BS Cell Biology and Genetics 2 — Questions and Answers
Question 1: What is a dominant allele?
- An allele whose trait is expressed even when only one copy is present (Correct answer)
- An allele that is only expressed when two copies are present
- The most common allele in a population
- An allele that causes a genetic disorder
Correct answer: An allele whose trait is expressed even when only one copy is present
A dominant allele produces its associated trait when at least one copy is present, masking the effect of the recessive allele.
Question 2: What is the term for an organism with two identical alleles for a gene?
- Homozygous (Correct answer)
- Heterozygous
- Diploid
- Haploid
Correct answer: Homozygous
A homozygous organism carries two identical alleles (either both dominant or both recessive) for a particular gene.
Question 3: What does the term 'genotype' refer to?
- The genetic makeup of an organism (Correct answer)
- The physical expression of traits
- The number of chromosomes in a cell
- The location of a gene on a chromosome
Correct answer: The genetic makeup of an organism
Genotype refers to the specific alleles an organism carries for a gene, which may or may not be visible in its appearance.
Question 4: How many chromosomes are in a typical human somatic cell?
- 46 (Correct answer)
- 23
- 48
- 92
Correct answer: 46
Human somatic (body) cells are diploid and contain 46 chromosomes arranged in 23 pairs.
Question 5: What is a mutation?
- A change in the DNA sequence of an organism (Correct answer)
- A normal variation in gene expression
- The movement of genes between chromosomes
- The silencing of a gene by methylation
Correct answer: A change in the DNA sequence of an organism
A mutation is any permanent change in the nucleotide sequence of an organism's DNA.
Question 6: What is the central dogma of molecular biology?
- DNA is transcribed into RNA, which is translated into protein (Correct answer)
- Protein is translated into RNA, which is transcribed into DNA
- RNA is directly converted into protein without DNA
- DNA directly produces protein without RNA intermediary
Correct answer: DNA is transcribed into RNA, which is translated into protein
The central dogma describes the flow of genetic information: DNA → RNA → Protein.
BS Cell Biology and Genetics 2
What is a dominant allele?