Human Genetics & Heredity MCQs 2026

Why does an X-linked recessive disorder like hemophilia predominantly affect males rather than females

1. AMales have only one X chromosome, so a single recessive allele is sufficient to cause the disorder✓
2. BFemales cannot carry the gene for this disorder at all✓
3. CThe disorder only affects Y chromosomes, which only males have✓
4. DMales are simply more susceptible for unrelated biological reasons✓

What term describes a female who carries one copy of a recessive X-linked disorder allele but does not show symptoms, due to having a second, normal X chromosome

1. ACarrier✓
2. BAffected individual (would show symptoms, a different status)✓
3. CHomozygous recessive (would require two copies of the allele, a different genetic status)✓
4. DHemizygous (a term specifically describing males with only one X chromosome, a different concept)✓

What is the term for identical twins, who develop from a single fertilized egg that splits into two separate embryos

1. AMonozygotic twins✓
2. BDizygotic twins (develop from two separately fertilized eggs, a different type)✓
3. CFraternal twins (a common name for dizygotic twins, a different type)✓
4. DConjoined twins (a rare condition where twins remain physically connected, a different concept)✓

What inherited disorder, common in some Mediterranean and Asian populations, results in abnormal hemoglobin production

1. ACystic fibrosis (a different inherited disorder, more common in populations of European descent)✓
2. BThalassemia✓
3. CHemophilia (a different inherited disorder, with a different inheritance pattern)✓
4. DHuntington's disease (a different inherited disorder, dominant rather than recessive, with different symptoms)✓

What inherited disorder causes thick, sticky mucus buildup, particularly affecting the lungs and digestive system, more common in populations of European descent

1. ACystic fibrosis✓
2. BThalassemia (a different inherited disorder, more common in different populations)✓
3. CSickle cell disease (a different inherited disorder, more common in different populations)✓
4. DTay-Sachs disease (a different inherited disorder, with different symptoms/population prevalence)✓

What inherited disorder causes red blood cells to take on an abnormal crescent shape, more common in populations of African descent

1. ACystic fibrosis (more common in populations of European descent, different disorder)✓
2. BThalassemia (a related, but distinct disorder, more common in different populations)✓
3. CSickle cell disease✓
4. DTay-Sachs disease (a different inherited disorder, with different symptoms/population prevalence)✓

What is the term for the branch of medicine and testing specifically focused on identifying genetic disorders before or shortly after birth

1. AGenetic screening/testing✓
2. BGenetic engineering (relates to directly modifying genes, a different practice)✓
3. CGenetic counseling (a related, but distinct practice, focused on advising individuals/families about genetic risk)✓
4. DGene therapy (relates to treating disorders by altering genes directly, a different practice)✓

What is the term for the professional guidance provided to individuals or families regarding genetic risks, testing options, and disease implications

1. AGenetic screening (a related, but distinct practice, focused on the testing itself)✓
2. BGenetic counseling✓
3. CGenetic engineering (relates to directly modifying genes, a different practice)✓
4. DGene therapy (relates to treating disorders by altering genes directly, a different practice)✓

What term describes traits controlled by multiple genes working together, producing a continuous range of possible outcomes, such as human height or skin color

1. AMonogenic traits (controlled by a single gene, a different category)✓
2. BPolygenic traits✓
3. CSex-linked traits (controlled by genes on sex chromosomes specifically, a different, related category)✓
4. DCodominant traits (relates to simultaneous expression of two alleles, a different concept)✓

What is the term for treating or preventing disease by directly introducing, altering, or removing genetic material within a patient's cells

1. AGenetic screening (relates to identifying disorders, a different practice)✓
2. BGenetic counseling (relates to providing advisory guidance, a different practice)✓
3. CGene therapy✓
4. DSelective breeding (a broader agricultural/animal breeding concept, a different practice)✓

What famous, historically significant royal family lineage is often cited as an example of hemophilia's spread through European nobility, tracing back to Queen Victoria

1. AThe British/European royal houses descended from Queen Victoria✓
2. BThe French Bourbon dynasty (a different royal lineage, not primarily associated with this specific hemophilia case study)✓
3. CThe Spanish Habsburg dynasty (associated with different genetic issues, primarily from inbreeding)✓
4. DThe Russian Romanov dynasty exclusively (though affected, the condition traces back through the broader Victorian lineage, not originating there)✓

What term describes the phenomenon where one gene's expression masks or influences the expression of a different gene at another location

1. APleiotropy (relates to one gene affecting multiple traits, the opposite relationship)✓
2. BPolygenic inheritance (relates to multiple genes affecting one trait, a different concept)✓
3. CCodominance (relates to simultaneous allele expression, a different concept)✓
4. DEpistasis✓

What term describes the phenomenon where a gene affects multiple, seemingly unrelated traits

1. APleiotropy✓
2. BPolygenic inheritance (relates to multiple genes affecting one trait, the opposite relationship)✓
3. CCodominance (relates to simultaneous allele expression, a different concept)✓
4. DEpistasis (relates to one gene masking the effect of another, a different concept)✓

What is the term for fraternal twins, who develop from two separate eggs fertilized by two separate sperm

1. AMonozygotic twins (develop from a single fertilized egg, a different type)✓
2. BDizygotic twins✓
3. CConjoined twins (a rare condition where twins remain physically connected, a different concept)✓
4. DIdentical twins (a common name for monozygotic twins, a different type)✓

What is the term for the specific version or form of a gene that determines a particular trait

1. AChromosome (the broader structure carrying many genes)✓
2. BAllele✓
3. CGenotype (relates to the overall genetic makeup, a broader concept)✓
4. DPhenotype (relates to observable characteristics, a different concept)✓

If a child inherits brown eye alleles from both parents, and brown is dominant over blue, what genotype do they have for this trait

1. AHeterozygous✓
2. BHomozygous dominant✓
3. CHomozygous recessive✓
4. DCodominant✓

What term describes an individual carrying two different alleles for a particular gene, such as one brown-eye allele and one blue-eye allele

1. AHomozygous dominant✓
2. BHomozygous recessive✓
3. CHeterozygous✓
4. DHemizygous✓

In humans, which parent's chromosome determines the biological sex of their child

1. AThe mother's (X chromosome only)✓
2. BThe father's (contributes either X or Y)✓
3. CBoth parents equally determine sex through combined contribution✓
4. DNeither parent; sex is randomly determined independent of chromosomes✓

What is the term for genetic disorders caused by an abnormality in a single gene

1. AMonogenic disorders✓
2. BPolygenic disorders (caused by multiple genes, a different category)✓
3. CChromosomal disorders (caused by abnormal chromosome number/structure, a different category)✓
4. DMultifactorial disorders (caused by combination of genes and environment, a different category)✓

What is the term for genetic disorders caused by abnormalities in the number or structure of chromosomes

1. AMonogenic disorders (caused by a single gene, a different category)✓
2. BPolygenic disorders (caused by multiple genes, a different category)✓
3. CChromosomal disorders✓
4. DMultifactorial disorders (caused by combination of genes and environment, a different category)✓

What inherited disorder, caused by a mutation on the X chromosome, impairs normal blood clotting and predominantly affects males

1. ACystic fibrosis (an autosomal recessive disorder, different inheritance pattern)✓
2. BHemophilia✓
3. CDown syndrome (a chromosomal disorder, different category)✓
4. DSickle cell disease (an autosomal recessive disorder, different inheritance pattern)✓