All Free Biology MCQs with Answers

• A. Periosteum
• B. Perichondrium
• C. Pericardium
• D. Pleural membrane

Explanation: All options are explained below: a)Periosteum: Periosteum is a dense layer of vascular connective tissue that covers the surface of bones.

• A. Non-ciliated columnar
• B. Non-ciliated squamous
• C. Ciliated columnar
• D. Ciliated squamous

Explanation: (b) : In the lung, each alveolar duct opens into a blind chamber, the alveolar sac, or infundibulum.

• A. Active Transport
• B. Osmosis
• C. Diffusion
• D. Active Transport and Diffusion

Explanation: In animals, oxygen and carbon dioxide move by diffusion across moist membranes.

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

Explanation: The most common unicellular exocrine glands are the goblet cells (mucus secreting cells) found in the epithelium of the trachea and the…

• A. Kidneys
• B. Brain
• C. Lungs
• D. Nasal passage

Explanation: "The explanation for this question will be added soon!".

• A. Removal of foreign particles from incoming air.
• B. Humidifies incoming air
• C. Bring the temperature of incoming air to body temperature.
• D. All the above

Explanation: "The explanation for this question will be added soon!".

• A. Bony rings
• B. Chitinous rings
• C. Turgid pressure
• D. Cartilaginous rings

Explanation: "The explanation for this question will be added soon!".

• A. Equal to that in the blood
• B. More than that in the blood
• C. Less than that in the blood
• D. Less than that of carbon dioxide.

Explanation: The correct option is b) More than that in the blood. Explanation of each option: a) Equal to that in the blood: This option suggests that…

• A. There is a negative pressure in the lungs
• B. There is a negative intarpleural pressure pulling at the lung walls
• C. There is a positive intrapleural pressure
• D. Pressure in the lungs is higher than the atmospheric pressure.

Explanation: Option B is correct. All options are explained below:a)There is a negative pressure in the lungs": This statement is not entirely…

• 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: The correct option is "a". All options are explained below: a)"Decrease the affinity of hemoglobin with oxygen": This statement is…

• A. Respiratory acidosis
• B. Respiratory alkalosis
• C. Emphysema
• D. Asthma

Explanation: The correct option is c) Emphysema. Explanation of each option: a)"Respiratory acidosis": Respiratory acidosis is not a chronic…

• A. Pneumonia
• B. Asthma
• C. Pleurisy
• D. Emphysema

Explanation: Note: The correct option is d) Emphysema. Explanation of each option: a)Pneumonia: Pneumonia is an inflammatory lung condition primarily…

• A. Cigarette smoking may lead to inflammation of bronchi
• B. Neural signals from pneumotoxic centre in pons region of brain can increase the duration of inspiration
• C. Asthma is a condition in which your airways narrow and swell and may produce extra mucus
• D. About 90% of carbon dioxide (CO2) is carried by haemoglobin as carbamino­ haemoglobin

Explanation: All options are explained below: a)Cigarette smoking may lead to inflammation of bronchi: Cigarette smoking is a well-known risk factor…

• A. Acts as a reserve during muscular exercise
• B. Raises the pCO2 of blood to 75 mm of Hg.
• C. Is enough to keep oxyhaemoglobin saturation at 96%
• D. Helps in releasing more O2 to the epithelial tissues.

Explanation: Option A is correct. All options are explained below: a)Acts as a reserve during muscular exercise (Correct Option):This statement is…

• A. One can conciously breathe in and breathe out by moving the diaphragm alone, without moving the ribs at all.
• B. The lungs can be made fully empty by forcefully breathing out all air from them.
• C. One can breathe out air totally without residual air.
• D. One can breathe out air through Eustachian tubes by closing both the nose and the mouth.

Explanation: Correct option is A)a)One can consciously breathe in and breathe out by moving the diaphragm alone, without moving the ribs at all: This…

• A. Bicarbonate in blood plasma and RBCs
• B. Free CO2 in blood plasma
• C. 70% carbamino­haemoglobin and 30% as bicarbonate
• D. Carbamino­haemoglobin in RBCs

Explanation: All options are explained below: a)Bicarbonate in blood plasma and RBCs (Correct Option):The bulk of carbon dioxide (CO2) released from…

• A. (ii) 2500 mL, (iii) 4500 mL
• B. (iii) 1200 mL, (iv) 2500 mL
• C. (iv) 3500 mL, (i) 1200 mL
• D. (i) 4500 mL, (ii) 3500 mL

Explanation: All options are explained below: a)(ii) 2500 mL, (iii) 4500 mL:This option pairs capacity (ii) with 2500 mL and capacity (iii) with 4500…

• A. They carry about 20­-25 percent of CO2
• B. They transport 99.5 percent of O2
• C. They transport about 80 percent oxygen only and the rest 20 percent of it is transported in dissolved state in blood plasma
• D. They do not carry CO2 at all.

Explanation: All options are explained below: a)They carry about 20-25 percent of CO2 (Correct Option): Red blood cells (RBCs) play a significant role…

• A. Inspiratory reserve volume plus expiratory reserve volume
• B. Total lung capacity minus residual volume
• C. Inspiratory reserve volume plus tidal volume
• D. Total lung capacity minus expiratory reserve volume

Explanation: All options are explained below: A. Inspiratory reserve volume plus expiratory reserve volume:The vital capacity of the lungs is…

• A. has only 2 protein subunits instead of 4
• B. has a higher affinity for oxygen that that of an adult
• C. has a lower affinity for oxygen than that of the adult
• D. its affinity for oxygen is the same as that of an adult.

Explanation: A. The hemoglobin of a human fetus has only 2 protein subunits instead of 4: This statement is not accurate.