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Practice each question, then open the answer or worked solution.
Mendel’s Law of independent assortment holds good for genes situated on the:
Ans: (a)
Independent assortment cannot take place in case of options (b), (c) and (d) therefore the answer is (a).
Occasionally, a single gene may express more than one effect. The phenomenon is called:
Ans: (c)
When a single gene may express more than one effect then the phenomenon is called pleiotropy.
In a certain taxon of insects some have 17 chromosomes and the others have 18
chromosomes. The 17 and 18 chromosome-bearing organisms are:
Ans: (a)
XO type of sex determination is seen in these insects. In such cases, the males
have only one X-chromosome and the females have a pair of X-chromosome therefore, the answer is (a).
The inheritance pattern of a gene over generations among humans is studied by the pedigree analysis. Character studied in the pedigree analysis is equivalent to:
Ans: The pattern of inheritance of Mendelian disorders can be traced through
pedigree analysis so the answer is (b).
It is said that Mendel proposed that the factor controlling any character is discrete and independent. His proposition was based on the:
Ans: (b)
Mendel proposed that the factor controlling any character is discrete and independent. His proposition was based on observations that the offspring of a cross, made between the plants having two contrasting characters, would show one character only. In a dihybrid cross, he observed that a particular character behaved independently from another character. Hence, ‘b’ is correct.
Two genes ‘A’ and ‘B’ are linked. In a dihybrid cross involving these two genes, the F1 heterozygote is crossed with homozygous recessive parental type (aa bb). What would be the ratio of offspring in the next generation?
Ans: (d)
The ratio of the offspring in the next generation would be 1: 1: 1: 1 hence option (d) is correct.
In the F2 generation of a Mendelian dihybrid cross the number of phenotypes and
genotypes are:
Ans: (d)
For example of dihybrid cross between round yellow (RRYY) and wrinkled green (rryy). In F2 generation there were four Phenotypes: round yellow, round green, wrinkled yellow and wrinkled green. The genotypes were; RRYY, RRYy, RRyy, RrYY, RrYy, Rryy, rrYY, rrYy and rryy. So (d) is correct.
Mother and father of a person with ‘O’ blood group have ‘A’ and ‘B’ blood group
respectively. What would be the genotype of both mother and father?
Ans: (c)
Possible genotype of parents are; IAi (A blood group) and IBi (B blood group) and phenotype of offspring is ii (O blood group) therefore, the answer is (c).