MCAT Jeopardy

Molecular Biology

100

In the lac operon, transcription is regulated by a repressor protein and only takes place in the presence of lactose. Which of the following is correct? A) The repressor protein binds to the promoter site to inhibit transcription. B) Lactose binds to the promoter site to initiate transcription. C)Lactose binds to the repressor protein to inhibit transcription. D)The repressor protein binds the operator site to inhibit transcription.

D)The repressor protein binds the operator site to inhibit transcription. **Lactose binds to the repressor protein at an allosteric site, causing a conformational change so that the repressor protein can no longer bind to the operator. RNA polymerase then is able to move forward to start site and transcription will occur.**

200

Which of the following is NOT a similarity between replication and transcription? A)Processing of pre-mRNA B)Regulation of transcription factors C)Coordinating amino acid addition in translation D)Maintaining telomeres

C)Coordinating amino acid addition in translation. Transfer RNA (tRNA), not snRNA, is typically involved in the process of coordinating the amino acids that are added to a growing protein during translation .

300

Which of the following is/are true with respect to eukaryotic mRNA? I.Monocistronic II.Transcription stops at the stop codon III.Has the same sequence as the template DNA that it was transcribed from A)I only B)I and II C)II and III D)all

A) I.Monocistronic. Eukaryotic mRNA is monocistronic, meaning only one protein is transcribed from each mRNA.

400

A competitive inhibitor of eukaryotic RNA polymerase III would have the greatest effect on: A)Replication. B)Reverse transcription. C)Translation. D)Mutation.

C)Translation.RNA polymerase III transcribes transfer RNA (tRNA), which then carries amino acids to ribosomes for use in translation.

Microbiology

100

Which of the following shape and proper name is matched incorrectly? A)Spiral w/ flagella-Cocci B)Rod-Bacilli C)Spiral-Spriochetes

A)Spiral w/ flagella-Cocci. The shape of cocci is round.

200

What is the cell wall of bacteria composed of? A)Polysaccharide cellulose B)Pectin C)Peptidoglycan D)Chitin

C)Peptidoglycan. It is a complex polymer unique to prokaryotes.

300

What is the purpose of Gram-Staining bacteria? A)Helps identifying whether the bacteria is Gram -/+ B) Helps identify the shape of the cell C)Helps identify the morphology and arrangement of the cell(s) D)all of above

D)all of above

400

If a bacterial cell is said to be peritrichous, what does that mean? A) It is a highly contagious pathogen. B)It has flagella located on each end of the cell. C)It has flagella located on one end of the cell. D)It has flagella located all over the cell.

D)It has flagella located all over the cell.

Genetics

100

One of Gregor Mendel's law states that " two alleles of an individual are separated and passed on to the next generation singly", which law states this? A)Law of Heredity B)Law of Independent Assortment C)Law of Segregation D)Law of Incomplete Dominance

C)Law of Segregation

200

In one strain of mouse, homozygotes for an allele of a gene develop heart defects, while in another strain of mouse, homozygotes with the same allele develop normally. Heterozygotes develop normally in both strains. What is the most likely explanation for the difference between the two strains? A)The allele is recessive. B)The development of the heart defect is influenced by more than one locus. C)The allele has pleiotrophic effects on development. D)The allele is codominant.

B)The development of the heart defect is influenced by more than one locus.** The genetic background of the two different strains of mice must affect whether or not the heart defect phenotype is expressed. Therefore, the heart defect phenotype must be influenced by some other locus that is different in the two strains of mice. **

300

The Harddy-Weinberg law states that the frequencies of alleles in the gene pool of a population will not change over time, provided that these assumptions are true. Which of these assumptions is not part of these assumptions? A)There is inbreeding. B)There is no mutation,migration, and natural selection. C)There is random mating. D)The population is sufficiently large to prevent random drift in allele frequencies.

A)There is inbreeding.

400

The pungent square depicts a cross between two pea plants that are homozygous for the color gene, with G the dominant green allele and g the recessive yellow allele. Draw the pungent square and determine what percentage of offspring will be green and what percentage will be yellow. A) 100% Yellow. B)50% Green,50% Yellow. C)75% Green,25% Yellow D)25% Green,75% Yellow.

C)75% Green,25% Yellow. 25% GG + 50% Gg= 75% Green 100%-75%=25% Yellow

Physiology

100

If a toxin prevents voltage-gated sodium channels from closing, which if the following will occur? I.Voltage-gated potassium channels will open but not close. II. The membrane will not depolarize to the normal resting membrane potential. III. The Na+/K+ ATPase will be inactivated. A)I only B)II only C)I and II only D)II and III only

C)I and II only. **Voltage-gated potassium channels are normally closed by the depolarization of the membrane, so if the membrane is not depolarized they will not close. Sodium Ions will continue to flow into the cell even as the Na+/K+ ATPase works to pump them out. This prevents the polarization of the membrane**.

200

Fill in the blank for the sensory modality. Modality:VISION, Receptor:RODS/CONES, Receptor type: ELECTROMAGNETIC , Organ:_____, Stimulus:______. A)O:Taste Bud,S:Food Chemical B)O:Skin,S:Pressure C)O:Aortic arch,S:Blood Pressure D)O:Retina,S:Light

D)O:Retina,S:Light

300

Flow of calcium into cells is essential to which of the following processes? A)Opening of Voltage-Gated sodium channels. B)Propagation of action potentials in motor neuron axons. C)Cardiac muscle contraction. D)ATP Hydrolysis.

C)Cardiac muscle contraction. **Action potential in cardiac muscle includes the opening of slow voltage-gated calcium channels which allows calcium into the cardinal muscle cells. This plays a role in the release of troponin/tropomyosin complex from actin filaments, allowing myosin heads to bind and initiate contraction. **

400

An overweight child (110lbs), a female athlete (110lbs), and an elderly man (110lbs) all require a cardiac output of about 5 L/min. But the child and elderly man have a stroke volume of 1/16 L, while the athlete's stroke volume(amount of blood pumped with each styole- time when ventricles are contracting) is 1/9 L. (Normal heart beat is 45 beats per minute, children and elderly have 80 bpm)How can the child and elderly man supply enough blood to their bodies?

The athlete's heart can provide the necessary cardiac output by pumping at a leisurely rate of 45 bpm. But the hearts of the child and elderly man will work hard to pump enough blood, their pulses will be 80 bpm.