General Science Questions (MCQs) for Competitive Examinations

Notes:
The melting point of a pure substance is always higher than the melting point of that substance when a small amount of an impurity is present. Melting point decreases with increase of impurity in water. Increase in impurity increases the electrostatic attraction between ions and thus more energy is needed to break the bonds. The surface tension of water increases when highly soluble impurities are added to it.

Notes:
Glycolysis, part of cellular respiration, is a series of reactions that constitute the first phase of most carbohydrate catabolism, catabolism meaning the breaking down of larger molecules into smaller ones. Glycolysis breaks down glucose and forms pyruvate with the production of two molecules of ATP. The entire process from conversion of glucose to pyruvate is anaerobic that is it does not take place in presence of oxygen.

Notes:
The brain’s limbic system controls emotional expression through the hypothalamus, which has control over the body’s emotional responses systems. The hypothalamus is responsible for regulating hunger, thirst, response to pain, levels of pleasure, sexual satisfaction, anger and aggressive behavior, etc. It also regulates pulse, blood pressure, breathing, and arousal in response to emotional circumstances.

Notes:
Mitochondria is an organelle found in large numbers in most cells, in which the biochemical processes of respiration and energy production occur. It is for this reason that mitochondria are often referred to as the powerhouses of the cell mitochondria also play a key role in the ageing process as well as in the onset of degenerative disease.

Notes:
African trypanosomiasis, also known as sleeping sickness, is a disease spread by an infected tsetse fly, found in rural areas of sub-Saharan Africa.The vast majority of human cases result from the transfer of T. brucei trypanosomes by tsetse flies as they suck human blood. Sleeping sickness is caused by two different parasites, Trypanosoma brucei rhodesiense and Trypanosoma brucei gambiense.

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:
Infection is the invasion of an organism’s body tissues by disease-causing agents, their multiplication, and the reaction of host tissues to the infectious agents and the toxins they produce. Infectious diseases can be spread from one person to another, for example through contact with bodily fluids, by aerosols (through coughing and sneezing), or via a vector, for example a mosquito.

Notes:
Growth hormone or somatotropin, also known as human growth hormone in its human form, is a peptide hormone that stimulates growth, cell reproduction and cell regeneration in humans and other animals. It is thus important in human development.

Notes:
Skeletal muscle is a form of striated muscle which is under the voluntary control of the somatic nervous system. Most skeletal muscles are attached to bones by bundles of collagen fibres known as tendons. It is one of three major muscle types, the others being cardiac muscle and smooth muscle.

Notes:
Stomata are tiny openings or pores in plant tissue that allow for gas exchange. Stomata allow a plant to take in carbon dioxide, which is needed for photosynthesis. They also help to reduce water loss by closing when conditions are hot or dry. Stomata look like tiny mouths which open and close as they assist in transpiration.