Define the term mycorrhiza. How are these associations affect a plant? Explain with examples

3

(a)

When did cyanobacteria evolved? Why are they referred  as the earliest colonisers of barren areas?

3

(a)

Justify the statement Euglena is a  taxonomic puzzle.

3

(a)

Why the members of class-Deuteromycetes are considered the fungi imperfecti?

3

(a)

There is a myth that immediately after heavy rains in forest, mushrooms appear in large number and make a very large ring or circle, which may be several metres in diameter. These are called 'fairy rings'. Can you explain the myth of fairy rings in biological terms?

3

(a)

Justify at what extent the phylogenetic relationship is useful as a criterion for classification.

3

(a)

The two kingdom classification system placed bacteria, algae, blue-green algae, fungi, mosses, ferns, gymnosperm, and angiosperms, together under one single kingdom-Plantae. According to you, what could have been the basis of such classification?

3

(a)

What is the special feature of Archaebacteria? How do these obtain food? How are they able to tolerate high temperatures as well as acidity?

3

(a)

How do some protozoans maintain osmotic pressure?

3

(a)

Give the name of the bacteria for following activities.
(i) Food poisoning
(ii) Denitrification of soil
(iii) Dairy industry
(iv) Vinegar production
(v) Retting of fibres
(vi) Genetic engineering

3

(a)