General Science Questions (MCQs) for Competitive Examinations

Notes:
Echo location, also called biosonar, is the biological sonar used by several kinds of animals. Echo-locating animals emit calls out to the environment and listen to the echoes of those calls that return from various objects near them. They use these echoes to locate and identify the objects. Echo-locating animals include some mammals and a few birds; most notably microchiropteran bats and odontocetes (toothed whales and dolphins).

Notes:
DPT refers to a class of combination vaccines against three infectious diseases in humans: diphtheria, pertussis (whooping cough), and tetanus. The vaccine components include diphtheria and tetanus toxoids and killed whole cells of the organism that cause pertussis (wP).

Notes:
Sclerenchyma cells are usually dead cells that have heavily thickened secondary walls containing lignin. The cells are rigid and non-stretchable and are usually found in non-growing regions of plant bodies, such as the bark or mature stems. Sclerenchyma is one of the three types of fundamental, tissue in plants; the other two types being Parenchyma and Collenchyma.

Notes:
Gymnosperm are flowerless plant that produces cones and seeds. The term gymnosperm literally means “naked seed”, as gymnosperm seed are not encased within an ovary. Rather they sit exposed on the surface of the leaf like structures called bracts.

Notes:
Phytochrome is a photoreceptor, a pigment that plants use to detect light. It is a protein with a bilin chromophore. It detects mainly red and far-red region of the visible spectrum and regulates germination of seeds in photoblastic seeds.

Notes:
Inorganic arsenic found in water is a confirmed carcinogen and is the most significant chemical contaminant in drinking-water globally. Prolonged ingestion of arsenic-containing drinking water is associated with bladder cancer and skin cancer. In addition, cancers of the lung, digestive tract, liver, kidney, and lymphatic and hematopoietic systems are also linked to arsenic exposure.

Notes:
The blood sugar concentration or blood glucose level is the amount of glucose (sugar) present in the blood of a human or animal. The body naturally tightly regulates blood glucose levels as a part of metabolic homeostasis. The mean normal blood glucose level in humans is about 4 mM (4 m mol/L or 72 mg/dL, i.e. milligrams/decilitre); however, this level fluctuates throughout the day.

Notes:
Red rot disease is caused by the fungus Glomerella tucumanensis. An older name,Colletotrichum falcatum, is still preferred by some pathologists. Red rot occurs in various parts of the sugar cane plant but it is usually considered a stalk and a seed-piece disease. Its symptoms are highly variable depending upon the susceptibility of the sugarcane variety and the environment.

Notes:
Aggregate fruits are the group of fruitlets which develop from the multicarpellary, apocarpous ovary. Flowers with apocarpous multiple gynoecium are apt to give rise to a number of fruits as there are a number of free ovaries, each capable of giving rise to one fruit. Berries are good example of such fruits.

Notes:
Thymosin is the hormone of the thymus. It stimulates the development of disease-fighting T cells. Throughout our childhood years, white blood cells called lymphocytes pass through the thymus, where they are transformed into T cells. Once T cells have fully matured in the thymus, they migrate to the lymph nodes throughout the body, where they aid the immune system in fighting disease.