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Principle of Inheritance

Questions on Principle of Inheritance

Final Question Paper - Principles of Inheritance and Variation

Part A: Multiple Choice Questions (MCQs) - (1 mark each)

  1. Who is known as the "Father of Genetics"? a) Charles Darwin b) Gregor Johann Mendel c) Thomas Hunt Morgan d) Walter Sutton

  2. Mendel conducted his experiments on which plant? a) Pisum sativum b) Mirabilis jalapa c) Antirrhinum majus d) Drosophila melanogaster

  3. The Law of Dominance states that: a) All traits are equally expressed b) Only one allele expresses itself in heterozygous individuals c) Both alleles express themselves d) Traits blend together

  4. A cross between F1 hybrid and its recessive parent is called: a) Back cross b) Test cross c) Monohybrid cross d) Dihybrid cross

  5. The graphical representation to calculate probability of offspring genotypes is: a) Pedigree chart b) Karyotype c) Punnett square d) Genetic map

  6. Alternative forms of a gene are called: a) Genotypes b) Phenotypes c) Alleles d) Chromosomes

  7. An individual with TT genotype is: a) Heterozygous b) Homozygous dominant c) Homozygous recessive d) Codominant

  8. In incomplete dominance, the F2 phenotypic ratio is: a) 3:1 b) 9:3:3:1 c) 1:2:1 d) 1:1

  9. The ABO blood group system is an example of: a) Incomplete dominance b) Codominance c) Multiple alleles d) Both b and c

  10. Which blood group genotype shows codominance? a) IAIA b) IBIB c) IAIB d) ii

  11. Traits controlled by multiple genes are called: a) Polygenic b) Pleiotropic c) Codominant d) Recessive

  12. When one gene affects multiple traits, it is called: a) Polygenic inheritance b) Pleiotropy c) Codominance d) Incomplete dominance

  13. The study of inheritance patterns through family history is: a) Karyotype analysis b) Pedigree analysis c) Genetic mapping d) Mutation analysis

  14. The Chromosomal Theory of Inheritance was proposed by: a) Mendel and Morgan b) Sutton and Boveri c) Watson and Crick d) Darwin and Wallace

  15. In humans, sex determination follows: a) XY type b) ZW type c) XO type d) Haplodiploidy

  16. In birds, which sex is heterogametic? a) Males b) Females c) Both d) Neither

  17. Honeybee males are: a) Diploid b) Haploid c) Triploid d) Tetraploid

  18. Linkage was discovered by: a) Mendel b) Morgan c) Sutton d) Boveri

  19. Crossing over occurs during: a) Prophase I of meiosis b) Metaphase I of meiosis c) Prophase II of meiosis d) Mitosis

  20. The frequency of crossing over is proportional to: a) Gene size b) Chromosome size c) Distance between genes d) Number of alleles

  21. A sudden heritable change in DNA is called: a) Variation b) Mutation c) Recombination d) Segregation

  22. Replacement of A by G is an example of: a) Transition b) Transversion c) Frameshift d) Deletion

  23. Haemophilia is a: a) Autosomal dominant disorder b) Autosomal recessive disorder c) X-linked dominant disorder d) X-linked recessive disorder

  24. Colour blindness is more common in: a) Males b) Females c) Both equally d) Neither

  25. Thalassemia is an: a) X-linked disorder b) Y-linked disorder c) Autosomal recessive disorder d) Autosomal dominant disorder

  26. Sickle-cell anaemia is caused by: a) Chromosome deletion b) Point mutation c) Frameshift mutation d) Chromosome duplication

  27. PKU is caused by deficiency of: a) Insulin b) Hemoglobin c) Phenylalanine hydroxylase d) Clotting factor

  28. Down's syndrome is also called: a) Trisomy 18 b) Trisomy 21 c) Monosomy X d) XXY syndrome

  29. Turner's syndrome has karyotype: a) 47, XXY b) 47, XYY c) 45, XO d) 46, XX

  30. Klinefelter's syndrome affects: a) Females only b) Males only c) Both sexes d) Neither sex

  31. The Law of Segregation is also known as: a) Law of Dominance b) Law of Independent Assortment c) Law of Purity of Gametes d) Law of Linkage

  32. Mendel conducted experiments for how many years? a) 5 years b) 7 years c) 10 years d) 12 years

  33. The period of Mendel's experiments was: a) 1856-1863 b) 1850-1857 c) 1860-1867 d) 1855-1862

  34. A dihybrid cross involves: a) One pair of contrasting characters b) Two pairs of contrasting characters c) Three pairs of contrasting characters d) Multiple pairs of characters

  35. The F2 ratio in a dihybrid cross is: a) 3:1 b) 1:2:1 c) 9:3:3:1 d) 1:1:1:1

  36. Test cross is used to determine: a) Phenotype b) Genotype c) Linkage d) Mutation

  37. Red flower (RR) × White flower (rr) gives pink flowers (Rr). This is: a) Complete dominance b) Incomplete dominance c) Codominance d) Multiple alleles

  38. How many alleles control ABO blood group? a) 2 b) 3 c) 4 d) 5

  39. Human skin color is an example of: a) Simple dominance b) Codominance c) Polygenic inheritance d) Sex-linked inheritance

  40. Phenylketonuria affects: a) Only males b) Only females c) Both sexes equally d) More females than males

  41. Starch synthesis in pea seeds is an example of: a) Polygenic inheritance b) Pleiotropy c) Codominance d) Incomplete dominance

  42. Standardized symbols in pedigree analysis represent: a) Only sex b) Only affected status c) Sex, affected status, and relationships d) Only relationships

  43. Chromosomes occur in pairs, similar to: a) Genes b) Alleles c) Phenotypes d) Mutations

  44. Homologous chromosomes separate during: a) Mitosis b) Meiosis c) Both mitosis and meiosis d) Neither

  45. In XY type sex determination, males are: a) Homogametic b) Heterogametic c) Hemizygous d) Homozygous

  46. In ZW type sex determination, the heterogametic sex is: a) Male b) Female c) Both d) Neither

  47. Grasshopper follows which type of sex determination? a) XY type b) ZW type c) XO type d) Haplodiploidy

  48. Linked genes are located: a) On different chromosomes b) On the same chromosome c) On sex chromosomes only d) On autosomes only

  49. Genes that do not assort independently are: a) Linked genes b) Allelic genes c) Polygenes d) Pleiotropic genes

  50. Recombination is caused by: a) Mutation b) Crossing over c) Segregation d) Dominance

  51. Spontaneous mutations occur due to: a) Mutagens b) Radiation c) Errors in DNA replication d) Chemicals

  52. Induced mutations are caused by: a) Natural processes b) Mutagens c) Inheritance d) Dominance

  53. Point mutations affect: a) Entire chromosome b) Multiple genes c) Single base pair d) Chromosome structure

  54. Frameshift mutations are caused by: a) Base substitution b) Insertion or deletion c) Chromosome rearrangement d) Crossing over

  55. Morgan studied sex-linked inheritance in: a) Pea plants b) Mice c) Drosophila d) Humans

  56. Eye color in Drosophila is: a) Autosomal b) Sex-linked c) Polygenic d) Pleiotropic

  57. Haemophilia is also known as: a) Sickle-cell disease b) Bleeder's disease c) Color blindness d) Thalassemia

  58. The most common type of color blindness affects: a) Blue and yellow b) Red and green c) Black and white d) All colors

  59. Mendelian disorders are caused by: a) Chromosome abnormalities b) Environmental factors c) Single gene mutations d) Multiple gene interactions

  60. Thalassemia affects: a) Globin chain synthesis b) Insulin production c) Enzyme activity d) Chromosome structure

  61. In sickle-cell anaemia, glutamic acid is replaced by: a) Alanine b) Valine c) Glycine d) Phenylalanine

  62. Sickle-shaped red blood cells occur under: a) High oxygen tension b) Low oxygen tension c) Normal oxygen tension d) All conditions

  63. PKU leads to accumulation of: a) Glucose b) Phenylalanine c) Hemoglobin d) Insulin

  64. Mental retardation in PKU is caused by: a) Chromosome abnormality b) Enzyme deficiency c) Hormone imbalance d) Vitamin deficiency

  65. Chromosomal disorders are caused by: a) Single gene mutations b) Environmental factors c) Chromosome abnormalities d) Dominant alleles

  66. Down's syndrome is caused by: a) Missing chromosome b) Extra chromosome c) Chromosome rearrangement d) Point mutation

  67. The karyotype of Down's syndrome is: a) 45, XO b) 47, XXY c) 47, XX or XY, +21 d) 46, XY

  68. Turner's syndrome affects: a) Males only b) Females only c) Both sexes d) Neither sex

  69. Sterile females with rudimentary ovaries indicate: a) Down's syndrome b) Turner's syndrome c) Klinefelter's syndrome d) Sickle-cell anaemia

  70. Klinefelter's syndrome shows: a) 45, XO b) 47, XXY c) 47, XYY d) 46, XX

  71. Gynecomastia is a symptom of: a) Turner's syndrome b) Down's syndrome c) Klinefelter's syndrome d) Hemophilia

  72. Mendel's laws apply to genes located on: a) Same chromosome only b) Different chromosomes only c) Sex chromosomes only d) Different chromosomes or far apart on same chromosome

  73. The unit of inheritance according to Mendel is: a) Chromosome b) Gene c) Allele d) Factor

  74. Discrete units controlling characters are called: a) Genes b) Factors c) Alleles d) Both a and b

  75. Gametes receive how many alleles for each gene? a) One b) Two c) Three d) Four

  76. The Law of Independent Assortment applies to: a) Linked genes b) Unlinked genes c) Sex-linked genes d) Lethal genes

  77. Back cross involves: a) F1 × F1 b) F1 × Parent c) F1 × Recessive parent d) Parent × Parent

  78. The purpose of test cross is to determine: a) Dominance b) Recessiveness c) Genotype of dominant phenotype d) Phenotype ratio

  79. Punnett square was developed by: a) Mendel b) Morgan c) Reginald C. Punnett d) Sutton

  80. Probability calculations in genetics use: a) Pedigree charts b) Karyotypes c) Punnett squares d) Genetic maps

  81. Observable characteristics are called: a) Genotype b) Phenotype c) Alleles d) Genes

  82. Genetic constitution is called: a) Phenotype b) Genotype c) Karyotype d) Ideotype

  83. TT genotype shows: a) Heterozygous dominant b) Homozygous dominant c) Heterozygous recessive d) Homozygous recessive

  84. Environment affects: a) Genotype only b) Phenotype only c) Both genotype and phenotype d) Neither

  85. Blended phenotype in heterozygote indicates: a) Complete dominance b) Incomplete dominance c) Codominance d) Multiple alleles

  86. Snapdragon flower color shows: a) Complete dominance b) Incomplete dominance c) Codominance d) Sex-linkage

  87. Four O'clock plant is: a) Pisum sativum b) Antirrhinum majus c) Mirabilis jalapa d) Drosophila melanogaster

  88. Both alleles fully express in: a) Incomplete dominance b) Codominance c) Complete dominance d) Recessiveness

  89. Blood group AB shows: a) Dominance of A b) Dominance of B c) Codominance of A and B d) Recessiveness of both

  90. More than two alleles for a gene in population indicates: a) Polygenic inheritance b) Multiple alleles c) Pleiotropy d) Linkage

  91. Human height is controlled by: a) Single gene b) Two genes c) Multiple genes d) Sex-linked genes

  92. Additive effect of multiple genes results in: a) Qualitative traits b) Quantitative traits c) Sex-linked traits d) Lethal traits

  93. Single gene affecting multiple traits is: a) Polygenic b) Pleiotropic c) Codominant d) Recessive

  94. PKU affects: a) Only intelligence b) Only skin color c) Multiple traits d) Only hair color

  95. Family history study is called: a) Karyotype analysis b) Pedigree analysis c) Linkage analysis d) Mutation analysis

  96. Pedigree analysis helps determine: a) Genotype only b) Phenotype only c) Mode of inheritance d) Mutation rate

  97. Autosomal dominant inheritance shows: a) Horizontal pattern b) Vertical pattern c) Random pattern d) Circular pattern

  98. X-linked recessive traits are more common in: a) Females b) Males c) Both equally d) Neither

  99. Genetic mapping uses: a) Pedigree analysis b) Crossing over frequency c) Mutation rate d) Dominance pattern

  100. The basic unit of genetic mapping is: a) Gene b) Chromosome c) Map unit d) Allele

Part B: Short Answer Questions (1 mark each)

  1. Define heredity.
  2. What is variation?
  3. Name the scientist known as "Father of Genetics".
  4. Which plant did Mendel use for his experiments?
  5. What is a monohybrid cross?
  6. State the Law of Dominance.
  7. What is the Law of Segregation also known as?
  8. Define dihybrid cross.
  9. What is a test cross?
  10. Who developed the Punnett square?
  11. Define gene.
  12. What are alleles?
  13. What is homozygous condition?
  14. Define heterozygous.
  15. What is a dominant allele?
  16. Define recessive allele.
  17. What is genotype?
  18. Define phenotype.
  19. What is incomplete dominance?
  20. Give an example of incomplete dominance.
  21. Define codominance.
  22. What are multiple alleles?
  23. Define polygenic inheritance.
  24. What is pleiotropy?
  25. What is pedigree analysis?
  26. Who proposed the Chromosomal Theory of Inheritance?
  27. What is sex determination?
  28. Which sex is heterogametic in humans?
  29. Define linkage.
  30. Who discovered linkage?
  31. What is crossing over?
  32. Define mutation.
  33. What are spontaneous mutations?
  34. What is a point mutation?
  35. Define transition mutation.
  36. What is a frameshift mutation?
  37. Define sex-linked inheritance.
  38. What is haemophilia?
  39. Name a common type of color blindness.
  40. What are Mendelian disorders?
  41. Define thalassemia.
  42. What causes sickle-cell anaemia?
  43. What is PKU?
  44. What are chromosomal disorders?
  45. What is Down's syndrome?
  46. Define Turner's syndrome.
  47. What is Klinefelter's syndrome?
  48. What is the karyotype of normal human male?
  49. What is the karyotype of normal human female?
  50. Define back cross.
  51. What is the purpose of test cross?
  52. How many years did Mendel conduct his experiments?
  53. What are factors according to Mendel?
  54. What is the Law of Independent Assortment?
  55. Define homogametic sex.
  56. What is haplodiploidy?
  57. Which type of sex determination is found in birds?
  58. What is XO type sex determination?
  59. Define recombination.
  60. What are induced mutations?
  61. Define transversion mutation.
  62. What is the most common form of color blindness?
  63. Which enzyme is deficient in PKU?
  64. What is trisomy 21?
  65. What is the karyotype of Turner's syndrome?
  66. What is gynecomastia?
  67. Define genetic mapping.
  68. What is map unit?
  69. What are linked genes?
  70. Define mutagen.
  71. What is the scientific name of garden pea?
  72. What is the scientific name of snapdragon?
  73. What is the scientific name of four o'clock plant?
  74. Which model organism did Morgan use?
  75. What is the normal number of chromosomes in humans?
  76. Define aneuploidy.
  77. What is monosomy?
  78. What is trisomy?
  79. Define autosome.
  80. What are sex chromosomes?
  81. What is hemizygous condition?
  82. Define locus.
  83. What is a genetic cross?
  84. What is F1 generation?
  85. What is F2 generation?
  86. Define hybrid.
  87. What is true breeding?
  88. What is reciprocal cross?
  89. Define expressivity.
  90. What is penetrance?
  91. What is genetic load?
  92. Define fitness.
  93. What is selection pressure?
  94. What is genetic drift?
  95. Define gene flow.
  96. What is founder effect?
  97. What is bottleneck effect?
  98. Define inbreeding.
  99. What is outbreeding?
  100. What is hybrid vigor?

Part C: Medium Answer Questions (2 marks each)

  1. Explain the difference between heredity and variation.
  2. Describe Mendel's choice of pea plant for his experiments.
  3. Explain the Law of Dominance with an example.
  4. Describe the Law of Segregation with a suitable example.
  5. Explain the Law of Independent Assortment.
  6. Differentiate between back cross and test cross.
  7. Describe the construction and use of Punnett square.
  8. Explain the terms genotype and phenotype with examples.
  9. Distinguish between homozygous and heterozygous conditions.
  10. Describe incomplete dominance with suitable example.
  11. Explain codominance with reference to ABO blood groups.
  12. Describe the concept of multiple alleles.
  13. Explain polygenic inheritance with an example.
  14. Describe pleiotropy with suitable examples.
  15. Explain the importance of pedigree analysis.
  16. Describe the Chromosomal Theory of Inheritance.
  17. Explain XY type of sex determination.
  18. Describe ZW type of sex determination.
  19. Explain haplodiploidy with example.
  20. Describe the concept of linkage.
  21. Explain crossing over and its significance.
  22. Describe the relationship between crossing over frequency and gene distance.
  23. Explain spontaneous and induced mutations.
  24. Describe point mutations with examples.
  25. Explain frameshift mutations.
  26. Describe sex-linked inheritance in Drosophila.
  27. Explain haemophilia as a sex-linked disorder.
  28. Describe color blindness and its inheritance pattern.
  29. Explain the characteristics of Mendelian disorders.
  30. Describe thalassemia as a genetic disorder.
  31. Explain sickle-cell anaemia and its molecular basis.
  32. Describe PKU and its effects.
  33. Explain the causes of chromosomal disorders.
  34. Describe Down's syndrome and its characteristics.
  35. Explain Turner's syndrome and its symptoms.
  36. Describe Klinefelter's syndrome and its effects.
  37. Compare autosomal and sex-linked inheritance.
  38. Explain the concept of genetic mapping.
  39. Describe the significance of test cross in genetics.
  40. Explain the molecular basis of dominance and recessiveness.
  41. Describe the pattern of inheritance in incomplete dominance.
  42. Explain how multiple alleles differ from polygenes.
  43. Describe the genetic basis of ABO blood group system.
  44. Explain the concept of genetic load.
  45. Describe the difference between qualitative and quantitative traits.
  46. Explain the role of environment in gene expression.
  47. Describe the concept of expressivity and penetrance.
  48. Explain the significance of Morgan's work on Drosophila.
  49. Describe the structure of a typical pedigree chart.
  50. Explain the concept of genetic counseling.
  51. Describe the methods of sex determination in different organisms.
  52. Explain the significance of crossing over in evolution.
  53. Describe the types of chromosomal mutations.
  54. Explain the concept of lethal genes.
  55. Describe the Hardy-Weinberg principle.
  56. Explain the concept of genetic equilibrium.
  57. Describe inbreeding and its effects.
  58. Explain heterosis or hybrid vigor.
  59. Describe the concept of genetic diversity.
  60. Explain the role of mutations in evolution.
  61. Describe the concept of genetic drift.
  62. Explain gene flow and its effects.
  63. Describe natural selection and its types.
  64. Explain the founder effect.
  65. Describe the bottleneck effect.
  66. Explain the concept of fitness in genetics.
  67. Describe the relationship between genotype and phenotype.
  68. Explain the concept of epistasis.
  69. Describe complementation in genetics.
  70. Explain the concept of genetic complementation.
  71. Describe the pattern of X-linked dominant inheritance.
  72. Describe the pattern of X-linked recessive inheritance.
  73. Describe the pattern of Y-linked inheritance.
  74. Explain the concept of genomic imprinting.
  75. Describe the concept of anticipation in genetics.
  76. Explain the concept of genetic mosaicism.
  77. Describe the concept of chimerism.
  78. Explain the concept of genetic linkage analysis.
  79. Describe the concept of recombination mapping.
  80. Explain the three-factor cross.
  81. Describe the concept of gene interaction.
  82. Explain complementary gene action.
  83. Explain supplementary gene action.
  84. Explain inhibitory gene action.
  85. Describe the concept of modifier genes.
  86. Explain the concept of position effect.
  87. Describe the concept of genetic suppression.
  88. Explain the concept of genetic enhancement.
  89. Describe the concept of genetic background.
  90. Explain the concept of genetic buffering.
  91. Explain the concept of genetic canalization.
  92. Explain the concept of genetic assimilation.
  93. Describe the concept of genetic accommodation.
  94. Explain the concept of genetic robustness.
  95. Describe the concept of genetic redundancy.
  96. Explain the concept of genetic network.
  97. Describe the concept of genetic pathway.
  98. Explain the concept of genetic circuit.
  99. Describe the concept of genetic module.
  100. Explain the concept of genetic system.

Part D: Long Answer Questions (3 marks each)

  1. Describe Mendel's experiments on monohybrid cross with suitable examples and explain the Law of Dominance and Law of Segregation.
  2. Explain Mendel's dihybrid cross experiments and describe how it led to the formulation of the Law of Independent Assortment.
  3. Describe the concept of incomplete dominance with suitable examples and explain how it differs from complete dominance.
  4. Explain the ABO blood group system in humans, describing the genetic basis, inheritance pattern, and significance of multiple alleles and codominance.
  5. Describe polygenic inheritance with suitable examples and explain how it differs from single gene inheritance.
  6. Explain the concept of pleiotropy with suitable examples and describe its significance in genetics.
  7. Describe the process and significance of pedigree analysis in human genetics, explaining different patterns of inheritance.
  8. Explain the Chromosomal Theory of Inheritance and describe how it provided the physical basis for Mendel's laws.
  9. Describe the different types of sex determination mechanisms found in various organisms with suitable examples.
  10. Explain the concept of linkage and crossing over, describing their significance in genetics and evolution.
  11. Describe the different types of mutations, their causes, and their significance in genetics and evolution.
  12. Explain sex-linked inheritance with suitable examples from Drosophila and humans.
  13. Describe haemophilia as a sex-linked genetic disorder, explaining its inheritance pattern, symptoms, and genetic basis.
  14. Explain the genetic basis, symptoms, and inheritance pattern of thalassemia.
  15. Describe sickle-cell anaemia, explaining its molecular basis, inheritance pattern, and clinical significance.
  16. Explain PKU as a metabolic genetic disorder, describing its cause, symptoms, and treatment.
  17. Describe the causes and characteristics of chromosomal disorders with suitable examples.
  18. Explain Down's syndrome, describing its cause, characteristics, and social implications.
  19. Describe Turner's syndrome and Klinefelter's syndrome, comparing their causes, symptoms, and effects.
  20. Explain the concept of genetic mapping and describe how crossing over frequency is used to determine gene distances.
  21. Describe the historical development of genetics, highlighting the contributions of Mendel, Morgan, and other scientists.
  22. Explain the molecular basis of gene expression and describe how genotype determines phenotype.
  23. Describe the concept of gene regulation and explain how environmental factors can influence gene expression.
  24. Explain the concept of genetic counseling and describe its importance in preventing genetic disorders.
  25. Describe the ethical implications of genetic testing and gene therapy in modern medicine.
  26. Explain the concept of population genetics and describe the factors that influence allele frequencies.
  27. Describe the Hardy-Weinberg principle and explain its significance in population genetics.
  28. Explain the concept of genetic drift and describe its effects on small populations.
  29. Explain the concept of gene flow and explain its role in maintaining genetic diversity.
  30. Explain the different types of natural selection and describe their effects on allele frequencies.
  31. Describe the concept of genetic load and explain its significance in population genetics.
  32. Explain the concept of inbreeding and describe its genetic and evolutionary consequences.
  33. Describe the concept of heterosis and explain its significance in agriculture and evolution.
  34. Explain the concept of genetic diversity and describe its importance for species survival.
  35. Describe the role of mutations in providing raw material for evolution.
  36. Explain the concept of genetic recombination and describe its significance in generating genetic diversity.
  37. Explain the concept of epistasis and explain how gene interactions can modify phenotypes.
  38. Explain the concept of genomic imprinting and describe its significance in inheritance.
  39. Describe the concept of genetic anticipation and explain its molecular basis.
  40. Explain the concept of genetic mosaicism and describe its causes and effects.
  41. Explain the concept of genetic complementation and explain its use in functional studies.
  42. Explain the concept of genetic suppression and describe its mechanisms.
  43. Describe the concept of position effect and explain its significance in gene expression.
  44. Explain the concept of genetic networks and describe how genes interact in regulatory circuits.
  45. Explain the concept of genetic pathways and explain their role in cellular processes.
  46. Explain the concept of genetic robustness and describe its importance in development.
  47. Explain the concept of genetic canalization and explain its role in developmental stability.
  48. Explain the concept of genetic assimilation and describe its evolutionary significance.
  49. Describe the concept of genetic accommodation and explain its role in evolution.
  50. Explain the concept of genetic redundancy and describe its significance in gene function.
  51. Describe the evolution of sex determination mechanisms and explain their adaptive significance.
  52. Explain the concept of dosage compensation and describe its mechanisms in different organisms.
  53. Describe the concept of genetic conflict and explain its role in evolution.
  54. Explain the concept of genetic hitchhiking and describe its effects on genome evolution.
  55. Describe the concept of genetic background effects and explain their significance in phenotype determination.
  56. Explain the concept of genetic modifier genes and describe their role in phenotype modification.
  57. Describe the concept of genetic threshold traits and explain their inheritance pattern.
  58. Explain the concept of genetic penetrance and expressivity and describe factors affecting them.
  59. Describe the concept of genetic heterogeneity and explain its significance in human genetics.
  60. Explain the concept of genetic anticipation and describe its molecular mechanisms.
  61. Describe the evolution of genetic systems and explain their adaptive significance.
  62. Explain the concept of genetic coevolution and describe its role in species interactions.
  63. Explain the concept of genetic arms race and explain its evolutionary implications.
  64. Explain the concept of genetic constraint and describe how it limits evolutionary change.
  65. Describe the concept of genetic correlation and explain its significance in evolution.
  66. Explain the concept of genetic variance and describe its components.
  67. Describe the concept of heritability and explain its significance in quantitative genetics.
  68. Explain the concept of genetic gain and describe its application in breeding programs.
  69. Describe the concept of genetic response to selection and explain its prediction.
  70. Explain the concept of genetic correlation between traits and describe its evolutionary significance.
  71. Describe the concept of genetic trade-offs and explain their role in evolution.
  72. Explain the concept of genetic homeostasis and describe its mechanisms.
  73. Explain the concept of genetic flexibility and explain its adaptive significance.
  74. Explain the concept of genetic memory and describe its role in cellular responses.
  75. Explain the concept of genetic noise and explain its effects on gene expression.
  76. Explain the concept of genetic buffering and describe its mechanisms.
  77. Explain the concept of genetic switches and explain their role in development.
  78. Explain the concept of genetic circuits and describe their regulatory functions.
  79. Explain the concept of genetic modules and explain their evolutionary significance.
  80. Explain the concept of genetic hierarchies and describe their organizational principles.
  81. Describe the concept of genetic information and explain its storage and transmission.
  82. Explain the concept of genetic code and describe its universal properties.
  83. Describe the concept of genetic redundancy and explain its evolutionary maintenance.
  84. Explain the concept of genetic innovation and describe its mechanisms.
  85. Explain the concept of genetic constraint and explain its role in limiting phenotypic variation.
  86. Explain the concept of genetic facilitation and describe its role in evolution.
  87. Describe the concept of genetic predisposition and explain its significance in disease susceptibility.
  88. Describe the concept of genetic resistance and describe its mechanisms.
  89. Describe the concept of genetic tolerance and explain its adaptive significance.
  90. Explain the concept of genetic plasticity and describe its role in environmental adaptation.
  91. Describe the concept of genetic canalization and explain its role in developmental stability.
  92. Explain the concept of genetic assimilation and describe Baldwin's effect.
  93. Describe the concept of genetic accommodation and explain its role in phenotypic evolution.
  94. Explain the concept of genetic drift and describe its effects on neutral alleles.
  95. Explain the concept of genetic hitchhiking and explain its effects on linked alleles.
  96. Explain the concept of genetic background selection and describe its evolutionary consequences.
  97. Describe the concept of genetic sweep and explain its detection methods.
  98. Describe the concept of genetic introgression and describe its role in speciation.
  99. Describe the concept of genetic isolation and explain its mechanisms.
  100. Explain the concept of genetic rescue and describe its application in conservation biology.

Answer Key

Part A: MCQ Answers

  1. b) Gregor Johann Mendel
  2. a) Pisum sativum
  3. b) Only one allele expresses itself in heterozygous individuals
  4. b) Test cross
  5. c) Punnett square
  6. c) Alleles
  7. b) Homozygous dominant
  8. c) 1:2:1
  9. d) Both b and c
  10. c) IAIB
  11. a) Polygenic
  12. b) Pleiotropy
  13. b) Pedigree analysis
  14. b) Sutton and Boveri
  15. a) XY type
  16. b) Females
  17. b) Haploid
  18. b) Morgan
  19. a) Prophase I of meiosis
  20. c) Distance between genes
  21. b) Mutation
  22. a) Transition
  23. d) X-linked recessive disorder
  24. a) Males
  25. c) Autosomal recessive disorder
  26. b) Point mutation
  27. c) Phenylalanine hydroxylase
  28. b) Trisomy 21
  29. c) 45, XO
  30. b) Males only
  31. c) Law of Purity of Gametes
  32. b) 7 years
  33. a) 1856-1863
  34. b) Two pairs of contrasting characters
  35. c) 9:3:3:1
  36. b) Genotype
  37. b) Incomplete dominance
  38. b) 3
  39. c) Polygenic inheritance
  40. c) Both sexes equally
  41. b) Pleiotropy
  42. c) Sex, affected status, and relationships
  43. a) Genes
  44. b) Meiosis
  45. b) Heterogametic
  46. b) Female
  47. c) XO type
  48. b) On the same chromosome
  49. a) Linked genes
  50. b) Crossing over
  51. c) Errors in DNA replication
  52. b) Mutagens
  53. c) Single base pair
  54. b) Insertion or deletion
  55. c) Drosophila
  56. b) Sex-linked
  57. b) Bleeder's disease
  58. b) Red and green
  59. c) Single gene mutations
  60. a) Globin chain synthesis
  61. b) Valine
  62. b) Low oxygen tension
  63. b) Phenylalanine
  64. b) Enzyme deficiency
  65. c) Chromosome abnormalities
  66. b) Extra chromosome
  67. c) 47, XX or XY, +21
  68. b) Females only
  69. b) Turner's syndrome
  70. b) 47, XXY
  71. c) Klinefelter's syndrome
  72. d) Different chromosomes or far apart on same chromosome
  73. d) Factor
  74. d) Both a and b
  75. a) One
  76. b) Unlinked genes
  77. b) F1 × Parent
  78. c) Genotype of dominant phenotype
  79. c) Reginald C. Punnett
  80. c) Punnett squares
  81. b) Phenotype
  82. b) Genotype
  83. b) Homozygous dominant
  84. c) Both genotype and phenotype
  85. b) Incomplete dominance
  86. b) Incomplete dominance
  87. c) Mirabilis jalapa
  88. b) Codominance
  89. c) Codominance of A and B
  90. b) Multiple alleles
  91. c) Multiple genes
  92. b) Quantitative traits
  93. b) Pleiotropic
  94. c) Multiple traits
  95. b) Pedigree analysis
  96. c) Mode of inheritance
  97. b) Vertical pattern
  98. b) Males
  99. b) Crossing over frequency
  100. c) Map unit

Part B: Short Answer Questions

  1. Heredity: The process by which characters are passed on from parent to progeny.
  2. Variation: The degree by which progeny differ from their parents.
  3. "Father of Genetics": Gregor Johann Mendel.
  4. Mendel's plant: Pisum sativum (garden pea).
  5. Monohybrid cross: A cross involving a single pair of contrasting characters.
  6. Law of Dominance: In a heterozygous individual, only one allele (the dominant allele) expresses itself.
  7. Law of Segregation also known as: Law of Purity of Gametes.
  8. Dihybrid cross: A cross involving two pairs of contrasting characters.
  9. Test cross: A cross between an F1 hybrid and its recessive parent.
  10. Punnett square developer: Reginald C. Punnett.
  11. Gene: A unit of inheritance; a segment of DNA.
  12. Alleles: Alternative forms of a gene.
  13. Homozygous condition: Having identical alleles for a particular trait (e.g., TT or tt).
  14. Heterozygous: Having two different alleles for a particular trait (e.g., Tt).
  15. Dominant allele: An allele that expresses its phenotype even in the presence of a recessive allele.
  16. Recessive allele: An allele that expresses its phenotype only when present in a homozygous state.
  17. Genotype: The genetic constitution of an individual.
  18. Phenotype: The observable characteristics of an individual.
  19. Incomplete dominance: Neither allele is completely dominant over the other, resulting in a blended phenotype.
  20. Example of incomplete dominance: Flower color in Snapdragon (Antirrhinum majus).
  21. Codominance: Both alleles express themselves fully in the heterozygote.
  22. Multiple alleles: More than two alleles exist for a single gene in a population.
  23. Polygenic inheritance: A trait controlled by three or more genes.
  24. Pleiotropy: A single gene affects multiple phenotypic traits.
  25. Pedigree analysis: The study of inheritance patterns in a family over several generations.
  26. Chromosomal Theory of Inheritance proposers: Walter Sutton and Theodor Boveri.
  27. Sex determination: The mechanism by which the sex of an individual is determined.
  28. Heterogametic sex in humans: Males (XY).
  29. Linkage: The tendency of genes on the same chromosome to be inherited together.
  30. Linkage discoverer: T.H. Morgan.
  31. Crossing over: The exchange of genetic material between homologous chromosomes during meiosis.
  32. Mutation: A sudden heritable change in the DNA sequence.
  33. Spontaneous mutations: Occur naturally due to errors during DNA replication or repair.
  34. Point mutation: Changes in a single base pair of DNA.
  35. Transition mutation: Replacement of a purine by a purine or a pyrimidine by a pyrimidine.
  36. Frameshift mutation: Insertions or deletions of base pairs that alter the reading frame.
  37. Sex-linked inheritance: Inheritance of genes located on the sex chromosomes.
  38. Haemophilia: An X-linked recessive disorder causing prolonged bleeding.
  39. Common type of color blindness: Red-green color blindness.
  40. Mendelian disorders: Genetic disorders caused by alteration or mutation in a single gene.
  41. Thalassemia: An autosomal recessive blood disorder with reduced synthesis of globin chains.
  42. Cause of sickle-cell anaemia: A point mutation in the beta-globin gene.
  43. PKU: Phenylketonuria, an autosomal recessive metabolic disorder.
  44. Chromosomal disorders: Caused by absence, excess, or abnormal arrangement of chromosomes.
  45. Down's syndrome: Trisomy 21.
  46. Turner's syndrome: Monosomy X (XO) in females.
  47. Klinefelter's syndrome: XXY condition in males.
  48. Karyotype of normal human male: 46, XY.
  49. Karyotype of normal human female: 46, XX.
  50. Back cross: A cross between an F1 hybrid and either of its parents.
  51. Purpose of test cross: To determine the genotype of an individual showing the dominant phenotype.
  52. Duration of Mendel's experiments: Seven years (1856-1863).
  53. Mendel's "factors": Now known as genes.
  54. Law of Independent Assortment: Segregation of one pair of characters is independent of another pair.
  55. Homogametic sex: Produces only one type of gamete (e.g., human females - XX).
  56. Haplodiploidy: A sex-determination system where males develop from unfertilized eggs and are haploid, and females develop from fertilized eggs and are diploid.
  57. Sex determination in birds: ZW type.
  58. XO type sex determination: Males have only one X chromosome (XO), and females have two (XX).
  59. Recombination: The process of forming new combinations of genes.
  60. Induced mutations: Caused by mutagens.
  61. Transversion mutation: Replacement of a purine by a pyrimidine or vice versa.
  62. Most common form of color blindness: Red-green color blindness.
  63. Enzyme deficient in PKU: Phenylalanine hydroxylase.
  64. Trisomy 21: Down's syndrome.
  65. Karyotype of Turner's syndrome: 45, XO.
  66. Gynecomastia: Development of breast tissue in males, a symptom of Klinefelter's syndrome.
  67. Genetic mapping: Determining the relative positions of genes on a chromosome.
  68. Map unit: A unit of measurement for the distance between genes on a chromosome.
  69. Linked genes: Genes located on the same chromosome.
  70. Mutagen: An agent that causes mutations.
  71. Scientific name of garden pea: Pisum sativum.
  72. Scientific name of snapdragon: Antirrhinum majus.
  73. Scientific name of four o'clock plant: Mirabilis jalapa.
  74. Morgan's model organism: Drosophila melanogaster (fruit fly).
  75. Normal number of chromosomes in humans: 46.
  76. Aneuploidy: The presence of an abnormal number of chromosomes in a cell.
  77. Monosomy: The condition of having a diploid chromosome complement in which one chromosome lacks its homologous partner.
  78. Trisomy: The condition of having an extra copy of a chromosome.
  79. Autosome: Any chromosome that is not a sex chromosome.
  80. Sex chromosomes: Chromosomes that determine the sex of an individual (X and Y in humans).
  81. Hemizygous condition: Having only a single copy of a gene instead of the customary two copies.
  82. Locus: The specific location of a gene on a chromosome.
  83. Genetic cross: The deliberate breeding of two different individuals that results in offspring that carry part of the genetic material of each parent.
  84. F1 generation: The first filial generation, which is the offspring of a cross between the parental generation.
  85. F2 generation: The second filial generation, which is the offspring of a cross between individuals of the F1 generation.
  86. Hybrid: The offspring of two plants or animals of different species or varieties.
  87. True breeding: An organism that always passes down certain phenotypic traits to its offspring of many generations.
  88. Reciprocal cross: A breeding experiment in which the mother's and father's phenotypes are the reverse of that examined in a previous breeding experiment.
  89. Expressivity: The degree to which a trait is expressed.
  90. Penetrance: The proportion of individuals with a particular genotype that show the expected phenotype.
  91. Genetic load: The presence of unfavorable genetic material in the genes of a population.
  92. Fitness: The ability of an organism to survive and reproduce in its environment.
  93. Selection pressure: An environmental factor that causes a difference in fitness between organisms with different phenotypes.
  94. Genetic drift: The change in the frequency of an existing gene variant in a population due to random sampling of organisms.
  95. Gene flow: The transfer of genetic material from one population to another.
  96. Founder effect: The reduction in genetic variation that results when a small subset of a large population is used to establish a new colony.
  97. Bottleneck effect: A sharp reduction in the size of a population due to environmental events or human activities.
  98. Inbreeding: The mating of closely related individuals.
  99. Outbreeding: The mating of unrelated individuals.
  100. Hybrid vigor: The increased vigor or general health, resistance to disease, and other superior qualities that are often manifested in hybrid organisms.

Part C: Medium Answer Questions

  1. Heredity vs. Variation: Heredity is the transmission of traits from one generation to the next, ensuring similarity. Variation refers to the differences among individuals of a species, which can be caused by genetic recombination, mutation, or environmental factors, and is the basis for evolution.
  2. Mendel's choice of pea plant: Mendel chose pea plants because they have a short life cycle, produce many offspring, have easily distinguishable contrasting traits (e.g., tall/dwarf, round/wrinkled), and their pollination could be easily controlled.
  3. Law of Dominance: This law states that in a heterozygous individual, one allele (the dominant one) will mask the effect of the other allele (the recessive one). For example, in a pea plant with alleles for tallness (T) and dwarfness (t), the Tt genotype will result in a tall plant because the tall allele is dominant.
  4. Law of Segregation: This law states that the two alleles for each trait segregate (separate) during gamete formation, so that each gamete receives only one allele for each trait. For example, a Tt plant will produce gametes with either the T or the t allele.
  5. Law of Independent Assortment: This law states that the alleles of different genes assort independently of one another during gamete formation. This applies to genes located on different chromosomes or far apart on the same chromosome.
  6. Back cross vs. Test cross: A back cross is a cross between an F1 hybrid and one of its parents. A test cross is a specific type of back cross where the F1 hybrid is crossed with its homozygous recessive parent.
  7. Punnett square: A Punnett square is a diagram that is used to predict the genotypes of a particular cross or breeding experiment. It is a simple graphical way of discovering all of the potential combinations of genotypes that can occur in children, given the genotypes of their parents.
  8. Genotype vs. Phenotype: Genotype is the genetic makeup of an organism (e.g., Tt). Phenotype is the observable physical properties of an organism (e.g., tall).
  9. Homozygous vs. Heterozygous: Homozygous means having two identical alleles for a particular gene (e.g., TT or tt). Heterozygous means having two different alleles for a particular gene (e.g., Tt).
  10. Incomplete dominance: Incomplete dominance is a form of intermediate inheritance in which one allele for a specific trait is not completely expressed over its paired allele. For example, in snapdragons, a cross between a red-flowered plant (RR) and a white-flowered plant (rr) results in an F1 generation of all pink-flowered plants (Rr).
  11. Codominance in ABO blood groups: In the ABO blood group system, the IA and IB alleles are codominant. This means that if an individual inherits both alleles (genotype IAIB), both A and B antigens will be produced on the surface of their red blood cells, resulting in the AB blood type.
  12. Multiple alleles: Multiple alleles exist in a population when there are many variations of a gene present. The ABO blood group system is an example, with three alleles (IA, IB, and i).
  13. Polygenic inheritance: Polygenic inheritance occurs when one characteristic is controlled by two or more genes. Human skin color and height are examples.
  14. Pleiotropy: Pleiotropy occurs when one gene influences two or more seemingly unrelated phenotypic traits. For example, the gene for phenylketonuria (PKU) can cause mental retardation and reduced hair and skin pigmentation.
  15. Importance of pedigree analysis: Pedigree analysis is important for studying the inheritance patterns of traits in humans, particularly genetic disorders. It can help determine whether a trait is dominant or recessive, and whether it is autosomal or sex-linked.
  16. Chromosomal Theory of Inheritance: This theory states that genes are located on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns.
  17. XY type of sex determination: In this system, females have two of the same kind of sex chromosome (XX), while males have two distinct sex chromosomes (XY). The male is the heterogametic sex.
  18. ZW type of sex determination: In this system, males have two of the same kind of sex chromosome (ZZ), while females have two distinct sex chromosomes (ZW). The female is the heterogametic sex.
  19. Haplodiploidy: This is a sex-determination system in which males develop from unfertilized eggs and are haploid, and females develop from fertilized eggs and are diploid. This is seen in bees, wasps, and ants.
  20. Linkage: Linkage is the tendency of genes that are located close to each other on a chromosome to be inherited together during meiosis.
  21. Crossing over and its significance: Crossing over is the exchange of genetic material between homologous chromosomes that results in recombinant chromosomes. It is a major source of genetic variation.
  22. Crossing over frequency and gene distance: The frequency of crossing over between two genes is proportional to the distance between them on the chromosome. The farther apart the genes, the higher the frequency of recombination.
  23. Spontaneous and induced mutations: Spontaneous mutations are random changes in the DNA that occur without a known cause. Induced mutations are caused by exposure to mutagens, such as radiation or chemicals.
  24. Point mutations: Point mutations are changes in a single nucleotide of DNA. An example is sickle-cell anemia, which is caused by a single nucleotide substitution in the beta-globin gene.
  25. Frameshift mutations: Frameshift mutations are genetic mutations caused by insertions or deletions of a number of nucleotides in a DNA sequence that is not divisible by three. This alters the reading frame of the entire subsequent sequence.
  26. Sex-linked inheritance in Drosophila: T.H. Morgan's work on Drosophila showed that the gene for eye color was located on the X chromosome. This was the first experimental evidence for sex-linked inheritance.
  27. Haemophilia as a sex-linked disorder: Haemophilia is an X-linked recessive disorder. This means that the gene for haemophilia is on the X chromosome, and the allele for the disorder is recessive to the normal allele. It is more common in males because they only have one X chromosome.
  28. Color blindness and its inheritance pattern: Color blindness is also an X-linked recessive disorder. Like haemophilia, it is more common in males.
  29. Characteristics of Mendelian disorders: Mendelian disorders are caused by mutations in a single gene. They are inherited in a predictable pattern (dominant, recessive, autosomal, or sex-linked).
  30. Thalassemia as a genetic disorder: Thalassemia is an autosomal recessive blood disorder characterized by less hemoglobin and fewer red blood cells in the body than normal.
  31. Sickle-cell anaemia and its molecular basis: Sickle-cell anemia is an autosomal recessive disorder caused by a point mutation in the beta-globin gene, which results in the substitution of a single amino acid (glutamic acid is replaced by valine). This causes the hemoglobin to polymerize under low oxygen conditions, leading to the sickling of red blood cells.
  32. PKU and its effects: Phenylketonuria (PKU) is an inborn error of metabolism that results in decreased metabolism of the amino acid phenylalanine. If untreated, PKU can lead to intellectual disability, seizures, behavioral problems, and mental disorders.
  33. Causes of chromosomal disorders: Chromosomal disorders are caused by errors in the number or structure of chromosomes. These errors can occur during meiosis or mitosis.
  34. Down's syndrome and its characteristics: Down's syndrome is caused by trisomy 21 (an extra copy of chromosome 21). Characteristics include intellectual disability, a characteristic facial appearance, and weak muscle tone.
  35. Turner's syndrome and its symptoms: Turner's syndrome is a chromosomal disorder in which a female is born with only one X chromosome (XO). Symptoms include short stature, a webbed neck, and underdeveloped ovaries.
  36. Klinefelter's syndrome and its effects: Klinefelter's syndrome is a chromosomal disorder in which a male is born with an extra X chromosome (XXY). Effects can include weaker muscles, greater height, poor coordination, less body hair, smaller genitals, and breast growth.
  37. Autosomal vs. sex-linked inheritance: Autosomal inheritance involves genes on autosomes (non-sex chromosomes), while sex-linked inheritance involves genes on the sex chromosomes (X and Y).
  38. Concept of genetic mapping: Genetic mapping is the process of determining the linear sequence of genes on a chromosome.
  39. Significance of test cross in genetics: A test cross is used to determine the genotype of an organism that shows a dominant phenotype. It is also used to determine the linkage between genes.
  40. Molecular basis of dominance and recessiveness: Dominance is determined by the protein product of the alleles. A dominant allele will produce a functional protein, while a recessive allele may produce a non-functional protein or no protein at all.
  41. Pattern of inheritance in incomplete dominance: In incomplete dominance, the F1 generation has a phenotype that is intermediate between the two parental phenotypes. The F2 generation has a 1:2:1 phenotypic ratio.
  42. Multiple alleles vs. polygenes: Multiple alleles refer to more than two alleles for a single gene in a population. Polygenes refer to multiple genes that control a single trait.
  43. Genetic basis of ABO blood group system: The ABO blood group system is controlled by three alleles: IA, IB, and i. IA and IB are codominant, and both are dominant to i.
  44. Genetic load: Genetic load is the presence of unfavorable genetic material in the genes of a population.
  45. Qualitative vs. quantitative traits: Qualitative traits are those that are expressed in discrete categories (e.g., blood type). Quantitative traits are those that are expressed on a continuous scale (e.g., height).
  46. Role of environment in gene expression: The environment can influence the expression of genes. For example, the Himalayan rabbit has black fur on its extremities due to the lower temperature in those areas.
  47. Expressivity and penetrance: Expressivity is the degree to which a trait is expressed. Penetrance is the proportion of individuals with a particular genotype that show the expected phenotype.
  48. Significance of Morgan's work on Drosophila: Morgan's work on Drosophila provided the first experimental evidence for the chromosomal theory of inheritance and for sex-linked inheritance.
  49. Structure of a typical pedigree chart: A pedigree chart uses standard symbols to represent males, females, affected individuals, and the relationships between them.
  50. Concept of genetic counseling: Genetic counseling is the process of advising individuals and families affected by or at risk of genetic disorders to help them understand and adapt to the medical, psychological, and familial implications of genetic contributions to disease.
  51. Methods of sex determination in different organisms: Different organisms have different methods of sex determination, including the XY system (humans), the ZW system (birds), haplodiploidy (bees), and environmental sex determination (some reptiles).
  52. Significance of crossing over in evolution: Crossing over is a major source of genetic variation, which is the raw material for evolution.
  53. Types of chromosomal mutations: Chromosomal mutations include deletions, duplications, inversions, and translocations.
  54. Lethal genes: Lethal genes are genes that cause the death of the organism that carries them.
  55. Hardy-Weinberg principle: The Hardy-Weinberg principle states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences.
  56. Genetic equilibrium: Genetic equilibrium is a condition where a gene pool is not changing in frequency because the evolutionary forces acting upon the allele are equal.
  57. Inbreeding and its effects: Inbreeding is the mating of closely related individuals. It can lead to an increase in the frequency of homozygous recessive genotypes, which can result in inbreeding depression.
  58. Heterosis or hybrid vigor: Heterosis is the increased vigor or general health, resistance to disease, and other superior qualities that are often manifested in hybrid organisms.
  59. Genetic diversity: Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species.
  60. Role of mutations in evolution: Mutations are the ultimate source of all genetic variation, which is the raw material for evolution.
  61. Genetic drift: Genetic drift is the change in the frequency of an existing gene variant in a population due to random sampling of organisms.
  62. Gene flow and its effects: Gene flow is the transfer of genetic material from one population to another. It can introduce new alleles into a population and can change the allele frequencies in the populations.
  63. Natural selection and its types: Natural selection is the process by which heritable traits that make it more likely for an organism to survive and successfully reproduce become more common in a population over successive generations. Types include directional, stabilizing, and disruptive selection.
  64. Founder effect: The founder effect is the reduction in genetic variation that results when a small subset of a large population is used to establish a new colony.
  65. Bottleneck effect: The bottleneck effect is a sharp reduction in the size of a population due to environmental events or human activities.
  66. Fitness in genetics: Fitness is the ability of an organism to survive and reproduce in its environment.
  67. Relationship between genotype and phenotype: The genotype of an organism is its genetic makeup, while the phenotype is its observable characteristics. The phenotype is determined by the genotype and the environment.
  68. Epistasis: Epistasis is a phenomenon in which the effect of a gene mutation is dependent on the presence or absence of mutations in one or more other genes, respectively termed modifier genes.
  69. Complementation in genetics: Complementation occurs when two strains of an organism with different homozygous recessive mutations that produce the same mutant phenotype produce offspring with the wild-type phenotype when mated or crossed.
  70. Genetic complementation: See above.
  71. Pattern of X-linked dominant inheritance: X-linked dominant traits are passed from an affected father to all of his daughters, but not to his sons. An affected mother has a 50% chance of passing the trait to each of her children.
  72. Pattern of X-linked recessive inheritance: X-linked recessive traits are more common in males than in females. An affected father cannot pass the trait to his sons. An affected mother will pass the trait to all of her sons.
  73. Pattern of Y-linked inheritance: Y-linked traits are passed from father to son.
  74. Genomic imprinting: Genomic imprinting is an epigenetic phenomenon that causes genes to be expressed in a parent-of-origin-specific manner.
  75. Anticipation in genetics: Anticipation is a phenomenon in which the signs and symptoms of some genetic conditions tend to become more severe and/or appear at an earlier age as the disorder is passed from one generation to the next.
  76. Genetic mosaicism: Genetic mosaicism is the presence of two or more populations of cells with different genotypes in one individual who has developed from a single fertilized egg.
  77. Chimerism: Chimerism is the presence of two or more genetically distinct cell lines in an individual, originating from different zygotes.
  78. Genetic linkage analysis: Genetic linkage analysis is a statistical method that is used to associate functionality of genes to their location on chromosomes.
  79. Recombination mapping: Recombination mapping is a method of genetic mapping that uses the frequency of recombination between genes to determine their relative positions on a chromosome.
  80. Three-factor cross: A three-factor cross is a cross in which the parental strains differ in three genes. It is used to determine the linkage and order of the genes on the chromosome.
  81. Gene interaction: Gene interaction is the effect of a gene at one locus on the expression of a gene at another locus.
  82. Complementary gene action: Complementary gene action occurs when two genes work together to produce a single trait.
  83. Supplementary gene action: Supplementary gene action occurs when a dominant gene at one locus produces a phenotypic effect, but a dominant gene at another locus has no effect on its own but modifies the effect of the first gene.
  84. Inhibitory gene action: Inhibitory gene action occurs when a dominant gene at one locus masks the effect of a dominant gene at another locus.
  85. Modifier genes: Modifier genes are genes that influence the expression of another gene.
  86. Position effect: The position effect is the effect on the expression of a gene when its location on a chromosome is changed, often by translocation.
  87. Genetic suppression: Genetic suppression is the restoration of the wild-type phenotype in an organism that is mutant for a particular gene by a mutation in a second gene.
  88. Genetic enhancement: Genetic enhancement is the use of genetic engineering to modify a person's non-pathological human traits.
  89. Genetic background: The genetic background is the set of all genes in the genome of an organism.
  90. Genetic buffering: Genetic buffering is the ability of a population to maintain a constant phenotype despite genetic and environmental perturbations.
  91. Genetic canalization: Genetic canalization is the tendency of a population to produce the same phenotype regardless of variability of its environment or genotype.
  92. Genetic assimilation: Genetic assimilation is a process by which a phenotype that is initially produced in response to an environmental stimulus becomes genetically encoded.
  93. Genetic accommodation: Genetic accommodation is the process by which a new phenotype, produced in response to an environmental stimulus, becomes genetically fixed in a population.
  94. Genetic robustness: Genetic robustness is the ability of a population to maintain a constant phenotype despite genetic and environmental perturbations.
  95. Genetic redundancy: Genetic redundancy is the existence of multiple genes in the genome of an organism that perform the same function.
  96. Genetic network: A genetic network is a set of interacting genes that control a particular biological process.
  97. Genetic pathway: A genetic pathway is a series of chemical reactions in a cell that are catalyzed by enzymes that are encoded by genes.
  98. Genetic circuit: A genetic circuit is a set of interacting genes that control a particular biological process.
  99. Genetic module: A genetic module is a set of interacting genes that control a particular biological process.
  100. Genetic system: A genetic system is the set of all genes in the genome of an organism.

Part D: Long Answer Questions

  1. Mendel's Monohybrid Cross: Mendel performed a monohybrid cross by first taking a purebred tall pea plant (TT) and a purebred dwarf pea plant (tt) as the parental (P) generation. He cross-pollinated them to produce the first filial (F1) generation. All offspring in the F1 generation were tall (genotype Tt). This observation led to the Law of Dominance, as the tall trait masked the dwarf trait. Next, Mendel allowed the F1 plants to self-pollinate. In the resulting F2 generation, he observed both tall and dwarf plants in a ratio of approximately 3:1. This reappearance of the dwarf trait led to the Law of Segregation, which states that the two alleles for each trait segregate (separate) during gamete formation, so that each gamete receives only one allele for each trait.
  2. Mendel's Dihybrid Cross: Mendel performed a dihybrid cross by crossing a pea plant that was homozygous for round, yellow seeds (RRYY) with a pea plant that was homozygous for wrinkled, green seeds (rryy). The F1 generation all had round, yellow seeds (RrYy). When the F1 generation was self-pollinated, the F2 generation had a phenotypic ratio of 9:3:3:1 (round yellow: round green: wrinkled yellow: wrinkled green). This showed that the alleles for seed shape and seed color assorted independently of one another, which led to the Law of Independent Assortment.
  3. Incomplete Dominance: Incomplete dominance is a form of intermediate inheritance in which one allele for a specific trait is not completely expressed over its paired allele. This results in a third phenotype in which the expressed physical trait is a combination of the phenotypes of both alleles. For example, in snapdragons, a cross between a red-flowered plant (RR) and a white-flowered plant (rr) results in an F1 generation of all pink-flowered plants (Rr). This differs from complete dominance, where the F1 generation would all show the dominant trait (e.g., all red flowers). When the pink (Rr) F1 plants are self-crossed, the F2 generation has a phenotypic ratio of 1 Red : 2 Pink : 1 White.
  4. ABO Blood Group System: The ABO blood group in humans is a classic example of both codominance and multiple alleles. The system is controlled by a single gene, the 'I' gene, which has three different alleles: IA, IB, and i. An individual inherits two of these three alleles. The IA and IB alleles are dominant over the 'i' allele. However, when IA and IB are inherited together, they are codominant, meaning both are fully expressed, resulting in the AB blood type. This demonstrates codominance. The fact that there are three possible alleles (IA, IB, i) in the population for this single gene demonstrates multiple alleles.
  5. Polygenic Inheritance: Polygenic inheritance occurs when one characteristic is controlled by two or more genes. Often the genes are large in quantity but small in effect. Examples of human polygenic inheritance are height, skin color, eye color and weight. This differs from single gene inheritance, where a single gene controls the trait.
  6. Pleiotropy: Pleiotropy occurs when one gene influences two or more seemingly unrelated phenotypic traits. Such a gene that exhibits multiple phenotypic expression is called a pleiotropic gene. For example, phenylketonuria (PKU) is a disease caused by a mutation in a single gene that codes for the enzyme phenylalanine hydroxylase. This enzyme is necessary to metabolize the amino acid phenylalanine. A lack of this enzyme can lead to mental retardation, eczema, and pigment defects.
  7. Pedigree Analysis: Pedigree analysis is the study of an inherited trait in a group of related individuals to determine the pattern and characteristics of the trait, including its mode of inheritance, age of onset, and expressivity. It is a graphical representation of a family tree that shows the inheritance of a trait or disease through several generations. It can be used to determine whether a trait is dominant or recessive, and whether it is autosomal or sex-linked.
  8. Chromosomal Theory of Inheritance: The Chromosomal Theory of Inheritance states that genes are found at specific locations on chromosomes, and that the behavior of chromosomes during meiosis can explain Mendel's laws of inheritance. It was proposed by Walter Sutton and Theodor Boveri.
  9. Sex Determination Mechanisms: Different organisms have different mechanisms for sex determination. In humans, it is the XY system, where females are XX and males are XY. In birds, it is the ZW system, where females are ZW and males are ZZ. In bees, it is haplodiploidy, where females are diploid and males are haploid.
  10. Linkage and Crossing Over: Linkage is the tendency of genes that are located close to each other on a chromosome to be inherited together. Crossing over is the exchange of genetic material between homologous chromosomes that results in recombinant chromosomes. Crossing over can break up linkages between genes.
  11. Mutations: A mutation is a change in the DNA sequence of an organism. Mutations can be caused by errors in DNA replication, exposure to mutagens, or viral infection. Mutations can be beneficial, harmful, or neutral. They are the ultimate source of all genetic variation.
  12. Sex-Linked Inheritance: Sex-linked inheritance is the inheritance of a trait that is determined by a gene located on one of the sex chromosomes. In humans, this is usually the X chromosome. Examples include hemophilia and red-green color blindness. In Drosophila, eye color is a sex-linked trait.
  13. Haemophilia: Haemophilia is an X-linked recessive disorder that affects the body's ability to control blood clotting. It is more common in males than in females. A male with the haemophilia allele on his X chromosome will have the disorder, while a female must have the allele on both of her X chromosomes to have the disorder.
  14. Thalassemia: Thalassemia is an autosomal recessive blood disorder that is characterized by the production of an abnormal form of hemoglobin. This results in the excessive destruction of red blood cells, which leads to anemia.
  15. Sickle-Cell Anaemia: Sickle-cell anemia is an autosomal recessive blood disorder that is caused by a point mutation in the beta-globin gene. This mutation causes the hemoglobin to be misshapen, which in turn causes the red blood cells to be sickle-shaped. These sickle-shaped cells can block blood flow, causing pain and organ damage.
  16. PKU: Phenylketonuria (PKU) is an inborn error of metabolism that is caused by a mutation in the gene that codes for the enzyme phenylalanine hydroxylase. This enzyme is necessary to metabolize the amino acid phenylalanine. Without this enzyme, phenylalanine builds up in the body and can cause mental retardation and other health problems. Treatment involves a diet that is low in phenylalanine.
  17. Chromosomal Disorders: Chromosomal disorders are caused by changes in the number or structure of chromosomes. These changes can be inherited from a parent or can occur spontaneously. Examples of chromosomal disorders include Down syndrome, Turner syndrome, and Klinefelter syndrome.
  18. Down's Syndrome: Down syndrome is a chromosomal disorder that is caused by the presence of an extra copy of chromosome 21. This is also known as trisomy 21. People with Down syndrome have a distinct facial appearance, intellectual disability, and developmental delays.
  19. Turner's and Klinefelter's Syndromes: Turner syndrome is a chromosomal disorder that affects females. It is caused by the absence of one of the X chromosomes. Klinefelter syndrome is a chromosomal disorder that affects males. It is caused by the presence of an extra X chromosome.
  20. Genetic Mapping: Genetic mapping is the process of determining the location of genes on a chromosome. This can be done by using the frequency of recombination between genes. The farther apart two genes are on a chromosome, the more likely they are to be separated by recombination.
  21. Historical Development of Genetics: The field of genetics began with the work of Gregor Mendel in the 19th century. Mendel's work was rediscovered in the early 20th century, and this led to the development of the chromosomal theory of inheritance. In the mid-20th century, the structure of DNA was discovered, and this led to the development of molecular genetics.
  22. Gene Expression: Gene expression is the process by which the information in a gene is used to create a functional product, such as a protein. The genotype of an organism determines its phenotype, but the environment can also influence the phenotype.
  23. Gene Regulation: Gene regulation is the process of controlling which genes in a cell are expressed. This is important for ensuring that the correct proteins are produced at the correct time and in the correct amount. Environmental factors can influence gene regulation.
  24. Genetic Counseling: Genetic counseling is the process of helping people understand and adapt to the medical, psychological, and familial implications of genetic contributions to disease.
  25. Ethical Implications of Genetic Testing: There are a number of ethical issues associated with genetic testing, including the potential for discrimination, the privacy of genetic information, and the use of genetic information for non-medical purposes.
  26. Population Genetics: Population genetics is the study of the genetic composition of populations, and how the genetic composition changes over time. The factors that can influence allele frequencies include mutation, natural selection, genetic drift, and gene flow.
  27. Hardy-Weinberg Principle: The Hardy-Weinberg principle states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences.
  28. Genetic Drift: Genetic drift is the change in the frequency of an existing gene variant in a population due to random sampling of organisms. It is more likely to occur in small populations.
  29. Gene Flow: Gene flow is the transfer of genetic material from one population to another. It can introduce new alleles into a population and can change the allele frequencies in the populations.
  30. Natural Selection: Natural selection is the process by which heritable traits that make it more likely for an organism to survive and successfully reproduce become more common in a population over successive generations.
  31. Genetic Load: Genetic load is the presence of unfavorable genetic material in the genes of a population.
  32. Inbreeding: Inbreeding is the mating of closely related individuals. It can lead to an increase in the frequency of homozygous recessive genotypes, which can result in inbreeding depression.
  33. Heterosis: Heterosis is the increased vigor or general health, resistance to disease, and other superior qualities that are often manifested in hybrid organisms.
  34. Genetic Diversity: Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It is important for the survival of a species because it allows the species to adapt to changing environments.
  35. Role of Mutations in Evolution: Mutations are the ultimate source of all genetic variation, which is the raw material for evolution.
  36. Genetic Recombination: Genetic recombination is the process of forming new combinations of genes. It is a major source of genetic variation.
  37. Epistasis: Epistasis is a phenomenon in which the effect of a gene mutation is dependent on the presence or absence of mutations in one or more other genes, respectively termed modifier genes.
  38. Genomic Imprinting: Genomic imprinting is an epigenetic phenomenon that causes genes to be expressed in a parent-of-origin-specific manner.
  39. Anticipation in Genetics: Anticipation is a phenomenon in which the signs and symptoms of some genetic conditions tend to become more severe and/or appear at an earlier age as the disorder is passed from one generation to the next.
  40. Genetic Mosaicism: Genetic mosaicism is the presence of two or more populations of cells with different genotypes in one individual who has developed from a single fertilized egg.
  41. Genetic Complementation: Genetic complementation occurs when two strains of an organism with different homozygous recessive mutations that produce the same mutant phenotype produce offspring with the wild-type phenotype when mated or crossed.
  42. Genetic Suppression: Genetic suppression is the restoration of the wild-type phenotype in an organism that is mutant for a particular gene by a mutation in a second gene.
  43. Position Effect: The position effect is the effect on the expression of a gene when its location on a chromosome is changed, often by translocation.
  44. Genetic Networks: A genetic network is a set of interacting genes that control a particular biological process.
  45. Genetic Pathways: A genetic pathway is a series of chemical reactions in a cell that are catalyzed by enzymes that are encoded by genes.
  46. Genetic Robustness: Genetic robustness is the ability of a population to maintain a constant phenotype despite genetic and environmental perturbations.
  47. Genetic Canalization: Genetic canalization is the tendency of a population to produce the same phenotype regardless of variability of its environment or genotype.
  48. Genetic Assimilation: Genetic assimilation is a process by which a phenotype that is initially produced in response to an environmental stimulus becomes genetically encoded.
  49. Genetic Accommodation: Genetic accommodation is the process by which a new phenotype, produced in response to an environmental stimulus, becomes genetically fixed in a population.
  50. Genetic Redundancy: Genetic redundancy is the existence of multiple genes in the genome of an organism that perform the same function.
  51. Evolution of Sex Determination Mechanisms: The evolution of sex determination mechanisms is a complex process that is not fully understood. However, it is thought that sex determination mechanisms have evolved to be as simple and efficient as possible.
  52. Dosage Compensation: Dosage compensation is the process by which the expression of genes on the sex chromosomes is equalized in males and females.
  53. Genetic Conflict: Genetic conflict is a type of evolutionary conflict that occurs when the fitness interests of different genes are not aligned.
  54. Genetic Hitchhiking: Genetic hitchhiking is the process by which an allele can increase in frequency in a population because it is linked to a beneficial allele.
  55. Genetic Background Effects: The genetic background is the set of all genes in the genome of an organism. The genetic background can influence the expression of a gene.
  56. Genetic Modifier Genes: Modifier genes are genes that influence the expression of another gene.
  57. Genetic Threshold Traits: Threshold traits are traits that are either present or absent, but are determined by the combined effect of multiple genes and environmental factors.
  58. Penetrance and Expressivity: Penetrance is the proportion of individuals with a particular genotype that show the expected phenotype. Expressivity is the degree to which a trait is expressed.
  59. Genetic Heterogeneity: Genetic heterogeneity is the phenomenon in which a single phenotype or genetic disorder may be caused by any one of a multiple number of alleles or non-allele (locus) mutations.
  60. Anticipation: Anticipation is a phenomenon in which the signs and symptoms of some genetic conditions tend to become more severe and/or appear at an earlier age as the disorder is passed from one generation to the next.
  61. Evolution of Genetic Systems: The evolution of genetic systems is a complex process that is not fully understood. However, it is thought that genetic systems have evolved to be as efficient as possible at storing, transmitting, and expressing genetic information.
  62. Genetic Coevolution: Genetic coevolution is the process by which two or more species reciprocally affect each other's evolution.
  63. Genetic Arms Race: A genetic arms race is a type of coevolution in which two species are in an evolutionary struggle with each other.
  64. Genetic Constraint: A genetic constraint is a factor that limits the ability of a population to evolve.
  65. Genetic Correlation: A genetic correlation is a type of correlation that occurs when two traits are influenced by the same genes.
  66. Genetic Variance: Genetic variance is the amount of variation in a trait that is due to genetic factors.
  67. Heritability: Heritability is the proportion of the total variation in a trait that is due to genetic factors.
  68. Genetic Gain: Genetic gain is the improvement in a trait that is achieved through selective breeding.
  69. Genetic Response to Selection: The genetic response to selection is the change in the average value of a trait in a population that occurs as a result of selection.
  70. Genetic Correlation Between Traits: A genetic correlation between traits is a type of correlation that occurs when two traits are influenced by the same genes.
  71. Genetic Trade-offs: A genetic trade-off is a situation in which an increase in the fitness of one trait is associated with a decrease in the fitness of another trait.
  72. Genetic Homeostasis: Genetic homeostasis is the ability of a population to maintain a constant genetic composition despite changes in the environment.
  73. Genetic Flexibility: Genetic flexibility is the ability of a population to adapt to changes in the environment.
  74. Genetic Memory: Genetic memory is the ability of a population to remember past environmental conditions and to respond accordingly.
  75. Genetic Noise: Genetic noise is the random fluctuation in the expression of genes.
  76. Genetic Buffering: Genetic buffering is the ability of a population to maintain a constant phenotype despite genetic and environmental perturbations.
  77. Genetic Switches: A genetic switch is a regulatory mechanism that can turn a gene on or off.
  78. Genetic Circuits: A genetic circuit is a set of interacting genes that control a particular biological process.
  79. Genetic Modules: A genetic module is a set of interacting genes that control a particular biological process.
  80. Genetic Hierarchies: A genetic hierarchy is a system in which genes are organized into different levels of control.
  81. Genetic Information: Genetic information is the information that is stored in the DNA of an organism.
  82. Genetic Code: The genetic code is the set of rules by which information encoded in genetic material (DNA or RNA sequences) is translated into proteins (amino acid sequences).
  83. Genetic Redundancy: Genetic redundancy is the existence of multiple genes in the genome of an organism that perform the same function.
  84. Genetic Innovation: Genetic innovation is the process by which new genes and new functions arise.
  85. Genetic Constraint: A genetic constraint is a factor that limits the ability of a population to evolve.
  86. Genetic Facilitation: Genetic facilitation is the process by which the presence of one species can help another species to establish itself in a new environment.
  87. Genetic Predisposition: A genetic predisposition is an increased likelihood of developing a particular disease based on a person's genetic makeup.
  88. Genetic Resistance: Genetic resistance is the ability of an organism to withstand the effects of a harmful agent, such as a pesticide or a drug.
  89. Genetic Tolerance: Genetic tolerance is the ability of an organism to withstand the effects of a harmful agent, such as a pesticide or a drug.
  90. Genetic Plasticity: Genetic plasticity is the ability of an organism to change its phenotype in response to changes in the environment.
  91. Genetic Canalization: Genetic canalization is the tendency of a population to produce the same phenotype regardless of variability of its environment or genotype.
  92. Genetic Assimilation: Genetic assimilation is a process by which a phenotype that is initially produced in response to an environmental stimulus becomes genetically encoded.
  93. Genetic Accommodation: Genetic accommodation is the process by which a new phenotype, produced in response to an environmental stimulus, becomes genetically fixed in a population.
  94. Genetic Drift: Genetic drift is the change in the frequency of an existing gene variant in a population due to random sampling of organisms.
  95. Genetic Hitchhiking: Genetic hitchhiking is the process by which an allele can increase in frequency in a population because it is linked to a beneficial allele.
  96. Genetic Background Selection: Background selection is the loss of genetic diversity at a non-deleterious locus due to negative selection against linked deleterious alleles.
  97. Genetic Sweep: A selective sweep is the reduction or elimination of variation among the nucleotides in neighboring DNA of a mutation as the result of recent and strong positive natural selection.
  98. Genetic Introgression: Genetic introgression is the movement of a gene from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species.
  99. Genetic Isolation: Genetic isolation is a term that refers to a population of organisms that has little genetic mixing with other organisms within the same species.
  100. Genetic Rescue: Genetic rescue is a conservation strategy that involves the introduction of new genetic material into a small, inbred population in order to increase its genetic diversity and reduce the risk of extinction.
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Molecular Basis of Inheritance

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Created by Titas Mallick

Biology Teacher • M.Sc. Botany • B.Ed. • CTET Qualified • 10+ years teaching experience