BASIC GENETICS
(MCQ)
What is a gene?
A. A type of protein
B. A segment of DNA that codes for a trait
C. A cell structure
D. A chromosome pair
Answer: B
Explanation: A gene is a section of DNA that determines a specific trait.
(MCQ)
What is the purpose of a Punnett square?
A. Measure DNA length
B. Predict genetic outcomes of a cross
C. Count chromosomes
D. Identify cells
Answer: B
Explanation: It is used to predict possible offspring genotypes.
(MCQ)
A monohybrid cross studies:
A. Two genes
B. One trait
C. Many chromosomes
D. DNA structure
Answer: B
Explanation: It focuses on one trait controlled by one gene.
(MCQ)
What is the first step in a Punnett square simulation?
A. Draw conclusions
B. Identify parental genotypes
C. Measure DNA
D. Count chromosomes
Answer: B
Explanation: You must determine the parents’ genetic makeup first.
(True/False)
All offspring from a genetic cross are identical.
Answer: False
Explanation: Variation occurs due to different allele combinations.
(MCQ)
What is a dominant allele?
A. An allele that is always hidden
B. An allele that only appears in females
C. An allele that expresses itself when present
D. A mutated gene only
Answer: C
Explanation: Dominant alleles show their trait even if only one copy is present.
(MCQ)
What letters are used to represent alleles in Punnett squares?
A. Numbers
B. Amino acids
C. Letters (e.g., A, a)
D. Symbols only
Answer: C
Explanation: Capital letters represent dominant alleles, lowercase represent recessive.
(MCQ)
If T = tall and t = short, what is Tt?
A. Homozygous dominant
B. Homozygous recessive
C. Heterozygous
D. Mutation
Answer: C
Explanation: One dominant and one recessive allele.
(MCQ)
What tool is used to visualize allele combinations?
A. Microscope
B. Punnett square
C. Pipette
D. Beaker
Answer: B
Explanation: The Punnett square organizes genetic possibilities.
(MCQ)
If two heterozygous parents are crossed, what is the chance of recessive offspring?
A. 0%
B. 75%
C. 50%
D.25%
Answer: D
Explanation: 1 out of 4 outcomes is recessive.
(True/False)
Recessive traits are only expressed when two recessive alleles are present.
Answer: True
Explanation: A recessive trait is only visible in the homozygous recessive condition.
(True/False)
Each parent contributes two alleles to offspring.
Answer: False
Explanation: Each parent contributes one allele per gene.
(True/False)
Tt and TT have the same phenotype.
Answer: True
Explanation: Both show the dominant trait (tall).
(MCQ)
Why are simulations useful in genetics?
A. They replace DNA
B. They allow safe experimentation
C. They eliminate variation
D. They remove probability
Answer: B
Explanation: They let students test genetic crosses safely.
(MCQ)
Which best describes inheritance?
A. Random change in DNA
B. Passing traits from parents to offspring
C. Cell division only
D. Protein synthesis
Answer: B
Explanation: Traits are passed through genes.
(MCQ)
What does genotype refer to?
A. Physical appearance
B. Genetic makeup
C. Environment
D. Cell shape
Answer: B
Explanation: Genotype is the genetic combination of alleles.
(MCQ)
What is the first step in setting up a Punnett square?
A. Write phenotypes
B. List parental alleles
C. Draw chromosomes
D. Calculate ratios
Answer: B
Explanation: You first identify the parents’ genotypes.
(True/False)
A recessive phenotype can appear in heterozygous individuals.
Answer: False
Explanation: Recessive traits require two recessive alleles.
(True/False)
Punnett squares are used to model inheritance patterns.
Answer: True
Explanation: They help visualize how traits are passed down.
(MCQ)
What does probability in genetics represent?
A. Guaranteed outcome
B. DNA mutation rate
C. Likelihood of a trait appearing
D. Cell size
Answer: C
Explanation: It shows chances, not certainty.
(MCQ)
What does homozygous mean?
A. Two different alleles
B. No alleles
C. One allele only
D. Two identical alleles
Answer: D
Explanation: Homozygous means both alleles are the same.
(True/False)
Punnett squares can predict exact appearance of every offspring.
Answer: False
Explanation: They predict probabilities, not certainties.
(MCQ)
Which genotype shows a recessive trait?
A. TT
B. Tt
C. tt
D. None
Answer: C
Explanation: Only homozygous recessive shows the trait.
(MCQ)
What does each box in a Punnett square represent?
A. A gene mutation
B. A possible offspring genotype
C. A chromosome
D. A protein
Answer: B
Explanation: Each box shows a possible genetic outcome.
(MCQ)
Why are Punnett squares important?
A. They predict inheritance patterns
B. They show DNA structure
C. They measure cells
D. They change genes
Answer: A
Explanation: They help predict trait distribution in offspring.