General Science Questions (MCQs) for Competitive Examinations

Notes:
Different fluids in the human body generally have a delicate range of acid-alkaline balance they maintain for optimal functioning. Human blood has a normal pH of about 7.41. The pH of urine has a wider range. Normal ranges for urine pH are from 4.5 to 8 and saliva has pH range of 6-8 to 7-0.

Notes:
A tannin is an astringent, bitter plant polyphenolic compound that binds to and precipitates proteins and various other organic compounds including amino acids and alkaloids. It refers to the use of wood tannins from oak in tanning animal hides into leather.

Notes:
According to the K+ ion theory the guard cells absorb K+ ions from the cells around them as they produce ATP (due to photosynthesis) and become hypertonic. This leads to absorption of water from nearby cells by endosmosis due to which the guard cells become turgid and the stomata opens. Decreasing light intensity and photosynthesis causes Stomatal closing.

Notes:
Myxine is a species of jawless fish (Agnatha). It is known as Hag fish in Europe. These are generally classified with the lampreys into the superclass Agnatha (jawless vertebrates) within the subphylum Vertebrata. All other living fishes (shark, rays, chimeras and bony fishes) possess true jaws derived from gill arches and are placed in the superclass Gnathostomata.

Notes:
Eutrophication is the ecosystem response to the addition of artificial or natural substances, such as nitrates and phosphates, through fertilizers or sewage. It leads not only to increased levels of nutrients, but increased Biological Oxygen Demand as well following the decay of algal bloom in stagnant water reservoirs.

Notes:
Bats are mammals of the order Chiroptera. With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more maneuverable than most birds, flying with their very long spread-out digits covered with a thin membrane or patagium. 

Notes:
The term xerophyte refers to a plant species that has evolved over time to adapt to dry and arid regions like deserts. Xerophytes have adapted to be able to keep extremely large amounts of water for a long period of time. Without this capability, the plant would die, as the desert region itself does not provide enough water to sustain life. They have thick cuticle, sunken stomata and leaves modified in form of spines such as in opuntia.

Notes:
A vein is an elastic blood vessel that transports blood from various regions of the body to the heart. Veins are components of the cardiovascular system, which circulates blood to provide nutrients to the cells of the body. Veins can be categorized into four main types: pulmonary, systemic, superficial, and deep veins.

Notes:
Vitamin C also known as ascorbic acid is found in citrus fruit such as orange, lemon, lime, grapefruit, grapes etc. It protects the immune system, reduces the severity of allergic reactions and helps fight off infections.

Notes:
Cod is the common name for the genus Gadus of demersal fishes, belonging to the family Gadidae. Cod is also used as part of the commons name for a number of other fishes, and there are species suggested to belong to genus Gadus that are not called cod (the Alaska pollock). Cod is popular as a food with a mild flavour and a dense, flaky white flesh. Cod livers are processed to make cod liver oil, an important source of vitamin A, vitamin D, vitamin E and omega-3 fatty acids (EPA and DHA).