Organisms and Populations — BIOLOGY STD 12 Science — Question

Ram saw a farmer spraying some chemicals on flowers. On asking farmer, he came to know that this act will lead to the formation of fruits without fertilisation. Ram thought that fruits developed in this way are not good to eat as chemicals are sprayed on it.
Next day, he asked his biology teacher about it, who explained him everything.

1. What chemicals were sprayed by the farmer?
2. Give difference between such a spray and usual pesticide spray?
3. What is parthenocarpy? Give its types.
4. What values are shown by Ram?

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?

1. List the three stages the annuals and biennial angiosperms have to pass through during their life cycle.
2. List and describe any two vegetative propagules in flowering plants.

Vaccination is important for preventing pneumonia.

Explain different types of growth models.

What do you understand by climax community?

Osmotic Pressure (O.P) and Turgor Pressure (T.P)

1. Identify the selectable markers in the diagram of E. coli vector shown above.
2. How is the coding sequence of a-galactosidase considered a better marker than the ones identified by you in the diagram? Explain.

Name and explain the type of interaction that exists in mycorrhizae and between cattle egret and cattle.