SCI 221 Nightingale College -Final exam SCI
221 Questions with Complete Solutions.
Course
SCI 221
1. What is homeostasis?
Answer: Homeostasis is the body's ability to maintain a stable internal environment despite
external changes.
Rationale: The body constantly adjusts internal conditions such as temperature, pH, and glucose
levels to keep them within a narrow, optimal range. This process is essential for survival and
proper functioning.
2. Which component of a feedback system detects changes in the environment?
Answer: The receptor detects changes in the environment and sends signals to the control
center.
Rationale: Receptors are specialized sensors that recognize stimuli (such as temperature or
pressure changes) and relay information to the brain or spinal cord for processing.
3. What is the primary function of the mitochondria?
Answer: The mitochondria are responsible for producing energy (ATP) through cellular
respiration.
Rationale: Mitochondria are known as the "powerhouses of the cell" because they convert
glucose and oxygen into ATP, which cells use as energy to perform functions such as muscle
contraction and nerve signaling.
4. Define osmosis.
Answer: Osmosis is the diffusion of water across a selectively permeable membrane from an
area of low solute concentration to an area of high solute concentration.
Rationale: Osmosis is crucial for cell hydration and maintaining balance between extracellular
and intracellular fluids. It also plays a role in kidney function and nutrient absorption.
,5. What is the role of hemoglobin in the human body?
Answer: Hemoglobin transports oxygen from the lungs to the body's tissues and facilitates the
return of carbon dioxide to the lungs for exhalation.
Rationale: Hemoglobin is a protein in red blood cells that binds to oxygen molecules, ensuring
that all body cells receive the oxygen they need for energy production. It also helps remove
carbon dioxide, a metabolic waste product.
6. Which organ is primarily responsible for regulating blood glucose levels?
Answer: The pancreas regulates blood glucose levels by secreting insulin (lowers glucose) and
glucagon (raises glucose).
Rationale: The pancreas ensures glucose homeostasis by releasing insulin when blood sugar is
high (after eating) and glucagon when blood sugar is low (during fasting). This regulation
prevents conditions like diabetes and hypoglycemia.
7. What is the function of the nephron in the kidney?
Answer: The nephron filters blood to form urine, removing waste products and excess
substances while maintaining fluid and electrolyte balance.
Rationale: Each kidney contains about a million nephrons, which filter waste (like urea and
toxins) while reabsorbing essential nutrients and water. This prevents dehydration and electrolyte
imbalances.
8. Describe the sliding filament theory of muscle contraction.
Answer: The sliding filament theory explains muscle contraction by describing how actin
filaments slide over myosin filaments, shortening the sarcomere and contracting the muscle.
Rationale: This mechanism allows muscles to generate force and movement. ATP provides the
energy for the myosin heads to pull the actin filaments, creating the contraction necessary for
body movement.
,9. What is the primary function of the lymphatic system?
Answer: The lymphatic system helps maintain fluid balance, absorbs fats from the digestive
tract, and supports the immune system by fighting infections.
Rationale: The lymphatic system removes excess fluid from tissues, transports immune cells to
fight infections, and absorbs fat-soluble nutrients from the intestines. It works alongside the
circulatory and immune systems.
10. Which hormone regulates the sleep-wake cycle?
Answer: Melatonin is the hormone that regulates the sleep-wake cycle, promoting sleep in
response to darkness.
Rationale: Melatonin is released by the pineal gland in response to low light levels. It helps
regulate the body's circadian rhythm, ensuring a healthy sleep-wake cycle, which is essential
for mental and physical well-being.
11. What is the main function of the digestive system?
Answer: The digestive system breaks down food into nutrients that can be absorbed and used
by the body for energy, growth, and repair.
Rationale: Digestion involves mechanical and chemical processes that convert food into
absorbable molecules, allowing the body to extract essential nutrients for survival.
12. Which organ is responsible for filtering toxins from the blood?
Answer: The liver is responsible for filtering toxins from the blood and metabolizing drugs.
Rationale: The liver processes harmful substances, detoxifies chemicals, and produces bile to
aid digestion. It also helps regulate blood sugar and cholesterol levels.
13. What is the function of alveoli in the respiratory system?
Answer: Alveoli are tiny air sacs in the lungs where gas exchange occurs—oxygen enters the
blood, and carbon dioxide is removed.
, Rationale: Alveoli have thin walls and a large surface area, making them highly efficient for
oxygen-carbon dioxide exchange, which is essential for respiration.
14. Which type of joint allows the greatest range of motion?
Answer: Ball-and-socket joints (found in the shoulder and hip) allow the greatest range of
motion.
Rationale: These joints permit movement in multiple directions, including rotation, making
them crucial for mobility and flexibility.
15. What role do enzymes play in digestion?
Answer: Enzymes break down macromolecules (proteins, fats, and carbohydrates) into
smaller, absorbable components.
Rationale: Enzymes such as amylase (carbohydrates), protease (proteins), and lipase (fats)
speed up digestion and ensure proper nutrient absorption.
16. How does the circulatory system work with the respiratory system?
Answer: The circulatory system transports oxygen-rich blood from the lungs to body tissues
and carries carbon dioxide back to the lungs for exhalation.
Rationale: This oxygen-carbon dioxide exchange ensures that cells receive oxygen for
metabolism and that waste gases are efficiently removed.
17. What is the function of the nervous system?
Answer: The nervous system transmits signals between the brain, spinal cord, and body,
coordinating functions such as movement, sensation, and thought.
Rationale: It is divided into the central (brain & spinal cord) and peripheral nervous
systems, which work together to regulate body functions and respond to stimuli.
221 Questions with Complete Solutions.
Course
SCI 221
1. What is homeostasis?
Answer: Homeostasis is the body's ability to maintain a stable internal environment despite
external changes.
Rationale: The body constantly adjusts internal conditions such as temperature, pH, and glucose
levels to keep them within a narrow, optimal range. This process is essential for survival and
proper functioning.
2. Which component of a feedback system detects changes in the environment?
Answer: The receptor detects changes in the environment and sends signals to the control
center.
Rationale: Receptors are specialized sensors that recognize stimuli (such as temperature or
pressure changes) and relay information to the brain or spinal cord for processing.
3. What is the primary function of the mitochondria?
Answer: The mitochondria are responsible for producing energy (ATP) through cellular
respiration.
Rationale: Mitochondria are known as the "powerhouses of the cell" because they convert
glucose and oxygen into ATP, which cells use as energy to perform functions such as muscle
contraction and nerve signaling.
4. Define osmosis.
Answer: Osmosis is the diffusion of water across a selectively permeable membrane from an
area of low solute concentration to an area of high solute concentration.
Rationale: Osmosis is crucial for cell hydration and maintaining balance between extracellular
and intracellular fluids. It also plays a role in kidney function and nutrient absorption.
,5. What is the role of hemoglobin in the human body?
Answer: Hemoglobin transports oxygen from the lungs to the body's tissues and facilitates the
return of carbon dioxide to the lungs for exhalation.
Rationale: Hemoglobin is a protein in red blood cells that binds to oxygen molecules, ensuring
that all body cells receive the oxygen they need for energy production. It also helps remove
carbon dioxide, a metabolic waste product.
6. Which organ is primarily responsible for regulating blood glucose levels?
Answer: The pancreas regulates blood glucose levels by secreting insulin (lowers glucose) and
glucagon (raises glucose).
Rationale: The pancreas ensures glucose homeostasis by releasing insulin when blood sugar is
high (after eating) and glucagon when blood sugar is low (during fasting). This regulation
prevents conditions like diabetes and hypoglycemia.
7. What is the function of the nephron in the kidney?
Answer: The nephron filters blood to form urine, removing waste products and excess
substances while maintaining fluid and electrolyte balance.
Rationale: Each kidney contains about a million nephrons, which filter waste (like urea and
toxins) while reabsorbing essential nutrients and water. This prevents dehydration and electrolyte
imbalances.
8. Describe the sliding filament theory of muscle contraction.
Answer: The sliding filament theory explains muscle contraction by describing how actin
filaments slide over myosin filaments, shortening the sarcomere and contracting the muscle.
Rationale: This mechanism allows muscles to generate force and movement. ATP provides the
energy for the myosin heads to pull the actin filaments, creating the contraction necessary for
body movement.
,9. What is the primary function of the lymphatic system?
Answer: The lymphatic system helps maintain fluid balance, absorbs fats from the digestive
tract, and supports the immune system by fighting infections.
Rationale: The lymphatic system removes excess fluid from tissues, transports immune cells to
fight infections, and absorbs fat-soluble nutrients from the intestines. It works alongside the
circulatory and immune systems.
10. Which hormone regulates the sleep-wake cycle?
Answer: Melatonin is the hormone that regulates the sleep-wake cycle, promoting sleep in
response to darkness.
Rationale: Melatonin is released by the pineal gland in response to low light levels. It helps
regulate the body's circadian rhythm, ensuring a healthy sleep-wake cycle, which is essential
for mental and physical well-being.
11. What is the main function of the digestive system?
Answer: The digestive system breaks down food into nutrients that can be absorbed and used
by the body for energy, growth, and repair.
Rationale: Digestion involves mechanical and chemical processes that convert food into
absorbable molecules, allowing the body to extract essential nutrients for survival.
12. Which organ is responsible for filtering toxins from the blood?
Answer: The liver is responsible for filtering toxins from the blood and metabolizing drugs.
Rationale: The liver processes harmful substances, detoxifies chemicals, and produces bile to
aid digestion. It also helps regulate blood sugar and cholesterol levels.
13. What is the function of alveoli in the respiratory system?
Answer: Alveoli are tiny air sacs in the lungs where gas exchange occurs—oxygen enters the
blood, and carbon dioxide is removed.
, Rationale: Alveoli have thin walls and a large surface area, making them highly efficient for
oxygen-carbon dioxide exchange, which is essential for respiration.
14. Which type of joint allows the greatest range of motion?
Answer: Ball-and-socket joints (found in the shoulder and hip) allow the greatest range of
motion.
Rationale: These joints permit movement in multiple directions, including rotation, making
them crucial for mobility and flexibility.
15. What role do enzymes play in digestion?
Answer: Enzymes break down macromolecules (proteins, fats, and carbohydrates) into
smaller, absorbable components.
Rationale: Enzymes such as amylase (carbohydrates), protease (proteins), and lipase (fats)
speed up digestion and ensure proper nutrient absorption.
16. How does the circulatory system work with the respiratory system?
Answer: The circulatory system transports oxygen-rich blood from the lungs to body tissues
and carries carbon dioxide back to the lungs for exhalation.
Rationale: This oxygen-carbon dioxide exchange ensures that cells receive oxygen for
metabolism and that waste gases are efficiently removed.
17. What is the function of the nervous system?
Answer: The nervous system transmits signals between the brain, spinal cord, and body,
coordinating functions such as movement, sensation, and thought.
Rationale: It is divided into the central (brain & spinal cord) and peripheral nervous
systems, which work together to regulate body functions and respond to stimuli.
