Human Reproduction — BIOLOGY STD 12 Science — Question

With the help of a flow-chart exhibit the events of eutrophication.

Mention three physical properties and three chemical properties of soil, that determine the type of vegetation in a given region.

Differentiate between external fertilisation and internal fertilisation with an example for each.

Write the full form of PCR. What are the three basic steps involved in a single PCR amplification cycle?

1. Explain linkage and recombination as put forth by T.H. Morgan based on his observations with Drosophila melanogaster crossing experiment.
2. Write the basis on which Alfred Sturtevant explained gene mapping.

Different animals respond to changes in their surroundings in different ways. Taking one example each, explain "some animals undergo aestivation while some others hibernation". How do fungi respond to adverse climatic conditions?

To maintain the continuity of its life, Plasmodium protozoa requires both mosquito and human hosts.” Explain.

1. Expand BOD.
2. At a particular segment of a river near a sugar factory, the BOD is much higher than the normal level. What is it indicative of? What will happen to the living organisms in this part of the river?
3. Under what conditions will the BOD be lowered in the river? How will it affect the aquatic life?

Name the group of bacteria involved in setting milk into curd. Explain the process they carry in doing so. Write another beneficial role of such bacteria.

A person has been diagnosed to be HIV positive.

1. Name the test which the person underwent.
2. Write the full name of the pathogen involved and describe its structure.
3. Which particular cells of this person are likely to get destroyed?