All Free Biology MCQs with Answers

• A. Motor neuron
• B. Effector
• C. Pituitary
• D. Spinal cord

Explanation: The pituitary gland does not directly participate in reflex actions. Reflex actions are rapid, involuntary responses to stimuli that…

• A. Spinal nerves
• B. Cranial nerves
• C. Temporal nerves
• D. Both A and B respectively

Explanation: The explanation for this question is as follows: Peripheral Nervous System (PNS):It comprises of sensory neurons and motor neurons, which…

• A. Sensory
• B. Motor
• C. Mixed
• D. All A, B and C are correct

Explanation: The explanation for this question is as follows:The axons of sensory neurons enter the dorsal surface of the spinal cord and form the…

• A. Corpus callosum
• B. Hippocampus
• C. Medulla Oblongata
• D. Thalamus

Explanation: The explanation for this question is as follow: Medulla controls several automatic functions, such as breathing, Heart rate, blood…

• A. Pons
• B. Mesencephalon
• C. Medulla Oblongata
• D. All of these

Explanation: The explanation for this question is as follows: Midbrain is also known as mesencephalon so option B is the correct answer.

• A. Thalmus and limbic system
• B. Thalamus and cerebrum
• C. Cerebrum, limbic system and thalamus
• D. Cerebrum and limbic system

Explanation: The forebrain contains the cerebrum, limbic system, thalamus, pituarity gland and the olfactory bulb.

• A. Sodium pumps
• B. Potassium pumps
• C. Calcium pumps
• D. None of the above

Explanation: The resting potential in nerve cells is maintained by sodium-potassium pumps.

• A. Hypothalamus
• B. Bones
• C. Skin
• D. Brain

Explanation: The sensory neuron has pain-sensitive endings in skin.Pain-sensitive endings are also known as nociceptors.

• A. Choline
• B. Acetaldehyde
• C. Acetylcholine
• D. Phosphatidylcholine

Explanation: Acetylcholine is the main neurotransmitter for synapses that lie outside the central nervous system (CNS).

• A. Forebrain
• B. Midbrain
• C. Hindbrain
• D. Limbic system

Explanation: Medulla, pons, and cerebellum are parts of the hindbrain. The hindbrain regulates vital autonomic functions like breathing, heart rate…

• A. Cerebrum
• B. Cerebellum
• C. Cerebral cortex
• D. Cerebral hemispheres

Explanation: Cerebellum is a part of hind brain that's why this option is different from others.

• A. 2
• B. 6
• C. 5
• D. 8

Explanation: The spinal cord and spine are divided into 5 regions from top to bottom: cervical, thoracic, lumbar, sacral and coccygeal.Each region…

• A. 0.17V
• B. -50 mV
• C. 0.05V
• D. Both A and B

Explanation: The correct answer is 0.05 V, which is equivalent to 50 mV. This value represents the peak of the action potential where the membrane…

• A. Encephalitis
• B. Creutzfeldt-Jakob Disease
• C. Spongiocitis of Cerebrum
• D. Spondylitis

Explanation: The common term for bovine spongiform encephalopathy is mad cow disease, which is a progressive neurological disorder in cattle.

• A. Proteins into amino acids
• B. Glycogen into glucose
• C. Starch into maltose
• D. Fats into vitamins

Explanation: In the mouth, saliva converts starch into maltose. Saliva contains the enzyme amylase, also called ptyalin, and can break down starch into…

• A. Perform chemical digestion
• B. Stabilize the pH
• C. Act as promoter of ptyallin
• D. Both B and C

Explanation: NaHCO3 is bicarbonate which neutralizes the pH in acidic enviroment.

• A. Esophagus and Stomach
• B. Pancreas and liver
• C. Stomach and Duodenum
• D. Stomach and Liver

Explanation: The pancreas and liver are the endocrine pair present in the digestive canal.While the liver is primarily known for its exocrine…

• A. Gastrin
• B. Secretin
• C. HCl
• D. Enterokinase

Explanation: When acidic chyme touches the lining of duodenum wall it stimulates the secretion of hormone secretin.

• A. Larynx
• B. Glottis
• C. Pharynx
• D. Bronchi

Explanation: In the glottis (upper end of larynx) the mucous membrane is stretched across into two than edged fibrous Bands called vocal cords, which…

• A. Contracts and relax
• B. Contracts and goes downward
• C. Relax and rises
• D. Relax and goes downward

Explanation: During inhalation, the diaphragm, which is a dome-shaped muscle that separates the chest cavity from the abdominal cavity, contracts and…