Biology MCQs

Notes:
Veins carry the deoxygenated blood from different parts of the body to the heart. There are two main veins that carry out this job. The superior vena cava carries deoxygenated blood from head, neck, thorax and hands to the right atrium of our heart. The inferior vena cava carries deoxygenated blood from legs, pelvic region and abdominal organs to the right atrium of our heart. Among the veins, only pulmonary vein carries oxygenated blood.

Notes:
Tuberculosis caused by Mycobacterium tuberculie which primarily affects lungs although can affect other body too while early 19th century was called ‘white plague’ because of the large number of the people dying of its infection.

Notes:
A tendon or sinew is a tough band of fibrous connective tissue that usually connects muscle to bone and is capable of withstanding tension. Tendons are similar to ligaments; both are made of collagen. Ligaments join one bone to another bone, while tendons connect muscle to bone.

Notes:
A wisdom tooth, in humans, is any of the usual four third molars. Wisdom teeth usually appear between the ages of 16 and 25. They are generally thought to be called wisdom teeth because they appear so late – much later than the other teeth, at an age where people are presumably “wiser” than as a child, when the other teeth erupt.

Notes:
The phosphate groups on DNA are ionic and charged. Each phosphate group on the DNA backbone has one unit of negative charge (-1). Charged molecules attract water and are hydrophilic. DNA has two hydrophilic polar external backbones made of sugars and phosphate groups joined by ester bonds. Therefore, DNA as nucleic acid is characterized by presence of phosphodiester bond.

Notes:
Vaccines containing antigens are introduced into the body, stimulating the immune system response by instructing B cells, with assistance from T cells, to produce antibodies. Antibodies are produced to fight the weakened or dead viruses in the vaccine. The immune system prepares to destroy real and stronger viruses in the future. When new antigens enter the body, white blood cells called macrophages engulf them; process the information contained in the antigens, and send it to the T cells to mobilise immune system. Hence, introduction of antigens in any form in body induces the production of antibodies to boost immunity.

Notes:
The excretory system is a collection of organs tasked with removing excess nitrogen and other toxins from the body. Several parts of the body such as sweat glands (excretion of sweat), liver (detoxifies and breaks down chemicals, poisons and other toxins that enter the body), lungs (disposal of carbon dioxide through exhalation) and kidneys (excretion of waste through urinary system) are involved in this process. The spleen also called grave yard of RBC is not considered as an excretory organ.

Notes:
Open circulatory system is the one in which blood does not circulate only inside blood vessels but it also falls in cavities that irrigate tissues. The internal organs are suspended in a network of blood-filled sinuses or open spaces which collectively form the haemocoel such as in cockroach and other insects.

Notes:
Cotton seed is a non-edible oilseed. Gossypol is a toxic compound found in the cotton plant. This compound is concentrated in the cotton seed but can also be found in other parts of the plant such as hulls, leaves and stems. Gossypol adversely affects the heart and liver.

Notes:
Quinine, as a component of the bark of the cinchona tree, was used to treat malaria from as early as the 1600s. The bark of trees in this genus is the source of a variety of alkaloids, the most familiar of which is quinine, an antipyretic (anti-fever) agent.