Zoology MCQs for NEET — Practice Questions with Answers

The text states, 'The sensitivity of the technique has been increased by use of polymerase chain reaction (PCR...). Consequently, DNA from a single cell is enough to perform DNA fingerprinting analysis.'

The section on PCR focuses on 'synthesised in vitro using two sets of primers and the enzyme DNA polymerase'. DNA ligase is used for 'joining of DNA' to prepare recombinant DNA, which is a separate step before or after amplification, but not directly part of the PCR amplification cycle itself.

The text mentions, 'It is being used to detect mutations in genes in suspected cancer patients too. It is a powerful technique to identify many other genetic disorders.'

While the specific temperature isn't mentioned for denaturation, it's a fundamental step of PCR to separate DNA strands. Denaturation usually involves high temperatures to break hydrogen bonds, making the single strands available for primer annealing. This is implied by the order of steps (Denaturation, then Annealing).

The definition of PCR mentions 'synthesised in vitro using two sets of primers and the enzyme DNA polymerase'. Primers are short stretches of DNA that bind to the template DNA and provide a free 3'-OH group for DNA polymerase to initiate synthesis during the extension phase.

Five factors known to affect Hardy-Weinberg equilibrium are gene migration (gene flow), genetic drift, mutation, genetic recombination, and natural selection. Random mating is a condition for the equilibrium to hold, not a factor that disturbs it.

The sum total of all allelic frequencies is 1. If $p$ represents the frequency of allele A and $q$ represents the frequency of allele a, then $p+q=1$. Given $p=0.7$, then $q = 1 - 0.7 = 0.3$.

The text states, 'Sometimes the change in allele frequency is so different in the new sample of population that they become a different species. The original drifted population becomes founders and the effect is called founder effect.' This directly links the founder effect to genetic drift.

The Hardy-Weinberg principle states that 'allele frequencies in a population are stable and is constant from generation to generation. The gene pool (total genes and their alleles in a population) remains a constant. This is called genetic equilibrium.'

The five factors that affect Hardy-Weinberg equilibrium are gene migration, genetic drift, mutation, genetic recombination, and natural selection. For equilibrium to be maintained, these factors must essentially be absent or have a negligible effect. Thus, the absence of natural selection is a key condition.