← Back to exam page

MCAT-Section-2-Biological-Sciences – Section Two : Biological Sciences

Loading demo links...

Showing 13–15 of 15 questions

Question 13

Compounds containing a hydroxyl group attached to a benzene ring are called phenols. Derivatives of phenols, such as naphthols and phenanthrols, have chemical properties similar to those of phenols, as do most of the many naturally-occurring substituted phenols. Like other alcohols, phenols have higher boiling points than hydrocarbons of similar molecular weight. Like carboxylic acids, phenols are more acidic than their alcohol counterparts. Phenols undergo a number of different reactions; both their hydroxyl groups and their benzene rings are highly reactive. A number of chemical tests can be used to distinguish phenols from alcohols and carboxylic acids.

Thymol, a naturally occurring phenol, is an effective disinfectant that is obtained from thyme oil. Thymol can also be synthesized from m-cresol, as shown in Reaction A below. Thymol can then be converted to menthol, another naturally-occurring organic compound; this conversion is shown in Reaction B.

Reaction A

Reaction B

Which of the following shows the order of decreasing acidity among the four compounds below?

Select an option, then click Submit answer.

  • ○

    I, III, IV, II
  • ○

    IV, I, II, III
  • ○

    IV, III, II, I
  • ○

    IV, II, I, III
Question 14

When food passes through alimentary canal, the proteins are digested in:

Select an option, then click Submit answer.

  • ○

    mouth, stomach and duodenum.
  • ○

    stomach, pancreas and caecum.
  • ○

    stomach, duodenum and ileum.
  • ○

    duodenum, ileum and live.
Question 15

Just as the ingestion of nutrients is mandatory for human life, so is the excretion of metabolic waste products. One of these nutrients, protein, is used for building muscle, nucleic acids, and countless compounds integral to homeostasis. However, the catabolism of the amino acids generated from protein digestion produces ammonia, which, if not further degraded, can become toxic. Similarly, if the same salts that provide energy and chemical balance to cells are in excess, fluid retention will occur, damaging the circulatory, cardiac, and pulmonary systems.

One of the most important homeostatic organs is the kidney, which closely regulates the excretion and reabsorption of many essential ions and molecules. One mechanism of renal function involves the secretion of antidiuretic hormone (ADH).

Diabetes insipidus (DI), is the condition that occurs when ADH is ineffective. As a result, the kidneys are unable to concentrate urine, leading to excessive water loss. There are two types of DI — central and nephrogenic. Central DI occurs when there is a deficiency in the quantity or quality of ADH produced. Nephrogenic DI occurs when the kidney tubules are unresponsive to ADH. To differentiate between these two conditions, a patient’s urine osmolarity is measured both prior to therapy and after a 24-hour restriction on fluid intake. Exogenous ADH is then administered and urine osmolarity is measured again. The table below gives the results of testing on four patients. Assume that a urine osmolarity of 285 mOsm/L of H2O is normal.

Based on the data in Table 1, which of the four patients most likely has nephrogenic diabetes insipidus?

Select an option, then click Submit answer.

  • ○

    Patient A
  • ○

    Patient B
  • ○

    Patient C
  • ○

    Patient D