C-value paradox refers to
the lack of correlation between genome size and genetic complexity of an organism
the presence of genetic sequences that propagate themselves within a genome
the coexistence of multiple alleles at a genetic locus
the concept that two or more genes may have the same function
ANSWER
(A): the C-value paradox is the lack of correlation between genome size and the genetic complexity of an organism.
Official answer: ASource: Official answer key, GATE 2023 BT (IIT Kanpur)
Recall the definition of "C-value": the amount of haploid DNA (genome size) contained in a cell of an organism.
The C-value paradox is the well-documented observation that genome size (C-value) does not correlate with the organism's morphological or genetic complexity — for example, some amoebae and lungfish have genomes far larger than the human genome despite not being more "complex," a discrepancy largely attributable to variable amounts of non-coding/repetitive DNA.
Option (A) states precisely this — lack of correlation between genome size and genetic complexity — so (A) is correct.
Option (B) describes the behaviour of selfish/transposable genetic elements, which is a proposed contributor to genome size expansion but is not itself the definition of the C-value paradox — incorrect.
Option (C) describes the coexistence of multiple alleles at a locus, a population-genetics concept (related to heterozygosity), unrelated to genome size — incorrect.
Option (D) describes functional redundancy among genes, unrelated to genome size or the paradox — incorrect.
Hence only (A) correctly defines the C-value paradox.
KEY IDEA
The C-value paradox: an organism's haploid genome size (its C-value) does not correlate with its morphological or organismal complexity — e.g., some amoebae, lungfish, and even some plants have vastly larger genomes than humans, largely due to variable amounts of non-coding/repetitive DNA rather than a greater number of functional genes.
WATCH OUT FOR
Confusing the C-value paradox (genome size vs. complexity mismatch) with related but distinct concepts also tested as distractors: transposable/selfish DNA propagation (a proposed cause of genome size variation, not the paradox itself), multiple alleles at a locus (a population-genetics idea unrelated to genome size), or gene functional redundancy (unrelated to genome size).
From the GATE 2023 BT paper. Every question of this paper · Download the full paper · All 9 Mutation & repair questions, with notes
