1. In a monohybrid cross showing incomplete dominance (e.g., Mirabilis jalapa / Antirrhinum majus), what is the phenotypic ratio in the F2 generation?
Correct Answer: B (1 : 2 : 1)
In incomplete dominance, the heterozygous genotype (Rr) exhibits an intermediate pink phenotype, making both phenotypic and genotypic ratios identical (1 Red : 2 Pink : 1 White).
In incomplete dominance, the heterozygous genotype (Rr) exhibits an intermediate pink phenotype, making both phenotypic and genotypic ratios identical (1 Red : 2 Pink : 1 White).
2. Human ABO blood groups provide an example of:
Correct Answer: B (Multiple allelism and Co-dominance)
ABO blood group is controlled by the I gene with 3 alleles (IA, IB, i) representing multiple allelism. When IA and IB are present together, both express fully as AB blood group, demonstrating co-dominance.
ABO blood group is controlled by the I gene with 3 alleles (IA, IB, i) representing multiple allelism. When IA and IB are present together, both express fully as AB blood group, demonstrating co-dominance.
3. When a single gene influences multiple phenotypic traits simultaneously, the phenomenon is termed:
Correct Answer: C (Pleiotropy)
Pleiotropy occurs when one single gene controls more than one distinct phenotypic trait (e.g., Phenylketonuria causing mental retardation, reduced hair, and skin pigmentation).
Pleiotropy occurs when one single gene controls more than one distinct phenotypic trait (e.g., Phenylketonuria causing mental retardation, reduced hair, and skin pigmentation).
4. Human skin color inheritance is a classic example of:
Correct Answer: A (Polygenic inheritance)
Human skin color is controlled by three distinct genes (A, B, C) where dominant alleles exert an additive or quantitative effect on the phenotype.
Human skin color is controlled by three distinct genes (A, B, C) where dominant alleles exert an additive or quantitative effect on the phenotype.
5. Who experimentally proved the Chromosomal Theory of Inheritance using Drosophila melanogaster?
Correct Answer: B (Thomas Hunt Morgan)
Sutton and Boveri proposed the Chromosomal Theory of Inheritance, but T.H. Morgan provided its experimental verification through his work with fruit flies (Drosophila).
Sutton and Boveri proposed the Chromosomal Theory of Inheritance, but T.H. Morgan provided its experimental verification through his work with fruit flies (Drosophila).
6. Who utilized the frequency of genetic recombination between gene pairs to construct the first genetic map of chromosomes?
Correct Answer: C (Alfred Sturtevant)
Alfred Sturtevant (a student of Morgan) used the percentage of crossing over / recombination frequency between linked genes to map their relative positions on chromosomes.
Alfred Sturtevant (a student of Morgan) used the percentage of crossing over / recombination frequency between linked genes to map their relative positions on chromosomes.
7. What is the mechanism of sex determination observed in birds?
Correct Answer: C (ZW female and ZZ male)
In birds, females are heterogametic (ZW) producing two types of eggs, while males are homogametic (ZZ) producing identical sperms.
In birds, females are heterogametic (ZW) producing two types of eggs, while males are homogametic (ZZ) producing identical sperms.
8. In honey bees, male drones develop by parthenogenesis and have:
Correct Answer: B (Haploid number (16 chromosomes) produced from unfertilized eggs)
Honey bees show haplodiploid sex determination: females (queens/workers) are diploid (32) from fertilized eggs, while males (drones) are haploid (16) developing parthenogenetically.
Honey bees show haplodiploid sex determination: females (queens/workers) are diploid (32) from fertilized eggs, while males (drones) are haploid (16) developing parthenogenetically.
9. Haemophilia and Red-Green Colour Blindness in humans are inherited as:
Correct Answer: C (X-linked recessive disorders)
Both haemophilia and colour blindness are sex-linked (X-linked) recessive conditions showing criss-cross inheritance (carrier mother to affected son).
Both haemophilia and colour blindness are sex-linked (X-linked) recessive conditions showing criss-cross inheritance (carrier mother to affected son).
10. Sickle cell anemia is caused by a point mutation that replaces Glutamic acid with Valine at which position of the beta-globin chain?
Correct Answer: B (6th position (GAG to GUG))
A single base substitution of adenine (A) by thymine (T) converts the GAG codon to GUG at the 6th codon of the beta-globin mRNA, substituting Glutamic acid with Valine.
A single base substitution of adenine (A) by thymine (T) converts the GAG codon to GUG at the 6th codon of the beta-globin mRNA, substituting Glutamic acid with Valine.
11. Thalassemia is an autosomal recessive blood disorder. Alpha-thalassemia is controlled by which closely linked genes on chromosome 16?
Correct Answer: B (HBA1 and HBA2 genes on chromosome 16)
Alpha-thalassemia is regulated by two adjacent genes (HBA1 and HBA2) on chromosome 16. Beta-thalassemia is controlled by a single HBB gene on chromosome 11.
Alpha-thalassemia is regulated by two adjacent genes (HBA1 and HBA2) on chromosome 16. Beta-thalassemia is controlled by a single HBB gene on chromosome 11.
12. Down’s syndrome is caused by which chromosomal aberration?
Correct Answer: B (Trisomy of chromosome 21 (2n + 1))
Described by Langdon Down in 1866, Down’s syndrome results from an extra copy of autosome 21 (trisomy 21), leading to 47 chromosomes.
Described by Langdon Down in 1866, Down’s syndrome results from an extra copy of autosome 21 (trisomy 21), leading to 47 chromosomes.
13. A genetic disorder characterized by a karyotype of 47, XXY showing gynaecomastia and sterile male features is:
Correct Answer: A (Klinefelter’s Syndrome)
Klinefelter’s syndrome is caused by an extra X chromosome in males (44 + XXY = 47), displaying tall stature, sterile testes, and feminine traits like breast development (gynaecomastia).
Klinefelter’s syndrome is caused by an extra X chromosome in males (44 + XXY = 47), displaying tall stature, sterile testes, and feminine traits like breast development (gynaecomastia).
14. Turner’s syndrome in human females is caused by:
Correct Answer: B (Monosomy of X chromosome (45, XO))
Turner’s syndrome occurs due to the absence of one X chromosome (44 + XO = 45). Affected females are sterile with rudimentary ovaries, short stature, and webbed neck.
Turner’s syndrome occurs due to the absence of one X chromosome (44 + XO = 45). Affected females are sterile with rudimentary ovaries, short stature, and webbed neck.
15. A cross between an unknown dominant phenotype individual and a homozygous recessive individual is known as a:
Correct Answer: C (Test cross)
A test cross involves crossing an organism showing a dominant trait with its homozygous recessive parent to determine whether the dominant organism is homozygous or heterozygous.
A test cross involves crossing an organism showing a dominant trait with its homozygous recessive parent to determine whether the dominant organism is homozygous or heterozygous.
16. Mendel’s Law of Independent Assortment holds good for genes that are located on:
Correct Answer: B (Different homologous chromosome pairs)
Independent assortment applies to genes located on separate, non-homologous chromosomes. Tightly linked genes on the same chromosome do not assort independently.
Independent assortment applies to genes located on separate, non-homologous chromosomes. Tightly linked genes on the same chromosome do not assort independently.
17. Frederick Griffith’s transforming principle experiment (1928) utilized which bacterium?
Correct Answer: B (Streptococcus pneumoniae)
Griffith used virulent smooth (S) strain and non-virulent rough (R) strain of Streptococcus pneumoniae to demonstrate transformation in mice.
Griffith used virulent smooth (S) strain and non-virulent rough (R) strain of Streptococcus pneumoniae to demonstrate transformation in mice.
18. Unequivocal proof that DNA is the genetic material was provided in 1952 by Hershey and Chase using:
Correct Answer: B (Radioactive Phosphorus-32 and Sulfur-35 on Bacteriophage T2)
Hershey and Chase labeled viral DNA with P-32 and protein coat with S-35. Only P-32 entered the E. coli host cells, confirming DNA as the hereditary material.
Hershey and Chase labeled viral DNA with P-32 and protein coat with S-35. Only P-32 entered the E. coli host cells, confirming DNA as the hereditary material.
19. In a double-stranded DNA segment, if Cytosine constitutes 20% of the total nitrogenous bases, what will be the percentage of Adenine according to Chargaff’s rules?
Correct Answer: B (30%)
According to Chargaff’s rule, G = C = 20% (Total G + C = 40%). Thus, A + T = 100% – 40% = 60%. Since A = T, Adenine = 60% / 2 = 30%.
According to Chargaff’s rule, G = C = 20% (Total G + C = 40%). Thus, A + T = 100% – 40% = 60%. Since A = T, Adenine = 60% / 2 = 30%.
20. The structural unit of chromatin packaging in eukaryotes (nucleosome) contains approximately how many base pairs of DNA wrapped around a histone octamer core?
Correct Answer: C (200 bp)
A typical nucleosome consists of approximately 200 base pairs of negatively charged DNA wrapped around an octamer of positively charged, basic histone proteins (two copies each of H2A, H2B, H3, and H4).
A typical nucleosome consists of approximately 200 base pairs of negatively charged DNA wrapped around an octamer of positively charged, basic histone proteins (two copies each of H2A, H2B, H3, and H4).
21. Meselson and Stahl proved the semiconservative nature of DNA replication in E. coli using which heavy isotope and centrifugation gradient?
Correct Answer: B (N-15 in Cesium Chloride (CsCl) density gradient)
They grew E. coli in heavy 15N medium and shifted them to normal 14N medium, separating hybrid and light DNA bands using CsCl density gradient equilibrium centrifugation.
They grew E. coli in heavy 15N medium and shifted them to normal 14N medium, separating hybrid and light DNA bands using CsCl density gradient equilibrium centrifugation.
22. During DNA replication, the enzyme responsible for continuous synthesis on the leading strand and discontinuous synthesis on the lagging strand is:
Correct Answer: C (DNA-dependent DNA Polymerase)
DNA polymerase catalyzes chain polymerization exclusively in the 5′ to 3′ direction, resulting in continuous synthesis on the 3′ to 5′ template and discontinuous Okazaki fragments on the 5′ to 3′ template.
DNA polymerase catalyzes chain polymerization exclusively in the 5′ to 3′ direction, resulting in continuous synthesis on the 3′ to 5′ template and discontinuous Okazaki fragments on the 5′ to 3′ template.
23. In prokaryotic transcription, the core RNA polymerase enzyme requires which factor for specific initiation and which factor for termination?
Correct Answer: A (Sigma for initiation and Rho for termination)
RNA polymerase transiently binds the Sigma factor to recognize promoter sequences for initiation, and binds the Rho factor at the terminator sequence to terminate transcription.
RNA polymerase transiently binds the Sigma factor to recognize promoter sequences for initiation, and binds the Rho factor at the terminator sequence to terminate transcription.
24. During post-transcriptional processing of eukaryotic pre-mRNA (hnRNA), “capping” involves the addition of:
Correct Answer: B (Methyl guanosine triphosphate (m7Gppp) at 5′-end)
In capping, an unusual nucleotide (methyl guanosine triphosphate) is added to the 5′-end of hnRNA. Tailing involves adding 200–300 adenylate residues to the 3′-end.
In capping, an unusual nucleotide (methyl guanosine triphosphate) is added to the 5′-end of hnRNA. Tailing involves adding 200–300 adenylate residues to the 3′-end.
25. Which of the following triplet codons acts as the dual-function START codon in protein translation?
Correct Answer: C (AUG)
AUG serves a dual purpose: it acts as the initiation/start codon for translation and codes for the amino acid Methionine (Met). UAA, UAG, and UGA are STOP codons.
AUG serves a dual purpose: it acts as the initiation/start codon for translation and codes for the amino acid Methionine (Met). UAA, UAG, and UGA are STOP codons.
26. The genetic code is described as “degenerate” because:
Correct Answer: B (Some amino acids are specified by more than one codon)
Because there are 61 codons specifying only 20 amino acids, most amino acids are coded by multiple codons, which is termed code degeneracy.
Because there are 61 codons specifying only 20 amino acids, most amino acids are coded by multiple codons, which is termed code degeneracy.
27. Which molecule serves as the “adapter molecule” during translation by reading mRNA codons and bringing specific amino acids?
Correct Answer: B (tRNA)
Francis Crick postulated the existence of tRNA as an adapter molecule that possesses an anticodon loop to read mRNA and an amino acid acceptor end (CCA 3′) to carry amino acids.
Francis Crick postulated the existence of tRNA as an adapter molecule that possesses an anticodon loop to read mRNA and an amino acid acceptor end (CCA 3′) to carry amino acids.
28. In the Lac Operon model of E. coli, what is the specific product of the lac ‘y’ structural gene?
Correct Answer: B (Permease)
In the lac operon: gene ‘z’ codes for Beta-galactosidase, gene ‘y’ codes for Permease (which increases cell permeability to beta-galactosides), and gene ‘a’ codes for Transacetylase.
In the lac operon: gene ‘z’ codes for Beta-galactosidase, gene ‘y’ codes for Permease (which increases cell permeability to beta-galactosides), and gene ‘a’ codes for Transacetylase.
29. In the Lac Operon, lactose acts as an inducer by binding directly to the:
Correct Answer: C (Repressor protein, inactivating it)
Allolactose/lactose binds to the repressor protein synthesized by the ‘i’ gene, altering its conformation so it cannot bind the operator, allowing RNA polymerase to transcribe the operon.
Allolactose/lactose binds to the repressor protein synthesized by the ‘i’ gene, altering its conformation so it cannot bind the operator, allowing RNA polymerase to transcribe the operon.
30. According to findings from the Human Genome Project (HGP), what percentage of the human genome codes for proteins?
Correct Answer: A (Less than 2%)
The HGP revealed that less than 2% of the human genome encodes proteins, while repetitive sequences make up a very large portion of the human genome.
The HGP revealed that less than 2% of the human genome encodes proteins, while repetitive sequences make up a very large portion of the human genome.
31. Which human chromosome was the last to be completely sequenced under the Human Genome Project (in May 2006)?
Correct Answer: A (Chromosome 1)
Chromosome 1, the largest human chromosome with 2,968 genes, was the last of the 24 human chromosomes to be sequenced, finished in May 2006.
Chromosome 1, the largest human chromosome with 2,968 genes, was the last of the 24 human chromosomes to be sequenced, finished in May 2006.
32. The basis of DNA Fingerprinting is the high degree of polymorphism exhibited by:
Correct Answer: B (Satellite DNA / VNTRs)
Developed by Alec Jeffreys, DNA fingerprinting uses VNTRs (minisatellites) that display high copy-number polymorphism between individuals and are inherited from parents.
Developed by Alec Jeffreys, DNA fingerprinting uses VNTRs (minisatellites) that display high copy-number polymorphism between individuals and are inherited from parents.
33. In the Miller-Urey experiment simulating prebiotic Earth conditions, what gas mixture was subjected to electric discharge?
Correct Answer: A (CH4, NH3, H2, and water vapor at 800 degrees C)
Stanley Miller created electric discharges in a closed flask containing methane (CH4), ammonia (NH3), hydrogen (H2) in a 2:1:2 ratio, and water vapor at 800°C, synthesizing amino acids.
Stanley Miller created electric discharges in a closed flask containing methane (CH4), ammonia (NH3), hydrogen (H2) in a 2:1:2 ratio, and water vapor at 800°C, synthesizing amino acids.
34. The forelimbs of humans, cheetahs, whales, and bats share a similar anatomical bone pattern (humerus, radius, ulna, carpals), which exemplifies:
Correct Answer: A (Homology arising from Divergent Evolution)
Homologous structures share a common anatomical origin and basic plan but perform different functions in response to different adaptations (divergent evolution).
Homologous structures share a common anatomical origin and basic plan but perform different functions in response to different adaptations (divergent evolution).
35. Wings of butterflies and wings of birds are classic examples of:
Correct Answer: B (Analogous organs resulting from Convergent Evolution)
Analogous structures have different anatomical origins and embryonic structures but perform similar functions (convergent evolution due to similar ecological niches).
Analogous structures have different anatomical origins and embryonic structures but perform similar functions (convergent evolution due to similar ecological niches).
36. Industrial melanism observed in the peppered moth (Biston betularia) in England is a classic demonstration of:
Correct Answer: B (Natural selection in action)
Post-industrialization soot on tree trunks favored dark melanic moths over white-winged moths due to camouflage against bird predation, illustrating natural selection.
Post-industrialization soot on tree trunks favored dark melanic moths over white-winged moths due to camouflage against bird predation, illustrating natural selection.
37. Darwin’s finches of the Galapagos Islands represent one of the best examples of:
Correct Answer: A (Adaptive radiation)
Adaptive radiation is the process of evolution of different species in a given geographical area starting from a point and radiating to other habitats/niches (e.g., Darwin’s finches and Australian marsupials).
Adaptive radiation is the process of evolution of different species in a given geographical area starting from a point and radiating to other habitats/niches (e.g., Darwin’s finches and Australian marsupials).
38. Hugo de Vries proposed the Mutation Theory of evolution based on his work with which plant?
Correct Answer: B (Oenothera lamarckiana)
Hugo de Vries formulated his Mutation Theory after studying variations in evening primrose, stating that large single-step discontinuous mutations (saltation) drive evolution.
Hugo de Vries formulated his Mutation Theory after studying variations in evening primrose, stating that large single-step discontinuous mutations (saltation) drive evolution.
39. According to Hardy-Weinberg equilibrium, the total sum of all allelic frequencies in a population is equal to:
Correct Answer: B (1)
Hardy-Weinberg principle states that allele frequencies in a stable, large, randomly-mating population remain constant from generation to generation: p + q = 1 and p^2 + 2pq + q^2 = 1.
Hardy-Weinberg principle states that allele frequencies in a stable, large, randomly-mating population remain constant from generation to generation: p + q = 1 and p^2 + 2pq + q^2 = 1.
40. In a population in Hardy-Weinberg equilibrium, if the frequency of a recessive allele (q) is 0.4, what is the frequency of heterozygous individuals (2pq)?
Correct Answer: C (0.48)
Given q = 0.4, then p = 1 – 0.4 = 0.6. The frequency of heterozygotes (2pq) = 2 x 0.6 x 0.4 = 0.48.
Given q = 0.4, then p = 1 – 0.4 = 0.6. The frequency of heterozygotes (2pq) = 2 x 0.6 x 0.4 = 0.48.
41. When natural selection favors intermediate/average phenotypes and eliminates extreme variants at both ends, it is called:
Correct Answer: A (Stabilizing selection)
Stabilizing selection favors average phenotypes (e.g., human birth weight ~3 kg), making the distribution curve narrower and taller around the mean.
Stabilizing selection favors average phenotypes (e.g., human birth weight ~3 kg), making the distribution curve narrower and taller around the mean.
42. When a small group of individuals colonizes a new geographical area and founds a new population with drastically different allele frequencies, this genetic drift effect is termed:
Correct Answer: B (Founder effect)
When a small founding sample drifts away to establish a new isolated colony, the original altered allele frequencies become fixed in the new population (Founder effect).
When a small founding sample drifts away to establish a new isolated colony, the original altered allele frequencies become fixed in the new population (Founder effect).
43. The first human-like hominid fossil ancestor with a cranial capacity of 650–800 cc that probably did not eat meat was:
Correct Answer: B (Homo habilis)
Homo habilis had a brain capacity between 650–800 cc, was the first maker of stone tools, and was vegetarian.
Homo habilis had a brain capacity between 650–800 cc, was the first maker of stone tools, and was vegetarian.
44. Fossils of Homo erectus discovered in Java (1891) had a cranial capacity of approximately:
Correct Answer: B (900 cc)
Homo erectus arose ~1.5 million years ago, possessed a brain capacity around 900 cc, and showed definite evidence of meat eating.
Homo erectus arose ~1.5 million years ago, possessed a brain capacity around 900 cc, and showed definite evidence of meat eating.
45. Which hominid ancestor had a cranial capacity of ~1400 cc, lived in near East and Central Asia 100,000 to 40,000 years ago, used hides for clothing, and buried their dead?
Correct Answer: C (Neanderthal man)
Neanderthal man possessed a large cranial capacity of 1400 cc, utilized animal hides to protect bodies, and buried their dead with ritual practices.
Neanderthal man possessed a large cranial capacity of 1400 cc, utilized animal hides to protect bodies, and buried their dead with ritual practices.
46. About 15 million years ago, primates known as Dryopithecus and Ramapithecus were existing. Ramapithecus was:
Correct Answer: B (More man-like and walked more erect)
According to NCERT, Dryopithecus was more ape-like (hairy and walked like gorillas/chimpanzees), while Ramapithecus was more man-like.
According to NCERT, Dryopithecus was more ape-like (hairy and walked like gorillas/chimpanzees), while Ramapithecus was more man-like.
47. Modern Homo sapiens arose during the ice age between:
Correct Answer: A (75,000 to 10,000 years ago)
Homo sapiens arose in Africa and moved across continents, evolving into modern human races during the Ice Age between 75,000–10,000 years ago. Prehistoric cave art developed ~18,000 years ago, and agriculture started ~10,000 years ago.
Homo sapiens arose in Africa and moved across continents, evolving into modern human races during the Ice Age between 75,000–10,000 years ago. Prehistoric cave art developed ~18,000 years ago, and agriculture started ~10,000 years ago.
48. The lobefin coelacanth caught in South Africa in 1938 was significant because it represents an evolutionary link between:
Correct Answer: B (Fishes and Amphibians)
Coelacanth (lobefin) fishes evolved into the first amphibians that could live on land and in water, providing fossil/living evidence of vertebrate transition to land.
Coelacanth (lobefin) fishes evolved into the first amphibians that could live on land and in water, providing fossil/living evidence of vertebrate transition to land.
49. The giant reptile Tyrannosaurus rex, which became extinct around 65 million years ago, was about:
Correct Answer: B (20 feet in height with huge dagger-like teeth)
According to NCERT, the largest carnivorous dinosaur Tyrannosaurus rex stood about 20 feet in height and had formidable, dagger-like teeth.
According to NCERT, the largest carnivorous dinosaur Tyrannosaurus rex stood about 20 feet in height and had formidable, dagger-like teeth.
50. The concept that evolutionary change is driven by large, sudden, single-step mutations is known as:
Correct Answer: B (Saltation)
Hugo de Vries termed single-step large mutations as saltation, distinguishing his abrupt mutation theory from Darwin’s slow, continuous, directional variations.
Hugo de Vries termed single-step large mutations as saltation, distinguishing his abrupt mutation theory from Darwin’s slow, continuous, directional variations.