Model Paper 3 — BIOLOGY STD 12 Science — Question

1. Name the respective forms in which the malarial parasite gains entry into

1. Human body
2. Body of female Anopheles

2. Name the hosts where the sexual and the asexual reproductions of malarial parasite occur respectively.
3. Name the toxin responsible for the appearance of symptoms of malaria in humans. Why do these symptoms occur periodically?

What background information did Watson and Crick have made available for developing a model of DNA? What was their contribution?

Explain xerarch succession highlighting the xeral communities.

Name the cell from which the endosperm develops in a coconut. Mention its ploidy. Explain the process of endosperm development in a coconut.

In a pea plant, smooth seed coat is dominant over wrinkled seed coat. What will be the expected ratio of phenotypes of the offspring in a cross between:

1. Heterozygous smooth × Heterozygous smooth
2. Heterozygous smooth × Homozygous wrinkled
3. Heterozygous smooth × Homozygous smooth

Ritro viruses do not follow central Dogma comment.

How would you justify circular flow of genetic information?

Given below are the events that are observed in an artificial hybridisation programme. Selection of parents → Emasculation → Bagging → Collection of pollen from other male plant → Dusting of pollen on stigma — Rebagging.
While, planning for crop improvement involving dioecious plants, which of the above mentioned steps would not be relevant?

Explain antibiotic resistance observed in bacteria in light of Darwinian selection theory.

Define biodiversity Name the two most biodiversity rich zones of India.