Body Fluids and Biomolecules Practice Quiz (18 questions)

1. The effects of pulmonary surfactant on alveolar mechanics include:

A. It causes alveoli to collapse during expiration.

B. It prevents alveoli from expanding during inspiration.

C. It promotes overstretching when alveoli expand.

D. It removes lubrication from the alveolar surfaces.

E. It permits alveoli to become smaller without collapsing.

Answer: (E)

Explanation

Surfactant lubricates alveoli, allowing them to expand without overstretching and become smaller without collapsing. It therefore does not promote collapse, inhibit expansion, cause overstretching, or remove lubrication.

2. Concerning globular and fibrous proteins, which statements are accurate?

A. Elastin belongs to the fibrous protein group.

B. Keratin is classified as a globular protein.

C. Albumin is an example of a globular protein.

D. Fibrinogen is classified among globular proteins.

E. Collagen is an example of a fibrous protein.

Answer: (A), (C), (E)

Explanation

Albumin is a functional globular protein, whereas collagen and elastin are fibrous proteins. Keratin and fibrinogen are also fibrous proteins, so classifying them as globular is inaccurate.

3. Concerning haematocrit, which statements accurately describe the measurement?

A. Haematocrit compares packed red-cell volume with total blood volume.

B. The measurement concerns the volume occupied by packed erythrocytes.

C. Haematocrit represents the proportion of white blood cells and platelets.

D. Haematocrit measures the liquid plasma fraction relative to whole blood volume.

E. Haematocrit measures packed red blood cells relative to whole blood volume.

Answer: (A), (B), (E)

Explanation

Haematocrit measures the volume of packed red blood cells relative to the volume of whole blood. It therefore concerns erythrocytes, not the plasma fraction or the buffy coat containing white cells and platelets.

4. A substance dissolves into a liquid to form a solution. What is the correct terminology?

A. A solute dissolves the solvent during solution formation.

B. The liquid that receives the substance is called the solute.

C. The dissolving substance is called the solvent.

D. The dissolving substance is called the solute.

E. The liquid that receives the substance is called the solvent.

Answer: (D), (E)

Explanation

A solute is the substance that dissolves, and the solvent is the medium in which it dissolves. The remaining statements reverse these definitions or incorrectly describe the interaction.

5. Regarding the chemical basis of life, which statements are correct?

A. Oxygen, phosphorus, calcium, and nitrogen comprise over 95% of living organisms.

B. More than 95% of an organism consists of oxygen, carbon, hydrogen, and nitrogen.

C. The four elements include carbon and hydrogen, alongside oxygen and nitrogen.

D. Oxygen, carbon, hydrogen, and nitrogen make up over 95% of living organisms.

E. The dominant elemental group includes hydrogen and nitrogen as well as oxygen.

Answer: (B), (C), (D), (E)

Explanation

Living organisms contain more than 95% oxygen, carbon, hydrogen, and nitrogen, so the statements identifying that group or its members are correct. Phosphorus and calcium are not part of the four-element group responsible for this proportion.

6. The classification of carbohydrate units is described accurately by which statements?

A. A monosaccharide consists of one carbohydrate unit.

B. A disaccharide contains two linked monosaccharides.

C. An oligosaccharide contains more than one linked monosaccharide.

D. An oligosaccharide contains one monosaccharide unit.

E. A disaccharide releases glucose monomers during fasting.

Answer: (A), (B), (C)

Explanation

A monosaccharide consists of one carbohydrate unit, a disaccharide contains two linked monosaccharides, and an oligosaccharide contains more than one linked monosaccharide. Hydrolysis of glycogen, rather than a disaccharide, releases glucose monomers during fasting to help maintain blood glucose levels. Thus, an oligosaccharide is not a single unit, and a disaccharide does not release glucose monomers during fasting.

7. Regarding the distinction between plasma and serum, which statements are correct?

A. Serum is the fluid remaining after blood has clotted.

B. Plasma suspends blood cells before the clotting process occurs.

C. Plasma and serum differ in their relationship to blood clotting.

D. Serum lacks platelets and fibrinogen after clot formation.

E. Plasma contains fibrinogen, a protein removed from serum during clotting.

Answer: (A), (B), (C), (D), (E)

Explanation

Plasma is the fluid that suspends blood cells and contains fibrinogen before clotting. Serum remains after clotting and lacks platelets and fibrinogen, so the five statements correctly distinguish the two fluids.

8. Regarding lactose intolerance, select the accurate statements:

A. Lactose digestion requires reduced lactase activity.

B. Lactose intolerance results from excessive lactase activity.

C. Lactose intolerance prevents colonic osmotic effects from lactose.

D. Insufficient brush-border lactase contributes to lactose intolerance.

E. Colonic bacteria ferment unabsorbed lactose and produce gas.

Answer: (D), (E)

Explanation

Lactose intolerance results from insufficient lactase in the small-intestinal brush border. Remaining lactose reaches colonic bacteria, where fermentation produces gas and osmotic effects; excessive lactase and reduced osmotic effects are incorrect descriptions.

9. Concerning the general composition of blood, select the correct statements:

A. Blood consists of plasma suspended within formed cellular elements.

B. Blood contains formed elements suspended in a liquid medium.

C. Plasma is composed of formed elements suspended in a liquid.

D. The liquid medium carrying blood cells is called plasma.

E. Formed elements are dissolved within serum in circulating blood.

Answer: (B), (D)

Explanation

Blood is made of formed elements suspended in plasma, so both statements describing that arrangement are correct. Plasma is the liquid component, whereas formed elements are suspended in it; serum is not the normal suspending fluid of circulating blood.

10. Regarding pulmonary surfactant, which of the following statements are accurate?

A. Pulmonary surfactant allows alveoli to become smaller while promoting collapse.

B. Pulmonary surfactant is produced by type 2 alveolar cells.

C. Pulmonary surfactant contains phospholipids and proteins.

D. Pulmonary surfactant increases surface tension at alveolar air–liquid interfaces.

E. Pulmonary surfactant reduces surface tension within alveoli.

Answer: (B), (C), (E)

Explanation

Pulmonary surfactant is a mixture of phospholipids and proteins produced by type 2 alveolar cells. It reduces surface tension at the alveolar air–liquid interface and allows alveoli to become smaller without collapsing. Therefore, it does not promote alveolar collapse or increase surface tension.

11. Which statements correctly distinguish the structural levels of proteins?

A. Primary structure consists of the amino acid chain.

B. Quaternary structure describes the amino acid sequence.

C. Tertiary structure contains two or more polypeptide chains.

D. Secondary structure includes alpha-helices and pleated sheets.

E. Secondary structure is stabilized by hydrogen bonding.

Answer: (A), (D), (E)

Explanation

Primary structure is the amino acid chain, while secondary structure includes alpha-helical and pleated-sheet folding caused by hydrogen bonding. Tertiary structure concerns three-dimensional folding, and quaternary structure involves multiple polypeptide chains, so the other structural assignments are incorrect.

12. A blood sample has a packed red-cell height of 45 units and a total blood-column height of 100 units. Which statements are correct?

A. The calculation divides red-cell height by total blood-component height.

B. The haematocrit is $55\%$ because plasma occupies the remaining column.

C. The result expresses packed red-cell volume as a percentage of whole blood.

D. The haematocrit is $45\%$ using the stated formula.

E. The formula multiplies total blood height by red-cell height.

Answer: (A), (C), (D)

Explanation

Using $HCT = \frac{\text{height of RBC}}{\text{height of all blood components}}\times 100$ gives $\frac{45}{100}\times100=45\%$. The calculation uses division followed by multiplication by 100; the remaining plasma does not change the haematocrit to 55%.

13. Regarding normal saline, which statement is correct?

A. Normal saline is a sterile, pyrogenic calcium solution used for electrolyte replacement.

B. Normal saline is a sterile, non-pyrogenic glucose solution used for intramuscular injection.

C. Normal saline is a sterile, pyrogenic 0.9% potassium chloride solution used intravenously.

D. Normal saline is a nonsterile, non-pyrogenic 9% sodium chloride solution used orally.

E. Normal saline is a sterile, non-pyrogenic 0.9% sodium chloride solution used intravenously.

Answer: (E)

Explanation

Normal saline is sterile, non-pyrogenic, contains 0.9% sodium chloride, and is administered intravenously. The other descriptions change its pyrogenicity, composition, concentration, sterility, or route of administration.

14. Plasma composition and proportion include which accurate statements?

A. Serum is the fluid remaining after blood clotting, unlike circulating plasma.

B. Water, inorganic salts, and proteins are components of plasma.

C. Plasma accounts for roughly 40–45% of the blood volume.

D. Plasma consists mainly of formed elements suspended in liquid.

E. Plasma represents approximately 55–60% of the total blood volume.

Answer: (A), (B), (E)

Explanation

Plasma accounts for about 55–60% of blood and contains water, inorganic salts, and proteins. It is not mainly formed elements, and the 40–45% figure does not describe plasma; serum is the post-clotting fluid.

15. Which statements correctly distinguish effective from ineffective osmoles?

A. Ineffective osmoles cannot affect osmotic pressure and can cross the membrane.

B. Effective osmoles affect osmotic pressure and can cross the membrane.

C. Effective osmoles include urea and can cross the membrane.

D. Ineffective osmoles include glucose while crossing the membrane.

E. Both osmole categories have identical effects on osmotic pressure and membrane crossing.

Answer: (A), (B)

Explanation

Effective osmoles affect osmotic pressure and can cross the membrane, whereas ineffective osmoles cannot affect osmotic pressure and can cross the membrane. Urea is an example of an ineffective osmole, while glucose is an example of an effective osmole, so the two categories do not have identical effects.

16. Regarding electrolytes and non-electrolytes in water, which propositions are correct?

A. Sodium, potassium, and chloride are examples of electrolytes.

B. Electrolytes dissociate in water to form charged ions.

C. Non-electrolytes such as lipids and creatinine remain uncharged in water.

D. Urea is an inorganic electrolyte that becomes charged in water.

E. Glucose dissociates in water to form charged ions like sodium.

Answer: (A), (B), (C)

Explanation

Electrolytes such as sodium, potassium, and chloride dissociate into charged ions in water. Glucose, lipids, creatinine, and urea are non-electrolytes and remain uncharged, making the third and fourth statements incorrect.

17. Which statements accurately describe the major elemental composition of living organisms?

A. The four elements account for less than 90% of a living organism.

B. Nitrogen forms part of the major elemental group found in living organisms.

C. Sulfur replaces nitrogen among the four dominant elements in living organisms.

D. Hydrogen is included among the elements making up over 95% of organisms.

E. Carbon belongs to the four elements composing over 95% of living organisms.

Answer: (B), (D), (E)

Explanation

Carbon, hydrogen, and nitrogen are members of the four-element group that comprises over 95% of living organisms. Sulfur does not replace nitrogen, and the stated proportion is above 95%, not below 90%.

18. Concerning surface tension and molecular interactions, which propositions are correct?

A. Adhesion between dissimilar molecules is the primary definition of surface tension.

B. Surface tension reflects a liquid surface behaving as though it were tense.

C. Cohesion acts between similar molecules such as water molecules.

D. Cohesive forces between water molecules contribute to surface tension.

E. Hydrogen bonds between water molecules support cohesive forces at the surface.

Answer: (B), (C), (D), (E)

Explanation

Surface tension results from cohesive forces between similar water molecules, with hydrogen bonds contributing to those forces. Adhesion acts between dissimilar molecules and is not the primary definition of surface tension.