The correct answer is Option (2) - A-iii, B-ii, C-i, D-iv
| COLUMN 1 |
COLUMN 2 |
| A. Multiple allelism |
(iii) Human blood groups |
| B. Back cross |
(ii) Tt x TT |
| C. Test cross |
(i) Tt x tt |
| D.Crossing over |
(iv) Non-sister chromatids |
Multiple allelism - Human blood groups (iii):
- Explanation: The example of ABO blood grouping provides a good example of multiple allele because there are more than two, i.e., three alleles, governing the same character. The majority of human genes are thought to have more than two normal versions or alleles. Traits controlled by a single gene with more than two alleles are called multiple allele traits. An example is ABO blood type.
Back cross - Tt x TT (ii):
- Explanation: A back cross is a cross between a hybrid organism (heterozygous) and one of its parents or an individual genetically similar to its parent. In this case, Tt (heterozygous) is crossed with TT (homozygous dominant), making it a back cross.
Test cross - Tt x tt (i):
- Explanation: A test cross is done to determine the genotype of an organism showing a dominant phenotype. This is done by crossing it with a homozygous recessive organism (in this case tt). For example, Tt (heterozygous) crossed with tt (homozygous recessive).
Crossing over - Non-sister chromatids (iv):
- Explanation: Crossing over refers to the exchange of genetic material between non-sister chromatids of homologous chromosomes during meiosis. This process increases genetic diversity by mixing alleles between homologous chromosomes.
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