Q15 of 805 Page 1

A criminal blew himself up in a local market when was chased by cops. His face was beyond recognition. Suggest and describe a modern technique that can help establish his identity.

The technique that can help establish his identity is “DNA fingerprinting”. Developed by Alec Jeffrey, DNA fingerprinting or DNA profiling is a technique to determine an individual’s DNA characteristics, which are unique as the fingerprints. About 99.9% of sequences of DNA are same in humans. The 0.1% DNA segment which is different in different humans makes all of us unique. In this 0.1% segment there are certain regions with repetitive sequences which form the basis of DNA fingerprinting.


The basic steps involved in the procedure are:


a. Isolation of DNA


b. Digestion of DNA by restriction endonuclease


c. Separation of DNA by gel electrophoresis


d. Transfer of DNA fragments to membrane (Southern blotting)


e. Hybridisation using labelled Variable Number of Tandem Repeats (VNTRs) probes


f. Detection of labelled segments by autoradiography


The bands obtained are unique to an individual and can be used for identification of people using existing database or comparing them with their relatives.


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9

In a flowering plant a microspore mother cell produce four male gametophytes while a megaspore mother cell form only one female gametophyte. Explain.

 13

Differentiate between an annual and a biennial plant. Provide one example of each.

 22

A group of youth were having a ‘rave party’ in an isolated area and was raided by police. Packets of ‘smack’ and syringes with needles were found littered around.

(a) Why is taking ‘smack’ considered an abuse?


(b) Write the chemical name of ‘smack’ and the name of its source plant.


(c) Syringes and needles used by the youth for taking the drug could prove to be very fatal. Why?


 25

Read the statement and answer the questions that follow.

A flower of brinjal has 520 ovules in its ovary. However, it produces a fruit with only 480 viable seeds.


(a) What could have prevented the rest of the 40 ovules from maturing into viable seeds ? Explain giving a reason.


(b) Describe the development of a dicot embryo in a viable seed.


(c) Why certain angiospermic seed are albuminous while others are ex-albuminous? Explain.


OR


(a) Name the hormones secreted and write their functions :


(i) by corpus luteum and placenta (any two).


(ii) during Follicular phase and parturition.


(b) Name the stages in a human female where:


(i) Corpus luteum and placenta co-exist.


(ii) Corpus luteum temporarily ceases to exist.