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LIFS1901 2022 Spring 6 Differences among Living Individuals Review Question Set

Multiple-Choice Questions

Choose the best answer for each question

1.    Regular individuals of the same species have different characters because they have

______

A.   different numbers of chromosomes.

B.   differences in some segments of some chromosomes.

C.   different genes.

D.   differences in DNA sequences.

E.   differences other than those described above.

2.    A mutation in a somatic stem cell of a human individual may result in _______

A.   the presence of this mutation in some of the cells in this individual.

B.   the presence of this mutation in essentially all the cells in this individual.

C.   the presence of this mutation in some of the cells in a child of this individual.

D.   the presence of this mutation in essentially all the cells in a child of this individual.

3.    What is the most probable reason for the existence of people with trisomy 21 but not people with trisomy 1?

A. Chromosome 1 contains less genes than chromosome 21.

B. Zygotes having 3 copies of chromosome 21 can develop into viable individuals but zygotes having 3 copies of chromosome 1 cannot.

C. Sister chromosomes 21 may segregate incorrectly in meiosis but sister chromosomes 1 always segregate correctly in meiosis.

D. A cell having 3 copies of chromosome 1 can readily remove the extra copy of  chromosome 1 but a cell having 3 copies of chromosome 21 cannot remove the extra copy of chromosome 21.

E. None of the above.

4.    If an adenine (A) base in the DNA undergoes a structural change during DNA           replication of a cell so that it prefers to pair with another A, the original A:T basepair in this cell will be changed into _______ basepair in some of its daughter cells.

A. T:A

B. G:C

C. C:G

D. A:A

E. All daughter cells should have the same A:T basepair as this cell.

5.    Which is most probably caused by gamma radiation hitting the backbone of chromosomal DNA?

A. chromosomal translocation

B. single basepair deletion

C. aneuploidy

D. polyploidy

E. single base substitution

6.    Which is most susceptible to dimer formation on exposure to ultraviolet (UV) radiation?

A. 5'-CG-3'

B. 5'-AT-3'

C. 5'-AC-3'

D. 5'-CT-3'

E. 5'-GT-3'

7.    How many single-nucleotide differences exist between the genomes of two unrelated human individuals on average?

A. Single digits

B. Tens

C. Hundreds

D. Thousands

E. Millions

Multiple-True/False Questions

For each question, there can be 0 to 4 true branches. Determine the validity of each of the 4 branches.

8.    A mutation in a germline cell of a human individual may result in _______

A.   the presence of this mutation in only some somatic cells in this individual.

B.   the presence of this mutation in only some sex cells in this individual.

C.   the presence of this mutation in only some sex cells in a child of this individual.

D.   the presence of this mutation in essentially all the cells in a child of this individual.

9.    Mutations in ______ change the expression level of the gene but NOT the amino- acid sequence of the protein encoded by the gene.

A. the protein-coding region of a gene

B. the transcription promoter of a gene

C. the ribosome-binding site of a gene

D. DNA sequence upstream or downstream of a gene

10.  DNA gain or loss DOES NOT happen in ______

A. chromosomal inversion

B. chromosomal translocation

C. chromosomal deletion

D. chromosomal duplication

11.  Chromosomal ______ is an example of aneuploidy.

A. duplication

B. deletion

C. inversion

D. translocation

12.  Chromosomal mutations may result in ______

A. evolution of a new species.

B. death of an embryo.

C. functional abnormalities in a born individual.

D. evolution of a new gene.

13.  _____ MAY NOT happen to an individual who has an inverted chromosome in each of his cells.

A. Abnormal appearance

B. Mental retardation

C. Shortened lifespan

D. Reduced fertility

14.  Determine the validity of the following statements about a triploid plant in which one set of chromosomes is made up of 10 chromosomes:

A. The copy numbers of various chromosomes in a typical body cell of this plant are expected to be the same.

B. The viability of this plant is expected to be lower than that of a diploid plant of the same species.

C. The fertility of this plant is expected to be lower than that of a diploid plant of the same species.

D. The copy number of every chromosome in a typical body/somatic cell of this plant is higher than 2.

E. The copy numbers of various chromosomes in a typical gamete of this plant are expected to be the same.

15.  ______ contributes to genetic variation in a population of sexually reproducing animals.

A. Random fusion of gametes during zygote formation

B. Crossing over between sister chromatids during meiosis

C. Mutation

D. Independent assortment of chromosomes during meiosis

16.  ______ in a cell causes base substitutions in some of its daughter cells.

A. Reactions between nitrogenous bases and water

B. Incorrect base pairing between DNA template and nucleotide substrates during DNA replication

C. Incorrect base pairing between DNA template and nucleotide substrates during DNA transcription

D. Reactions between nitrogenous bases and reactive oxygen species

17.  ______ in a cell causes DNA gain and/or loss in some of its daughter cells.

A. Unequal crossover between sister chromosomes

B. RNA polymerase slippage

C. Spontaneous structural change in nitrogenous bases

D. DNA polymerase slippage

18.  Chemicals that disrupt spindle fibers can cause _______.

A. chromosomal translocations

B. single base substitutions

C. single basepair deletions

D. aneuploidies

E. polyploidies

19.  Chemicals that react with nitrogenous bases can cause _______.

A. chromosomal translocations

B. single base substitutions

C. single basepair deletions

D. aneuploidies

E. polyploidies

20.  Transposons contribute to genetic variation by ______.

A. removing nitrogenous bases from DNA

B. inserting themselves into chromosomal DNA randomly

C. reacting with nitrogenous bases

D. disrupting spindle fibers

E. appearing on different chromosomal locations, thus enabling unequal crossovers to occur

Short-Answer Question

21.  Changes in nitrogenous base in a certain position of human genome do not change any observable character of the individuals carrying them. State 2 possible reasons for this fact. (4/3% of course assessment)

22.  Shown below is the nitrogenous base sequence of a portion of the protein coding strand of a gene:

30     32    34    36    38     40    42    44

5’-----TGCTTCAAACCGAGTGA-----3’

The bases are numbered starting at 1 for the A in the start codon of the gene (not shown above).

a.  From this base sequence, you can determine several encoded amino acids. If the position of the amino acid (Met) coded by the start codon is defined as 1, what  are the positions of amino acids that you can determine? Write out the amino     acid sequence at these positions. (1% of course assessment)

b. If the C at base position 39 is mutated to A, write out the amino acid sequence  that you can determine from the mutated base sequence. What kind of mutation is this in regard to protein coding? (1% of course assessment)

c.   If the C at base position 39 is mutated to T, write out the amino acid sequence that you can determine from the mutated base sequence. What kind of mutation is this in regard to protein coding? (1% of course assessment)

d. If the C at base position 40 is mutated to T, write out the amino acid sequence  that you can determine from the mutated base sequence. What kind of mutation is this in regard to protein coding? (1% of course assessment)

e.  If the C at base position 40 is deleted, write out the amino acid sequence that you can determine from the mutated base sequence. What kind of mutation is this in regard to protein coding? (1% of course assessment)

 

Key (For multiple-true/false questions, the listed branch/branches is/are true and the unlisted one/ones is/are false.)

1.    D

2.    A

3.    B

4.    A

5.    A

6.    D

7.    E

8.    B, D

9.    B, C

10.  A, B

11.  None

12.  All

13.  A, B, C

14.  A, C, D

15.  A, C, D

16.  A, B, D

17.  A, D

18.  D, E

19.  B, C

20.  B, E

21.  Possible reasons

   This genomic position is outside of a gene.

   Even though this genomic position is within a gene, the expression of this

gene remains the same no matter which nitrogenous bases is in this location. For instance, all 4 different nitrogenous bases in this position together with   the bases in the two neighboring positions give codons that code for the same amino acid.

   Even though this genomic position is within a gene and the changes in

nitrogenous base in this genomic position affect the expression of the gene,     the difference in gene expression caused by the difference in nitrogenous base in this genomic position is not big enough to cause a difference in the               character controlled by this gene. [This possibility is especially applicable to   diploid organisms. Many characters are exhibited as long as there is one         normal copy of the genes controlling them.]

22.  (a)  amino acid positions 11 to 15, amino acid sequence: AlaSerAsnArgVal (b)  AlaSerLysArgVal, missense

(c)  AlaSerAsnArgVal, silent

(d)  AlaSerAsn, nonsense         (e)  AlaSerAsnGlu, frameshift