Solved Examples on Heredity and Variation

Question1: If two genes are present at the same locus and after interacting with each other produce different effect are called [CBSE PMT 2001]

(a)      Codominance       

(b)      Dominance

(c)       Epistasis     

(d)      None of the above

Answer: a

Solution:

In co-dominance both the gene expressed for a particular character in F1 hybrid progeny. There is no blending of characters, whereas both the characters are expressed equally.

Question2: Blood groups are named because of the agglutinogen A and B present in [CPMT 1992, 93]

(a)      Plasma         

(b)      RBC  

(c)       WBC 

(d)      Platelet

Answer: b

Solution:

Blood groups are named because of the agglutinogen A and B present in RBC.

Question3: A normal woman whose father was albino marries an albino; what proportion of normal and albino can be expected among their offspring [CBSE PMT1994]

(a)      All albino    

(b)      One normal : one albino           

(c)       All normal  

(d)      Two normal : one albino

Answer: b

Solution:

The normal woman got one recessive albino gene from her father, and one normal pigment gene from her mother. The man she married has two albino genes. 50% of their offspring will have two albino genes, and will be albino themselves. 50% of their offspring will appear normal, with one normal pigment gene, and one recessive albino gene.

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