Chemistry for Physiology MCQs

A buffer is any acid and base which together control the concentration of pH in the blood.

A buffer is the solution which allows CO₂ to be lost from the lungs in order to control the pH of the lungs.

A buffer is a weak base and its acid salt or a weak acid and its basic salt. The ratio of the two components helps maintain blood pH levels.

A buffer is a mixture of two acids which together help to maintain blood pH

A buffer has two conjugate components, one dealing with acid, while the other destroys base. Their concentration ratio determines the pH of the solution they are in.

Author: rikazzz Comment

Chemistry for Physiology

Given that 1 mol of glucose has a mass of 180 g, how many millimole of glucose does 40 g of glucose contain?

0.222

180

222

278

Number of moles of glucose = 40/180 = 0.222 mol. Number of millimoles = 222.

Author: rikazzz Comment

Chemistry for Physiology

What chemical symbol for the element/atom occurs in an amino acid but not in fats and carbohydrates?

N

H

O

C

Amino acids contain an “amine” group – a nitrogen atom bonded to a hydrogen atom. Nitrogen atoms do not occur in fats or carbohydrates.

Author: rikazzz Comment

Chemistry for Physiology

A buffered solution is able to resist change to its pH when an acid is added to the solution by doing which of the following?

Removing hydrogen ions from the solution

Removing hydroxide ions from the solution

Removing hydrogen peroxide from the solution

Removing hydronium ions from the solution

A buffered solution contains two entities, one of which can remove hydronium ions from solution, turning them into water. Sometimes “hydrogen ions” is used instead of the more correct hydronium ions. Hydrogen peroxide is not produced by adding acid to a solution.

Author: rikazzz Comment

Chemistry for Physiology

Which of the following quantities of substance would, when dissolved in 1 L of water, produce a solution with the highest osmolarity?

1 mol of glucose molecules (C₆H₁₂O₆)

1 mol of Na⁺Cl− (sodium chloride)

1 mol of haemoglobin molecules

1 osmole of K⁺ (potassium ions)

Sodium chloride is an ionic substance, so when it dissolves, 1 mol of it would separate into 1 mol of individual Na⁺ ions and 1 mol of Cl− ions giving a total of 2 osmoles of separate particles (ions) per litre.

Author: rikazzz Comment

Chemistry for Physiology

One of the statements below about buffers is correct. Which one?

A buffer consists of an acid and a base.

A buffer will react with water to produce hydronium ions.

A solution that is neither acidic nor basic is called a buffer.

The components of a buffer are conjugate pairs.

A buffer has two components. Each component converts to the other as it destroys acid (or base). Choice A is incorrect as a buffer is a weak acid and its slightly basic salt (or vice versa).

Author: rikazzz Comment

Chemistry for Physiology

A solution of glucose is used for an infusion. Over a 3-h period, 250 ml of solution is used containing a total of 5 g of glucose. What is the concentration of the glucose solution used?

2%

20%

0.2%

5%

5 g per 250 ml = 20 g per 1000 ml (multiply by 4) = 2 g per 100 ml = 2%.

Author: rikazzz Comment

Chemistry for Physiology

Only one of the definitions of osmotic pressure below is correct. Which one?

The hydrostatic pressure required to halt osmosis is called osmotic pressure.

Water pressure that develops in a solution as a result of osmosis into that solution is called osmotic pressure.

Osmotic pressure is the pressure exerted by the movement of water across a semipermeable membrane due to the difference in solution concentration.

Osmotic pressure is the force required to prevent water from moving by osmosis across a selectively permeable membrane.

The other three choices, despite all being quotations from anatomy and physiology textbooks, are wrong. Osmotic pressure is not a force; water movement does not exert a pressure; osmosis between compartments in the body does not cause water pressure to develop.

Author: rikazzz Comment

Chemistry for Physiology

Given the concentration of Na+ inside the cell, it is about 10 mmol/L, while it is 140 mmol/L in the extracellular fluid. The values for K+ are 140 mmol/L inside the cell and 4 mmol/L extracellularly. In what directions would these ions diffuse?

Na+ would diffuse into the cell while K+ would diffuse out.

K+ would diffuse into the cell while Na+ would diffuse out.

Both Na+ and K+ would diffuse out of the cell.

Both Na+ and K+ would diffuse into of the cell.

Na would diffuse form 140 mmol/L to 10 – the direction of its concentration gradient which is from outside to inside. K would diffuse from 140 mmol/L to 4, that is, from inside to outside.

Author: rikazzz Comment

Chemistry for Physiology

Human blood has an osmolarity that lies within the range 280–300 mosmol/L. Which of the following statements is correct?

An isotonic solution has osmolarity that is either less than 280 or greater than 300 mosmol/L.

A hypotonic solution has osmolarity between 280 and 300 mosmol/L.

A hypertonic solution has osmolarity between 280 and 300 mosmol/L.

An isotonic solution has osmolarity between 280 and 300 mosmol/L.

An isotonic solution has the same osmolarity as blood.

Author: rikazzz Comment