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Heredity and Evolution — Science STD 10 — Question

CBSE BoardEnglish MediumSTD 10ScienceHeredity and Evolution4 Marks
Question
Question numbers i - iv are based on the table given below. Study the table and answer the following questions.

S. No.GenerationPhenotypic ratio
1.F_(1) generation23 pairs
2.F_(2) generation22 pairs

(i) State the law of dominance.

(ii) What is the dominant allele?

(iii) Define the term phenotype.

(iv) What is the meaning of genotype ?

✓

Answer

(i) According to the law of dominance, the parent contains two alleles out of which one is the dominant allele while the other is the recessive allele.

(ii) The allele that expresses itself and reduces the expression of other alleles is termed as the dominant allele.

(iii) The set of the morphological characteristics of an organism that are resulted from the interactions of the genes is known as the phenotype of the individual. For example, in pea plants, tallness is a phenotypic trait.

or

(iv) The set of the alleles in DNA that carries the information for the expression of a trait in an individual is known as its genotype. For example, genotype 'TT' expresses the tallness in plants.

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