Heredity is the process by which traits or characteristics are passed from parents to their offspring. It is the reason why offspring resemble their parents and inherit specific features.
Key Points:
- Genes and DNA control inheritance.
- Dominant traits (e.g., brown eyes) are expressed if one allele is present.
- Recessive traits (e.g., blue eyes) are expressed only when both alleles are recessive.
- Mendel’s Laws describe how traits are inherited:
- Segregation – each parent passes one allele for a trait.
- Independent Assortment – genes for different traits are inherited separately.
Example: Eye color inheritance – brown eyes (dominant) vs blue eyes (recessive).
Practice Questions PDF
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Questions on Heredity
Showing 31–59 of 5931.A breeder has a pea plant that produces purple flowers. Since purple is dominant over white, the plant's genotype could be PP or Pp. How can the breeder determine the exact genotype of this purple-flowered plant? 32.A pea plant has the genotype RrYy, where R is round, r is wrinkled, Y is yellow, and y is green. What is its phenotype? 33.Why is variation crucial for the survival of a species in a changing environment? 34.How do 'gene' and 'allele' differ in their meaning within the context of heredity? 35.In humans, what determines the sex of an offspring? 36.A sudden change in the genetic material of an organism, which may be beneficial, harmful, or neutral, is called a: 37.Can environmental factors modify the expression of inherited traits? Give an example. 38.In a cross between two pea plants heterozygous for two traits: tall (T) dominant over dwarf (t) and purple flowers (P) dominant over white (p). What proportion of the offspring are expected to be dwarf with white flowers? 39.Mendel's Law of Segregation states that: 40.Explain the fundamental role of DNA in heredity and how it relates to protein synthesis. 41.A genetic disorder is observed in a family. Both parents are unaffected, but their son has the disorder. Their daughter is unaffected. This pattern suggests which type of inheritance? 42.Which of the following processes is primarily responsible for creating new combinations of alleles on a chromosome, contributing to genetic variation? 43.If a pure dominant tall pea plant (TT) is crossed with a pure dwarf pea plant (tt), and the F1 generation is then backcrossed with the dwarf parent. What will be the genotypic ratio in the progeny of this backcross? 44.Why are sex-linked diseases like hemophilia more common in males than in females? 45.A geneticist crossed purebred red-flowered snapdragons with purebred white-flowered snapdragons. The F1 generation had pink flowers. If the F1 plants are self-pollinated, what phenotypic ratio is expected in the F2 generation? 46.Distinguish between acquired and inherited traits, providing one example for each in humans. 47.If a recessive allele is expressed only when present in two copies, what would be the phenotypic outcome in a heterozygous individual carrying one dominant and one recessive allele for a particular trait? 48.In guinea pigs, black coat (B) is dominant over white coat (b), and short hair (S) is dominant over long hair (s). A dihybrid cross is performed between a homozygous black, short-haired guinea pig and a white, long-haired guinea pig. What will be the genotype of the F1 generation? 49.Assertion (A): Human males are heterogametic. Reason (R): They produce two different types of gametes, X-bearing and Y-bearing. 50.A tall pea plant (TT) is crossed with a dwarf pea plant (tt). What percentage of the F2 generation plants will be dwarf? 51.How is the equal genetic contribution of male and female parents ensured in the progeny? 52.A study found that children with light-coloured eyes are likely to have parents with light-coloured eyes. On this basis, can we say anything about whether the light eye colour trait is dominant or recessive? Why or why not? 53.A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic make-up of the tall parent can be depicted as (a) TTWW (b) TTww (c) TtWW (d) TtWw 54.How is the sex of the child determined in human beings? 55.A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits – blood group A or O – is dominant? Why or why not? 56.How do Mendel’s experiments show that traits are inherited independently? 57.How do Mendel’s experiments show that traits may be dominant or recessive? 58.How does the creation of variations in a species promote survival? 59.If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?