1. Genetic material in animals is primarily located in which cellular organelle?
a) Mitochondria
b) Nucleus
c) Golgi apparatus
d) Endoplasmic reticulum
Answer: b) Nucleus
2. Which term refers to alternative forms of a gene?
a) Chromosome
b) Allele
c) Genotype
d) Phenotype
Answer: b) Allele
3. Mendel’s law of segregation states that:
a) Genes located on the same chromosome will be inherited together
b) Genes are inherited in discrete units
c) Each allele segregates into separate gametes during gamete formation
d) Phenotypic traits are determined by multiple genes
Answer: c) Each allele segregates into separate gametes during gamete formation
4. In a monohybrid cross between two heterozygous individuals (Aa x Aa), what is the phenotypic ratio of the offspring?
a) 1:1
b) 3:1
c) 2:1:1
d) 9:3:3:1
Answer: b) 3:1
5. In a dihybrid cross (AaBb x AaBb), what is the expected phenotypic ratio according to Mendel’s law of independent assortment?
a) 3:1
b) 9:3:3:1
c) 1:2:1
d) 1:1:1:1
Answer: b) 9:3:3:1
6. What is the term for an organism with two different alleles for a particular gene?
a) Homozygous
b) Heterozygous
c) Dominant
d) Recessive
Answer: b) Heterozygous
7. Which of the following genetic disorders is caused by an autosomal recessive allele?
a) Huntington’s disease
b) Hemophilia
c) Cystic fibrosis
d) Duchenne muscular dystrophy
Answer: c) Cystic fibrosis
8. In humans, the sex chromosomes of a male individual are:
a) XX
b) XY
c) YY
d) XO
Answer: b) XY
9. Incomplete dominance is characterized by:
a) The expression of both alleles equally in the heterozygous phenotype
b) One allele completely masking the expression of the other allele
c) Intermediate phenotype in heterozygotes
d) Multiple alleles controlling a single trait
Answer: c) Intermediate phenotype in heterozygotes
10. A trait controlled by multiple genes is called:
a) Monogenic
b) Polygenic
c) Pleiotropic
d) Homologous
Answer: b) Polygenic
11. What is the probability of rolling a six on a fair six-sided die?
a) 1/2
b) 1/3
c) 1/6
d) 1/12
Answer: c) 1/6
12. What is the probability of flipping a coin and getting heads twice in a row?
a) 1/4
b) 1/2
c) 1/3
d) 1/8
Answer: a) 1/4
13. Which of the following represents a homozygous recessive genotype?
a) AA
b) Aa
c) aa
d) AB
Answer: c) aa
14. What is the term for the observable characteristics of an organism?
a) Genotype
b) Phenotype
c) Allele
d) Trait
Answer: b) Phenotype
15. Which of the following is a sex-linked trait?
a) Eye color in humans
b) Height in humans
c) Seed color in peas
d) Hemophilia in humans
Answer: d) Hemophilia in humans
16. A carrier of a genetic disorder:
a) Always expresses the disorder
b) Has two copies of the mutant allele
c) Is heterozygous for the mutant allele
d) Is homozygous for the mutant allele
Answer: c) Is heterozygous for the mutant allele
17. Which of the following is an example of codominance?
a) Blood type inheritance
b) Flower color in pea plants
c) Height in humans
d) Skin color in humans
Answer: a) Blood type inheritance
18. The Law of Independent Assortment states that:
a) Alleles of different genes assort independently of each other during gamete formation
b) Alleles of the same gene always segregate together during gamete formation
c) Traits are determined by the environment rather than genetics
d) Genetic traits are inherited through blending of parental characteristics
Answer: a) Alleles of different genes assort independently of each other during gamete formation
19. Which of the following genetic disorders is caused by a mutation in the X chromosome and primarily affects males?
a) Color blindness
b) Hemophilia
c) Cystic fibrosis
d) Tay-Sachs disease
Answer: b) Hemophilia
20. What is the term for a gene located on a sex chromosome?
a) Autosomal gene
b) Sex-linked gene
c) Recessive gene
d) Dominant gene
Answer: b) Sex-linked gene
21. A test cross involves crossing an organism with:
a) Another organism of the same genotype
b) An organism that is homozygous dominant
c) An organism that is homozygous recessive
d) An organism that is heterozygous
Answer: c) An organism that is homozygous recessive
22. Which of the following genetic disorders is caused by a trisomy of chromosome 21?
a) Cystic fibrosis
b) Down syndrome
c) Hemophilia
d) Duchenne muscular dystrophy
Answer: b) Down syndrome
23. The principle of segregation was first described by:
a) Charles Darwin
b) Gregor Mendel
c) Thomas Hunt Morgan
d) James Watson and Francis Crick
Answer: b) Gregor Mendel
24. Which of the following techniques is used to determine the genetic makeup of an individual?
a) Gel electrophoresis
b) Polymerase chain reaction (PCR)
c) DNA sequencing
d) Southern blotting
Answer: c) DNA sequencing
25. In a pedigree analysis, squares represent:
a) Males
b) Females
c) Affected individuals
d) Carrier individuals
Answer: a) Males
26. Which of the following represents a homozygous dominant genotype?
a) AA
b) Aa
c) aa
d) AB
Answer: a) AA
27. A Punnett square is used to:
a) Predict the phenotypic ratio of offspring
b) Determine the genotype of an individual
c) Determine the probability of genetic disorders
d) Analyze the inheritance patterns of multiple traits
Answer: a) Predict the phenotypic ratio of offspring
28. Which of the following genetic disorders is caused by a mutation in a single gene and primarily affects African populations?
a) Sickle cell anemia
b) Huntington’s disease
c) Cystic fibrosis
d) Hemophilia
Answer: a) Sickle cell anemia
29. Epigenetics refers to:
a) Changes in DNA sequence
b) Changes in gene expression without altering DNA sequence
c) The study of gene mutations
d) The study of genetic disorders
Answer: b) Changes in gene expression without altering DNA sequence
30. The ratio of phenotypes in a dihybrid cross between two heterozygous individuals is:
a) 1:1
b) 3:1
c) 9:3:3:1
d) 1:2:1
Answer: c) 9:3:3:1
31. The process by which DNA is copied into RNA is called:
a) Transcription
b) Translation
c) Replication
d) Mutation
Answer: a) Transcription
32. Which of the following statements about DNA replication is true?
a) DNA polymerase adds nucleotides in the 3′ to 5′ direction
b) Replication occurs during prophase of mitosis
c) Both DNA strands are synthesized in the same direction
d) Replication is bidirectional, starting at a single origin of replication
Answer: d) Replication is bidirectional, starting at a single origin of replication
33. In the lac operon of E. coli, the lacZ gene encodes:
a) A repressor protein
b) Permease
c) β-galactosidase
d) Lactose
Answer: c) β-galactosidase
34. A frameshift mutation results from:
a) A substitution of one nucleotide for another
b) The insertion or deletion of nucleotides that are not multiples of three
c) A mutation in a single nucleotide
d) The deletion of a whole chromosome
Answer: b) The insertion or deletion of nucleotides that are not multiples of three
35. In eukaryotic cells, mRNA undergoes which of the following modifications before leaving the nucleus?
a) Splicing
b) Translation
c) Replication
d) Transcription
Answer: a) Splicing
36. The genetic code is said to be degenerate because:
a) Each codon specifies only one amino acid
b) Some amino acids are specified by multiple codons
c) There is no redundancy in the code
d) Each codon specifies multiple amino acids
Answer: b) Some amino acids are specified by multiple codons
37. Which of the following is an example of a point mutation?
a) Deletion
b) Insertion
c) Substitution
d) Inversion
Answer: c) Substitution
38. In DNA, adenine (A) pairs with:
a) Cytosine (C)
b) Thymine (T)
c) Guanine (G)
d) Uracil (U)
Answer: b) Thymine (T)
39. Which of the following enzymes is responsible for unwinding the DNA double helix during replication?
a) Helicase
b) DNA polymerase
c) Primase
d) Ligase
Answer: a) Helicase
40. Which of the following is NOT a function of RNA?
a) Carrying genetic information
b) Serving as a template for protein synthesis
c) Catalyzing chemical reactions
d) Regulating gene expression
Answer: c) Catalyzing chemical reactions
41. The lac operon is an example of a(n):
a) Inducible operon
b) Repressible operon
c) Constitutive operon
d) Mutagenic operon
Answer: a) Inducible operon
42. Which of the following is NOT a type of chromosomal mutation?
a) Deletion
b) Duplication
c) Transcription
d) Inversion
Answer: c) Transcription
43. A silent mutation:
a) Results in a change in amino acid sequence
b) Results in premature termination of protein synthesis
c) Does not change the amino acid sequence
d) Causes a frameshift mutation
Answer: c) Does not change the amino acid sequence
44. What is the term for a region of DNA that regulates gene expression by binding to specific transcription factors?
a) Promoter
b) Enhancer
c) Silencer
d) Operator
Answer: b) Enhancer
45. The central dogma of molecular biology states that:
a) DNA is transcribed into RNA, which is translated into protein
b) RNA is transcribed into DNA, which is translated into protein
c) Protein is transcribed into RNA, which is translated into DNA
d) Protein is translated into DNA, which is transcribed into RNA
Answer: a) DNA is transcribed into RNA, which is translated into protein
46. Which of the following enzymes is responsible for synthesizing RNA during transcription?
a) DNA polymerase
b) RNA polymerase
c) Helicase
d) Ligase
Answer: b) RNA polymerase
47. What is the term for a mutation that results in the substitution of one amino acid for another in a protein?
a) Missense mutation
b) Nonsense mutation
c) Frameshift mutation
d) Silent mutation
Answer: a) Missense mutation
48. Which of the following is a function of tRNA during translation?
a) Carrying amino acids to the ribosome
b) Unwinding the DNA double helix
c) Synthesizing RNA from a DNA template
d) Joining together adjacent Okazaki fragments
Answer: a) Carrying amino acids to the ribosome
49. In eukaryotic cells, mRNA is processed by which of the following modifications before translation?
a) Splicing
b) Capping
c) Polyadenylation
d) All of the above
Answer: d) All of the above
50. Which of the following genetic disorders is caused by a deletion of a portion of chromosome 15 and is characterized by developmental delays and behavioral problems?
a) Down syndrome
b) Turner syndrome
c) Angelman syndrome
d) Klinefelter syndrome
Answer: c) Angelman syndrome