a crucial adaptation that allows for embryo development to proceed under optimal conditions, often linked to the maturation of the seed and fruit, and prevents early germination when conditions might be unsuitable for seedling survival.

The egg cell (part of the egg apparatus) is fertilized by one of the male gametes, forming the zygote, which then develops into the embryo. The NCERT text describes the egg apparatus consisting of 'two synergids and one egg cell'.

The NCERT text states: 'in some varieties some of the nucellar cells surrounding the embryo sac start dividing, protrude into the embryo sac and develop into the embryos. In such species each ovule contains many embryos. Occurrence of more than one embryo in a seed is referred to as polyembryony'.

Though not explicitly detailed in the provided excerpts, the 'triple fusion' question (Question 11 from the NCERT exercise: 'What is triple fusion? Where and how does it take place? Name the nuclei involved in triple fusion.') implies the formation of the primary endosperm nucleus from the fusion of a male gamete with the two polar nuclei in the central cell. This primary endosperm nucleus then develops into the endosperm, which provides nourishment to the developing embryo.

The introductory text mentions 'the end products of sexual reproduction, the fruits and seeds.' General biological understanding (and implied by the NCERT structure) is that the entire ovule, after successful fertilization, matures into a seed. The other options are parts of the ovule or its attachment.

While the direct formation of endosperm is not detailed in the provided excerpts, the context of sexual reproduction and the mentioned 'triple fusion' in an NCERT question highly infer the endosperm's role. It is a well-established fact that endosperm provides nutritive tissue for the developing embryo.

The NCERT sections describe 'Embryo sac formation' (Megasporogenesis and Megagametogenesis), then 'Pollination' for gamete transfer, leading to 'Pollen-pistil interaction' and finally 'Fertilization.' After fertilization, the 'Post-fertilisation: Structures and Events' lead to fruit and seed development. So, embryo sac formation precedes pollination, which precedes fertilization, followed by fruit and seed development.

According to the NCERT text, 'Growth, at a cellular level, is principally a consequence of increase in the amount of protoplasm.' (Chapter: PLANT_GROWTH_AND_DEVELOPMENT, Section 13.1.2).

The NCERT text states: 'Growth is, therefore, measured by a variety of parameters some of which are: increase in fresh weight, dry weight, length, area, volume and cell number.' Turgor pressure, while related to growth, is not listed as a direct measurement parameter for growth in this section. (Chapter: PLANT_GROWTH_AND_DEVELOPMENT, Section 13.1.2).

The NCERT text explicitly states: 'In the former [maize root apical meristem], growth is expressed as increase in cell number...' (Chapter: PLANT_GROWTH_AND_DEVELOPMENT, Section 13.1.2).