Question 1
Genic system of sex determination is seen in _______________
A. Yeast
B. Fishes
C. Reptiles
D. Mammals
View Answer
Answer: Option A
Explanation:
Yeast and other eukaryotic microorganism have this genic system of sex determination. In this case there is no special sex chromosome.
Question 2
In bees the males are produced by _________
A. Mitosis and then fertilization
B. Meiosis and then fertilization
C. Mitosis but no fertilization
D. Meiosis but no fertilizaton
View Answer
Answer: Option C
Explanation:
Bees have XO system of sex determination. In it the males are produced by parthenogenesis i.e. here is mitosis occurring in the mother that gives the zygote for male offspring.
Question 3
In case of XO system if an organism has AA+XO it will be a _______
A. Male
B. Neuter
C. Female
D. Bisexual
View Answer
Answer: Option A
Explanation:
In XO system presence of one copy of X chromosome produces a male, while there is no Y chromosome. Two copies give a female.
Question 4
Parthenogenesis can also take place in human beings.
A. True
B. False
View Answer
Answer: Option B
Explanation:
Although intriguing but parthenogenesis is not possible for human beings. This is because of imprinting where some genes from a particular parent are turned off in offspring depending on its gender.
Question 5
In XO system a male has a mother but not a _____________
A. Grand father
B. Father
C. Grand mother
D. Sibling
View Answer
Answer: Option B
Explanation:
The males are produced by parthenogenesis, i.e. by mitosis. While fertilization only takes place in case of a female child, only the two X chromosomes come together. Thus, the male has a mother but no father; they do however have a grandfather.
Question 6
In yeast a MAT a type yeast can mate with __________
A. MAT alpha
B. MAT beta
C. MAT a
D. It can’t mate
View Answer
Answer: Option A
Explanation:
There are two mating types in yeast, MAT a and MAT alpha. Only yeast cells of opposite mating types can mate. In this case MAT, a can thus mate with MAT alpha. There is no MAT beta.
Question 7
In yeast the gene responsible for sex determination is ______________
A. SXL
B. XCE
C. MAT
D. XIST
View Answer
Answer: Option C
Explanation:
In yeast, the genes at the MAT locus are responsible for determining the sex. Sex is mainly determined as mating factor and it alternates with every generation.
Question 8
In ZZ/ZW system which of the following is true?
A. All organisms have ZZ chromosome
B. The chromosomes are shaped like Z
C. Females have ZW constitution
D. Male is heterozygous
View Answer
Answer: Option C
Explanation:
ZZ/ZW sex determination system is much like XX/XY system. However, in this case male is homozygous ZZ and female is heterozygous ZW. In this case to avoid confusion different notation is used and not because of the shape.
Question 9
The XO system of sex determination is found in ______________
A. Insects
B. Birds
C. Reptiles
D. Mammals
View Answer
Answer: Option A
Explanation:
Insects have this XO system of sex determination. Thus it can be seen in Grasshopper, cockroaches, bees etc. Other options here have different modes of sex determination other than XO.
Question 10
Which of the following is true for a genic mode of sex determination?
A. It is seen in higher eukaryotes
B. Gene locus determines gender
C. XX will always give female in this case
D. It makes use of parthenogenesis for producing male offspring
View Answer
Answer: Option B
Explanation:
Genic mode of sex determination is seen in eukaryotic microorganisms. In this case, there is no separate chromosome but allele at the gene locus determines sex.