Different varieties of the same gene are called
- (a)Genotypes
- (b)Sib pairs
- (c)Alleles
- (d)Isomers
Correct — C, Alleles. Alleles are the alternative forms, or different varieties, of the same gene that sit at the same position (locus) on homologous chromosomes. For example, a gene for seed colour may exist as an allele for yellow and an allele for green. Since the question defines exactly this, different versions of one gene, the term is alleles.
- (a)Genotypes — Genotype is the overall genetic make-up of an organism, the particular combination of alleles it carries, not the alternative forms of a single gene.
- (b)Sib pairs — Sib pairs are pairs of siblings, a term used in genetic studies of relatives; it has nothing to do with variant forms of a gene.
- (d)Isomers — Isomers are chemistry terms for compounds with the same molecular formula but different structures; they are not variant forms of a gene.
A gene is a unit of heredity occupying a fixed position on a chromosome. The same gene can exist in more than one form, and these alternative forms are called alleles. In a diploid organism the two homologous chromosomes carry one allele each for a gene, and the pair together, along with all other genes, makes up the genotype.
The wording 'different varieties of the same gene' is the textbook definition of alleles. The distractors mix in a broader genetics term (genotype), a study term (sib pairs) and a chemistry term (isomers) to test whether the candidate holds the precise meaning.
- Alleles are the alternative forms of a single gene at the same locus.
- A common example is the alleles for yellow and green seed colour in Mendel's peas.
- Genotype is the whole set of alleles an organism carries, not a variant of one gene.
- Dominant and recessive describe how two different alleles express in an organism.
- Confusing allele (one form of a gene) with genotype (the whole set of alleles).
- Being misled by the chemistry term isomers, which is unrelated to genes.
Asked as the term for alternative forms of the same gene; the definition points straight to alleles, with genotype as the common distractor.
No directly related past PYQ was found.
- practice — not a real PYQ
The genetic make-up of an organism, the combination of alleles it carries, is called its
- (a)phenotype
- (b)genotype
- (c)allele
- (d)locus
Answer(b) genotype — the full set of alleles present in the organism.
- practice — not a real PYQ
The fixed position on a chromosome occupied by a gene is called its
- (a)allele
- (b)locus
- (c)genome
- (d)codon
Answer(b) locus — the specific site where a gene and its alleles reside.