All Free Biology MCQs with Answers

• A. Bronchioles
• B. Trachea
• C. Alveolar Sacs
• D. Alveoli

Explanation: The site for gaseous exchange is the alveoli. Inhaled oxygen moves from the alveoli to the blood in the capillaries, and carbon dioxide…

• A. Asthma
• B. Emphysema
• C. Tuberculosis
• D. Cancer

Explanation: In emphysema, the inner walls of the air sacs are damaged, causing them to eventually rupture.

• A. 4%
• B. 0.04%
• C. 0.4%
• D. 0.0045%

Explanation: Exhaled air contains 4.4% carbon dioxide.

• A. Unicellular exocrine gland
• B. Unicellular endocrine glands
• C. Multicellular exocrine gland
• D. Multicellular endocrine glands

Explanation: the goblet cells are unicellular exocrine gland. Goblet cells are scattered in the epithelial linings of the intestinal and respiratory…

• A. Dorsal
• B. Ventral
• C. Lower part
• D. All of the above

Explanation: In summary, the correct answer is "a) Dorsal." The expiratory center in the medulla is located in the dorsal (back) part of the brainstem.

• A. Chloroplasts
• B. Mesophyll
• C. Thylakoids
• D. Stomata

Explanation: Carbon dioxide and oxygen cannot pass through the cuticle, but move in and out of leaves through openings called stomata (stoma = "hole").

• A. Glottis
• B. Epiglottis
• C. Larynx
• D. Vocal cord

Explanation: Epiglottis is a small, leaf-shaped sheet of elastic cartilage that protects your larynx (voice box) and helps you swallow

• A. Histamine
• B. Heparin
• C. Epinephrine
• D. Antibodies

Explanation: Asthma is a chronic lung disease affecting people of all ages. It is caused by inflammation and muscle tightening around the airways…

• A. Carboxyhemoglobin
• B. Plasma proteins
• C. Bicarbonate ions
• D. In dissolved form

Explanation: Carbon dioxide can be transported through the blood via three methods. It is dissolved directly in the blood, bound to plasma proteins or…

• A. Inspiratory Reserve Volume
• B. Tidal Volume
• C. Expiratory Reserve Volume
• D. Residual Volume

Explanation: Residual volume is the volume of air which remains in the lungs after the most forceful expiration.

• A. Decrease the affinity of haemoglobin with oxygen
• B. Release bicarbonate ions by the liver
• C. Reduce the rate of heart beat
• D. Reduce the blood supply to the brain

Explanation: Reduction in pH of blood causes oxygen haemoglobin dissociation curve to shift to right which indicates dissociation of oxygen from…

• A. Inflammation of the trachea
• B. Accumulation of fluid in the lungs
• C. Bacterial infection of the lungs
• D. Allergic reaction of the mast cells in the lungs.

Explanation: Note: The correct option is d) Allergic reaction of the mast cells in the lungs.

• A. Falling CO2 concentration
• B. Rising CO2 and falling O2 concentration
• C. Falling O2 concentration
• D. Rising CO2 concentration

Explanation: When lungs become concentrated with the same CO2 as in blood, it no longer leaves the blood and keeps rising.

• A. Have more RBCs and their hemoglobin has a lower binding affinity to O2 .
• B. Are not physically fit to play games like football.
• C. Suffer from altitude sickness with symptoms like nausea, fatigue, etc.
• D. Have the usual RBC count but their haemoglobin has a very high binding affinity to O 2.

Explanation: After about six months at high altitude the body acclimatises: it produces more red blood cells (polycythaemia) and raises 2,3-BPG, which…

• A. Attached to haemoglobin
• B. Dissolved in the blood
• C. As Bicarbonates
• D. As Carbonates

Explanation: When systemic arterial blood flows through capillaries, carbon dioxide diffuses from the tissues into the blood.

• A. Carbohydrate
• B. Respiratory pigment
• C. Vitamin
• D. Skin pigment

Explanation: Haemoglobin (Hb) is a conjugated protein. It consists of a basic protein globin joined to a nonprotein group heme.

• A. passive transport
• B. active transport
• C. osmosis
• D. diffusion.

Explanation: (d) : Diffusion is the net flow of a substance from a region of higher concentration to a region of lower concentration.

• A. 3.34%
• B. 4%
• C. 0.0314%
• D. 0.34%.

Explanation: (c) : The atmosphere (air) is a mixture of several gases. Near the earth's surface it consists of 78% nitrogen, 21% oxygen, 0.93% argon…

• A. Transitional epithelium + Tunica externa of blood vessel
• B. Squamous epithelium + Endothelium of blood vessel
• C. Squamous epithelium + Tunica media of blood vessel
• D. None of the above

Explanation: In lungs, the air is separated from the venous blood through squamous epithelium and endothelium of blood vessel.

• A. Residual volume
• B. Inspiratory reserve volume
• C. Vital capacity
• D. Tidal volume.

Explanation: All options are explained below: a)Residual volume (Correct Option): Residual volume is the volume of air that remains in the lungs even…