BIO/BIOCHEM EXAM 5

Assuming all other conditions are equal, which of the following amino acids is expected to have the most positive charge at physiological pH? A. ARG B. MET C. ASN D. ASP

A. ARG

Unlike the cells from which human organs are composed, the cell of a unicellular organism such as algae: A. has a genome where nearly all material codes for protein. B. typically utilizes mitosis for cellular division. C. can perform catabolic reactions to gain energy from macromolecules. D. contains membrane-bound organelles to execute cell functions.

A. has a genome where nearly all material codes for protein.

A fatty acid is composed of a carboxylic acid head and a tail end composed primarily of: A. hydrocarbon groups. B. phosphate groups. C. amino groups. D. sulfate groups.

A. hydrocarbon groups.

If the patient had normal production of sperm, which of the following would describe its correct pathway through the male reproductive system? A. seminiferous tubules → epididymis → vas deferens → ejaculatory duct → urethra → penis B. seminiferous tubules → epididymis → ejaculatory duct → vas deferens → urethra → penis C. epididymis → vas deferens → ejaculatory duct → seminiferous tubules → urethra → penis D. epididymis → seminiferous tubules → vas deferens → ejaculatory duct → urethra → penis

A. seminiferous tubules → epididymis → vas deferens → ejaculatory duct → urethra → penis

A researcher analyzing a genome measures a cytosine composition of 19%. What is the expected adenine composition of this genome? A. 19% B. 31% C. D.

B. 31% - In DNA sequences, cytosine binds to guanine and adenine binds to thymine. Thus (A+T) + (G+C) = 100%. If A+T = 62%, then G+C = 38%. Therefore A = T = 31%.

During oxidative phosphorylation, which membrane complex transfers electrons from succinate to coenzyme Q? A. Complex I B. Complex II C. Complex III D. Complex IV

B. Complex II

If analysis of the patient's semen revealed decreased levels of fructose, which structural components of mature sperm would be directly affected? I. Head II. Midpiece III. Tail A. I B. II C. I,II D. I,II,III

B. II

Some eukaryotic cells are covered with small ciliary projections used for absorption, while others contain larger flagella used for propulsion. These cellular structures are composed of: A. microfilaments. B. microtubules. C. intermediate filaments. D. myosin.

B. microtubules.

Each of the following structures are derived from the mesoderm EXCEPT: A. kidneys. B. spinal cord. C. triceps. D. circulatory system.

B. spinal cord.

Women over 35 years of age have an increased risk of nondisjunction due to errors in what phase of meiosis? A. Prophase I B. Metaphase I C. Anaphase II D. Prophase II

C. Anaphase II

Which of the following molecules would be expected to have the lowest tissue concentrations in active skeletal muscle deprived of O2? A. Glyceraldehyde 3-phosphate B. Lactate C. Citrate D. Pyruvate

C. Citrate

Diabetes mellitus is characterized by dysregulation of the hormone insulin. Which of the following statements about insulin is/are correct? I. Insulin is produced by the beta cells of the pancreas. II. Insulin directly acts on glucose in the blood. III. Insulin is a peptide hormone. A. I B. I, II C. I, III D. I,II,III

C. I, III

During normal development in the seminiferous tubules, what class of Tex11 non-expressing somatic cells is responsible for nourishing sperm cells? A. Leydig cells B. Chromaffin cells C. Sertoli cells D. Granulosa cells

C. Sertoli cells

A bacterium has a faulty lac operon in which there is a structural defect in the operator. In this bacterium: A. there is a mutation in a segment of DNA that binds a promoter. B. a missense mutation is found in the gene that codes for the repressor. C. there is a structural problem with a segment of DNA that binds a repressor. D. there will be no proteins available capable of digesting lactose.

C. there is a structural problem with a segment of DNA that binds a repressor.

A follow-up experiment revealed that the genetic content of the bacterial cells was altered by the transfer of material from the phage. This process is best described as: A. transformation. B. conjugation. C. transduction. D. translation.

C. transduction.

Which of the following DNA oligomers, if in a double-stranded alpha helix conformation, would melt at the lowest temperature? A. 5'-CGCGCGTATCGACAAG-3' B. 5'-GGCGCGTATCGACAAG-3' C. 5'-GACGCGTCTCGACGGC-3' D. 5'-GATGCATATCGATAAA-3'

D. 5'-GATGCATATCGATAAA-3' - Double-stranded DNA comes apart (melts) into two single-stranded fragments at elevated temperatures. Because there are three hydrogen bonds holding C and G residues together and only two such bonds between A and T, the more A/T residues in a segment, the lower the melting point. Conversely, the more C/G residues, the higher the melting point. Among the segments listed, choice D has the most A/T residues and thus the lowest melting point.

Which of the following factors would be most likely to cause acetic acid to completely dissociate in aqueous solution? A. Higher temperatures, which increase the pKa of the acid B. Enzymes that catalyze the forward reaction C. Continuous addition of acetic acid to the solution D. Continuous removal of protons from the solution

D. Continuous removal of protons from the solution

Several Salmonella species are facultative anaerobes. Assuming that other external conditions are controlled for, would the expected growth rate of a Salmonella colony be slower in the presence or absence of O2? A. In the presence of O2, because aerobic respiration produces CO2, a byproduct that is lethal to facultative anaerobes. B. In the presence of O2, because the final product of aerobic respiration contains more energy than the final product of fermentation. C. In the absence of O2, because the bacteria will need to produce pyruvate decarboxylase, an enzyme required for entrance to the Krebs cycle D. In the absence of O2, because these conditions result in lower production of ATP, which can fuel binary fission.

D. In the absence of O2, because these conditions result in lower production of ATP, which can fuel binary fission.

Which of the following segments of amino acids would be most likely to be found in the membrane-spanning domain of the sodium channel in a nerve axon? A. DDR B. EVE C. LAD D. LIV

D. LIV

A particular oncogene product with an unusually high number of proline residues is most likely to use these residues: A. to aid in the formation of alpha helices. B. to be found primarily throughout beta-pleated sheets. C. to aid only in the formation of antiparallel beta-pleated sheets. D. to be found in turn regions of the protein.

D. to be found in turn regions of the protein.