Test Prep Test Prep Certifications OAT Questions & Answers

• Question 61:

  Which of the following is NOT an example that leads to an increase in entropy?

  A. Smashing a diamond into a thousand pieces

  B. Burning wood to create a fire

  C. Adding NaCl to water

  D. Melting ice

  E. All of the following are examples of increase in entropy

  Correct Answer: E

  One needs a conceptual background on entropy and what increases it (and decreases it). Anything that goes from a more ordered state to a disordered state (solid diamond piece into a thousand pieces, solid ice cube into a fluid water etc.) is an increase in entropy.

• Question 62:

  What is the percent of oxygen by mass in FeCr2O4?

  A. 6.4%

  B. 12.5%

  C. 19.3%

  D. 22.4%

  E. 28.6%

  Correct Answer: E

  It necessary to utilize the periodic table (provided in the exam) and adds up the entire molecular weight of FeCr2O4.

  Fe = 55.8 Cr = 52 (×2) O = 16 (×4)

  Total molecular weight: ~223.85 Divide the oxygen species by this: (16 × 4) / (223.85) = 0.286 Multiply by a 100 to get the percentage form: 0.286 × 100 = 28.6%

• Question 63:

  If a compound is 80% optically pure S, which of the following is true?

  A. 90% S, 10% R

  B. 80% S, 20% R

  C. 10% S, 90% R

  D. 20% S, 80% R

  E. 35% S, 65% R

  Correct Answer: A

  80% optically pure signifies that 80% is enantiomer A, and the remaining 20% is racemic. Thus, 80% is pure S, and 20% is R + S (a racemic mixture). Therefore, it is 90% S and 10% R.

• Question 64:

  In a strenuously exercising muscle, NADH begins to accumulate in high concentration. Which of the following metabolic process will be activated to reduce the concentration of NADH?

  A. Glycolysis

  B. The Krebs cycle

  C. Lactic acid fermentation

  D. Oxidative phosphorylation

  E. Acetyl CoA synthesis

  Correct Answer: C

  Lactic acid fermentation converts pyruvate into lactate using high-energy electrons from NADH. This process allows ATP production to continue in anaerobic conditions by providing NAD+ so that ATP can be made in glycolysis.

• Question 65:

  Which of the following is NOT a natural dispersal process that would lead to species colonization on an island?

  A. Mussels carried into a lake on the hull of a ship

  B. Drought connecting an island to other land

  C. Floating seeds

  D. Animals swimming long distances

  E. Birds adapted to flying long distances

  Correct Answer: A

  Transportation by humans or human-associated means is not considered a natural dispersal process.

• Question 66:

  Which of the following is NOT considered a poikilothermic animal?

  A. Naked mole-rat

  B. Frog

  C. Lizard

  D. Termites

  E. Mouse

  Correct Answer: E

  Poikilotherms have a variable and fluctuating internal body temperatures as opposed to homeotherms. Fish, reptiles and amphibians are all classic, traditional definitions of poikilotherms. The mouse (a mammal) is a homeotherm and the outlier of the answer choices.

• Question 67:

  A white rabbit mates with a black rabbit, resulting in a mix of black and white offspring. This is an example of:

  A. Epistasis

  B. Incomplete Dominance

  C. Complete Dominance

  D. Co-dominance

  E. Pleiotropy

  Correct Answer: D

  When both parental traits are expressed, this is an example of co-dominance. Incomplete dominance would reveal offspring to have grey color.

• Question 68:

  Chlorophyll is associated with which of the following metals?

  A. Zinc

  B. Iron

  C. Magnesium

  D. Silver

  E. Manganese

  Correct Answer: C

  Chlorophyll has a central magnesium atom associated with it (whereas hemoglobin has iron).

• Question 69:

  Which of the following statements is incorrect regarding the circulatory system?

  A. Aorta is the heart's largest blood vessel.

  B. Blood passes from the left atrium to the left ventricle via the mitral valve.

  C. Circulating lymph is picked up and returned to the lymphatic system.

  D. The sinoatrial node is found in the right atrium.

  E. All of the above are correct.

  Correct Answer: C

  Circulating lymph is returned to the circulatory system! All the other answer choices are indeed correct.

• Question 70:

  Which of the following hormones is incorrectly matched to its function?

  A. Oxytocin – Acts on mammary glands allowing milk letdown.

  B. GRH – Stimulates anterior pituitary to release FSH and LH.

  C. TRH – Causes thyroid to secrete hormones T3 and T4.

  D. Thyroxine – regulates metabolism via controlling the oxidation rate of cells.

  E. Parathyroid Hormone – Increases blood levels of calcium.

  Correct Answer: C

  Thyroid Stimulating Hormone (TSH) acts on the thyroid to secrete T3 and T4. Thyroid Releasing Hormone (TRH) acts on the anterior pituitary to release TSH.