During translation, amino acids are joined by peptide bonds

13 Jun During translation, amino acids are joined by peptide bonds

Question
11. During translation, amino acids are joined by peptide bonds to make polypeptides. The formation of these peptide bonds is catalyzed by:
A) DNA.

B) mRNA.

C) tRNA.

D) rRNA.

12. If an allele (R) at a gene with two alleles shows complete dominance, individuals with the genotypes ______ will have the same phenotype.

A) RR and rr.

B) RR and Rr

C) Rr and rr

D) Each of the three possible genotypes will have a different phenotype.

13. The arms of a human and the wing of a bat are _________________ structures, composed of the same bones that have been modified for different functions.

A) analogous

B) vestigial

C) homologous

D) convergent

14. Xeroderma pigmentosum is an autosomal recessive genetic disorder. People who are homozygous for the disease-causing allele have skin that is damaged by exposure to ultraviolet radiation; this can lead to skin cancer at an early age. The mutation that causes this disorder is in a gene that functions:

A) to repair DNA by excising (removing) nucleotides damaged by UV light.

B) in lysosomes, to break down lipids that otherwise accumulate in the nervous system.

C) to produce the UV blocking pigment melanin in the skin cells

D) in red blood cells to carry oxygen to the skin.

15. The Amish are a religious sect descended from a small group of colonists who came to the United States over 200 years ago. Their religious beliefs have kept them isolated from society. The Amish have a much higher than average incidence of both polydactyly (extra fingers and toes) and dwarfism in their communities. This is most likely explained by:

A) inheritance of acquired characters.

B) the founder effect.

C) disruptive selection.

D) natural selection.

16. In the structure of DNA that Watson and Crick proposed, the sides of the “ladder” of the DNA molecule are always the same distance apart, making the molecule a constant width. This occurs because when the bases hydrogen bond to form the rungs of the “ladder”, a:

A) purine always pairs with a pyrimidine.

B) purine always pairs with a purine.

C) pyrimidine always pairs with a pyrmidine.

D) The structure of the double helix is not determined by how the bases pair.

17. The RNA transcript of DNA that travels to the cytoplasm, carrying the instructions to make a protein, is called:

A) rRNA.

B) tRNA.

C) mRNA.

D) RNA polymerase.

18. When DNA is replicated, the error rate is approximately one error for every 10,000 nucleotides copied. However, that error rate is reduced to only 1 error for every 1 billion nucleotides. The DNA sequence is “corrected” by:

A) repeating S phase to see if the error rate is lower the second time around.

B) enzymes that proofread the DNA and repair errors.

C) messenger RNA during the process of transcription.

D) Any errors made during DNA replication cannot be corrected. If errors are detected after S phase, the cell is destroyed.

19. Mendel’s principle of segregation says that:

A) when gametes are formed, each gamete receives only one allele for a particular gene.

B) some genes are dominant to others.

C) a testcross must be used to determine the genotype of an organism with a dominant phenotype.

D) all of the above

20. Tay-Sachs disease is lethal before reproductive age, but the allele persists in Louisiana French Canadians because:

A) it is a dominant allele.

B) new mutations causing this disease are common in that population.

C) it is not expressed in the phenotype of heterozygous individuals.

D) the disease is contagious and can be transmitted by nonheritable means.