Organisms and Populations — BIOLOGY STD 12 Science — Question

Explain grazing food chain.

Can you list 10 recombinant proteins which are used in medical practice? Find out where they are used as therapeutics. (use internet).

While creation and presence of variation is directionless, natural selection is directional as it is in the context of adaptation. Comment.

In isolating recombinant insulin from a culture of E. coli, the cells were filtered and the filtrate was subjected to a purification protocol. However, no insulin was obtained.Why?

Answer the following:

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

Name the host and the site where the following occur in the life cycle of a malarial parasite:

1. Formation of gametocytes.
2. Fusion of gametocytes.

State where the signals for parturition arise from, in humans.

Study the schematic representation of evolutionary history of plant forms given below and mention

1. The plant forms ferns and conifers are most related to.
2. The nearest ancestors of flowering plants.
3. The most primitive group of plants.
4. Common ancestry of Psilophyton provides to.
5. The common ancestor of Psilophyton and seed ferns.
6. The common ancestors of mosses and tracheophytes.

Describe the contraceptive technique which are highly effective but have very poor reversibility.###Explain: Surgical Methods / Sterilization.

In an artificial hybridisations programme observed events as follows. Rearrange them in collect series as per hysridisation programme.
(a) Re bagging
(b) Choose parents
(c) Bagging
(d) spread pollen on stigma
(e) Emasculation
(f) collect pollen from male parental plant