All Free Biology MCQs with Answers

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

Explanation: Most of the Carbon dioxide about 70% is carried as bicarbonate ions.

• A. Blood buffer
• B. Neutralization of H2CO3by Na2CO3
• C. Absorption by leukocytes
• D. Non-occumulation

Explanation: The bicarbonate buffering system of blood is an important buffer system in the acid-base homeostasis of living things, including humans.

• A. Histoplasmosis
• B. Tuberculosis
• C. Cystic Fibrosis
• D. Pneumonia

Explanation: The correct answer is Cystic Fibrosis. Unlike histoplasmosis, tuberculosis, and pneumonia, which are infections caused by a fungus…

• A. 50 times
• B. 20 times
• C. 70 times
• D. 100 times

Explanation: Hemoglobin significantly enhances the oxygen-carrying capacity of blood by approximately 70 times compared to plasma.

• A. Cigarette smoking reduces inflammation of the bronchi
• B. Neural signals from pneumotaxic 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 carbamino­haemoglobin

Explanation: Asthma involves the narrowing and swelling of airways and increased mucus production, which can lead to breathing difficulties.

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

Explanation: The unused oxygen in the blood acts as a reserve, which can be utilized during physical activities such as exercise when the body's oxygen…

• A. Has only 2 protein subunits instead of 4
• B. Has a higher affinity for oxygen than 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: .Fetal hemoglobin has a higher affinity for oxygen compared to adult hemoglobin.

• A. Inspired air contains more O2 than exhaled air:
• B. Expired air has 100 times greater CO2 as inspired air
• C. Amount of N2 is equal in both inhaled and exhaled air
• D. Exhaled air is comparatively drier than inhaled air

Explanation: Exhaled air has saturated water contents as compared to inhaled air which has variable water contents.

• A. The Johnson were not wealthy.
• B. The Johnsons were not wealthy.
• C. Johnsons were not wealthy.
• D. The Johnsons was not wealthy.

Explanation: The sentence is structured correctly, using the plural form "The Johnsons" with the verb "were".

• A. Gram + bacteria
• B. Gram - bacteria
• C. Chalko Virus
• D. Treponema palladium

Explanation: Gonorrhoea is caused by Neisseria gonorrhoeae, a Gram-negative diplococcus that commonly infects the mucous membranes of the reproductive…

• A. Appear darker than smooth muscles by naked eye
• B. Alternating dark and light bands appear on their surface when visualized by naked eye
• C. Alternating dark and light bands appear on their surface when visualized via a microscope
• D. All of these

Explanation: The striated appearance of skeletal muscle tissue is a result of repeating bands of the proteins actin and myosin that are present along…

• A. H zone
• B. M line
• C. Z line
• D. Z zone

Explanation: The sarcomere is the fundamental unit of contraction and is defined as the region between two Z-lines.

• A. 5
• B. 6
• C. 7
• D. 8

Explanation: The myosin filament is surrounded by six actin filaments and each actin filament is in turn surrounded by three myosin filaments.

• A. Primary Xylem and Seconday Xylem
• B. Primary xylem and Secondary phloem
• C. Secondary xylem and Secondary phloem
• D. Primary xylem and Primary phloem

Explanation: The correct option is D "Primary xylem and primary phloem". The "primary xylem and phloem" are conducting and supporting vascular tissues…

• A. Higher turgor pressure
• B. Cortex and pith with higher turgor pressure
• C. Collenchyma cells
• D. All of these

Explanation: Option A: A Higher turgor pressure: The pressure exerted by the fluid inside plant cells against the cell wall, providing support to young…

• A. Cellulose
• B. Lignin
• C. Murein
• D. Pectin

Explanation: Sclerenchyma cells have thick secondary cell walls usually impregnated with lignin, an organic substance that makes the walls tough and…

• A. A band becomes short
• B. I band elongates
• C. There is no change in sarcomere
• D. Z lines gets closer

Explanation: Option D is correct since the sarcomere shortens during muscle contraction. A sarcomere is a structure bound by two consecutive Z lines.

• A. Silica
• B. Polyester threads
• C. Groups of cell fibers
• D. Calcium and Phosphorus

Explanation: Option C is correct since muscles are composed of 'muscle fibers' which are further composed of 'myofibrils' which are composed of…

• A. Synovial joint
• B. Fibrous joint
• C. Cartilaginous joint
• D. None of these joint None of these

Explanation: The root of the tooth and the socket of the mandible and the maxilla is an example of fibrous joint.

• A. Four bones
• B. Six bones
• C. Eight bones
• D. Ten bones
• E. Many bones

Explanation: Your wrist is made up of eight small bones called carpal bones while your forearm contains two long bones;radius and ulna