Respiration and Circulation — BIOLOGY STD 12 Science — Question

What are decomposers? What is their function in ecosystem?

The cytological observations made in a number of insects led to the development of the concept of genetic/ chromosomal basis of sex-determination mechanism. Honey bee is an interesting example to study the mechanism of sex-determination. Study the schematic cross between the male and the female honey bees given below and answer the questions that follow:

1. Identify the cell divisions ‘A’ and ‘B’ that lead to gamete formation in female and male honey bees respectively.
2. Name the process ‘C’ that leads to the development of male honey bee (drone).

Why is predation required in a community of different organisms?

When Mendel crossed a tall pea plant with a dwarf pea plant the offspring obtained from this cross were all tall.

Palaeontological evidence support the theory of organic evolution. Explain with an example.

Name the type and give the effect of the following drug in human.
Barbiturates.

Human pregnancy shows three prominent trimesters. Answer the following question based on these trimester.

1. What is morning sickness during the first trimester?
2. Name the hormone secreted in the second trimester.
3. The organ which secretes hormone in second trimester is

1. List the two methodologies which were involved in human genome project. Mention how they were used.
2. Expand ‘YAC’ and mention what was it used for.

Give Significance: DNA.

What is adenohypophysis ? Name the hormones secreted by it.