Human Reproduction — BIOLOGY STD 12 Science — Question

1. Why are engineered vectors preferred?
2. A vector is engineered with three features, which facilitate its cloning within the host cell. List the three features and explain each one of them.

You are planning to set up a Dairy Farm. Describe the various aspects you would consider before you start the venture.

1. Explain the development of female gametophyte from a megaspore mother cell in an angiosperm.
2. Draw a leballed diagram of a fully-developed embryo sac.

OR

1. Describe the process of megasporogenesis in angiosperms, until 8-nucleate stage.
2. Draw the labelled structure of mature embryo sac.

Malarial parasite ‘Plasmodium’ completes its life cycle in two hosts. Draw its complete life cycle and explain various stages it follows throughout its life.

List 10 modern day animals and using the various resources available link it to a corresponding ancient fossil. Name both of them.

Why is thermoregulation more effectively achieved in larger animals than in smaller ones?

Describe the post-fertilisation changes in a flower.

What are the basic characteristics of a modern landfil site. List any three and also mention the reasons for their use.

What evidence for biological evolution is obtained from, comparative anatomy? Describe in detail

Answer the following questions:
Draw a diagrammatic sectional view of the female reproductive system of human and label the parts:

1. Where the secondary oocytes develop.
2. Which helps in collection of ovum after ovulation.
3. Where fertilisation occurs.
4. Here implantation of embryo occurs.