Genetics & Heredity Patterns 2026 Exam Guide

1. What is the fundamental unit of heredity? A) Protein B) Gene C) Ribosome D) Mitochondrion Correct Answer: B) Gene 2. Which law of Mendel states that two alleles for a trait separate during gamete formation? A) Law of Independent Assortment B) Law of Segregation C) Law of Dominance D) Law of Probability Correct Answer: B) Law of Segregation 3. What does "Genotype" refer to? A) The physical appearance of an organism B) The genetic constitution of an individual organism C) The environmental influence on a trait D) The number of chromosomes in a cell Correct Answer: B) The genetic constitution of an individual organism 4. "Phenotype" is defined as: A) The genetic sequence of an organism B) The observable physical or biochemical characteristics of an organism, determined by both genetics and environment C) The number of mutations in a genome D) The location of a gene on a chromosome Correct Answer: B) The observable physical or biochemical characteristics of an organism 5. In a heterozygous individual (e.g., Aa), which allele is expressed in the phenotype for a simple dominant trait? A) The recessive allele B) The dominant allele C) Both alleles equally (codominance) D) Neither allele Correct Answer: B) The dominant allele 6. What is "Codominance"? A) One allele is completely dominant over the other B) Both alleles in a heterozygote are fully and distinctly expressed in the phenotype (e.g., AB blood type) C) The recessive allele masks the dominant one D) The phenotype is a blend of the two alleles Correct Answer: B) Both alleles in a heterozygote are fully and distinctly expressed in the phenotype 7. What is "Incomplete Dominance"? A) The dominant allele is not present B) The phenotype of the heterozygote is an intermediate blend of the two homozygous phenotypes C) The recessive allele is mutated D) Both alleles are masked by a third gene Correct Answer: B) The phenotype of the heterozygote is an intermediate blend of the two homozygous phenotypes 8. "Polygenic Inheritance" refers to traits that are: A) Controlled by a single gene B) Influenced by two or more genes working together (e.g., skin color, height) C) Always determined by the environment D) Located on the X chromosome only Correct Answer: B) Influenced by two or more genes working together 9. What are "Autosomes"? A) Sex chromosomes (X and Y) B) Any chromosome that is not a sex chromosome C) Chromosomes found in mitochondria D) Pieces of DNA that code for proteins Correct Answer: B) Any chromosome that is not a sex chromosome 10. "X-linked recessive" disorders are more commonly expressed in males because: A) Males have two X chromosomes B) Males have only one X chromosome and therefore no second allele to mask the recessive mutation C) Females do not have X chromosomes D) The Y chromosome suppresses the X chromosome Correct Answer: B) Males have only one X chromosome and therefore no second allele to mask the recessive mutation 11. What is "Epigenetics"? A) Changes in the DNA sequence itself B) Heritable changes in gene expression that do not involve alterations to the underlying DNA sequence (e.g., methylation) C) The process of natural selection D) Mutations caused by radiation Correct Answer: B) Heritable changes in gene expression that do not involve alterations to the underlying DNA sequence 12. "DNA Methylation" typically results in: A) Increased gene expression B) Gene silencing or repression C) Faster DNA replication D) Increased mutation rates Correct Answer: B) Gene silencing or repression 13. What is a "Mutation"? A) A change in the nucleotide sequence of the genome B) The process of DNA repair C) A synonym for gene expression D) The result of natural selection Correct Answer: A) A change in the nucleotide sequence of the genome 14. A "Point Mutation" involves: A) Deletion of a whole chromosome B) A change in a single nucleotide base pair C) Insertion of thousands of base pairs D) Duplication of a gene Correct Answer: B) A change in a single nucleotide base pair 15. What is the effect of a "Silent Mutation"? A) The protein sequence changes drastically B) There is no change in the amino acid sequence, usually due to the redundancy of the genetic code C) The protein is not produced at all D) The mutation is lethal to the organism Correct Answer: B) There is no change in the amino acid sequence 16. A "Frameshift Mutation" is caused by: A) Substitution of one base B) Insertion or deletion of nucleotides that is not a multiple of three, shifting the reading frame of the codons C) Silent mutations D) Point mutations Correct Answer: B) Insertion or deletion of nucleotides that is not a multiple of three 17. "Linkage" refers to: A) Genes located on different chromosomes B) Genes located close together on the same chromosome, tending to be inherited together C) The process of crossing over D) Mutations happening simultaneously Correct Answer: B) Genes located close together on the same chromosome 18. What is "Crossing Over" (Recombination)? A) The exchange of genetic material between homologous chromosomes during meiosis B) The random separation of chromosomes C) The mutation of DNA during replication D) The process of protein synthesis Correct Answer: A) The exchange of genetic material between homologous chromosomes during meiosis 19. "Aneuploidy" refers to: A) Having the correct number of chromosomes B) An abnormal number of chromosomes in a cell (e.g., Trisomy 21) C) A change in a single gene D) A mutation in mitochondrial DNA Correct Answer: B) An abnormal number of chromosomes in a cell 20. What is "Non-disjunction"? A) The failure of chromosomes to separate properly during meiosis or mitosis B) The double replication of DNA C) The spontaneous repair of DNA D) The fusion of two cells Correct Answer: A) The failure of chromosomes to separate properly during meiosis or mitosis 21. "GWAS" (Genome-Wide Association Studies) are used to: A) Create new human species B) Identify genetic variants associated with complex diseases by scanning the genomes of large populations C) Count the number of genes in a cell D) Map the location of all genes on one chromosome Correct Answer: B) Identify genetic variants associated with complex diseases by scanning the genomes of large populations