PAX Science NLN Exams collection (answered) 2023/2024.

PAX Science NLN Exams collection
(answered) 2023/2024.
 Course
 PAX Science NLN
1. Which of the following is the primary function of red blood cells?

 A. Carry oxygen to the tissues and organs.

 B. Produce antibodies to fight infection.

 C. Digest food particles.

 D. Clot blood to prevent excessive bleeding.

Answer: A. Carry oxygen to the tissues and organs.
Rationale: Red blood cells contain hemoglobin, which binds to oxygen and transports it from
the lungs to the rest of the body.



2. Which of the following best describes the process of osmosis?

 A. Movement of water from an area of lower concentration to an area of higher
concentration.

 B. Movement of water from an area of higher concentration to an area of lower
concentration.

 C. Movement of ions across the cell membrane.

 D. Active transport of solutes across the membrane.

Answer: B. Movement of water from an area of higher concentration to an area of lower
concentration.
Rationale: Osmosis is a type of passive transport where water molecules move through a semi-
permeable membrane from an area of higher concentration to lower concentration.



3. Which of the following is the most common cause of peptic ulcers?

 A. Stress

 B. Bacterial infection by Helicobacter pylori

 C. Excessive alcohol consumption

,  D. Smoking

Answer: B. Bacterial infection by Helicobacter pylori.
Rationale: Helicobacter pylori is a bacterium that disrupts the protective lining of the stomach
and can cause peptic ulcers.



4. What part of the brain is responsible for controlling heart rate and breathing?

 A. Cerebellum

 B. Medulla Oblongata

 C. Cerebrum

 D. Thalamus

Answer: B. Medulla Oblongata.
Rationale: The medulla oblongata controls vital functions such as heart rate, breathing, and
blood pressure.



5. Which of the following is a characteristic of a chemical change?

 A. A change in shape

 B. A change in temperature

 C. A new substance is formed

 D. A change in state (e.g., solid to liquid)

Answer: C. A new substance is formed.
Rationale: Chemical changes involve the formation of new substances through reactions, such
as the rusting of iron or burning wood.



6. Which of the following is an example of a monosaccharide?

 A. Sucrose

 B. Lactose

 C. Glucose

 D. Starch

,Answer: C. Glucose.
Rationale: Glucose is a monosaccharide, a simple sugar that serves as a primary source of
energy for cells.



7. What is the main role of the mitochondria in cells?

 A. Synthesize proteins

 B. Regulate water balance

 C. Produce energy (ATP)

 D. Store genetic material

Answer: C. Produce energy (ATP).
Rationale: Mitochondria are the powerhouses of the cell, generating ATP through cellular
respiration, which provides energy for cellular activities.



8. Which of the following is an example of an exothermic reaction?

 A. Boiling water

 B. Freezing water

 C. Melting ice

 D. Photosynthesis

Answer: B. Freezing water.
Rationale: Exothermic reactions release energy in the form of heat. Freezing water releases
energy as it changes from liquid to solid.



9. What is the primary function of the kidneys?

 A. Produce red blood cells

 B. Filter waste products from the blood

 C. Regulate blood sugar levels

 D. Control body temperature

, Answer: B. Filter waste products from the blood.
Rationale: The kidneys filter waste, excess substances, and fluids from the blood to form urine,
which is excreted from the body.



10. Which of the following describes the process of mitosis?

 A. Division of a cell into four daughter cells

 B. Division of a cell into two genetically identical daughter cells

 C. Division of a cell into two genetically different daughter cells

 D. Formation of gametes

Answer: B. Division of a cell into two genetically identical daughter cells.
Rationale: Mitosis is the process of cell division that results in two identical daughter cells,
crucial for growth and tissue repair.

11. Which of the following is the function of the endocrine system?

 A. To break down food for digestion

 B. To circulate blood throughout the body

 C. To secrete hormones for regulating body functions

 D. To filter waste from the blood

Answer: C. To secrete hormones for regulating body functions.
Rationale: The endocrine system releases hormones that control important functions, such as
metabolism, growth, and reproduction.



12. Which of the following describes the function of the small intestine?

 A. Absorbs nutrients from digested food

 B. Stores bile for digestion

 C. Breaks down proteins

 D. Produces digestive enzymes

Answer: A. Absorbs nutrients from digested food.
Rationale: The small intestine is the primary site for nutrient absorption during digestion.