Ecosystems — BIOLOGY STD 12 Science — Question

What is a bioreactor used for? Name a commonly used bioreactor and any two of its components.

Biotechnology has helped farmers to get pest resistant cotton crops. Explain the technique adopted along with its mode of action. (Mention six points).

A person shows strong unusual hypersensitive reactions when exposed to certain substances present in the air, identify the condition. Name the cells responsible for such reactions. What precaution should be taken to avoid such reactions.

Describe the experiment of S.L. Miller on the origin of life. Write the conclusion drawn at the end of the experiment.

What is Vasectomy? Represent it diagrammatically.

The immune system of a person is suppressed. In the ELISA test, he was found positive to a pathogen.

1. Name the disease the patient is suffering from.
2. What is the causative organism?
3. Which cells of body are affected by the pathogen?

Explain the mechanism of ‘sex determination’ in birds. How does it differ from that of human beings?

Given below are the events that are observed in an artificial hybridisation programme. Selection of parents → Emasculation → Bagging → Collection of pollen from other male plant → Dusting of pollen on stigma — Rebagging.
While, planning for crop improvement involving dioecious plants, which of the above mentioned steps would not be relevant?

Why are human females rarely haemophilic? Explain. How do haemophilic patients suffer?

Answer the following questions:
What is meant by ADA deficiency? How is gene therapy a solution to this problem? Why is it not a permanent cure?