All Free Biology MCQs with Answers

• A. Muscle fibrin
• B. Muscle fibers
• C. Sarcomere
• D. None of these

Explanation: Muscle contraction occurs when sarcomeres within muscle fibers shorten.

• A. Tendon
• B. Ligament
• C. Reticular Tissue
• D. Cartilage

Explanation: Option: A Tendons attach muscles to bones and are non-elastic. PTB XII Chap # 16 page # 42 Option B : Ligaments attach bone to bone and…

• A. myofibril
• B. Z-line
• C. M-line
• D. Fibroin

Explanation: Correct option:A(Definition) The basic unit of muscle fiber is the myofibril.

• A. Movement of calcium ions from the axon terminals into the synaptic cleft
• B. Movement of calcium ions from the synaptic cleft into the axon terminals
• C. Movement of sodium ions into the axon terminals from the synaptic cleft
• D. Movement of sodium ions into the synaptic cleft from the axon terminals
• E. None of the above

Explanation: Explanation for this question will be added soon.

• A. K+
• B. Na+
• C. Ca*
• D. Cl-

Explanation: During the non-conducting state of a neuron, the neuron membrane is permeable to the efflux of potassium ions (K+).

• A. Stay in synaptic cleft indefinitely
• B. Recycled in synaptic cleft
• C. Degraded by enzyme
• D. Taken up by postsynaptic membrane

Explanation: After transmitting the nerve impulse, the neurotrasmitters are degraded by enzymes.

• A. Volta
• B. Jenner
• C. Salk
• D. Galvani

Explanation: Galvani experimented with the dissected leg of a frog and discovered the remarkable effects of static electricity, which caused their legs…

• A. Extra cellular sodium is high
• B. Extra cellular potassium is high
• C. Intracellular sodium is high
• D. Intracellular potassium is less

Explanation: Option A: This is true at rest, but not during an action potential. During an action potential, the concentration of sodium ions outside…

• A. Cell bodies of sensory neurons
• B. Cell bodies of interneurons
• C. Axons of interneurons
• D. Cell bodies of motor neurons

Explanation: Gray matter, the inner matter of the spinal cord does not contain cell bodies of sensory neurons.

• A. -70 mV
• B. -60 mV
• C. -50 mV
• D. -40 mV

Explanation: The resting membrane potential of a neuron is the electrical potential inside the cell relative to the adjacent extracellular space.

• A. Epinephrine
• B. Acetylcholine
• C. Dopamine
• D. Serotonin

Explanation: Acetylcholine is a type of chemical messenger, or neurotransmitter, that plays a vital role in the central and peripheral nervous system.

• A. -70 mv
• B. -70 Volt
• C. 70mv
• D. -90 mv

Explanation: In most neurons the resting potential has a value of approximately −70 mV.

• A. Synaptic knob
• B. Synaptic cleft
• C. Synaplic delay
• D. Synaptic vesicle

Explanation: A synapse is the small gap between two neurons, where nerve impulses are relayed by a neurotransmitter from the axon of a presynaptic…

• A. Axon
• B. Auxin
• C. Sehwann cell
• D. Dendrites

Explanation: An extension or process called an axon carries impulses away from the cell body.

• A. Hormones
• B. Activators
• C. Neurotransmitters
• D. Enzymes

Explanation: Neurotransmitters are chemical compounds released by neurons after depolarization that act on other neurons to produce a response.

• A. 10
• B. 30
• C. 2
• D. 3

Explanation: The concentration of Na+ ions is approximately 10 times greater in fluids outside (extracellular) the cell compared to inside…

• A. Postsynaptic neuron
• B. Presynaptic neuron
• C. Synapses
• D. Dendrites

Explanation: Neurotransmitters are synthesized and stored within the presynaptic neuron, specifically in structures called synaptic vesicles.

• A. Impulse
• B. Synapse
• C. Axon
• D. Cleft

Explanation: A synapse is a specialized junction between two neurons (nerve cells) where they communicate.

• A. Serotonin
• B. Aspartame
• C. Ascorbic acid
• D. Hydrazine

Explanation: Serotonin is a compound that conducts nerve impulses in the brain. It contains 68.2%C,6.86%H,15.9%N, and 9.08%O .

• A. Grana
• B. Stroma
• C. Thylakoid
• D. Both grana and stroma

Explanation: Dark reactions (light-independent reactions) of photosynthesis take place in the stroma of chloroplasts.