Physiology Block 1

Which of the following describes extrinsic regulation of organs?

1. Cells within the organ sense and adjust to changes

2. Neighboring cells coordinate without outside input

3. The nervous or endocrine system regulates the organ externally

4. Processes occur only through intrinsic signals

3

Phospholipids are described as amphipathic because they:

1. Contain only nonpolar groups

2. Contain both polar and nonpolar regions

3. Dissolve completely in water

4. Contain only polar groups

2

During an increase in blood acidity, which action of the bicarbonate buffer system would help minimize the change in pH?

1. HCO3− accepts H+ to form H2CO3

2. H2CO3 releases H+ into the blood

3. HCO3− releases additional OH− and becomes NaCl

4. H+ is converted directly into oxygen

1

If the hydrogen ion concentration of a solution increases tenfold, what happens to its pH?

1. It increases by 1 pH unit

2. It decreases by 1 pH unit

3. It increases by 10 pH units

4. It does not change

2

A person's core temperature rises during exercise. Which response would most directly oppose the initial disturbance?

1. Constriction of skin blood vessels

2. Shivering

3. Increased sweating

4. Increased skeletal muscle contraction

3

A molecule cannot dissolve readily in blood plasma because most of its structure is nonpolar. Which term best describes this molecule?

1. Hydrophilic

2. Hydrophobic

3. Cationic

4. Amphipathic

2

Pulmonary surfactant helps keep the lungs from collapsing primarily because phospholipids:

1. Increase the surface tension of water

2. Decrease surface tension at the air-fluid interface

3. Form covalent bonds between adjacent alveoli

4. Increase hydrogen ion concentration in alveolar fluid

2

After a meal, blood glucose rises and insulin is released. As blood glucose returns toward its normal range, insulin secretion decreases. Which principle is demonstrated?

1. Positive feedback

2. Negative feedback

3. Feedforward control

4. Loss of homeostasis

2

When blood glucose falls during fasting, glucagon secretion increases and raises blood glucose. In this feedback loop, glucagon primarily functions as:

1. A stimulus that moves glucose farther from its normal range

2. Part of the effector response that opposes the fall in glucose

3. A receptor that directly measures glucose concentration

4. A positive-feedback signal that continuously amplifies itself

2

High temperature disrupts weak interactions that maintain the three-dimensional shape of an enzyme. Which protein structure is most directly affected?

1. Primary structure

2. Tertiary structure

3. DNA structure

4. Nucleotide structure

2

Sodium chloride dissolves in water and separates into Na+ and Cl−. Why does water promote this dissociation?

1. Water is nonpolar and repels both ions

2. Water's partial charges interact with and surround the oppositely charged ions

3. Water forms peptide bonds with sodium and chloride

4. Water transfers neutrons between sodium and chloride

2

What type of bond is responsible for holding the two strands of a DNA molecule together?

1. Ionic bond

2. Covalent bond

3. Hydrogen bond

4. Peptide bond

3

Local cells within an exercising skeletal muscle detect changes in their environment and signal nearby blood vessels to dilate without direct input from the brain. This is best classified as:

1. Extrinsic regulation

2. Intrinsic regulation

3. Positive feedback

4. Clinical regulation

2

A mutation changes the amino acid sequence of a receptor. The altered sequence causes the receptor to fold incorrectly and prevents ligand binding. Which sequence best describes what occurred?

1. Primary structure changed → tertiary structure changed → function changed

2. Tertiary structure changed → DNA sequence changed → primary structure changed

3. Secondary structure changed → atomic number changed → function changed

4. Quaternary structure changed → peptide bonds disappeared → DNA changed

1

Hemoglobin consists of four polypeptide chains associated into one functional protein. This arrangement represents which level of protein structure?

1. Primary

2. Secondary

3. Tertiary

4. Quaternary

4

A patient has a blood pH of 7.30. Based on the normal blood pH range in the study guide, this patient is experiencing:

1. Alkalosis

2. Acidosis

3. Neutrality

4. Normal physiological variation

2

If blood pH rises above 7.45, the condition is called:

1. Acidosis

2. Neutrality

3. Buffering

4. Alkalosis

4

Hydrogen bonds form between neighboring regions of a polypeptide and produce an alpha helix. Which level of protein structure has formed?

1. Primary

2. Secondary

3. Tertiary

4. Quaternary

2

A membrane phospholipid spontaneously orients with its phosphate-containing region toward water and its fatty acid region away from water. What property explains this behavior?

1. The entire molecule is hydrophobic

2. The entire molecule is hydrophilic

3. The molecule is amphipathic

4. The molecule is an isotope

3

Which of the following best describes a negative feedback loop?

1. Amplifies the change away from the set point

2. Reverses the change to maintain homeostasis

3. Stops once the change occurs

4. Increases the change from the set point.

2