Q: Which equation represents the number of possible genotypes for a gene with three alleles in a diploid organism?

$$\frac{3 \times (3+1)}{2} = 6$$

Question 1

Which of the following best describes the difference between a gene and an allele?

Accepted Answer

A gene is a sequence of DNA that codes for a product, while an allele is an alternative form of that gene.

Question 2

If an organism has a haploid number of $$n = 23$$, how many chromosomes are present in a diploid cell?

Accepted Answer

$$46$$

Question 3

Which of the following best describes a homologous chromosome pair?

Accepted Answer

Two chromosomes that have the same genes in the same order but may have different alleles.

Question 4

A diploid organism has a diploid number of $$2n = 24. $$How many pairs of chromosomes does this organism have in its gametes?

Accepted Answer

$$12$$

Question 5

Which genotype represents a heterozygous individual for a gene with alleles A and a?

Accepted Answer

A/a

Question 6

In Mendel’s pea plant experiments, what phenotypic ratio did he observe in the F2 generation for a single gene trait with dominant and recessive alleles?

Accepted Answer

3:1

Question 7

Which of the following statements about dominant alleles is correct?

Accepted Answer

Dominant alleles determine phenotype when present in either homozygous or heterozygous form.

Question 8

Which equation correctly represents the probability of an offspring inheriting a recessive phenotype in a Mendelian monohybrid cross between two heterozygous parents?

Accepted Answer

$$P = \frac{1}{4}$$

Question 9

A heterozygous male Chagrian alien (long horns are dominant) mates with a female with short horns. What is the expected phenotypic ratio of their offspring?

Accepted Answer

1:1 long horned to short horned

Question 10

Which of the following best describes a null mutation?

Accepted Answer

A mutation that results in no functional product being produced.

Question 11

Which of the following is true about X-linked recessive traits in humans?

Accepted Answer

All sons of affected mothers will have the trait.

Question 12

If a gene is Y-linked, which individuals in a pedigree will express the trait?

Accepted Answer

Only males

Question 13

Which of the following best explains why Mendel’s results contradicted the theory of Blending Inheritance?

Accepted Answer

Mendel observed that traits could disappear in one generation and reappear in the next.

Question 14

Which equation represents the number of possible genotypes for a gene with three alleles in a diploid organism?

Accepted Answer

$$\frac{3 	imes (3+1)}{2} = 6$$

Question 15

Which of the following is a correct application of pedigree analysis for determining autosomal recessive inheritance?

Accepted Answer

Trait must be recessive if two parents without trait produce offspring with it.

Question 16

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 17

A mutation in the hemoglobin gene causes sickle cell anemia. Which change in the DNA sequence leads to the disease?

Accepted Answer

A missense mutation that changes glutamic acid to valine.

Question 18

Which of the following best describes a hemizygous genotype?

Accepted Answer

An individual with only one allele present at a locus (e.g., XY).

Question 19

Which of the following is true about the inheritance of X-linked dominant traits?

Accepted Answer

All daughters of affected fathers will have the trait.

Patterns of Inheritance: Single-Gene Traits and Mendelian Genetics

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