Evolution — BIOLOGY STD 12 Science — Question

During reproduction, the chromosome number (2n) reduces to half (n) in the gametes and again resume the original number (2n) in the offspring, what are the processes through which these events take place?

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.

Answer the following questions:
State the principle of independent assortment.

Mention any two measures for prevention and control of alcohol and drug abuse among adolescents.

Write a note on barrier method: (i) Condoms (ii) Diaphragm, cervical caps, vaults

Which part in the male reproductive system stores sperms?

'in-situ' conservation can help endangered/threatened species. Justify the statement.

What type of organs eye of an Octopus and that of a human called? Give another example from the animal group and one from the plants of such organs. Name and explain the evolutionary process they exhibit.

Draw a pyramid of biomass and pyramid of energy in sea. Give your comments on the type of pyramids drawn.

Observe the diagram of Genetic code and answer the following questions:

i. How many codons codes for amino acids and how many do not?
ii. Explain the following giving one example of each.
a. Unambiguous and specific codon
b. Degeneration codon
c. Universal codon
d. Initiator codon