1. During gas exchange in the alveoli, what happens to oxygen?

A. Oxygen is released from the bloodstream into the alveoli.
B. Oxygen is absorbed from the alveoli into the bloodstream.
C. Oxygen is converted into carbon dioxide.
D. Oxygen is stored in the alveoli for later use.

Correct answer: B

Rationale: During gas exchange in the alveoli, oxygen is absorbed from the alveoli into the bloodstream. In the alveoli, oxygen diffuses across the thin walls of the alveoli and into the surrounding capillaries where it binds to hemoglobin in red blood cells. This oxygen-rich blood is then transported to the body's tissues for cellular respiration. Therefore, option B is correct as it accurately describes the direction of oxygen movement during the process of gas exchange in the lungs.

2. Which part of the respiratory system is responsible for gas exchange between the blood and inhaled air?

A. Trachea
B. Larynx
C. Alveoli
D. Pharynx

Correct answer: C

Rationale: The correct answer is C, 'Alveoli.' The alveoli are tiny air sacs located at the end of the bronchioles in the lungs where gas exchange occurs. Oxygen from the inhaled air diffuses through the thin walls of the alveoli and into the bloodstream, while carbon dioxide from the blood diffuses into the alveoli to be exhaled. The trachea (A) is the windpipe that carries air to and from the lungs; the larynx (B) contains the vocal cords and helps with swallowing; and the pharynx (D) is the part of the throat that connects the mouth and nasal cavity to the esophagus and trachea, but it is not directly involved in gas exchange.

3. What is the function of arrector pili muscles?

A. To control sweat production
B. To contract and cause goosebumps
C. To produce sebum
D. To sense touch

Correct answer: B

Rationale: The correct answer is B: 'To contract and cause goosebumps.' Arrector pili muscles are small muscles attached to hair follicles in the skin. When these muscles contract, they cause the hair to stand upright, resulting in the appearance of goosebumps. This physiological response is a remnant of our evolutionary past when our ancestors had more hair, and the raised hair helped to trap air for insulation or to make them look larger when threatened. Therefore, the function of arrector pili muscles is not to control sweat production (A), produce sebum (C), or sense touch (D), but rather to create the physical response of goosebumps.

4. Which of the following is a characteristic of alkenes?

A. They have a double bond between carbon atoms.
B. They are saturated hydrocarbons.
C. They contain only single bonds.
D. They are derivatives of ammonia.

Correct answer: A

Rationale: Alkenes have a double bond between carbon atoms, making them unsaturated hydrocarbons. The other choices do not accurately describe alkenes.

5. During a healthy heartbeat, the P wave on an ECG represents

A. The repolarization of the ventricles.
B. The electrical conduction through the AV node.
C. The contraction phase of the ventricles (systole)
D. The depolarization of the atria.

Correct answer: D

Rationale: The correct answer is D: The P wave on an ECG represents the depolarization of the atria. During a healthy heartbeat, the P wave is the first positive deflection seen on the ECG and reflects the initiation of the electrical impulse in the atria, leading to atrial contraction. It is followed by the QRS complex, which represents the depolarization of the ventricles. Options A, B, and C are incorrect because the P wave specifically corresponds to atrial depolarization, not repolarization of the ventricles, electrical conduction through the AV node, or ventricular contraction. Understanding the sequence of electrical events in the heart as represented on an ECG is crucial for interpreting cardiac function and identifying potential abnormalities.

6. How do isotopes affect the atomic mass of an element?

A. Isotopes have no effect on the atomic mass of an element.
B. Isotopes cause the atomic mass of an element to vary slightly.
C. Isotopes cause the atomic mass of an element to be exactly the same for all isotopes of that element.
D. Isotopes cause the atomic mass of an element to vary greatly.

Correct answer: B

Rationale: The atomic mass of an element is the average mass of all the isotopes of that element. Since isotopes have different numbers of neutrons, they also have slightly different masses. This variation in mass is what causes the atomic mass of an element to be a decimal number, rather than a whole number.