WGU D118 INTEGRATIVE LIFE
SCIENCE COMPREHENSIVE
OBJECTIVE ASSESSMENT QUESTIONS
AND CORRECT DETAILED ANSWERS
1. During an action potential, what specific event is responsible for the rapid depolarization
phase?
A. Efflux of potassium ions
B. Active transport of calcium ions
C. Influx of chloride ions
D. Influx of sodium ions
Answer: D
Conceptual Explanation: Depolarization is primarily caused by the rapid influx of sodium
ions (Na+) through voltage-gated channels once the threshold is reached.
2. Which structure in the brain is primarily responsible for the consolidation of short-term
memory into long-term memory?
A. Thalamus
B. Amygdala
C. Hippocampus
,D. Medulla Oblongata
Answer: C
Conceptual Explanation: The hippocampus is essential for forming new memories and
converting short-term memories into long-term storage, a process called consolidation.
3. In the sliding filament model of muscle contraction, what role does Calcium (Ca2+) play?
A. It binds to myosin to trigger the power stroke
B. It binds to tropomyosin to release ATP
C. It pumps sodium out of the sarcoplasmic reticulum
D. It binds to troponin, causing a conformational change in tropomyosin
Answer: D
Conceptual Explanation: Calcium binds to troponin, which shifts tropomyosin away from
the myosin-binding sites on the actin filament, allowing contraction to occur.
4. Which neurotransmitter is primarily involved in the brain’s reward system and movement
control?
A. Dopamine
B. GABA
C. Serotonin
D. Glutamate
, Answer: A
Conceptual Explanation: Dopamine is the key neurotransmitter associated with reward,
motivation, and the regulation of motor functions via the basal ganglia.
5. Which hormone is released by the posterior pituitary in response to low blood volume or
high blood osmolarity?
A. Oxytocin
B. Antidiuretic Hormone (ADH)
C. Aldosterone
D. Cortisol
Answer: B
Conceptual Explanation: ADH (also known as vasopressin) is stored in the posterior
pituitary and acts on the kidneys to increase water reabsorption, concentrating the urine.
6. In genetics, what is the term for a situation where one gene masks or interferes with the
expression of another gene?
A. Epistasis
B. Incomplete dominance
C. Codominance
D. Pleiotropy
Answer: A
SCIENCE COMPREHENSIVE
OBJECTIVE ASSESSMENT QUESTIONS
AND CORRECT DETAILED ANSWERS
1. During an action potential, what specific event is responsible for the rapid depolarization
phase?
A. Efflux of potassium ions
B. Active transport of calcium ions
C. Influx of chloride ions
D. Influx of sodium ions
Answer: D
Conceptual Explanation: Depolarization is primarily caused by the rapid influx of sodium
ions (Na+) through voltage-gated channels once the threshold is reached.
2. Which structure in the brain is primarily responsible for the consolidation of short-term
memory into long-term memory?
A. Thalamus
B. Amygdala
C. Hippocampus
,D. Medulla Oblongata
Answer: C
Conceptual Explanation: The hippocampus is essential for forming new memories and
converting short-term memories into long-term storage, a process called consolidation.
3. In the sliding filament model of muscle contraction, what role does Calcium (Ca2+) play?
A. It binds to myosin to trigger the power stroke
B. It binds to tropomyosin to release ATP
C. It pumps sodium out of the sarcoplasmic reticulum
D. It binds to troponin, causing a conformational change in tropomyosin
Answer: D
Conceptual Explanation: Calcium binds to troponin, which shifts tropomyosin away from
the myosin-binding sites on the actin filament, allowing contraction to occur.
4. Which neurotransmitter is primarily involved in the brain’s reward system and movement
control?
A. Dopamine
B. GABA
C. Serotonin
D. Glutamate
, Answer: A
Conceptual Explanation: Dopamine is the key neurotransmitter associated with reward,
motivation, and the regulation of motor functions via the basal ganglia.
5. Which hormone is released by the posterior pituitary in response to low blood volume or
high blood osmolarity?
A. Oxytocin
B. Antidiuretic Hormone (ADH)
C. Aldosterone
D. Cortisol
Answer: B
Conceptual Explanation: ADH (also known as vasopressin) is stored in the posterior
pituitary and acts on the kidneys to increase water reabsorption, concentrating the urine.
6. In genetics, what is the term for a situation where one gene masks or interferes with the
expression of another gene?
A. Epistasis
B. Incomplete dominance
C. Codominance
D. Pleiotropy
Answer: A
