1. What is the difference between active and passive immunity?

A. Active immunity is short-lived, while passive immunity is long-lasting.
B. Active immunity involves the body's own immune response, while passive immunity provides immediate protection through antibodies from another source.
C. Active immunity only protects against bacterial infections, while passive immunity works against both bacteria and viruses.
D. Passive immunity requires repeated vaccinations, while active immunity is a one-time process.

Correct answer: A

Rationale: The correct answer is A: "Active immunity involves the body's own immune response, while passive immunity provides immediate protection through antibodies from another source." Active immunity is long-lasting because it involves the body's immune system producing memory cells that remember specific pathogens, providing long-term protection. Passive immunity, on the other hand, is short-lived as it involves receiving pre-formed antibodies from an external source, such as through maternal transfer or injection of antibodies, which do not create memory cells for long-lasting protection.

2. Which of the following structures is responsible for preventing the backflow of blood from the left ventricle into the left atrium?

A. Aortic valve
B. Pulmonary valve
C. Tricuspid valve
D. Mitral valve

Correct answer: D

Rationale: The correct answer is D, the mitral valve. The mitral valve, also known as the bicuspid valve, is located between the left atrium and the left ventricle. Its main function is to prevent the backflow of blood from the left ventricle into the left atrium during ventricular contraction. The aortic valve (A) is responsible for preventing the backflow of blood from the aorta into the left ventricle, the pulmonary valve (B) prevents backflow from the pulmonary artery into the right ventricle, and the tricuspid valve (C) prevents backflow from the right ventricle into the right atrium. Therefore, the mitral valve is specifically responsible for preventing backflow in the left side of the heart, making it the correct answer in this case.

3. The intricate network of blood vessels responsible for transporting blood throughout the body is the:

A. Lymphatic system
B. Circulatory system
C. Nervous system
D. Respiratory system

Correct answer: B

Rationale: The correct answer is B: Circulatory system. The circulatory system is responsible for transporting blood, oxygen, nutrients, and other substances throughout the body. It consists of the heart, blood vessels (arteries, veins, and capillaries), and blood. The lymphatic system (A) is a separate system that helps to maintain fluid balance in the body and plays a role in the immune response. The nervous system (C) is responsible for transmitting signals between different parts of the body and the brain. The respiratory system (D) is responsible for the exchange of oxygen and carbon dioxide in the body through breathing. In this question, the circulatory system is specifically mentioned as the network of blood vessels responsible for transporting blood, making it the correct answer.

4. What is the difference between emphysema and chronic bronchitis, both chronic obstructive pulmonary diseases (COPD)?

A. Emphysema damages alveoli, while chronic bronchitis inflames airways.
B. Emphysema causes coughing, while chronic bronchitis leads to shortness of breath.
C. Emphysema is more reversible than chronic bronchitis.
D. Emphysema affects only smokers, while chronic bronchitis can occur in non-smokers.

Correct answer: A

Rationale: The correct answer is A. Emphysema and chronic bronchitis are both types of COPD, but they have distinct characteristics. Emphysema is characterized by the destruction of the alveoli in the lungs, which impairs the exchange of oxygen and carbon dioxide. This damage to the alveoli leads to difficulty breathing and decreased lung function. On the other hand, chronic bronchitis involves inflammation and narrowing of the airways, leading to excessive mucus production and a persistent cough. While both conditions are chronic and progressive, emphysema primarily affects the alveoli, while chronic bronchitis primarily affects the airways. Understanding these differences is crucial for appropriate diagnosis and management of COPD.

5. What is the purpose of genetic counseling?

A. To treat genetic disorders.
B. To diagnose genetic diseases in newborns.
C. To provide information and support to individuals and families with genetic risks.
D. To collect DNA samples for research purposes.

Correct answer: C

Rationale: To provide information and support to individuals and families with genetic risks. Genetic counselors explain the implications of genetic testing, discuss risks and options, and offer emotional and psychological support.

6. Which of the following is a characteristic of unsaturated fatty acids?

A. They are solid at room temperature.
B. They contain only single bonds.
C. They have a higher melting point.
D. They contain double or triple bonds.

Correct answer: D

Rationale: Unsaturated fatty acids contain double or triple bonds in their hydrocarbon chains. The other choices do not accurately describe unsaturated fatty acids.