Question 13 Marks
In a certain species of animals, black fur (B) is dominant over brown fur (b). Show possible ratio of genotype and phenotypes of the affspring.
Answer
View full question & answer→Parents BB
Questions
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Question 23 Marks
Given below are some pictures. Match them with the correct options.
| Pictures | Cross | ||
| 1. |  | a. | Incomplete |
| 2. |  | b. | Sex determination |
| 3. |  | c. | Dihybrid cross |
| 4. |  | d. | Pedigree analysis |
Answer
View full question & answer→(1 - b), (2 - d), (3 - a), (4 - c)
Question 33 Marks
(i) A pure tall plant (TT) is crossed with a pure dwarf plant (tt).
Draw Punnett squares to show (1) $F_1$ generation (2) $F_2$ generation.
(ii) Give the Phenotype of the $F_2$ generation.
(iii) Give the Phenotypic and Genotypic ratio of the $F_1$ and $F_2$ generation.
(iv) Name any one $X$-linked disease found in humans.
Draw Punnett squares to show (1) $F_1$ generation (2) $F_2$ generation.
(ii) Give the Phenotype of the $F_2$ generation.
(iii) Give the Phenotypic and Genotypic ratio of the $F_1$ and $F_2$ generation.
(iv) Name any one $X$-linked disease found in humans.
Answer
(ii) Phenotype of the $F _2$ generation - 3 Tall and 1 dwarf.
(iii) Phenotypic ratio of $F _1$ generation =All tall, $1: 0$
Genotypic ratio of $F _1$ generation $= All Tt , 1: 0$
Phenotypic ratio of $F _2$ generation $=3: 1$ (Tall : Dwarf)
Genotypic ratio of $F _2$ generation $=1( TT ): 2( Tt ): 1( tt )$
(iv) Colour blindness.
View full question & answer→(ii) Phenotype of the $F _2$ generation - 3 Tall and 1 dwarf.(iii) Phenotypic ratio of $F _1$ generation =All tall, $1: 0$
Genotypic ratio of $F _1$ generation $= All Tt , 1: 0$
Phenotypic ratio of $F _2$ generation $=3: 1$ (Tall : Dwarf)
Genotypic ratio of $F _2$ generation $=1( TT ): 2( Tt ): 1( tt )$
(iv) Colour blindness.
Question 43 Marks
Explain the following terms:
(i) Mutation
(ii) Homologous chromosomes
(iii) Alleles
(i) Mutation
(ii) Homologous chromosomes
(iii) Alleles
Answer
View full question & answer→(i) Mutation is a sudden change in certain characters or traits of an organism.
(ii) The chromosomes having the same structural features and the same pattern of genes are called homologous chromosomes.
(iii) The two altemative forms of a gene are called alleles. Each gene consists of an allelomorphic pair.
(ii) The chromosomes having the same structural features and the same pattern of genes are called homologous chromosomes.
(iii) The two altemative forms of a gene are called alleles. Each gene consists of an allelomorphic pair.