Human Reproduction — BIOLOGY STD 12 Science — Question

Elaborate how invasion by an alien species reduces the species diversity of an area.

Try to trace the various component of human evolution (Hint: brain size and function, skeletal structure dietary preferences, etc.).

Answer the following questions:
When and where does spermatogenesis occur in a human male?

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 a 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.

Give the term/ reason:
Mechanism responsible for parturition.

A true breeding pea plant homozygous for axial violet flowers is crossed with another pea plant with terminal white flowers (aavv).
What would be the phenotype and genotype of F₁ and F₂ generations?

Answer the following questions:
Draw a diagram of a mature human male gamete. Label the following parts: Acrosome, nucleus, middle piece and tail.

What is a biogeochemical cycle. What is the role of the reservoir in a biogeochemical cycle. Give an example of a sedimentary cycle with reservoir located in earth’s crust.

Double fertilisation is immediately followed by development of endosperm. Explain the link between the two processes.

What is genetic engineering? List the steps involved in rDNA technology.