Ecosystems — BIOLOGY STD 12 Science — Question

1. What are meiocytes?
2. If the chromosome number in meiocytes of human beings, housefly, potato, apple, dog and maize are 46, 12, 48, 34,78 and 20, respectively. What will be the chromosome numbers in gametes of these species?

Draw a labelled diagram of a Graafian follicle?

‘‘A very small sample of tissue or even a drop of blood can help determine paternity’’. Provide a scientific explanation to substantiate the statement.

The outline structure of a drug is given below,

1. Which group of drugs does this represent?
2. What are the modes of consumption of these drugs?
3. Name the organ of the body which is affected by consumption of these drugs.

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In which food would you find lactic acid bacteria? Mention some of their useful applications.

Life style diseases are increasing alarmingly in India. We are also dealing with large scale malnutrition in the population. Is there any method by which we can address both of these problems together?

Differentiate between perisperm and endosperm by giving one example of each.

1. What precaution(s) would you recommend to a patient requiring repeated blood transfusion?
2. If the advise is not followed by the patient, there is an apprehension that the patient might contract a disease that would destroy the immune system of his/her body. Explain with the help of schematic diagram only how the immune system would get affected and destroyed.

What is vegetative propagation? Give two suitable examples.

Rajesh was doing gel electrophoresis to purify DNA fragments. Given below is the sketch of the observations of the experiment performed by him.

1. At which end he would have loaded the samples and where?
2. Analyse the reason for different positions taken up by the DNA bands.
3. Elaborate the step he would have followed to visualise DNA bands.