Mendel first crossed pure-bred pea plants having round-yellow seeds with pure-bred pea plants having wrinkled-green seeds and found that only round-yellow seeds were produced in the F₁ generation. When F₁ generation pea plants having round-yellow seeds were cross-bred by self pollination, then peas having round-yellow seeds, round green seeds, wrinkled-yellow seeds and wrinkled-green seeds were produced. Mendel collected a total of 2160 seeds.
(a) What will be the number of (i) round green seeds (ii) wrinkled green seeds (iii) round yellow seeds, and (iv) wrinkled-yellow seeds?
(b) Which 'ratio' as established by Mendel have you made use of in answering the part (a) above?

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Solution

(a)
$(i) Number of round green seeds = \frac{2160}{16} \times 3 = 405 (ii) Number of wrinkled green seeds = \frac{2160}{16} \times 1 = 135 (iii) Number of round yellow seeds = \frac{2160}{16} \times 9 = 1215 (iv) Number of wrinkled yellow seeds = \frac{2160}{16} \times 3 = 405$

(b) The dihybrid ratio (which is 9: 3: 3: 1) has been used to answer part (a).

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(a) (i) Number of round green seeds = 216016×3 =405(ii) Number of wrinkled green seeds = 216016×1 =135(iii) Number of round yellow seeds = 216016×9 =1215(iv) Number of wrinkled yellow seeds = 216016×3 =405 (b) The dihybrid ratio (which is 9: 3: 3: 1) has been used to answer part (a).