From Gregor Mendel’s foundational pea plant experiments to our modern understanding of the human genome, the principles of inheritance are the bedrock of genetics. These rules govern how traits are passed from one generation to the next, explaining the molecular basis of both normal variation and genetic disease. For PharmD students, a strong grasp of these principles is essential for understanding hereditary diseases, pharmacogenomics, and the future of personalized medicine. This quiz will test your knowledge of the core concepts of classical and molecular genetics.
1. A specific version or variant of a gene is known as a(n):
- Locus
- Chromosome
- Allele
- Genotype
Answer: Allele
2. An individual who has two identical alleles for a particular trait is described as:
- Heterozygous
- Dominant
- Recessive
- Homozygous
Answer: Homozygous
3. Gregor Mendel’s “Law of Segregation” states that:
- Alleles for different traits are passed independently of one another.
- An organism’s two alleles for a trait separate from each other during gamete formation so that each gamete receives only one allele.
- One allele will always be dominant over the other.
- All offspring will have the same phenotype as the parents.
Answer: An organism’s two alleles for a trait separate from each other during gamete formation so that each gamete receives only one allele.
4. The observable physical or biochemical characteristics of an organism, such as eye color, are known as its:
- Genotype
- Phenotype
- Karyotype
- Allele
Answer: Phenotype
5. The specific genetic makeup of an individual for a particular trait (e.g., TT, Tt, or tt) is its:
- Phenotype
- Karyotype
- Genotype
- Genome
Answer: Genotype
6. If a trait is expressed in an individual who has only one copy of the gene for that trait (e.g., the “T” in a “Tt” individual), the trait is considered:
- Recessive
- Sex-linked
- Dominant
- Polygenic
Answer: Dominant
7. A Punnett square is a tool used to:
- Sequence a gene.
- Predict the probable outcomes of a genetic cross.
- Visualize a full set of chromosomes.
- Analyze a DNA fingerprint.
Answer: Predict the probable outcomes of a genetic cross.
8. In a cross between two heterozygous parents (Tt x Tt), what is the expected genotypic ratio of the offspring?
- 1 TT : 1 Tt : 1 tt
- 3 Tt : 1 tt
- All Tt
- 1 TT : 2 Tt : 1 tt
Answer: 1 TT : 2 Tt : 1 tt
9. In the same cross (Tt x Tt), where T is dominant for tall and t is recessive for short, what is the expected phenotypic ratio of the offspring?
- 1 tall : 1 short
- 3 tall : 1 short
- All tall
- 1 tall : 2 medium : 1 short
Answer: 3 tall : 1 short
10. Mendel’s “Law of Independent Assortment” applies to:
- Genes that are located very close together on the same chromosome.
- Alleles of a single gene.
- Genes located on different chromosomes or far apart on the same chromosome.
- Only genes in pea plants.
Answer: Genes located on different chromosomes or far apart on the same chromosome.
11. A situation where the heterozygous phenotype is an intermediate blend between the two homozygous phenotypes (e.g., a red flower and a white flower producing a pink flower) is known as:
- Codominance
- Incomplete dominance
- Epistasis
- Pleiotropy
Answer: Incomplete dominance
12. A situation where both alleles for a trait are fully and separately expressed in a heterozygote, such as in the AB blood type, is called:
- Incomplete dominance
- Recessive inheritance
- Codominance
- Polygenic inheritance
Answer: Codominance
13. The physical location of a gene on a chromosome is called its:
- Telomere
- Locus
- Centromere
- Arm
Answer: Locus
14. A trait that is determined by the interaction of multiple genes is described as:
- Sex-linked
- Recessive
- Dominant
- Polygenic
Answer: Polygenic
15. “Pleiotropy” is a phenomenon where:
- Multiple genes influence a single trait.
- A single gene influences multiple, seemingly unrelated phenotypic traits.
- An allele is only expressed in one gender.
- An environmental factor alters the phenotype.
Answer: A single gene influences multiple, seemingly unrelated phenotypic traits.
16. The central dogma of molecular biology describes the flow of genetic information as:
- Protein → RNA → DNA
- RNA → DNA → Protein
- DNA → RNA → Protein
- DNA → Protein → RNA
Answer: DNA → RNA → Protein
17. The process of copying a gene’s DNA sequence into an RNA sequence is called:
- Replication
- Translation
- Transcription
- Transformation
Answer: Transcription
18. The process of synthesizing a protein from an mRNA template is called:
- Replication
- Transcription
- Translation
- Splicing
Answer: Translation
19. A “mutation” is a permanent alteration in the:
- Protein sequence.
- RNA sequence.
- DNA sequence.
- Chromosome number.
Answer: DNA sequence.
20. A “frameshift” mutation is caused by:
- The insertion or deletion of a number of nucleotides that is not a multiple of three.
- A single base-pair substitution.
- A change that does not alter the amino acid sequence.
- A mutation in a non-coding region.
Answer: The insertion or deletion of a number of nucleotides that is not a multiple of three.
21. A “nonsense” mutation is one that:
- Changes one amino acid to another.
- Has no effect on the protein sequence.
- Creates a premature stop codon.
- Inserts a single nucleotide.
Answer: Creates a premature stop codon.
22. A “missense” mutation is one that:
- Results in a different amino acid being incorporated into the protein.
- Creates a stop codon.
- Does not change the amino acid.
- Deletes three bases.
Answer: Results in a different amino acid being incorporated into the protein.
23. Traits that are controlled by genes located on the sex chromosomes (X or Y) are known as:
- Autosomal traits
- Polygenic traits
- Sex-linked traits
- Dominant traits
Answer: Sex-linked traits
24. X-linked recessive disorders are more common in males than females because:
- Males have two X chromosomes.
- Males only have one X chromosome, so a single recessive allele will be expressed.
- The Y chromosome carries a protective factor.
- Females cannot be carriers of X-linked traits.
Answer: Males only have one X chromosome, so a single recessive allele will be expressed.
25. A graphical representation of a family’s genetic history used to track the inheritance of a trait is called a:
- Karyotype
- Punnett square
- Pedigree chart
- Histogram
Answer: Pedigree chart
26. In a pedigree, a filled-in circle represents a(n):
- Unaffected male
- Affected male
- Unaffected female
- Affected female
Answer: Affected female
27. The phenomenon where the severity of a genetic disease increases with each successive generation is known as:
- Incomplete penetrance
- Anticipation
- Variable expressivity
- Genomic imprinting
Answer: Anticipation
28. “Penetrance” refers to the:
- The severity of a disease in an individual.
- The proportion of individuals with a particular genotype that also expresses the associated phenotype.
- The physical location of a gene.
- A type of mutation.
Answer: The proportion of individuals with a particular genotype that also expresses the associated phenotype.
29. “Genomic imprinting” is a principle of inheritance where:
- A gene is expressed differently depending on whether it was inherited from the mother or the father.
- All genes are expressed equally from both parents.
- A gene is silenced by a mutation.
- A gene is located on a sex chromosome.
Answer: A gene is expressed differently depending on whether it was inherited from the mother or the father.
30. The field of pharmacogenomics is based on the principle that:
- An individual’s genetic makeup can influence their response to medications.
- All patients respond to drugs in the same way.
- The cost of a drug determines its efficacy.
- The placebo effect is the primary driver of drug response.
Answer: An individual’s genetic makeup can influence their response to medications.
31. The “Human Genome Project” was an international research effort to:
- Cure all genetic diseases.
- Determine the complete sequence of human DNA.
- Clone a human being.
- Create a universal vaccine.
Answer: Determine the complete sequence of human DNA.
32. A “somatic” mutation is one that occurs in a body cell and:
- Will be passed on to the offspring.
- Will not be passed on to the offspring.
- Only occurs in sperm or egg cells.
- Is always harmless.
Answer: Will not be passed on to the offspring.
33. A “germline” mutation occurs in a sperm or egg cell and:
- Cannot be passed on to the next generation.
- Can be passed on to the next generation.
- Only affects the individual in which it occurs.
- Is the basis for all cancers.
Answer: Can be passed on to the next generation.
34. The law of segregation is a direct result of which process?
- Mitosis
- Meiosis
- Transcription
- Translation
Answer: Meiosis
35. A “carrier” for a recessive disorder is an individual who is:
- Homozygous dominant (TT)
- Homozygous recessive (tt) and affected.
- Heterozygous (Tt) and phenotypically unaffected.
- A-symptomatic but can spread the disease.
Answer: Heterozygous (Tt) and phenotypically unaffected.
36. The inheritance of mitochondrial DNA is unique because:
- It is inherited from both the mother and the father.
- It is inherited almost exclusively from the mother.
- It is not inherited at all.
- It is only present in males.
Answer: It is inherited almost exclusively from the mother.
37. “Epistasis” is a phenomenon where:
- The expression of one gene is affected by the expression of one or more independently inherited genes.
- A single gene affects multiple traits.
- Both alleles are expressed equally.
- An allele is neither dominant nor recessive.
Answer: The expression of one gene is affected by the expression of one or more independently inherited genes.
38. The inheritance of a single-gene disorder like cystic fibrosis or sickle cell anemia follows which pattern of inheritance?
- Polygenic
- Multifactorial
- Mendelian
- Epigenetic
Answer: Mendelian
39. A “dihybrid cross” is a cross between two individuals who are heterozygous for:
- One specific trait.
- Two different traits.
- All of their traits.
- No traits.
Answer: Two different traits.
40. The basic principles of inheritance provide the foundation for understanding:
- Hereditary disease risk.
- The selective breeding of plants and animals.
- The molecular basis of evolution.
- All of the above.
Answer: All of the above.
41. An autosomal recessive disorder requires an individual to have:
- One copy of the recessive allele.
- Two copies of the recessive allele to be affected.
- One dominant and one recessive allele.
- At least one dominant allele.
Answer: Two copies of the recessive allele to be affected.
42. For an autosomal dominant disorder, an affected individual:
- Must have two copies of the dominant allele.
- Only needs one copy of the dominant allele to be affected.
- Must be homozygous.
- Cannot pass the trait to their children.
Answer: Only needs one copy of the dominant allele to be affected.
43. The “wild-type” allele is the term used to describe:
- A mutated form of a gene.
- The allele that is considered the “normal” or most common in a population.
- A recessive allele.
- An allele that causes disease.
Answer: The allele that is considered the “normal” or most common in a population.
44. “Genetic linkage” refers to the tendency of:
- Alleles that are located close together on the same chromosome to be inherited together.
- Alleles on different chromosomes to be inherited together.
- Dominant alleles to be linked to other dominant alleles.
- Recessive alleles to be linked to other recessive alleles.
Answer: Alleles that are located close together on the same chromosome to be inherited together.
45. The process of “crossing over” during meiosis is important because it:
- Prevents the segregation of alleles.
- Creates new combinations of alleles on a chromosome, increasing genetic diversity.
- Ensures that all offspring are identical to the parents.
- Duplicates the number of chromosomes.
Answer: Creates new combinations of alleles on a chromosome, increasing genetic diversity.
46. “Variable expressivity” is the phenomenon where:
- A genotype does not always produce the expected phenotype.
- A phenotype is expressed to a different degree of severity among individuals with the same genotype.
- A single gene affects many traits.
- A trait is only expressed in one gender.
Answer: A phenotype is expressed to a different degree of severity among individuals with the same genotype.
47. A “test cross” is performed to determine the genotype of an individual with a dominant phenotype by crossing them with an individual who is:
- Homozygous dominant.
- Heterozygous.
- Homozygous recessive.
- Also showing the dominant phenotype.
Answer: Homozygous recessive.
48. The study of how environmental factors can cause heritable changes in gene expression without changing the DNA sequence is known as:
- Mendelian genetics
- Molecular genetics
- Epigenetics
- Population genetics
Answer: Epigenetics
49. A “complex” or “multifactorial” trait is one that is influenced by:
- A single gene only.
- Multiple genes and environmental factors.
- Environmental factors only.
- The process of mitosis.
Answer: Multiple genes and environmental factors.
50. The ultimate reason a pharmacist must understand the basic principles of inheritance is because:
- They are fundamental to understanding the genetic basis of disease and the growing field of personalized medicine.
- They are required to compound all medications.
- They are the basis for all pharmacy law.
- They are only relevant for genetic counselors.
Answer: They are fundamental to understanding the genetic basis of disease and the growing field of personalized medicine.
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
Mail- Sachin@pharmacyfreak.com