Microbes in Human Welfare — BIOLOGY STD 12 Science — Question

Treatment of wastewater is done in a sewage treatment plant to make it less polluting. Explain the following with reference to this treatment process:
a. Primary sludge
b. Activated sludge
c. Anaerobic sludge digesters

How does temperature affect the organisms?

Study the figure given below and answer the questions:

1. How does the repressor molecule get inactivated?
2. When does the transcription of lac mRNA stop?
3. Name the enzyme transcribed by the gene ‘Z’.

Differentiate between immigration and emigration.

Why is there a statutory ban on amniocentesis? Why is the technique so named?

Explain two situations when independent assortment of genes occur, resulting in 50% recombination?

Two independent monohybrid crosses were carried out involving a tall pea plant with a dwarf pea plant. In the first cross, the offspring population had equal number of tall and dwarf plants, whereas in the second cross it was different. Work out the crosses, and explain giving reasons for the difference in the offspring populations.

OR

Work out a cross to find the genotype of a tall pea plant. Name the type of cross.

How are auto-immune diseases different from immunodeficiency disease? Give one example of each in human.

List the three major functions of a gene.

In a sea shore, the benthic animals live in sandy, muddy and rocky substrata and accordingly developed the following adaptations. Find the suitable substratum against each adaptation.

1. Burrowing ______________________.
2. Building cubes ________________________.
3. Holdfasts/ peduncle _________________________.