1. What is the primary function of the epiglottis in the respiratory system?

A. Filtration of air
B. Production of mucus
C. Prevention of food entering the trachea
D. Oxygen exchange in the alveoli

Correct answer: C

Rationale: The primary function of the epiglottis in the respiratory system is to prevent food from entering the trachea. When we swallow, the epiglottis covers the opening to the trachea, directing food and liquids to the esophagus instead of the airway. This action helps to protect the respiratory system from foreign objects that could obstruct airflow and cause choking or aspiration pneumonia. Filtration of air and production of mucus are functions associated with other respiratory structures like the nasal passages and bronchial tubes, while oxygen exchange in the alveoli occurs in the lungs, not the epiglottis.

2. Which type of muscle is characterized by voluntary control and is responsible for body movement?

A. Cardiac muscle
B. Smooth muscle
C. Skeletal muscle
D. Connective tissue

Correct answer: c

Rationale: The correct answer is C: Skeletal muscle. Skeletal muscles are characterized by voluntary control, meaning they are under conscious control, allowing us to move our body parts as desired. These muscles are attached to bones and are responsible for movements such as walking, running, and lifting objects. Cardiac muscle (A) is found in the heart and is involuntary, while smooth muscle (B) is found in internal organs and is also involuntary. Connective tissue (D) provides support and structure to the body but is not responsible for body movements.

3. Lymphedema, a chronic condition, occurs when:

A. Lymph nodes become inflamed
B. Lymph vessels become blocked
C. The spleen malfunctions
D. Bone marrow production decreases

Correct answer: B

Rationale: The correct answer is B: "Lymph vessels become blocked." Lymphedema is a chronic condition characterized by swelling due to the accumulation of lymph fluid. This occurs when lymph vessels become blocked, preventing the proper drainage of lymph fluid. Inflammation of lymph nodes (option A) is not the direct cause of lymphedema. The spleen malfunctioning (option C) and bone marrow production decreasing (option D) are not directly related to the development of lymphedema. Understanding the blockage of lymph vessels is crucial in comprehending the pathophysiology of lymphedema.

4. Which of the following is a common property of bases?

A. Conductivity in aqueous solutions
B. Sour taste
C. Reactivity with metals to produce hydrogen gas
D. Turns red litmus paper blue

Correct answer: D

Rationale: Bases are substances that can accept protons or donate hydroxide ions in a chemical reaction. One common property of bases is that they turn red litmus paper blue. This is a classic test to distinguish between acids (which turn blue litmus paper red) and bases. Conductivity in aqueous solutions (Option A) is a property of both acids and bases, sour taste (Option B) is a property of acids, and reactivity with metals to produce hydrogen gas (Option C) is a property of acids, not bases.

5. What is the "lock-and-key" model?

A. Protein folding
B. Enzyme-substrate interaction
C. Muscle contraction
D. Blood clotting

Correct answer: B

Rationale: Rationale: The "lock-and-key" model is a concept used to describe the specificity of the interaction between enzymes and their substrates. In this model, the enzyme's active site is like a lock that can only be opened by the specific substrate molecule, which acts as the key. This specific binding ensures that enzymes catalyze specific reactions and do not interact with other molecules indiscriminately. Protein folding (option A) refers to the process by which a protein adopts its functional three-dimensional structure, but it is not specifically related to the lock-and-key model. Muscle contraction (option C) and blood clotting (option D) are biological processes that involve complex mechanisms but are not directly related to the lock-and-key model of enzyme-substrate interaction.

6. The K-capture process, a type of electron capture, involves the capture of an electron from which electron shell:

A. The outermost s-orbital
B. An inner p-orbital
C. An inner d-orbital
D. Any available electron shell

Correct answer: A

Rationale: The K-capture process involves the capture of an electron from the innermost electron shell, known as the K-shell. The K-shell is represented by the outermost s-orbital in an atom's electron configuration. When an electron from the K-shell is captured, it results in the transition of a proton to a neutron in the nucleus, thereby changing the atomic number of the element. Therefore, option A, 'The outermost s-orbital,' is the correct answer as it accurately describes the electron shell involved in the K-capture process.