Q31. What are ‘linked genes’?
a) Genes located on different chromosomes
b) Genes that are likely to be inherited together
c) Genes that always cause genetic disorders
d) Genes that do not follow Mendelian inheritance
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Correct Answer: b) Genes that are likely to be inherited together
Explanation: Linked genes are genes that are located close to each other on the same chromosome and are therefore likely to be inherited together. Due to their proximity, they tend not to assort independently during meiosis and often travel together during the process of genetic recombination.
Q32. What is the purpose of a ‘gene knockout’ in research?
a) To increase the expression of a gene
b) To repair a defective gene
c) To completely turn off a gene
d) To clone a gene
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Correct Answer: c) To completely turn off a gene
Explanation: A ‘gene knockout’ is a genetic technique in which an organism is engineered to carry genes that have been made inoperative, or “knocked out.” This is done to study the role of the specific gene by observing the effects of its absence.
Q33. What is a ‘silent mutation’?
a) A mutation that has no effect on phenotype
b) A mutation that is not expressed
c) A mutation in a non-coding region of DNA
d) A mutation that results in a stop codon
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Correct Answer: a) A mutation that has no effect on phenotype
Explanation: A silent mutation is a change in the nucleotide sequence of DNA that does not result in a change in the amino acid sequence of the protein produced. Therefore, it has no effect on the phenotype or the function of the protein.
Q34. Which genetic principle explains the segregation of alleles?
a) Independent assortment
b) Law of dominance
c) Law of segregation
d) Chromosomal theory of inheritance
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Correct Answer: c) Law of segregation
Explanation: The Law of Segregation, one of Mendel’s principles of genetics, states that allele pairs separate or segregate during the formation of gametes (eggs and sperm), so that each gamete carries only one allele for each gene. This principle explains how the offspring can sometimes express a trait that neither parent visibly expresses.
Q35. What is epigenetics?
a) The study of genetic mutations
b) The study of chromosomes and their structure
c) The study of changes in organisms caused by modification of gene expression
d) The study of gene and allele frequencies in a population
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Correct Answer: c) The study of changes in organisms caused by modification of gene expression
Explanation: Epigenetics involves the study of changes in organisms caused by the modification of gene expression rather than alteration of the genetic code itself. It’s about how genes are turned on or off and expressed to varying degrees, which can influence the characteristics of an organism.
Q36. What is the main cause of genetic diversity within a species?
a) Mutation
b) Gene therapy
c) Cloning
d) Genetic engineering
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Correct Answer: a) Mutation
Explanation: Mutation is the main cause of genetic diversity within a species. Mutations are changes in the DNA sequence that can lead to variations in traits. These genetic variations are crucial for the process of natural selection and the evolution of species.
Q37. In genetics, what does ‘penetrance’ refer to?
a) The physical expression of a gene
b) The proportion of individuals carrying a particular variant of a gene that also express an associated trait
c) The likelihood of a gene being passed on to the next generation
d) The rate at which a gene mutates
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Correct Answer: b) The proportion of individuals carrying a particular variant of a gene that also express an associated trait
Explanation: Penetrance in genetics refers to the proportion of individuals carrying a particular variant of a gene (allele) that also exhibit the phenotype associated with the allele. High penetrance means most people with the allele show symptoms of the trait or disease, while low penetrance means many do not.
Q38. Which concept in genetics explains why certain traits skip a generation?
a) Codominance
b) Incomplete dominance
c) Recessive inheritance
d) Mitochondrial inheritance
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Correct Answer: c) Recessive inheritance
Explanation: Recessive inheritance is a concept in genetics that can explain why certain traits skip a generation. Recessive traits only manifest in individuals who have two copies of the recessive allele. If a trait is recessive, a child can inherit it even if it was not expressed in the parents but both parents were carriers.
Q39. What role do telomeres play in genetics?
a) They replicate genes
b) They link chromosomes together
c) They protect the ends of chromosomes
d) They cause mutations
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Correct Answer: c) They protect the ends of chromosomes
Explanation: Telomeres are repetitive nucleotide sequences at the ends of each chromosome. They protect the chromosome ends from deterioration or from fusion with neighboring chromosomes. During cell division, telomeres length decreases, which is associated with aging.
Q40. What is the function of tRNA in protein synthesis?
a) It replicates DNA
b) It carries amino acids to the ribosome
c) It transcribes DNA to RNA
d) It modifies proteins after synthesis
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Correct Answer: b) It carries amino acids to the ribosome
Explanation: Transfer RNA (tRNA) is involved in protein synthesis, where its main function is to transport specific amino acids to the ribosome. At the ribosome, these amino acids are then assembled into proteins according to the genetic code carried by mRNA.