1. What is the feedback mechanism in the endocrine system that helps maintain hormone balance?

A. Positive feedback, where a hormone stimulates its own release
B. Negative feedback, where a hormone suppresses its own release
C. Cascade effect, where one hormone triggers the release of another
D. Dual hormone system, where two hormones work together

Correct answer: B

Rationale: The correct answer is B: Negative feedback, where a hormone suppresses its own release. In the endocrine system, negative feedback is a crucial mechanism that helps maintain hormone balance. When hormone levels rise, they signal the body to decrease further hormone production, preventing an excess. This ensures that hormone levels stay within a narrow range, promoting stability and homeostasis. Positive feedback (option A) would lead to an amplification of hormone release, which is not ideal for maintaining balance. Cascade effect (option C) involves a sequential activation of hormones but does not directly regulate hormone levels. Dual hormone system (option D) refers to two hormones working together but doesn't specifically address the feedback mechanism for maintaining hormone balance.

2. Which of the following best describes a chemical change?

A. Melting ice to form water
B. Dissolving sugar in water
C. Burning wood to produce ash
D. Crushing a can to reduce its size

Correct answer: c

Rationale: Chemical changes involve the formation of new substances with different chemical properties. Burning wood involves a chemical reaction where wood undergoes combustion, breaking down its chemical structure to produce new substances like ash and gases.

3. A triangular scarf has sides measuring 10cm, 12cm, and 15cm. What is its perimeter?

A. 27cm
B. 32cm
C. 37cm
D. 45cm

Correct answer: C

Rationale: Simply add the lengths of all sides: perimeter = side1 + side2 + side3 = 10cm + 12cm + 15cm = 37cm.

4. Histamine, released during an allergic reaction, causes symptoms like:

A. Fever and fatigue
B. Runny nose and itchiness
C. Muscle aches and joint pain
D. Cough and shortness of breath

Correct answer: B

Rationale: The correct answer is B: 'Runny nose and itchiness.' Histamine is a chemical released by the body during an allergic reaction. It causes various symptoms such as itching, sneezing, runny nose, and watery eyes. These symptoms are commonly associated with allergic reactions like hay fever or hives. Fever and fatigue (option A) are not directly caused by histamine release. Muscle aches and joint pain (option C) are not typical symptoms of histamine release during an allergic reaction. Cough and shortness of breath (option D) are more commonly associated with asthma or respiratory allergies rather than histamine release.

5. A solution is formed when:

A. One substance dissolves in another
B. Two or more substances react chemically
C. A solid changes to a liquid
D. None of the above

Correct answer: A

Rationale: One substance dissolves in another. A solution is a homogeneous mixture where one substance (solute) dissolves in another (solvent).

6. An IV bag contains 500ml of saline solution and needs to be infused over 4 hours. What is the flow rate in drops per minute, assuming 20 drops per milliliter?

A. 12.5 drops/min
B. 25 drops/min
C. 50 drops/min
D. 100 drops/min

Correct answer: C

Rationale: Calculate the total volume in drops (500ml * 20 drops/ml = 10,000 drops). Divide this by the infusion time in minutes (4 hours * 60 minutes/hour = 240 minutes) to get the flow rate.