Q2 of 805 Page 1

Mention the combination(s) of sex chromosomes in a male and a female bird.

In human and other mammals the sex chromosomes are X and Y where homogametic females carry XX and the heterogametic male carries XY; sex-determination system, where male determine the gender of the offspring. Unlike human female birds determine the sex of the offspring, and female carry the heterogametic chromosome, which expressed in ZW while the male bird has homogametic ZZ sex-determination system.


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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.


 1

Name the vegetative Propagules in (i) Potato, and (ii) Pistia.

 3

A region of a coding DNA strand has the following nucleotide sequence:

– A T G C –


What shall be the nucleotide sequence in (i) sister DNA segment it replicates, and (ii) m-RNA polynucleotide it transcribes?


 4

List the type of cry genes that provide resistance to corn plants and cotton plants respectively against lepidopterans.