All Free Biology MCQs with Answers

• A. Formation of carboxy-hemoglobin
• B. The high concentration of oxyhemoglobin
• C. Low level of carbon monoxide (CO)
• D. Low level of hemoglobin

Explanation: The correct answer is the formation of carboxy-hemoglobin. This occurs when carbon monoxide binds to hemoglobin with a much higher…

• A. 60 mm Hg
• B. 120 mm Hg
• C. 80 mm Hg
• D. 102 mm Hg

Explanation: So, when we talk about the normal systolic blood pressure of the aorta, we're referring to the pressure in the main artery of the body…

• A. Inter-auricular septum
• B. Ventricular septum
• C. Tricuspid valve
• D. Bicuspid valve

Explanation: Option C is correct.In the human heart, the right atrium communicates with the right ventricle through the tricuspid valve.

• A. Lower dorsal
• B. Upper dorsal
• C. On the interatrial septum
• D. Near the coronary sinus

Explanation: The sinoatrial (SA) node, also known as the natural pacemaker, is located in the upper dorsal (posterior) wall of the right atrium, near…

• A. Liver
• B. Kidney
• C. Ovaries
• D. Heart

Explanation: Meiosis is a process that occurs in sex cells, such as sperm and egg cells in the human body, to make more of them.

• A. Prototherians
• B. Eutherians
• C. Metatherian
• D. All of above

Explanation: Metatherians, also known as marsupials, are a group of mammals that give birth to relatively undeveloped embryos.

• A. Identical twins
• B. Siames twins
• C. Fraternal twins
• D. Double twins

Explanation: When a woman's ovary releases two eggs which are fertilized by two different sperms, it results in the formation of fraternal twins.

• A. Vas deferens, urethra, epididymis
• B. Epididymis, vas deferens, urethra
• C. Epididymis, urethra, vas deferens
• D. Urethra, epididymis, vas deferens

Explanation: The correct sequence of sperm transport is: Epididymis → Vas deferens → Urethra.

• A. Somatic cells
• B. Sertoli cells
• C. Stem cells
• D. Totipotent cells

Explanation: Sertoli cells are the epithelial supporting cells of the seminiferous tubules.

• A. Plasma membrane
• B. Vitelline membrane
• C. Corona radiata
• D. All of the above

Explanation: Mature ova (egg cells) in humans are surrounded by all three: plasma membrane, vitelline membrane, and corona radiata.

• A. Hypothalamus
• B. Pituitary gland
• C. Prostate
• D. Sertoli cells

Explanation: The correct answer is Sertoli cells. Inhibin is produced by Sertoli cells within the testes and is part of the transforming growth…

• A. ciliated epithelium
• B. Squamaus epithelium
• C. Columnar epithelium
• D. Cubodial epithelium

Explanation: The inner surface of the fallopian tube is lined by ciliated epithelium.

• A. Perimetrium
• B. Myometrium
• C. Endometrium
• D. Cervix

Explanation: The embryo implants in the endometrium of the uterus. The endometrium is the innermost layer of the uterine wall, and it undergoes cyclic…

• A. Chest wall is raised and diaghram is lowered
• B. Chest wall is raised and diaghram is also raised
• C. Chest wall is lowered and diaghram is raised
• D. Chest wall is lowered and diaghram is also lowered

Explanation: Ok we will go through inspiration and expiration on a conceptual basis During inspiration, air moves in the lungs, so atmospheric pressure…

• A. Fibrous
• B. Hyaline
• C. Elastic
• D. Neurotic

Explanation: Hyaline cartilage is found at the ends of long bones and in the nose at the larynx and trachea.

• A. Digestive
• B. Circulatory
• C. Respiratory
• D. Excretory

Explanation: Instead of nostrils, grasshoppers breathe through openings in the thorax and abdomen called spiracles.

• A. Fishes
• B. Amphibians
• C. Birds
• D. Mammals

Explanation: Alveoli, small air sacs in the lungs where gas exchange occurs, are present in fishes.

• A. Birds
• B. Crocodiles
• C. Fishes
• D. Toads

Explanation: Correct Answer: BirdsThe presence of a diaphragm in birds allows for effective respiration by assisting in lung function.

• A. Birds
• B. Crocodiles
• C. Fishes
• D. Toads

Explanation: Mammals are characterized by a well-developed diaphragm that separates the thoracic chamber from the abdominal cavity.

• A. The cardiac center
• B. Ventilation center
• C. Pons
• D. Carotid sinus

Explanation: The rhythmicity of respiration is primarily maintained by the respiratory centers located in the pons region of the brainstem.