In which of the following the two sexes have the same number of sex chromosomes and the sex of the offspring is determined by the fertilizing ovum.
a, cockroach
b, bug
c,fowl
d, fumea
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In roundworms and some insects (true bugs, grasshoppers, cockroaches), the females have two sex chromosomes, XX, while the males have only one sex chromosome, X.
The males are heterogametic with half the male gametes (gynosperms) carrying X-chromosome (A+X) while the other half (androsperms) being devoid of it (A + 0). The sex ratio produced in the progeny is 1: 1
There is no second sex chromosome. Therefore, the males are designated as X0.
The females are homogametic because they produce only one type of eggs (A+X).
ZW—ZZ TYPE - DEFINITION
concept
In birds and some reptiles both the sexes possess two sex chromosomes but unlike human beings the females contain heteromorphic sex chromosomes (AA + ZW) while the males have homomorphic sex chromosomes (AA + ZZ).
Because of having heteromorphic sex chromosomes, the females are heterogametic (female heterogamety) and produce two types of eggs, (A + Z) and (A + W).
The male gametes or sperms are of one type (A + Z). 1:1 sex ratio is produced in the offspring.
Explanation:
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