BIOL 2030 GENETICS MIDTERM EXAM BANK: 200 EXAM
QUESTIONS WITH COMPLETE SOLUTIONS (2026/2027)
1. A chromosome segment that lacks a centromere is known as:
A) Dicentric
B) Acentric
C) Monosomic
D) Trisomic
Correct Answer: B – Acentric chromosomes lack a centromere and are
typically lost during cell division because they cannot attach to spindle
microtubules.
2. Which condition describes an organism with an extra or missing
chromosome?
A) Polyploidy
B) Aneuploidy
C) Euploidy
D) Haploidy
Correct Answer: B – Aneuploidy is the condition of having an abnormal
number of chromosomes, either extra or missing.
3. Continuous variation of phenotypes produces a distribution that is:
A) Bell-shaped curve
B) Discontinuous with distinct classes
C) Uniform with no variation
,D) Bimodal with two peaks
Correct Answer: A – Continuous variation results in a bell-shaped curve
with overlapping phenotypes, typical of quantitative traits.
4. Cystic fibrosis is a recessive disorder in which symptoms vary
because:
A) The gene is dominant
B) Loss of function varies among different mutations
C) It is caused by a chromosome deletion
D) It only affects males
Correct Answer: B – The severity of cystic fibrosis depends on the
degree of loss of function in the CFTR gene, leading to variable
symptoms.
5. The field of genetics that focuses on chromosome variations is
called:
A) Molecular genetics
B) Population genetics
C) Cytogenetics
D) Transmission genetics
Correct Answer: C – Cytogenetics is the study of chromosome
structure, function, and variation.
6. Loss of chromosomal material resulting in large-scale deletions is
typically:
A) Benign with no phenotype
,B) Lethal, acting like monosomies
C) Always compensated by the homolog
D) Only affects non-coding DNA
Correct Answer: B – Large-scale deletions are often lethal because they
result in a significant loss of genetic material, similar to monosomy.
7. A chromosome with two centromeres is called:
A) Acentric
B) Monocentric
C) Dicentric
D) Telocentric
Correct Answer: C – Dicentric chromosomes have two centromeres and
can cause problems during cell division due to improper segregation.
8. Discontinuous variation is characterized by:
A) A continuous range of phenotypes
B) Distinct, separate phenotypic classes
C) A bell-shaped distribution
D) Environmental influence on phenotype
Correct Answer: B – Discontinuous variation shows phenotypes that fall
into discrete categories, such as Mendel's pea traits.
9. Dispermy, the fertilization of one egg by two sperm, results in:
A) Haploid zygote
B) Diploid zygote
C) Triploid zygote
, D) Tetraploid zygote
Correct Answer: C – Dispermy results in a triploid (3n) zygote, which is
usually inviable.
10. DNA repair systems are important because:
A) They prevent all mutations
B) They repair damaged DNA and are under genetic control
C) They only function in cancer cells
D) They are not found in prokaryotes
Correct Answer: B – DNA repair systems are enzyme systems that repair
damaged DNA, and mutations in these systems can lead to cancer.
11. Duplications of chromosomal regions:
A) Always result in a phenotype
B) Act like trisomy and can be lethal
C) Have no effect on gene expression
D) Are always beneficial
Correct Answer: B – Duplications increase gene dosage and can act like
trisomy, often being lethal for large regions.
12. UV radiation causes thymine dimers by:
A) Breaking phosphodiester bonds
B) Crosslinking adjacent thymine bases
C) Adding methyl groups to cytosine
D) Deleting entire genes
QUESTIONS WITH COMPLETE SOLUTIONS (2026/2027)
1. A chromosome segment that lacks a centromere is known as:
A) Dicentric
B) Acentric
C) Monosomic
D) Trisomic
Correct Answer: B – Acentric chromosomes lack a centromere and are
typically lost during cell division because they cannot attach to spindle
microtubules.
2. Which condition describes an organism with an extra or missing
chromosome?
A) Polyploidy
B) Aneuploidy
C) Euploidy
D) Haploidy
Correct Answer: B – Aneuploidy is the condition of having an abnormal
number of chromosomes, either extra or missing.
3. Continuous variation of phenotypes produces a distribution that is:
A) Bell-shaped curve
B) Discontinuous with distinct classes
C) Uniform with no variation
,D) Bimodal with two peaks
Correct Answer: A – Continuous variation results in a bell-shaped curve
with overlapping phenotypes, typical of quantitative traits.
4. Cystic fibrosis is a recessive disorder in which symptoms vary
because:
A) The gene is dominant
B) Loss of function varies among different mutations
C) It is caused by a chromosome deletion
D) It only affects males
Correct Answer: B – The severity of cystic fibrosis depends on the
degree of loss of function in the CFTR gene, leading to variable
symptoms.
5. The field of genetics that focuses on chromosome variations is
called:
A) Molecular genetics
B) Population genetics
C) Cytogenetics
D) Transmission genetics
Correct Answer: C – Cytogenetics is the study of chromosome
structure, function, and variation.
6. Loss of chromosomal material resulting in large-scale deletions is
typically:
A) Benign with no phenotype
,B) Lethal, acting like monosomies
C) Always compensated by the homolog
D) Only affects non-coding DNA
Correct Answer: B – Large-scale deletions are often lethal because they
result in a significant loss of genetic material, similar to monosomy.
7. A chromosome with two centromeres is called:
A) Acentric
B) Monocentric
C) Dicentric
D) Telocentric
Correct Answer: C – Dicentric chromosomes have two centromeres and
can cause problems during cell division due to improper segregation.
8. Discontinuous variation is characterized by:
A) A continuous range of phenotypes
B) Distinct, separate phenotypic classes
C) A bell-shaped distribution
D) Environmental influence on phenotype
Correct Answer: B – Discontinuous variation shows phenotypes that fall
into discrete categories, such as Mendel's pea traits.
9. Dispermy, the fertilization of one egg by two sperm, results in:
A) Haploid zygote
B) Diploid zygote
C) Triploid zygote
, D) Tetraploid zygote
Correct Answer: C – Dispermy results in a triploid (3n) zygote, which is
usually inviable.
10. DNA repair systems are important because:
A) They prevent all mutations
B) They repair damaged DNA and are under genetic control
C) They only function in cancer cells
D) They are not found in prokaryotes
Correct Answer: B – DNA repair systems are enzyme systems that repair
damaged DNA, and mutations in these systems can lead to cancer.
11. Duplications of chromosomal regions:
A) Always result in a phenotype
B) Act like trisomy and can be lethal
C) Have no effect on gene expression
D) Are always beneficial
Correct Answer: B – Duplications increase gene dosage and can act like
trisomy, often being lethal for large regions.
12. UV radiation causes thymine dimers by:
A) Breaking phosphodiester bonds
B) Crosslinking adjacent thymine bases
C) Adding methyl groups to cytosine
D) Deleting entire genes
