General Science Questions (MCQs) for Competitive Examinations

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:
Abscisic acid also called plant stress hormone is responsible for responsible for dormancy of various types. It maintains dormancy in seeds and buds, stimulates the closing of stomata. Gibberellins are responsible for cell division and growth in cell size.

Notes:
Chameleons have specialized cells, chromatophores, which contain pigments in their cytoplasm, in three layers below their transparent outer skin. Dispersion of the pigment granules in the chromatophores sets the intensity of each color. Chromatophores contain pigments and reflect light, which are responsible for creating coloration. In chameleons, there are four types of chromatophores: xanthophores, erythrophores, iridiophores, and melanophores (Cooper and Greenberg, 1992).

Notes:
Monocost and dicots differ in the location of stomata and shape of guard cells. In monocots stomata are Dumb-bell shaped in dicots they are bean-shaped.

Notes:
Conduction is the process by which vital nutrients are transported to the different parts of a plant. This process is independent of the light factor. Respiration process in plants is the intake of carbon-dioxide and exhales oxygen during the day as the plants gets energy through the photosynthesis process in which the carbon-dioxide is converted into sugars using the sun light energy, as this process uses carbon-dioxide and water, the resulting gas oxygen is given out as a waste product. During the night, as the photosynthesis process does not take place it exhales the carbon-dioxide itself.

Notes:
The masseter is located in the jaw and is one of the muscles of mastication or chewing. ? The bite strength of an average man is between 117 to 265 pounds. ? This ability to exert a force on an external object is an example of absolute strength.

Notes:
Insects and birds have the simplest surface waxes that serve to water proof feathers. The interlocking feather barbs and a special waxy coating create a shield that water runs off of. Besides, while a few components present in surface lipids can prevent growth of pathogens, the total surface with waxed layer certainly functions to prevent microbial entry into the organism.

Notes:
Muscle fatigue refers to the decline in muscle force generated over time. Several factors contribute to muscle fatigue, the most important being lactic acid accumulation. Lactic acid is formed and accumulated in the muscle under conditions of high energy demand, rapid fluctuations of the energy requirement and insufficient supply of O2.

Notes:
Smut of wheat is caused by Ustilago tritici. Rust is caused by Puccinia grlaminae. Mild symptoms may be present prior to heading, including yellowish leaf streaks and stiff, dark green leaves. Affected plants head out early, producing sterile heads with clumped, sooty olive-black spores in place of healthy glumes and kernels.

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.