Practice Questions for Science Class 10th "Heridity"

Multiple Choice Questions (MCQs):

1. B) Gregor Mendel - Gregor Mendel is known as the father of genetics due to his pioneering work on pea plants.
2. A) Pea plant - Mendel conducted his experiments on garden pea plants.
3. A) William Bateson - William Bateson coined the term 'genetics' to describe the study of heredity and variation.
4. B) Phenotype - Phenotype refers to the physical expression or characteristics of an organism due to its genetic makeup.
5. C) Heterozygous - Tt represents a heterozygous genotype where one allele is dominant (T) and one is recessive (t).
6. D) Law of Natural Selection - This is not one of Mendel's laws; it's part of Darwin's theory of evolution.
7. B) Heterozygous - An individual with two different alleles for a gene pair is heterozygous.
8. C) Co-dominance - In co-dominance, both alleles are expressed equally in the phenotype.
9. C) Hemophilia - Hemophilia is an example of a sex-linked trait, usually carried on the X chromosome.
10. B) XX or XY - In humans, females are XX, and males are XY.
11. C) Allele - An allele is one of two or more versions of a gene.
12. B) 25% - For two carriers (Aa and Aa), there's a 1 in 4 chance (25%) of an offspring expressing the recessive trait (aa).
13. B) Genetic outcomes - A Punnett square predicts the possible genotypes of offspring from given parental genotypes.
14. B) Genotype - The genetic makeup or the combination of alleles for a given gene or set of genes is the genotype.
15. B) Sex-linked - Traits passed from fathers to sons only are usually X-linked recessive traits.
16. A) Law of Segregation - This law explains that traits can skip generations due to the separation of alleles during gamete formation.
17. B) Aneuploidy - An extra chromosome results in aneuploidy, like in Down syndrome (trisomy 21).
18. C) yy - Green seeds in pea plants are a recessive trait, so the genotype must be yy.
19. C) Genetics - Genetics is the study of heredity and the variation of inherited characteristics.
20. B) Heterozygous - An organism with two different alleles for a gene is heterozygous.

Short Answer Questions:

21. Allele: An allele is one of two or more alternative forms of a gene at a given locus on a chromosome.
22. Genotype vs. Phenotype: Genotype is the genetic constitution of an organism, while phenotype is the observable physical or biochemical characteristics which result from the genotype and environmental influences.
23. Dominant vs. Recessive Traits: Dominant traits mask the expression of recessive traits in heterozygous individuals. Recessive traits are only expressed if both alleles are recessive.
24. Mendel's Control: Mendel controlled variables like cross-pollination, used purebred lines for experiments, and tracked traits over generations to minimize environmental influence.
25. Law of Segregation: This law states that during gamete formation, the two alleles for each gene segregate so that each gamete carries only one allele.
26. Co-dominance: Both alleles contribute to the phenotype, e.g., in human blood groups, AB type where both A and B antigens are expressed.
27. Pea Plants: They have easily distinguishable traits, can self-pollinate or be cross-pollinated, and have a short generation time.
28. Incomplete Dominance: Neither allele is completely dominant, leading to a blend of traits, e.g., red and white flowers producing pink in snapdragons.
29. Sex Determination: Humans have 23 pairs of chromosomes, one pair being sex chromosomes. XX results in female, XY in male.
30. Sex-linked Traits: Traits on sex chromosomes, often X-linked. They differ from autosomal traits which are on non-sex chromosomes, showing different inheritance patterns.
31. Punnett Square: For two heterozygous parents (e.g., Bb x Bb), a Punnett square shows 25% BB, 50% Bb, and 25% bb, predicting phenotypes.
32. Role of Genes: Genes carry instructions for traits; variations in genes lead to variation in traits.
33. Law of Independent Assortment: Genes for different traits segregate independently of one another during gamete formation, e.g., seed color and shape in peas.
34. Genetic Disorder: Abnormalities due to genetic mutations. Examples include cystic fibrosis and Down syndrome.
35. Carrier: An individual with one copy of a recessive allele for a disorder, showing no symptoms but can pass the allele to offspring.
36. Trait Skipping: Due to recessive traits not being expressed unless both alleles are present, or through sex-linked inheritance.
37. Pedigree Chart: A diagram showing the occurrence and appearance of phenotypes of a particular gene or organism and its ancestors over multiple generations.
38. Mutation vs. Variation: Mutation is a change in DNA sequence, while variation refers to differences within populations, including from mutations.
39. Genetic Variation and Evolution: Variation provides raw material for natural selection, leading to evolution by favoring traits that enhance survival and reproduction.
40. F1 and F2 Generations: F1 (first filial) shows immediate results of crossbreeding, while F2 (second filial) reveals the segregation of alleles, confirming Mendel's laws.

Long Answer Questions:

41. Mendel's Experiments:

• Mendel crossbred pea plants, tracking traits like seed color, shape, etc., across generations. His observations led to three laws: Segregation, Independent Assortment, and Dominance.

42. Genetic Inheritance with Punnett Square:

• Example: Monohybrid cross of tall (T) and short (t) pea plants (Tt x Tt). The Punnett square shows 3:1 ratio of tall to short in F2, demonstrating Mendelian ratios.

43. Role of DNA in Heredity:

• DNA carries genetic information; genes on DNA code for proteins that define traits. Transcription and translation convert DNA's code into functional proteins.

44. Mendelian vs. Non-Mendelian:

• Mendelian: Traits follow Mendel's laws, e.g., pea plant colors.
• Non-Mendelian: Includes co-dominance (ABO blood groups), incomplete dominance (flower color blending), and polygenic traits (skin color).

45. Genetic Counseling:

• Helps families understand genetic risks, inheritance patterns, and options for testing, prevention, or management of genetic disorders.

46. Ethical Considerations:

• Issues include privacy, consent, potential for discrimination, and the moral implications of altering human genetics or selecting for certain traits.

47. Genetic Mutations:

• Beneficial: Mutations can lead to adaptations, like sickle cell trait offering malaria resistance.
• Harmful: Mutations can cause diseases like cystic fibrosis.

48. Meiosis and Diversity:

• Meiosis involves crossing over, independent assortment, and random segregation of chromosomes, increasing genetic variation in gametes.

49. Gene Interaction:

• When genes at different loci interact to produce a phenotype, e.g., epistasis where one gene masks the expression of another.

50. Polygenic Inheritance:

• Traits controlled by multiple genes, like height or skin color, contrast with Mendelian traits controlled by single genes, showing a range of phenotypes.

51. Environmental Impact on Gene Expression:

• Example: Diet affecting gene expression in obesity, or sunlight influencing skin pigmentation through vitamin D synthesis.

52. Heredity and Human Disease:

• Understanding inheritance helps in diagnosing, predicting, and potentially preventing genetic diseases like Huntington's or BRCA-related cancers.

53. Blood Group Inheritance:

• A, B, O blood groups show co-dominance (A and B are co-dominant over O), with phenotypes determined by combinations of these alleles.

54. Human Genome Project:

• Aimed to sequence all human DNA; implications include identifying disease-causing genes, personalized medicine, and understanding human evolution.

55. Genetic Drift and Gene Flow:

• Genetic drift randomly changes allele frequencies, while gene flow introduces new alleles into populations, both impacting genetic diversity.

56. Genetic Recombination:

• During meiosis, recombination shuffles genes, ensuring offspring are genetically diverse, promoting adaptability.

57. Cloning and Heredity:

• Cloning can produce organisms with identical genes, useful for research but raises ethical issues about genetic diversity and identity.

58. Hardy-Weinberg Principle:

• Describes allele frequency in a non-evolving population, providing a baseline to detect evolutionary changes.

59. Genetic Basis of Natural Selection:

• Selection favors certain alleles, leading to changes in population genetics over time, driving evolution.

60. Epigenetics:

• Changes in gene expression without altering DNA sequence, influenced by environment, like methylation patterns affecting gene activity.

Application-Based Questions:

61. Red and White Flowers: If all F1 are red, red is likely dominant. The cross was probably RR x rr, with R being dominant.
62. Eye Color: Possible eye colors are brown (BB or Bb) or blue (bb), with a 3:1 ratio of brown to blue.
63. Blood Types: Child can only be A or B, as O is recessive and cannot mask A or B.
64. Snapdragon Flowers: This shows incomplete dominance, where the heterozygous phenotype is intermediate.
65. Color Blindness: There's a 50% chance for a son to be color blind (X^cY).
66. Eye Color of Children: Parents could be Bb (one brown, one blue gene each), producing the observed ratio.
67. Dihybrid Cross: With YyRr x YyRr, expect a 9:3:3:1 phenotypic ratio for yellow round, yellow wrinkled, green round, and green wrinkled seeds.
68. Hemophilia and Pedigree: Hemophilia's X-linked nature means it only appears in males if inherited from a carrier mother.
69. Test Cross: Cross the dominant phenotype with a homozygous recessive; if any offspring show the recessive trait, the parent was heterozygous.
70. Tall Cross: All F1 would be phenotypically tall (TT or Tt), but genotypically, you'd get 50% TT and 50% Tt.

Critical Thinking Questions:

71. Non-Mendelian Inheritance: Traits might show incomplete dominance, co-dominance, or be polygenic, not fitting Mendel's strict laws.
72. Breeding in Agriculture: Genetics allows for selective breeding for desired traits, increasing yield, resistance, or nutritional content.
73. Heritability vs. Inheritance: Heritability measures how much of the variation in a trait is due to genetics, while inheritance refers
74. Genetic Diversity and Conservation: Genetic diversity ensures species resilience, adaptability, and survival. Conservation biology uses this knowledge to manage populations, prevent inbreeding, and maintain ecosystem health.
75. Genetic Technology and Disease Treatment: Advancements like gene therapy, CRISPR, and genetic screening can lead to personalized medicine, targeting genetic disorders at their molecular level, potentially offering cures or significant symptom management.
76. Societal Impact of Genetic Screening: Screening for non-disease traits could lead to ethical issues like eugenics, discrimination, or social stratification. It might also affect employment, insurance, and personal identity.
77. Environment and Genetic Predispositions: Environmental factors can activate or silence genes (epigenetics), influencing phenotype. For example, diet affects obesity genes, or sunlight impacts vitamin D synthesis, altering gene expression.
78. Predicting Human Genetic Outcomes: Human genetics is complex with multiple genes, environmental interactions, and ethical constraints on experiments, making predictions less straightforward than in plants like peas.
79. Identical Twins: Despite sharing DNA, environmental factors, epigenetics, and even minor genetic differences from mutations can lead to phenotypic differences in traits or health outcomes.
80. Heredity and Antibiotic Resistance: Understanding how resistance genes are inherited and spread can guide strategies to limit resistance development, like reducing antibiotic use and improving infection control practices.