PAX Science NLN Exams collection (answered) 2022/2023.

PAX Science NLN Exams collection (answered)
2022/2023.
 Course
 PAX Science NLN

Question 1:

What is the primary function of red blood cells in the human body?

 A) Transport nutrients
 B) Fight infections
 C) Carry oxygen
 D) Regulate body temperature

Answer: C) Carry oxygen
Rationale: Red blood cells contain hemoglobin, which binds to oxygen in the lungs and
transports it to tissues throughout the body.



Question 2:

Which part of the cell is responsible for energy production?

 A) Nucleus
 B) Ribosome
 C) Mitochondria
 D) Golgi apparatus

Answer: C) Mitochondria
Rationale: Mitochondria are known as the powerhouses of the cell, converting glucose and
oxygen into ATP (adenosine triphosphate), the cell's energy currency.



Question 3:

Which of the following is a function of the skeletal system?

 A) Producing hormones
 B) Storing fat
 C) Facilitating movement
 D) Regulating temperature

Answer: C) Facilitating movement
Rationale: The skeletal system provides a framework for muscles to attach, allowing for
movement. It also supports and protects internal organs.

,Question 4:

What type of bond is formed when two atoms share electrons?

 A) Ionic bond
 B) Hydrogen bond
 C) Covalent bond
 D) Metallic bond

Answer: C) Covalent bond
Rationale: A covalent bond occurs when two atoms share one or more pairs of electrons,
resulting in a stable balance of attractive and repulsive forces between atoms.



Question 5:

What is the primary role of enzymes in biochemical reactions?

 A) To increase the temperature of reactions
 B) To act as substrates
 C) To lower activation energy
 D) To provide energy

Answer: C) To lower activation energy
Rationale: Enzymes are catalysts that speed up biochemical reactions by lowering the
activation energy needed for the reaction to proceed.



Question 6:

Which organ is responsible for filtering blood and producing urine?

 A) Liver
 B) Kidney
 C) Heart
 D) Pancreas

Answer: B) Kidney
Rationale: The kidneys filter waste and excess substances from the blood to produce urine,
playing a crucial role in maintaining fluid and electrolyte balance.



Question 7:

,Which of the following processes describes the movement of water across a selectively
permeable membrane?

 A) Diffusion
 B) Osmosis
 C) Active transport
 D) Facilitated diffusion

Answer: B) Osmosis
Rationale: Osmosis is the process by which water moves across a selectively permeable
membrane from an area of lower solute concentration to an area of higher solute
concentration.



Question 8:

What is the primary purpose of the integumentary system?

 A) To facilitate digestion
 B) To protect the body from environmental damage
 C) To regulate blood flow
 D) To aid in respiration

Answer: B) To protect the body from environmental damage
Rationale: The integumentary system, which includes the skin, hair, and nails, serves as the
body's first line of defense against pathogens, physical injury, and UV radiation.



Question 9:

Which type of muscle is under voluntary control?

 A) Cardiac muscle
 B) Smooth muscle
 C) Skeletal muscle
 D) Involuntary muscle

Answer: C) Skeletal muscle
Rationale: Skeletal muscle is under voluntary control, meaning it can be consciously
controlled to facilitate movement, unlike cardiac and smooth muscles, which are involuntary.



Question 10:

In which phase of cellular respiration is the majority of ATP produced?

 A) Glycolysis

,  B) Krebs cycle
 C) Electron transport chain
 D) Fermentation

Answer: C) Electron transport chain
Rationale: The electron transport chain generates the majority of ATP in cellular respiration
by utilizing high-energy electrons derived from earlier stages (glycolysis and Krebs cycle) to
produce ATP.

Question 11:

What is the basic unit of life?

 A) Tissue
 B) Organ
 C) Cell
 D) Organism

Answer: C) Cell
Rationale: The cell is considered the basic structural and functional unit of all living
organisms, serving as the smallest unit capable of independent life.



Question 12:

Which of the following best describes homeostasis?

 A) The ability to reproduce
 B) The ability to maintain a stable internal environment
 C) The ability to grow and develop
 D) The ability to respond to stimuli

Answer: B) The ability to maintain a stable internal environment
Rationale: Homeostasis refers to the processes that organisms use to maintain stable internal
conditions despite changes in external environments.



Question 13:

What is the primary component of the plasma membrane?

 A) Proteins
 B) Nucleic acids
 C) Lipids
 D) Carbohydrates