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Question
Explain the following term :
Heterozygous
Solution
Heterozygous:
The condition in which a pair of homologous chromosomes carries
dissimilar alleles for a particular character.
For example -
(i) A daughter (XXo) from a normal homozygous mother for colour vision (XX) anda colour blind father has one normal and one defective allele (XoY).
(ii) Certain tongue rollers are heterozygous with Rr genotype.
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RELATED QUESTIONS
Considering the relationship in the first pair, complete the second pair:
rr : Homozygous : : Rr : ....................
The F2 progeny of a monohybrid cross showed phenotypic and genotypic ratio as 1:2:1 unlike that the Mendel’s monohybrid F2 ratio. With the help of a suitable example, work out a cross and explain how it is possible.
Mention the Phenotype and Genotype ratios of the offspring in F2 generation.
In Mendel’s experiments, tall pea plants (T) are dominant over dwarf pea plants (t).
What is a Dihybrid Cross?
Define the following:
Heterozygous
Explain the following term : Homozygous
RR (Red) Antirrhinum is crossed with white (rr) one. Offspring (Rr) are pink. This is an example of ______.
A heterozygous violet-flowered pea plant is crossed to another homozygous violet- flowered pea plant. What percent of the progeny plants will have the recessive trait, i.e., white flowers?
In the following crosses write the characteristics of the progeny
| Cross | Progeny |
| (a) RR YY × RR YY | __________________ |
| Round, yellow Round, yellow | __________________ |
| (b) Rr Yy × Rr Yy | __________________ |
| Round, yellow Round, yellow | __________________ |
| (c) rr yy × rr yy | __________________ |
| wrinkled, green wrinkled, green | __________________ |
| (d) RR YY × rr yy | __________________ |
| Round, yellow wrinkled green | __________________ |
How many pairs of contrasting characters in pea bad were chosen by Mendel?
