NEET UG · Biology

Genetics: Principles of Inheritance and Variation

28 practice questions, each with the answer and an explanation.

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Random questions from this topic, one at a time. You see the answer and the explanation straight after each one.

All 28 questions

  1. In Mendel's dihybrid cross between yellow round () and green wrinkled () garden peas, what is the expected phenotypic ratio in the generation?
  2. What is the expected genotypic ratio in the generation of a standard Mendelian monohybrid cross ()?
  3. A cross between a red-flowered snapdragon (Antirrhinum majus, ) and a white-flowered snapdragon () produces all pink-flowered progeny (). This phenomenon is known as:
  4. Human ABO blood groups are determined by the gene , which has three alleles: , , and . How many different genotypes and phenotypes are possible in the human population?
  5. In Morgan's experiments with Drosophila melanogaster, when two genes on the same chromosome are located very close to each other, what frequency of recombinant progeny is observed?
  6. Sickle-cell anemia is caused by a point mutation in the -globin gene that results in which specific amino acid substitution at the sixth position of the -globin chain?
  7. Which chromosomal disorder in humans is characterized by the karyotype , causing sterile males with tall stature and gynecomastia?
  8. Turner's syndrome in humans is caused by which chromosomal aberration?
  9. A man with red-green color blindness () marries a homozygous normal woman (). What is the expected phenotype of their children?
  10. Down's syndrome is an autosomal aneuploid condition caused by:
  11. What is the primary genetic difference between a test cross and a back cross?
  12. Which phenomenon is observed when a single gene mutation produces multiple phenotypic effects across completely different physiological systems?
  13. Which sex-determination mechanism operates in birds and butterflies?
  14. In honeybees (Apis mellifera), male drones are produced through which mechanism?
  15. What is the map distance between two linked genes on a chromosome if the frequency of recombinant offspring in a test cross is ?
  16. Thalassemia and sickle-cell anemia are both hereditary disorders of hemoglobin synthesis. How do they fundamentally differ in their molecular pathology?
  17. Which law of Mendelian inheritance states that when two pairs of traits are combined in a hybrid, segregation of one pair of characters is independent of the other pair of characters?
  18. In a pedigree chart, what does a horizontal line connecting a square and a circle represent?
  19. Phenylketonuria (PKU) is an inborn error of metabolism inherited as an autosomal recessive trait. It results from a deficiency of which hepatic enzyme?
  20. In human skin color inheritance, controlled by three polygenes (), an individual with genotype exhibits an intermediate skin color termed:
  21. Why was the fruit fly Drosophila melanogaster selected by Thomas Hunt Morgan as an ideal model organism for genetics research?
  22. Hemophilia is an X-linked recessive bleeding disorder in humans. If a carrier mother () and a normal father () have children, what is the probability that a son will be hemophilic?
  23. Which of the following conditions is an example of an autosomal dominant genetic disorder in humans?
  24. Sutton and Boveri noted that the behavior of chromosomes during meiosis mirrors the behavior of Mendelian factors (genes). This concept is known as the:
  25. A trihybrid plant with genotype is testcrossed ($AaBbCc \times aabbcc$). Assuming all three gene loci assort independently, what is the expected phenotypic ratio of the offspring?
  26. Cystic fibrosis is an autosomal recessive genetic disease caused by a mutation in the gene on chromosome 7. If both parents are asymptomatic carriers (), what is the risk that their first c…
  27. What is the genetic cause of Gynandromorphs occasionally observed in Drosophila?
  28. Which statistical test is routinely employed in classical genetics to determine whether the observed frequencies of phenotypic progeny deviate significantly from expected Mendelian ratios?

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