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. What is the main difference between a telescope and a microscope?

A. Telescopes magnify distant objects, while microscopes magnify small objects.
B. Telescopes use lenses, while microscopes use mirrors.
C. Telescopes collect light, while microscopes emit light.
D. They both magnify objects but serve different purposes.

Correct answer: A

Rationale: While both instruments magnify objects, telescopes are designed to observe distant objects, while microscopes are used to magnify tiny objects close to the observer.

3. What is the recommended daily intake of protein for adults to maintain healthy muscle mass?

A. 0.5 grams per kilogram of body weight
B. 1 gram per kilogram of body weight
C. 1.5 grams per kilogram of body weight
D. 2 grams per kilogram of body weight

Correct answer: C

Rationale: The recommended daily intake of protein for adults to maintain healthy muscle mass is 1.5 grams per kilogram of body weight. Protein is essential for muscle repair and growth, and consuming an adequate amount helps support overall muscle health. 1 gram per kilogram of body weight is generally recommended for sedentary individuals, but for those looking to maintain or build muscle mass, a higher intake of 1.5 grams per kilogram of body weight is advised. Consuming too little protein can lead to muscle loss, while consuming too much may strain the kidneys. Therefore, 1.5 grams per kilogram of body weight strikes a balance for most adults looking to support their muscle health.

4. Which type of glial cell provides structural support and insulation for neurons in the central nervous system?

A. Schwann cells
B. Astrocytes
C. Oligodendrocytes
D. Microglia

Correct answer: C

Rationale: The correct answer is C: Oligodendrocytes. Oligodendrocytes are a type of glial cell found in the central nervous system that provide structural support and insulation for neurons by forming myelin sheaths around axons. Schwann cells, on the other hand, are found in the peripheral nervous system. Astrocytes play a role in nutrient transfer and maintaining the blood-brain barrier. Microglia are responsible for immune defense and clearing debris in the CNS. Therefore, oligodendrocytes are specifically responsible for providing structural support and insulation for neurons in the central nervous system.

5. The critical angle is defined as the minimum angle of incidence in a denser medium for which light undergoes:

A. Total internal reflection
B. Continued refraction
C. Specular reflection
D. Increased dispersion

Correct answer: A

Rationale: The critical angle is the minimum angle of incidence at which light is totally internally reflected rather than refracted. When light travels from a denser medium to a rarer medium at an angle greater than the critical angle, it undergoes total internal reflection. This phenomenon is crucial in applications like fiber optics and mirages. Continued refraction (option B) occurs when light enters a medium at an angle less than the critical angle. Specular reflection (option C) refers to the reflection of light at a smooth surface. Increased dispersion (option D) involves the separation of light into its constituent colors due to varying refractive indices, which is not directly related to the critical angle. Therefore, the correct answer is A - total internal reflection.

6. The bones of the skull are classified as what type of bone?

A. Long bone
B. Short bone
C. Flat bone
D. Irregular bone

Correct answer: C

Rationale: The correct answer is C: Flat bone. The bones of the skull are classified as flat bones due to their thin, flattened shape. Flat bones provide protection to vital organs and have a broad surface for muscle attachment. Long bones, like the femur, are characterized by their elongated shape, while short bones, such as those in the wrist and ankle, are cube-shaped. Irregular bones have complex shapes and do not fit into the other bone categories. In this case, the flat bones of the skull best fit the classification.