Heredity and Traits Quiz

Grade 6 · Science · Quiz

Test your knowledge of genes, alleles, dominant and recessive traits, and heredity.

Questions

Humans have how many chromosomes in most of their cells?
1. 23
2. 46
3. 64
4. 92
Show answer
Answer: 46
Humans have 46 chromosomes arranged in 23 pairs. One chromosome in each pair comes from each parent.
You inherit one chromosome in each pair from your mother and one from your father.
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Answer: True
Sexual reproduction combines one set of chromosomes from each parent, giving offspring a unique combination of genetic material.
If B (brown eyes) is dominant and b (blue eyes) is recessive, what eye color would a person with genotype BB have?
1. Blue
2. Green
3. Brown
4. Hazel
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Answer: Brown
BB means both alleles are the dominant brown-eye allele, so the phenotype is definitely brown eyes.
The genetic makeup of an organism is called its ___.
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Answer: genotype
The genotype is the actual allele combination (e.g., BB, Bb, bb). The phenotype is what that combination looks like (e.g., brown eyes).
Two parents both have genotype Bb for eye color. What fraction of offspring would be expected to have blue eyes (bb)?
1. 1/4
2. 1/2
3. 3/4
4. All of them
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Answer: 1/4
Bb × Bb cross produces: BB (25%), Bb (50%), bb (25%). Only bb shows blue eyes, so the probability is 1 in 4 (25%).
A dominant allele needs two copies to be expressed in the phenotype.
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Answer: False
A dominant allele only needs ONE copy to be expressed. Even one dominant allele (Bb) produces the dominant phenotype.
What tool do scientists use to predict the probability of offspring traits?
1. DNA ladder
2. Punnett square
3. Chromosome map
4. Gene probe
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Answer: Punnett square
A Punnett square uses a 2x2 grid to show all possible allele combinations, allowing prediction of offspring trait probabilities.
Traits are inherited through segments of DNA called ___.
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Answer: genes
Genes are specific DNA sequences that code for proteins determining traits. Each person inherits two copies of each gene (one from each parent).
Which statement about recessive alleles is TRUE?
1. They are always expressed
2. They are expressed only when two copies are present
3. They are stronger than dominant alleles
4. They are found only on X chromosomes
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Answer: They are expressed only when two copies are present
Recessive alleles are 'hidden' when paired with a dominant allele. They only appear in the phenotype in a homozygous recessive (bb) genotype.
Gregor Mendel did his famous genetics experiments using fruit flies.
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Answer: False
Mendel used pea plants — not fruit flies. He studied traits like seed color, pod shape, and plant height, counting thousands of offspring.

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