Mendelian principles, alleles, multiple alleles - Question Bank

1. Gregor Mendel's work laid the foundation for genetics by establishing principles of heredity based on:
A) Continuous variation and blending inheritance
B) Particulate inheritance and discrete units of heredity
C) Gene linkage and crossing over
D) The role of chromosomes in inheritance
2. The concept of 'alleles' is fundamental to understanding genetic variation within a population because:
A) Alleles are the only units of heredity.
B) Different alleles at a locus lead to different traits.
C) Alleles are always dominant.
D) Alleles are passed down independently.
3. Which term describes the interaction between different genes where one gene masks the expression of another gene at a different locus?
A) Linkage
B) Recombination
C) Epistasis
D) Dominance
4. If a trait is determined by multiple alleles, how many alleles for that trait can an individual diploid organism possess at any given time?
A) As many alleles as exist in the population
B) Only one allele
C) Only two alleles
D) Three alleles
5. What is the primary difference between Mendelian inheritance and non-Mendelian inheritance patterns?
A) Mendelian inheritance involves genes on sex chromosomes.
B) Non-Mendelian inheritance includes codominance, incomplete dominance, and multiple alleles.
C) Mendelian inheritance always results in a 3:1 phenotypic ratio.
D) Non-Mendelian inheritance is only observed in plants.
6. Which of the following scenarios best demonstrates Mendel's Law of Segregation?
A) A cross between a homozygous dominant and a homozygous recessive individual
B) A cross between two heterozygous individuals for a single trait
C) A cross between two individuals showing codominance
D) A cross between individuals for two different traits on separate chromosomes
7. In the context of alleles, the term 'heterozygous' means an individual has:
A) Two identical alleles for a trait
B) Two different alleles for a trait
C) One dominant and one recessive allele
D) Only one allele for a trait
8. The gene for sickle-cell anemia is an example of:
A) Complete dominance
B) Incomplete dominance
C) Codominance
D) Pleiotropy
9. Pleiotropy refers to the phenomenon where:
A) One gene controls multiple traits
B) Multiple genes control one trait
C) Alleles show codominance
D) Genes are linked on a chromosome
10. If a gene has three or more alleles in a population, this is an example of:
A) Polyploidy
B) Multiple alleles
C) Pleiotropy
D) Epistasis
11. Which of Mendel's principles explains how traits for different genes are inherited independently, provided they are on different chromosomes?
A) Law of Segregation
B) Law of Dominance
C) Law of Independent Assortment
D) Principle of Allelic Interaction
12. What type of alleles are responsible for the different blood types A, B, AB, and O in humans?
A) Alleles showing complete dominance
B) Alleles showing incomplete dominance
C) Multiple alleles
D) Sex-linked alleles
13. In a dihybrid cross between two individuals heterozygous for two traits (e.g., AaBb x AaBb), assuming independent assortment and complete dominance, what is the expected phenotypic ratio of the offspring?
A) 1:1
B) 3:1
C) 1:2:1
D) 9:3:3:1
14. A dihybrid cross involves the inheritance of:
A) One trait
B) Two traits
C) Three traits
D) Sex-linked traits
15. If gene A is epistatic to gene B, then the phenotype of gene A will be expressed regardless of:
A) The genotype of gene A
B) The phenotype of gene B
C) The genotype of gene B
D) The presence of other genes
16. What is the term for a gene that influences the expression of another gene?
A) Allele
B) Locus
C) Epistatic gene
D) Hypostatic gene
17. The position of a gene on a chromosome is called its:
A) Allele
B) Genotype
C) Locus
D) Phenotype
18. In codominance, such as in the ABO blood system (alleles I^A and I^B), both traits are:
A) Expressed and blended
B) Expressed and neither masks the other
C) Expressed only if the other is absent
D) Expressed in alternating generations
19. In snapdragons, crossing a red-flowered plant (RR) with a white-flowered plant (WW) produces pink-flowered offspring (RW). This is an example of:
A) Complete dominance
B) Codominance
C) Incomplete dominance
D) Multiple alleles
20. What is the term for a situation where both alleles in a heterozygous individual contribute to the phenotype?
A) Incomplete dominance
B) Codominance
C) Complete dominance
D) Epistasis
21. If a father has blood type A and a mother has blood type B, what are the possible blood types of their children?
A) Only AB
B) Only O
C) A, B, AB, or O
D) Only A or B
22. A person with blood type O has which genotype?
A) I^A I^B
B) I^A i
C) I^B i
D) ii
23. A person with blood type AB has which combination of alleles?
A) I^A I^A or I^A i
B) I^B I^B or I^B i
C) I^A I^B
D) ii
24. In the ABO blood group system, alleles I^A and I^B are:
A) Recessive to i
B) Dominant to i
C) Codominant to each other
D) Both recessive and dominant
25. In the ABO blood group system, the alleles are I^A, I^B, and i. Which allele is recessive?
A) I^A
B) I^B
C) i
D) All alleles are codominant
26. Which human blood group system is a classic example of multiple alleles?
A) Rh blood group system
B) ABO blood group system
C) Kell blood group system
D) Duffy blood group system
27. What does the term 'multiple alleles' refer to?
A) A single gene having many different alleles
B) Multiple genes controlling a single trait
C) Alleles that are linked on the same chromosome
D) Alleles that only appear in multiple copies
28. Which of the following is an example of a trait exhibiting complete dominance?
A) Blood type AB in humans
B) Flower color in pea plants (purple dominant to white)
C) Roan coat color in cattle
D) Sickle-cell anemia
29. What is the term for a gene that is located on a sex chromosome?
A) Autosomal gene
B) Sex-linked gene
C) Mitochondrial gene
D) Nuclear gene
30. In a test cross, an individual with a dominant phenotype is crossed with an individual that is:
A) Homozygous dominant
B) Heterozygous
C) Homozygous recessive
D) Wild-type
31. What is a test cross used for?
A) To determine the phenotype of a dominant trait
B) To determine the genotype of an individual showing a dominant phenotype
C) To determine the genotype of an individual showing a recessive phenotype
D) To determine the number of alleles present
32. In a monohybrid cross between two heterozygous parents (Aa x Aa), what is the expected phenotypic ratio of the offspring, assuming complete dominance?
A) 1:1
B) 1:2:1
C) 2:1
D) 3:1
33. In a monohybrid cross between two heterozygous parents (Aa x Aa), what is the expected genotypic ratio of the offspring?
A) 1:1
B) 3:1
C) 1:2:1
D) 9:3:3:1
34. A cross between two individuals that are heterozygous for a single trait is called a:
A) Dihybrid cross
B) Monohybrid cross
C) Test cross
D) Back cross
35. The allele whose effect is masked by a dominant allele in a heterozygous individual is called:
A) Dominant allele
B) Recessive allele
C) Homozygous allele
D) Wild-type allele
36. In a heterozygous individual, the allele that is expressed and masks the effect of the other allele is called:
A) Recessive allele
B) Dominant allele
C) Codominant allele
D) Epistatic allele
37. The genetic makeup of an organism, represented by the combination of alleles it possesses, is called its:
A) Phenotype
B) Genotype
C) Karyotype
D) Genome
38. What is the term for the observable physical characteristics of an organism, determined by its genotype and environmental influences?
A) Genotype
B) Phenotype
C) Allele
D) Karyotype
39. The Law of Independent Assortment is best illustrated by crosses involving:
A) One trait (monohybrid cross)
B) Two traits (dihybrid cross)
C) Three traits (trihybrid cross)
D) Linked genes
40. Which of Mendel's principles states that alleles of different genes assort independently of one another during gamete formation?
A) Law of Segregation
B) Law of Dominance
C) Law of Independent Assortment
D) Principle of Phenotypic Expression
41. The Law of Segregation applies to the inheritance of alleles for:
A) A single gene
B) Two different genes
C) Multiple genes
D) Linked genes
42. Which of Mendel's principles states that during gamete formation, the alleles for each gene segregate from each other so that each gamete carries only one allele for each gene?
A) Law of Independent Assortment
B) Law of Dominance
C) Law of Segregation
D) Principle of Genotypic Ratio
43. An organism with two different alleles for a particular trait is described as:
A) Homozygous
B) Heterozygous
C) Monohybrid
D) Dihybrid
44. What is the term for an organism that has two identical alleles for a particular trait?
A) Heterozygous
B) Homozygous
C) Dominant
D) Recessive
45. In Mendelian genetics, what term describes different versions of the same gene?
A) Genotype
B) Phenotype
C) Alleles
D) Loci
46. What term did Mendel use to describe the hereditary units that are passed from parents to offspring?
A) Genes
B) Factors
C) Chromosomes
D) Alleles
47. Mendel's experiments were primarily conducted on which plant species?
A) Pea plants (Pisum sativum)
B) Corn (Zea mays)
C) Tobacco (Nicotiana tabacum)
D) Snapdragons (Antirrhinum)
48. Who is considered the father of modern genetics?
A) Charles Darwin
B) Gregor Mendel
C) James Watson
D) Francis Crick
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