2nd Year NotesBiology class 12th

2nd Year Biology Chapter 22 Variation & Genetics

2nd Year Biology Chapter 22 Variation & Genetics Question And Answer

Short And Simple Question Answer

Q 1. Difference between phenotype and genotype?

Ans. Phenotype is how a trait looks, genotype is the genetic makeup.

Q 2. Define population?

Ans. A group of interbreeding organisms of the same species.

Q 3. What is the product rule?

Ans. Multiply probabilities of individual phenotypes for independent events.

Q 4. Name types of dominance relations among alleles?

Ans. Complete, incomplete, codominance, overdominance.

Q 5. Who discovered ABO blood group?

Ans. Karl Landsteiner in 1901.

Q 6. What is epistasis?

Ans. When one gene interferes with the effect of another gene.

Q 7. What are polygenetic traits?

Ans. Traits influenced by multiple genes.

Q 8. What is Crossover or recombinant frequency?

Ans. Proportion of recombinant types between genes.

Q 9. Organism lacking sex chromosomes?

Ans. Some eukaryotic microorganisms like yeast.

Q 10. True color blindness: monochromacy or dichromacy?

Ans. Monochromacy is true color blindness.

Q 11. Why did Mendelian factors behave like chromosomes?

Ans. Mendelian factors (genes) are located on chromosomes.

Q 12. How is sexual dimorphism exhibited in Drosophila?

Ans. Male and female Drosophila have distinct morphology.

Q 13. Difference between gene and genome?

Ans. Gene is a unit of biological information, genome is an organism’s genetic material.

Q 14. What are genes and alleles?

Ans. Genes are parts of DNA, alleles are gene variants.

Q 15. Difference between Monohybrid and dihybrid?

Ans. Monohybrid involves one trait, dihybrid involves two.

Q 16. Difference between Homozygous and heterozygous?

Ans. Homozygous has identical alleles, heterozygous has different alleles.

Q 17. Difference between Dominance and epistasis?

Ans. Dominance is the effect of an allele, epistasis is gene interaction.

Q 18. Difference between Autosome and sex chromosome?

Ans. Autosomes are non-sex chromosomes, sex chromosomes determine gender.

Q 19. Difference between Allele and multiple allele?

Ans. Alleles are gene variants, multiple alleles have more than two options.

Q 20. Difference between Sex limited and sex influenced trait?

Ans. Sex-limited traits occur in one sex due to anatomy, sex-influenced traits occur in both sexes but may be more common in one.

Q 21. Incomplete dominance vs. codominance?

Ans. Incomplete: Heterozygote’s phenotype is in between. E.g., 4 O’clock flower. Codominance: Both alleles expressed. E.g., MN blood type.

Q 22. Dominant vs. recessive trait?

Ans. Dominant: Appears in hybrids. Recessive: Suppressed in hybrids.

Q 23. Continuous vs. discontinuous variations?

Ans. Continuous: Many phenotypes (e.g., human height). Discontinuous: Two distinct phenotypes (e.g., Mendel’s pea shape).

Q 24. Wild type vs. mutant?

Ans. Wild type: Normal traits. Mutant: Trait due to mutation.

Q 25. What is a gene pool?

Ans. All alleles in a population.

Q 26. Why was pea lucky for Mendel?

Ans. 7 traits, 7 pairs of chromosomes. Independent assortment. Deviation with 8 traits.

Q 27. What is a test cross?

Ans. Cross for genotype of dominant phenotype.

Q 28. Consequences of non-segregation at meiosis?

Ans. Non-disjunction affects gamete purity.

Q 29. Missing combinations without independent assortment?

Ans. Recombination is missing.

Q 30. Equal chance for alleles in gametes?

Ans. Meiosis and segregation.

Q 31. Dominant allele effect on recessive?

Ans. Dominant doesn’t modify recessive.

Q 32. Which traits assort independently?

Ans. Traits on different chromosomes.

Q 33. Why blood group phenotype constant?

Ans. Genes don’t change throughout life.

Q 34. Universal blood donor?

Ans. O blood group individuals.

Q 35. ABO incompatibility and Rh protection?

Ans. ABO incompatibility can protect against Rh incompatibility.

Q 36. Genes not obeying independent assortment?

Ans. Genes on the same chromosome.

Q 37. Separating linked genes?

Ans. Crossing over.

Q 38. Multifactorial inheritance?

Ans. Trait influenced by genes and environment.

Q 39. What is MODY?

Ans. Early-onset diabetes with genetic cause.

Q 40. Child’s intelligence vs. parents?

Ans. Child may have higher intelligence.

Q 41. What is Locus?

Ans. Gene’s position on a chromosome.

Q 42. What are Alleles?

Ans. Gene partner variations.

Q 43. Why is Mendel famous?

Ans. Discovered laws of heredity.

Q 44. Mendel’s law of segregation?

Ans. Alleles separate in gametes.

Q 45. What is Punnett square?

Ans. Tool for genetic trait predictions.

Q 46. Mendel’s Law of independent Assortment?

Ans. Alleles for different traits assort independently.

Q 47. What is Linkage group?

Ans. Genes on the same chromosome.

Q 48. What is Over dominance?

Ans. Heterozygote exceeds both homozygotes.

Q 49. Who discovered ABO blood group?

Ans. Karl Landsteiner.

Q 50. Why is Bernstein famous?

Ans. Explained ABO genetic basis.

Q 51. Antigens produced by IA, IB, and i alleles?

Ans. IA – Antigen A, IB – Antigen B, i – No antigen.

Q 52. ABO blood system genotypes and phenotypes?

Ans. IAIA or IAi – Phenotype A, IBIB or IBi – Phenotype B, ii – Phenotype O.

Q 53. Why blood group phenotype doesn’t change?

Ans. Genes active from early embryonic stage.

Q 54. Antibodies in A, B, AB, and O blood?

Ans. A – Anti-B, B – Anti-A, AB – None, O – Anti-A and Anti-B.

Q 55. What is antiserum?

Ans. Serum with antibodies.

Q 56. Why is O called universal donor?

Ans. O has no antibodies, can donate to all.

Q 57. Why are AB individuals universal recipients?

Ans. AB can receive from all blood types.

Q 58. What is Rh blood group?

Ans. Defined by Rh-factor on RBCs.

Q 59. What is Erythroblastosis foetalis?

Ans. Mother’s Rh antibodies harm Rh+ foetus.

Q 60. Why called erythroblastosis foetalis?

Ans. Foetus releases immature erythroblasts.

Q 61. What is Bombay phenotype?

Ans. Like O but not genotypically O.

Q 62. Define pleiotropy?

Ans. One gene affecting multiple traits.

Q 63. W allele effect on cats?

Ans. White fur and deafness.

Q 64. Two aspects of phenotypic expression?

Ans. Qualitative and Quantitative.

Q 65. Environmental factors affecting wheat grain color?

Ans. Light, water, and nutrients.

Q 66. Tallness and shortness in humans?

Ans. Tallness is recessive, more shortness alleles = shorter.

Q 67. What is gene linkage?

Ans. Genes staying together on a chromosome.

Q 68. Define crossing over?

Ans. Exchange of chromosome segments.

Q 69. Human chromosome pairs?

Ans. 22 autosomes and 1 sex pair.

Q 70. What is SRY?

Ans. Male determining gene on Y-chromosome.

Q 71. Grasshopper chromosome numbers?

Ans. Female: 24 (XX), Male: 23 (XO).

Q 72. Homogametic vs. heterogametic?

Ans. Homogametic: Same sex chromosomes. Heterogametic: Different sex chromosomes.

Q 73. What is nullo gamete?

Ans. Gamete with no sex chromosome.

Q 74. XX-XY and WZ-ZZ sex determination in animals?

Ans. Common in birds, butterflies, and moths.

Q 75. XXY in humans and Drosophila?

Ans. XXY human: Sterile male (Klinefelter’s). XXY Drosophila: Fertile female.

Q 76. X:A ratio for females and males?

Ans. X:A > 1.0 for females, X:A < 0.5 for males.

Q 77. Monoecious vs. dioecious plants?

Ans. Monoecious has both sexes, dioecious has separate male and female plants.

Q 78. Why is Correns famous?

Ans. Discovered sex-determining pollen.

Q 79. Why is T.H. Morgan famous?

Ans. Found sex linkage in Drosophila supporting chromosomal theory.

Q 80. Why can a single X-linked recessive allele express in males?

Ans. Y chromosome lacks the gene.

Q 81. What are Sex-linked and X-linked traits?

Ans. Traits on X chromosome, often called sex-linked.

Q 82. Pattern of sex-linked inheritance?

Ans. Passes from maternal grandfather to grandson.

Q 83. What are Y-linked genes?

Ans. Genes unique to the Y chromosome.

Q 84. X- and Y-linked genes?

Ans. Genes on both X and Y chromosomes.

Q 85. Why are X- and Y-linked genes called pseudoautosomal?

Ans. Their inheritance pattern resembles autosomes.

Q 86. X-linked dominant and recessive traits?

Ans. Haemophilia is X-linked recessive, while others are X-linked dominant.

Q 87. What is haemophilia?

Ans. Blood clotting disorder.

Q 88. Types of haemophilia?

Ans. A, B, and C.

Q 89. Percentage of haemophilia types?

Ans. A: 80%, B: 20%, C: <1%.

Q 90. Which haemophilia affects men more?

Ans. Haemophilia A and B.

Q 91. When can a woman have haemophilia A or B?

Ans. If she’s homozygous for the recessive allele.

Q 92. Pattern of inheritance of haemophilia?

Ans. Zigzags from maternal grandfather to grandson.

Q 93. What are opsins?

Ans. Light-absorbing proteins in cone cells.

Q 94. What is dichromat? Types of dichromatic blindness?

Ans. Dichromat sees two primary colors but can’t perceive the third. Types: Protanopia, Deuteranopia, Tritanopia.

Q 95. Differentiate between protanopia, deuteranopia, and tritanopia?

Ans. Protanopia: Red color blindness. Deuteranopia: Green color blindness. Tritanopia: Blue color blindness.

Q 96. What are protanomalous and deuteranomalous?

Ans. Abnormal perception of red and green shades due to altered opsins.

Q 97. What is Monochromacy?

Ans. Can perceive only one color, true color blindness.

Q 98. What is Blue cone monochromacy?

Ans. Red and green cone cells are absent.

Q 99. Why is red-green color blindness more common in men?

Ans. Y chromosome lacks the alternate gene.

Q 100. Pattern of X-linked dominant inheritance?

Ans. More common in females, all daughters of affected father are affected.

Q 101. Pattern of Y-Linked inheritance?

Ans. Passes from father to son only.

Q 102. What are sex-limited traits?

Ans. Traits affecting structures or functions present in only one sex.

Q 103. What are sex-influenced traits?

Ans. Traits common but more prevalent in one sex due to hormonal differences.

Q 104. Risk of son inheriting pattern baldness?

Ans. Son has a high risk.

Q 105. What is Diabetes mellitus?

Ans. Hereditary disease with high blood sugar.

Q 106. Effects of diabetes?

Ans. Kidney failure, blindness, amputation, heart disease.

Q 107. What is Type I diabetes?

Ans. Early-onset, insulin-dependent diabetes.

Q 108. What is Type II diabetes?

Ans. Common in adults, non-insulin dependent diabetes.

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