Match List-I with List-II

Choose the correct answer from the options given below:

(A)-(III), (B)-(I), (C)-(IV), (D)-(II)

The correct answer is Option (1) → (A)-(III), (B)-(I), (C)-(IV), (D)-(II)

(A) Allele → (III) One of two or more alternative nucleotide sequences at a single gene locus

• Allele: An allele is a variant form of a gene.
• At a specific locus (position on a chromosome), different individuals can have different alleles.
• For example, the gene for flower color in pea plants may have two alleles: purple (dominant) and white (recessive).
• These are alternative sequences that produce different traits.

(B) Locus → (I) The position on the chromosome where a gene occurs

• Locus (plural: loci): This refers to the specific physical location of a gene on a chromosome.
• Think of it as the address where a particular gene "lives."
• Every gene has a specific locus that can be found across individuals of a species.

(C) Gene → (IV) A length of DNA that codes for a particular polypeptide or protein

• A gene is a segment of DNA that contains the instructions to make a protein or polypeptide.
• These proteins determine traits (like eye color, blood type, etc.).
• For example, the insulin gene codes for the insulin protein, which regulates blood sugar.

(D) Test Cross → (II) Testing a suspected heterozygote by crossing it with a known homozygous recessive

• A test cross is used in genetics to determine the genotype of an organism that shows a dominant trait.
• You cross it with a homozygous recessive (which always contributes the recessive allele).
• The resulting offspring's traits reveal whether the parent was homozygous dominant or heterozygous.