Human Reproduction — BIOLOGY STD 12 Science — Question

Answer the following questions:
Write the specific location and the functions of the following cells in human males:

1. Leydig cells.
2. Sertoli cells.
3. Primary spermatocyte.

A person in your colony has recently been diagnosed with AIDS. People/residents in the colony want him to leave the colony for the fear of spread of AIDS.

1. Write your view on the situation, giving reasons.
2. List the possible preventive measures that you would suggest to the residents of your locality in a meeting organised by you so that they understand the situation.
3. Write the symptoms and the causative agent of AIDS.

How do ecologists estimate the total number of species present in the world?

Explain the role of lactose as inducer in lac Operon.###What is lac operon concept? Describe its mechanism.###In the medium where E. coli was growing, lactose was added, which induced the lac operon. Then, why does lac operon shut down some time after addition of lactose in the medium?###Define the operon and name its Constituent Genes.

Describe female reproductive system.

How is sex determined in human beings?

What are the three types of ecological pyramids. What information is conveyed by each pyramid with regard to structure, function and energy in the ecosystem.

Study the schematic representation of the genes involved in the lac operon given below and answer the questions that follow.

1. Identify and name the regulatory gene in this operon. Explain its role in 'switching off the operon.
2. Why is lac operon's regulation referred to as negative regulation?
3. Name the inducer molecule and the products of the genes 'z' and 'y of the operon. Write the function of these gene products.

List any two major causes other than anthropogenic causes of the loss of biodiversity.