1. Vaccines work by:

A. Directly killing pathogens
B. Introducing weakened or inactive versions of pathogens to trigger immune response
C. Stimulating production of specific antibodies immediately
D. None of the above

Correct answer: B

Rationale: The correct answer is B: Introducing weakened or inactive versions of pathogens to trigger an immune response. Vaccines work by exposing the immune system to a harmless version of a pathogen, which allows the body to recognize and develop a defense against the pathogen without causing illness. This process stimulates the immune system to produce memory cells that can quickly recognize and attack the pathogen if encountered in the future. Vaccines do not directly kill pathogens (option A) or immediately stimulate the production of specific antibodies (option C). Therefore, option B is the most accurate description of how vaccines work.

2. What is the meaning of the phrase "to be on the same page"?

A. To be physically close
B. To agree or understand each other
C. To be sharing the same goal
D. To be facing the same direction

Correct answer: B

Rationale: The phrase means to be in agreement or share the same understanding.

3. Which type of carbohydrate is the main component of the cell wall in plant cells?

A. Starch
B. Glucose
C. Cellulose
D. Chitin

Correct answer: C

Rationale: The correct answer is C: Cellulose. Cellulose is a structural polysaccharide and the main component of the cell wall in plant cells. Starch, option A, is a storage polysaccharide found in plants, while glucose, option B, is a simple sugar and a basic unit of carbohydrates, not the main component of plant cell walls. Chitin, option D, is a structural polysaccharide found in the exoskeletons of arthropods and fungal cell walls, not in plant cell walls. Understanding the unique composition of plant cell walls helps in differentiating the types of carbohydrates present in various cellular structures.

4. A patient's oxygen flow rate is set at 4 liters per minute. How many cubic centimeters of oxygen are delivered per minute?

A. 400 cubic centimeters
B. 4,000 cubic centimeters
C. 40,000 cubic centimeters
D. 400,000 cubic centimeters

Correct answer: B

Rationale: Remember 1 liter is equal to 1000 cubic centimeters. Multiply the flow rate in liters per minute by the conversion factor: 4 liters/minute * 1000 cmÂ³/liter = 4,000 cubic centimeters/minute.

5. The main idea of the passage is that

A. history solely teaches us about past events and has no relevance to the present.
B. understanding history is crucial for comprehending current trends and shaping the future.
C. historical knowledge is merely an interesting collection of facts with no practical value.
D. learning from history requires solely focusing on its successes and ignoring its failures.

Correct answer: B

Rationale: Choice B accurately captures the passage's emphasis on history's multifaceted impact, providing insights into the present and potential visions for the future.

6. A closed system in ecology is one that:

A. Exchanges energy but not matter
B. Exchanges both energy and matter
C. Exchanges neither energy nor matter
D. Recycles nutrients efficiently

Correct answer: A

Rationale: Rationale: In ecology, a closed system is one that does not exchange matter with its surroundings but can exchange energy. This means that while energy can enter or leave the system, the amount of matter within the system remains constant. This definition aligns with option A, making it the correct answer. Options B and C are incorrect because a closed system does not exchange matter, and option D is not directly related to the definition of a closed system in ecology.