1. Which organ plays a significant role in immune cell production and maturation?

A. Liver
B. Kidneys
C. Bone marrow
D. Spleen

Correct answer: C

Rationale: The correct answer is C: Bone marrow. The bone marrow is the primary site for the production and maturation of immune cells, including white blood cells, which are crucial for the body's immune response. Stem cells in the bone marrow differentiate into various types of immune cells, such as T cells, B cells, and natural killer cells, which play essential roles in fighting infections and diseases. While the liver and kidneys have other important functions in the body, such as filtering toxins and metabolizing substances, they are not directly involved in immune cell production and maturation. The spleen acts as a reservoir for blood and is involved in filtering blood and storing red blood cells but is not the primary site for immune cell production.

2. Which type of muscle is characterized by involuntary contractions, is striated, and is primarily found in the heart?

A. Skeletal muscle
B. Smooth muscle
C. Cardiac muscle
D. Elastic muscle

Correct answer: C

Rationale: The correct answer is C: Cardiac muscle. Cardiac muscle is characterized by involuntary contractions, meaning it contracts without conscious control. It is striated, which refers to the striped appearance of muscle fibers under a microscope. Cardiac muscle is primarily found in the heart, where it plays a crucial role in pumping blood throughout the body. Skeletal muscle (option A) is also striated but is under voluntary control. Smooth muscle (option B) is non-striated and found in organs like the intestines. Elastic muscle (option D) is not a recognized type of muscle tissue.

3. Which of the following is an example of aseptic technique?

A. Washing hands with soap and water before surgery
B. Coughing into your elbow
C. Sharing a stethoscope without cleaning
D. Leaving a wound dressing exposed

Correct answer: A

Rationale: Rationale: Aseptic technique refers to practices that help prevent the introduction of harmful microorganisms into a sterile environment. Washing hands with soap and water before surgery is an essential component of aseptic technique as it helps reduce the number of microorganisms on the hands, decreasing the risk of introducing pathogens into the surgical site. Coughing into your elbow is a good hygiene practice to prevent the spread of respiratory infections but is not specifically related to aseptic technique. Sharing a stethoscope without cleaning can introduce microorganisms from one patient to another, compromising aseptic conditions. Leaving a wound dressing exposed can lead to contamination and infection, which is contrary to aseptic technique.

4. Which of the following is NOT a property of a catalyst?

A. Increases the rate of a reaction
B. Remains unchanged after the reaction
C. Lowers the activation energy
D. Creates new products

Correct answer: D

Rationale: A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It remains unchanged after the reaction, which eliminates option B. A catalyst works by lowering the activation energy required for the reaction to occur, which eliminates option C. A catalyst does not create new products in a reaction; it only facilitates the conversion of reactants into products more efficiently. Therefore, option D is NOT a property of a catalyst.

5. Which property of a substance refers to its ability to undergo a chemical change and form new substances?

A. Density
B. Mass
C. Reactivity
D. Volume

Correct answer: c

Rationale: Reactivity refers to a substance's ability to undergo chemical changes, forming new substances with different properties.

6. Which property of a substance measures the amount of matter per unit volume?

A. Density
B. Mass
C. Weight
D. Volume

Correct answer: a

Rationale: Density is the property that measures the amount of matter (mass) per unit volume of a substance. It is calculated as mass divided by volume.