Select the correct statement(s) with respect to mechanism of sex determination in grasshopper. [2023]
(A) It is an example of female heterogamety.
(B) Male produces two different types of gametes either with or without X chromosome.
(C) Total number of chromosomes (autosomes and sex chromosomes) is same in both males and females.
(D) All eggs bear an additional X chromosome besides the autosomes.
Choose the correct answer from the options given below:
(B) and (D) only
(A), (C) and (D) only
(A) only
(A) and (C) only
(1)
In grasshopper, males are heterogametic, i.e., some sperms bear X-chromosome whereas some do not and female is homogametic (XX). Eggs fertilised by sperms having an X-chromosome become female, and eggs fertilised by sperms without X-become males. Thus, female is (2A + XX) and male is (2A + XO). Thus, females have more number of chromosomes than male grasshopper.
XO type of sex determination can be found in: [2022]
Drosophila
Birds
Grasshoppers
Monkeys
(3)
Grasshopper is an example of XO type of sex-determination in which the males have only X chromosome besides the autosomes, whereas females have a pair of X-chromosomes.
Select the incorrect statement. [2019]
Human males have one of their sex-chromosome much shorter than other.
Male fruit fly is heterogametic.
In male grasshoppers, 50% of sperms have no sex-chromosome.
In domesticated fowls, sex of progeny depends on the type of sperm rather than egg.
(4)
In birds, e.g., fowls, males have homomorphic sex chromosomes (AA + ZZ) and females have heteromorphic sex chromosomes (AA + ZW). So, males produce only one type of sperms containing (A + Z) whereas females produce two types of eggs (A + Z and A + W). Therefore, the sex of the progeny depends on the type of the egg which is fertilised by the sperm.
Which of the following pairs is wrongly matched? [2018]
Starch synthesis in pea : Multiple alleles
ABO blood grouping : Co-dominance
XO type sex determination : Grasshopper
T.H. Morgan : Linkage
(1)
The gene for starch synthesis in pea seeds can produce more than one effect which implies it is a pleiotropic gene.
