A-Level Biology Question Analysis Topic: Biology - Short Questions
Exam Questions:
1) Amniocentesis is a technique used for some specific purpose. Can you list down its uses. Also in spite being useful, there is a statutory ban on amniocentesis. Give reason to justify the ban.
2) Name and describe the technique that helps in separating the DNA fragments formed by the use of restriction endonuclease.
Answers:
For A-Level Biology, you should know:
1) Usage for amniocentesis include:
(i) to legally prevent female genital mutilation or the abuse of sex-determining methods.
(ii) to find a defective chromosome, or a genetic condition.
Reason for ban:
to avoid changing the population's sex ratio by preventing female foeticide.
2)
(i) To distinguish between DNA fragments of various lengths, electrophoresis is used.
(ii) When DNA is negatively charged, it will move towards the positively charged electrode when an electric current is applied to the gel. The DNA fragments are arranged in size order as shorter DNA strands travel through the gel more quickly than longer ones.
(iii) After they have been separated, the DNA on the gel can be seen due to the use of dyes or radioactive markers. They will appear on the gel as bands.
(iv) Samples and a DNA marker with known-length fragments are passed through the gel at the same time. One can measure the approximate length of the DNA fragments in the samples by comparing the bands of the DNA samples with those from the DNA marker.
Work hard for your A-Level Biology examination!
End of analysis. Great!
