Human Reproduction — BIOLOGY STD 12 Science — Question

Given below is a schematic representation of a lac operon. Answer the following questions:

i. Identify i and p.
ii. Name the inducer for this operon.
iii. Explain the function of inducer for this operon.

Explain Gause's Competitive Exclusion Principle with the help of a suitable example.

Refer to the diagram given below and answer the questions that follow.

1. The parasite reproduces in human host by which method?
2. The sexual stages of parasite are referred to as?
3. Where does the fertilisation and development of parasite takes place in mosquito body?
4. What are sporozoites?
5. What is the cause of cycles of fever during malaria?

Name the group of bacteria involved in setting milk into curd. Explain the process they carry in doing so. Write another beneficial role of such bacteria.

Pollen grains are both useful and harmful. Justify the statement.

Describe the structure of RNA polynucleotide chain having four different types of nucleotides.

How has the use of Agrobacterium as vectors helped in controlling Meloidegyne incognitia infestation in tobacco plants? Explain in correct sequence.

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?

One of the twins born to parents having normal colour vision was colour blind whereas the other twin had normal vision. Work out the cross. Give two reasons how it is possible.