How many of the following statements are correct?      

i) Genes which code for a pair of contrasting traits are known as alleles, i.e., they are slightly different forms of the same gene.

ii) T is used for the tall trait and t for the ‘dwarf’ and T and t are alleles of each other.

iii) Allelic combinations may be homozygous (TT and tt) or heterozygous (Tt).

iv)In a typical test cross an organism showing a dominant phenotype is crossed with recessive parent to determine the genotype of the dominant phenotype.

 

i) Genes which code for a pair of contrasting traits are known as alleles, i.e., they are slightly different forms of the same gene.

ii) Alleles are located on the same loci of homologous chromosomes. Each allele is represented by an alphabet. The dominant allele is in the upper case and the recessive allele is in the lower case.

 Example: A character the height of a pea plant is represented by two traits: tall and dwarf.

T is for tallness and t for dwarfness.

iii)  In a diploid organism, each gene is represented by 2 copies of alleles. Allelic combinations may be homozygous (TT and tt) or heterozygous (Tt).

iv)In a typical test cross an organism showing a dominant phenotype is crossed with recessive parent to determine the genotype of the dominant phenotype.