Question

C-value paradox is
A. Diploid DNA content
B. Haploid DNA content
C. Variation of C-value
D. Consistency of C-value

Answer 1

Hint: C-value paradox is related to the DNA amount present in terms of known function. It means that very similar or identical can show huge differences in the C-values such as in complex eukaryotes, the amount of genomic DNA is much greater as compared to the amount required for the encoding of the protein.

Complete answer:
In the haploid genome of an organism, the amount of DNA present is known as the C-Value. This C-value varies greatly over a wide range with the organism complexity from prokaryotes to invertebrates and vertebrates as well as plants. The C-value paradox is associated with the excessive amount of DNA present in the eukaryotic organisms and the variation in the C-value between the species of eukaryotes having identical complexity. The C-value paradox is explained based on junk DNA in the chromosomes and the huge amount of structural DNA present. For example, Around 21,000 genes are present in the human genome and its haploid genome, about 3.3 billion base pairs are present whereas around 19 to 20,000 protein-encoding genes are present in a nematode named Caenorhabditis elegans which usually lives in the soil and its haploid genome, around 100 million base pairs are present. Certain factors which help in explaining the C-value paradox include:
> Repetitive DNA
> Introns in genes
> Pseudogenes
>Intergenic sequences

So, the correct option is (C) Variation of C-value.

Note:
The student might get confused between the definition of C-value and the C-value paradox. C-value means the value of haploid DNA content per nucleus which remains constant and is measured typically in picograms whereas the C-value paradox is the amount of DNA present in the haploid genome which varies greatly between the organisms having identical complexity.