Ecosystems and Energy Flow — BIOLOGY STD 12 Science — Question

Enlist any four barriers that contribute to innate immunity.

Name the type of pollination as a result of which genetically different types of pollen grains of the same species land on the stigma.

If there are two pathogenic viruses, one with DNA and other with RNA, which would mutate faster? And Why?

1. Highlight the role of thymus as a lymphoid organ.
2. Name the cells that are released from the above mentioned gland. Mention how they help in immunity.

Enumerate the methods available for breeding for disease-resistance in plants.

A cross was carried out between two pea plants showing contrasting traits of height of the plants. The result of the cross showed 50% parental characters.

1. Work out the cross with the help of a Punnett square.
2. Name the type of the cross carried out.

Name indicating their functions, a few additional enzymes, other than DNA polymerase and ligase, that are involved in the replication of DNA with high degree of processivity and accuracy.

Where are fimbriae present in a human female reproductive system? Give their function.

Why is it difficult to get rid of water hyacinth' from a water body? Name one abiotic component and one biotic component of the ecosystem that gets affected by its spread in the water body.

In the biosphere immense biological diversity exists at all levels of biological organisation. Explain any two levels of biodiversity.