BIOS115 FINAL EXAM
QUESTIONS AND ANSWERS
2024/2025
Which of the following human cells contains a genes that specifies eye color?
A. Cells in the eye
B. Cells in the heart
C. Gametes (sperm and egg)
D. Cells in the eye and gametes
E. All of the above - ANS >>All of the above (cells in the eye, heart, and gametes)
An inherited disease that affects women and not men is likely to be caused by:
A. a mutation in a gene on the X chromosome, which is a sex chromosome
B. a mutation in a gene on a non-sex chromosome (autosome)
C. without additional information, either answer A or B is possible - ANS >>without additional
information, either answer A (sex chromosome) or B (autosome) is possible
An isolated population of prairie dogs has longer than average teeth. As a result they can eat grass with
less effort and are better able to survive. The mutation(s) that resulted in longer teeth:
A. allowed the teeth to grow longer over several generations until they reached an optimal length for
eating grass
B. arose in many members of the population at the same time
C. happened by chance
D. occurred because the prairie dogs needed to be more efficient at eating grass to survive and
reproduce
E. would only occur in a prairie dog population that eats grass and would not occur in a population that
lives on seeds - ANS >>happened by chance
Starting with a population of genetically identical mice, you discover two new independent mutant
strains in which all of the animals have epileptic seizures. In both strains, you know that the epileptic
,seizures are due to a single DNA mutation. You cross a mutant mouse from one strain to a mutant mouse
from the second strain and find that none of their many offspring undergo spontaneous seizures. From
this experiment, you would conclude that the two mutant strains most likely have mutations in:
A. the same DNA base position within a particular gene
B. the same gene, but not necessarily the same DNA base position
C. two different genes - ANS >>the same gene, but not necessarily the same DNA base position
A young man develops skin cancer that does not spread to any other tissues; the mutation responsible
for the cancer arose in a single skin cell. If he and his wife (who does not have skin cancer) have children
after the skin cancer diagnosis, which of the following statements is most likely to be true?
A. All the man's children will inherit the mutation
B. All the man’s children will inherit the mutation if the mutation is dominant
C. Some of the man's children may inherit the mutation depending on which of his chromosomes they
inherit
D. None of the man's children will inherit the mutation - ANS >>None of the man's children will inherit
the mutation
The MLH1 gene is located on chromosome 3 in humans and four different alleles have been identifies.
The maximum number of alleles a SINGLE NORMAL INDIVIDUAL can have is:
A. 1
B. 2
C. 3
D. 4 - ANS >>2
A population of buffalos is isolated such that no new buffalos can come into their territory. Which of the
following is primarily responsible for the appearance of new alleles in this population?
A. Reassortment of chromosomes during the process of creating sperm or eggs
B. Mutations in cells that will become sperm or eggs
C. Changes in the environment that favor some buffalo traits over others
D. Random mating between the buffalos in the population - ANS >>Mutations in cells that will become
sperm or eggs
, Cystic fibrosis in humans is caused by mutations in a single gene and is inherited as an autosomal (non-
sex chromosome) recessive trait. A normal couple has two children. The first child has cystic fibrosis, and
the second child is unaffected. What is the probability that the second child is a carrier (heterozygous)
for the mutation that causes the disease?
A. 1/4
B. 1/2
C. 2/3
D. 3/4
E. 1 - ANS >>1/2
The following DNA sequence (coding strand) occurs near the middle of the coding region of a gene.
DNA:
50 55 60 65
5'- A A T G A A T G G G A G C C T G A A G G A G -3'
The corresponding mRNA sequence is shown below. Note that the coding strand of DNA has the same
sequence as the mRNA, except that there are U's in the mRNA where there are T's in DNA. The first
triplet of nucleotides AAU is in frame for coding, and encodes asparagine as the codon table indicates
RNA:
50 55 60 65
5'- A A U G A A U G G G A G C C U G A A G G A G -3'
Which of the following DNA mutations is almost certain to result in a shorter than normal mRNA?
A. A to G at position 50
B. G to A at position 53
C. C to A at position 58
D. None of the above - ANS >>None of the above
For the same DNA sequence, which of the following DNA mutations is almost certain to result in a
shorter than normal protein?
A. T to C at position 59
QUESTIONS AND ANSWERS
2024/2025
Which of the following human cells contains a genes that specifies eye color?
A. Cells in the eye
B. Cells in the heart
C. Gametes (sperm and egg)
D. Cells in the eye and gametes
E. All of the above - ANS >>All of the above (cells in the eye, heart, and gametes)
An inherited disease that affects women and not men is likely to be caused by:
A. a mutation in a gene on the X chromosome, which is a sex chromosome
B. a mutation in a gene on a non-sex chromosome (autosome)
C. without additional information, either answer A or B is possible - ANS >>without additional
information, either answer A (sex chromosome) or B (autosome) is possible
An isolated population of prairie dogs has longer than average teeth. As a result they can eat grass with
less effort and are better able to survive. The mutation(s) that resulted in longer teeth:
A. allowed the teeth to grow longer over several generations until they reached an optimal length for
eating grass
B. arose in many members of the population at the same time
C. happened by chance
D. occurred because the prairie dogs needed to be more efficient at eating grass to survive and
reproduce
E. would only occur in a prairie dog population that eats grass and would not occur in a population that
lives on seeds - ANS >>happened by chance
Starting with a population of genetically identical mice, you discover two new independent mutant
strains in which all of the animals have epileptic seizures. In both strains, you know that the epileptic
,seizures are due to a single DNA mutation. You cross a mutant mouse from one strain to a mutant mouse
from the second strain and find that none of their many offspring undergo spontaneous seizures. From
this experiment, you would conclude that the two mutant strains most likely have mutations in:
A. the same DNA base position within a particular gene
B. the same gene, but not necessarily the same DNA base position
C. two different genes - ANS >>the same gene, but not necessarily the same DNA base position
A young man develops skin cancer that does not spread to any other tissues; the mutation responsible
for the cancer arose in a single skin cell. If he and his wife (who does not have skin cancer) have children
after the skin cancer diagnosis, which of the following statements is most likely to be true?
A. All the man's children will inherit the mutation
B. All the man’s children will inherit the mutation if the mutation is dominant
C. Some of the man's children may inherit the mutation depending on which of his chromosomes they
inherit
D. None of the man's children will inherit the mutation - ANS >>None of the man's children will inherit
the mutation
The MLH1 gene is located on chromosome 3 in humans and four different alleles have been identifies.
The maximum number of alleles a SINGLE NORMAL INDIVIDUAL can have is:
A. 1
B. 2
C. 3
D. 4 - ANS >>2
A population of buffalos is isolated such that no new buffalos can come into their territory. Which of the
following is primarily responsible for the appearance of new alleles in this population?
A. Reassortment of chromosomes during the process of creating sperm or eggs
B. Mutations in cells that will become sperm or eggs
C. Changes in the environment that favor some buffalo traits over others
D. Random mating between the buffalos in the population - ANS >>Mutations in cells that will become
sperm or eggs
, Cystic fibrosis in humans is caused by mutations in a single gene and is inherited as an autosomal (non-
sex chromosome) recessive trait. A normal couple has two children. The first child has cystic fibrosis, and
the second child is unaffected. What is the probability that the second child is a carrier (heterozygous)
for the mutation that causes the disease?
A. 1/4
B. 1/2
C. 2/3
D. 3/4
E. 1 - ANS >>1/2
The following DNA sequence (coding strand) occurs near the middle of the coding region of a gene.
DNA:
50 55 60 65
5'- A A T G A A T G G G A G C C T G A A G G A G -3'
The corresponding mRNA sequence is shown below. Note that the coding strand of DNA has the same
sequence as the mRNA, except that there are U's in the mRNA where there are T's in DNA. The first
triplet of nucleotides AAU is in frame for coding, and encodes asparagine as the codon table indicates
RNA:
50 55 60 65
5'- A A U G A A U G G G A G C C U G A A G G A G -3'
Which of the following DNA mutations is almost certain to result in a shorter than normal mRNA?
A. A to G at position 50
B. G to A at position 53
C. C to A at position 58
D. None of the above - ANS >>None of the above
For the same DNA sequence, which of the following DNA mutations is almost certain to result in a
shorter than normal protein?
A. T to C at position 59
