1. Lymph nodes, found along lymphatic vessels, are important for:

A. Storing blood
B. Producing antibodies
C. Filtering lymph and trapping harmful substances
D. All of the above

Correct answer: D

Rationale: The correct answer is D, 'All of the above.' Lymph nodes are important for various functions in the immune system. They filter lymph, trapping harmful substances like bacteria and viruses, which helps in preventing infections. Lymph nodes also play a crucial role in producing antibodies, which are essential for fighting off pathogens. Additionally, lymph nodes do not store blood; that is the function of the spleen. Therefore, the correct answer is D because lymph nodes perform all the mentioned functions in supporting the body's immune response.

2. A lampshade consists of a cylindrical base (diameter 20cm, height 10cm) and a hemispherical top (same diameter as the base). What is its total surface area?

A. 785 sq cm
B. 1130 sq cm
C. 1570 sq cm
D. 2055 sq cm

Correct answer: D

Rationale: Calculate the surface area of the cylinder (base + lateral surface) and the hemisphere (half of a sphere's surface area). Add both areas to find the total surface area.

3. The energy absorbed during a chemical reaction is called:

A. Kinetic energy
B. Potential energy
C. Heat energy
D. Endothermic energy

Correct answer: D

Rationale: Endothermic means "inward heat," indicating energy is absorbed during the reaction.

4. The tiny air sacs in the lungs where gas exchange takes place are called:

A. Bronchi
B. Trachea
C. Alveoli
D. Pleura

Correct answer: A

Rationale: The correct answer is C: 'Alveoli.' Alveoli are the tiny air sacs in the lungs where gas exchange takes place. Oxygen from the air is diffused into the blood, and carbon dioxide from the blood is diffused into the air in the alveoli. Bronchi (option A) are the large air passages that lead from the trachea into the lungs. Trachea (option B) is the windpipe that connects the larynx to the bronchi. Pleura (option D) is a thin membrane that surrounds the lungs and lines the chest cavity. Understanding these structures is essential for comprehending respiratory function and gas exchange in the human body.

5. 7 is divisible by which of the following numbers?

A. 2 only
B. 3 only
C. 1 and 7 only
D. 2, 3, and 7

Correct answer: D

Rationale: Rationale: 1. 7 is divisible by 1 because every number is divisible by 1. 2. 7 is divisible by 7 because any number is divisible by itself. 3. 7 is not divisible by 2 because 7 is an odd number and not divisible by 2. 4. 7 is not divisible by 3 because the sum of the digits of 7 (7) is not divisible by 3. Therefore, 7 is divisible by 1, 7, and itself (7), making the correct answer D) 2, 3, and 7.

6. Which of the following organs is responsible for churning and mechanically breaking down food?

A. Small intestine
B. Large intestine
C. Stomach
D. Esophagus

Correct answer: C

Rationale: Rationale: The stomach is responsible for churning and mechanically breaking down food. It contains muscles that contract and relax to mix food with digestive juices, breaking it down into smaller particles. This mechanical digestion process helps prepare the food for further digestion and absorption in the small intestine. The small intestine is primarily responsible for the absorption of nutrients, the large intestine absorbs water and salts, the esophagus is a muscular tube that transports food from the mouth to the stomach.