Question

Refer the given statements.
(i) Incomplete or mosaic inheritance is an example of pre-Mendelian concept of blending inheritance.
(ii) Test cross is a special type of back cross.
(iii) Chromosomal aberrations are commonly observed in cancer cells.
(iv) Thalassaemia is a Mendelian disorder.
Which of the above statements are correct ?

• A. (i) and (ii) only
• B. (ii), (iii) and (iv) only
• C. (ii) and (iv) only
• D. (i) and (iv) only

Answer 1

Answer: (B)

Incomplete (partial or mosaic) dominance is the phenomenon where none of the two contrasting alleles or factors is dominant. The expression of the character in a hybrid or $F_1$ individual is intermediate or a fine mixture of the expression of the two factors (as found in homozygous state). Incomplete or mosaic inheritance is not an example of pre-Mendelian concept of blending inheritance because the parental types reappear in the $F_2$ generation.