During the depolarization phase of an action potential, there is a rapid influx of: MCQ with Answer and Explanation

During the depolarization phase of an action potential, there is a rapid influx of:
A. Potassium ions (K+)
B. Calcium ions (Ca2+)
C. Sodium ions (Na+)
D. Chloride ions (Cl-)
Answer: Option C
Solution (By JKExamLibrary)
An action potential is initiated when a stimulus causes the membrane potential to reach a threshold. This opens voltage-gated sodium channels, leading to a rapid influx of sodium ions (Na+) into the neuron. This makes the inside of the cell positively charged relative to the outside, a process called depolarization. Repolarization follows with the efflux of K+ ions.

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Practice More Biology Questions

Question #1
Consider statements about human diseases: 1. Cholera is caused by a bacterium. 2. Polio is caused by a virus. 3. Ringworm is caused by a fungus. Which are correct?
A. 1, 2 and 3
B. 1 and 2 only
C. 1 and 3 only
D. 2 and 3 only

Correct Answer: Option A


Explanation:
Cholera is an acute diarrheal disease caused by the bacterium Vibrio cholerae, typically transmitted through contaminated water and food. Polio (poliomyelitis) is a highly infectious viral disease caused by the poliovirus, which can invade the nervous system and cause paralysis. Ringworm (dermatophytosis) is a common superficial fungal infection of the skin, hair, or nails caused by dermatophytes like Microsporum, Trichophyton, and Epidermophyton. All three statements correctly identify the causative agents.

This question belongs to: Science Biology
Question #2
The muscle type that is under voluntary control is:
A. Visceral muscle
B. Cardiac muscle
C. Skeletal muscle
D. Smooth muscle

Correct Answer: Option C


Explanation:
Skeletal muscle, attached to bones, is striated and under conscious (voluntary) control. Smooth and cardiac muscles are involuntary. Skeletal muscles are responsible for locomotion and posture.

This question belongs to: Science Biology
Question #3
The condition in which the blood does not clot properly due to deficiency of clotting factor VIII is:
A. Thalassemia
B. Hemophilia A
C. Leukemia
D. Anemia

Correct Answer: Option B


Explanation:
Hemophilia A is an X-linked recessive bleeding disorder caused by deficiency of factor VIII. Hemophilia B is factor IX deficiency. Anemia is low RBCs, thalassemia abnormal hemoglobin, leukemia cancer of WBCs.

This question belongs to: Science Biology