Organisms and Populations — BIOLOGY STD 12 Science — Question

Mention three physical properties and three chemical properties of soil, that determine the type of vegetation in a given region.

Explain by taking three different examples, how certain organisms pull through the adverse conditions, when unable to migrate under stressful period.

Pancreas is both exocrine as well as endocrine gland.

Rearrange Ramapithecus, Australopithecus and Homo habilis in the order of their evolution on the Earth. Comment on their evolutionary characteristics.

Rohan saw Mr. Sharma collecting different plant specimens. He was confused to see him doing this collection and approached him asking about it.
Mr. Sharma told him that he will cross different plant specimens in his laboratory for obtaining better varieties of plants.

1. Why is he interested in such experiments?
2. Name this technique.
3. What precautions he should take while applying this technique?
4. What values are shown by Rohan?

Sketch and label human male reproductive system'.

Draw a schematic transverse section of a mature anther of an angiosperm. Label its epidermis, middle layers, tapetum, endothecium, sporogenous tissue and the connective.

A woman has certain queries as listed below, before starting with contraceptive pills. Answer them.
What schedule should be followed for taking these pills?

Give the role of following mycoherbicides:
(i) Phytophthora
(ii) Alternaria
(iii) Fusarium

Three microbes are listed below. Name the product produced by each one of them and mention their use:

1. Aspergillus niger.
2. Trichoderma polysporum.
3. Monascus purpureus.