12 Class

What is the difference between a foetus and an embryo?

by

The main difference between a fetus and an embryo lies in their developmental stages. An embryo refers to the early stage of development after fertilization and implantation, lasting from the moment of conception until about eight weeks in humans. During this period, the basic structures and organs begin to form. On the other hand, a … Read more

Explain the development of dicot embryo.

by

The zygote divides to form two- celled proembryo. The larger cell positioned closer to the micropyle is termed the basal or suspensor initial cell, while the smaller cell closer to the chalaza is referred to as the terminal or embryonal initial cell. The suspensor cell divides in a single plane, transversely, leading to the formation … Read more

Explain the stages involved in the maturation of microspore into male gametophyte.

by

Pollen grain marks the begining of male gametophyte. First Mitotic Division During the initial mitotic division, it generates a larger, naked vegetative cell and a smaller, thinly-walled generative cell. The vegetative cell is rich in food and having irregular shaped nucleus. The generative cell floats in the cytoplasm of vegetative cell. Second Mitotic Division In … Read more

Describe the process of double fertilization.

by

Double fertilization is a unique and crucial process in flowering plants, involving two sperm cells and two female gametes, ultimately leading to both embryo and food source development. It was discovered by Nawaschin in the liliaceous plants like Lilium and Fritillaria. Pollen grains, carrying two male gametes, which lands on the stigma, the sticky landing … Read more

Describe three devices by which cross pollination is encouraged in Angiosperms by avoiding self pollination.

by

Three Devices Encouraging Cross-pollination in Angiosperms: 1. Dioecy: Separate male and female flowers on different plants, preventing self-pollination. Examples: Willow, spinach, hemp. 2. Dichogamy: Timing mismatch between pollen release and stigma receptivity. 3. Hermaphroditism with Structural Barriers: Physical separation of male and female parts within the same flower. Examples: Hibiscus, iris, snapdragon. Bonus: Self-incompatibility: Genetic … Read more

Incompatibility is a natural barrier in the fusion of gametes. How will you explain this statement?

by

Incompatibility refers to a suite of pre-zygotic barriers in plants that prevent fertilization between genetically incompatible individuals. This mechanism essentially serves as a natural “bouncer” system, promoting outbreeding and enhancing offspring fitness.

Pollination and seeds formation are very crucial for the fruit formation. Justify the statement.

by

The statement that pollination and seed formation are crucial for fruit formation is absolutely correct. Here’s why: Pollination: Triggers fruit development: Pollination acts as the initial signal for the ovary of the flower to start developing into a fruit.  Provides genetic diversity: Pollen grains typically carry male genetic material from another plant, which, upon fertilization, leads to the … Read more