Human Health and Disease — BIOLOGY STD 12 Science — Question

What is urethral meatus?

With the help of a flow chart, show the phenomenon of biomagnification of DDT in an aquatic food chain.

Prior to a sports event blood & urine samples of sportspersons are collected for drug tests.

1. Why is there a need to conduct such tests?
2. Name the drugs the authorities usually look for.
3. Write the generic names of two plants from which these drugs are obtained.

In pea plants, the colour of the flower is either violet or white, whereas human skin colour shows many gradations. Explain giving reasons, how it is possible.

Three water samples namely river water, untreated sewage water and secondary effluent discharged from a sewage treatment plant were subjected to BOD test. The samples were labelled A, B and C but the laboratory attendant did not note which was which. The BOD values of the three samples A, B and C were recorded as 20 mg/L, 8 mg/L and 400 mg/L respectively. Which sample of the water is most polluted? Can you assign the correct label to each assuming the river water is relatively clean?

Describe which is the second effective and popular method of contraception in India.

Rearrange the following in the correct sequence to accomplish an important biotechnological reaction:

1. In vitro synthesis of copies of DNA of interest,
2. Chemically synthesised oligonucleotides,
3. Enzyme DNA-polymerase,
4. Complementry region of DNA,
5. Genomic DNA template,
6. Nucleotides provided,
7. Primers,
8. Thermostable DNA-polymers (From Thermus aquaticus),
9. Denaturation of dsDNA.

Write the names of important microbes used in industries. Name any five products in which microbes are used for manufacturing purpose.

Mention the function of mitochondria in sperm.

This is the pedigree of a family tracing the movement of the gene for haemophilia. Explain the pattern of inheritance of the disease in the family.