General Science Questions (MCQs) for Competitive Examinations

Notes:
Acidity and alkalinity are expressed on the pH scale, which ranges from 0 (strongly acidic) to 14 (strongly basic or alkaline). A pH of 7.0, in the middle of this scale, is neutral. Blood is normally slightly basic, with a normal pH range of 7.35 to 7.45.

Notes:
Bile or gall is a dark green to yellowish brown fluid, produced by the liver that aids the digestion of lipids in the small intestine. It neutralizes the acid in food to provide the alkaline conditions needed in the small intestine. Besides, it breaks down large fat globules into smaller globules so that the pancreatic enzymes can easily act on them. This process is known as emulsification of fats. It does not convert proteins into amino acids.

Notes:
Credit for developing cell theory is usually given to three scientists: Theodor Schwann, Matthias Jakob Schleiden, and Rudolf Virchow. In 1839, Schwann and Schleiden suggested that cells were the basic unit of life. In 1858, Rudolf Virchow concluded that all cells come from pre-existing cells, thus completing the classical cell theory.

Notes:
One way of analyzing carrying capacity of the earth is to calculate its net primary productivity (NPP). This is the total amount of solar energy converted into biochemical energy through plant photosynthesis, minus the energy needed by those plants for their own life processes. It represents the total food resource on earth. In the food chain, meat products stay at the top. Even at the current levels where deforestation and other forms of destruction of vegetation has been rampant, plant products can sustain an extended population base.

Notes:
The cerebellum is important for making postural adjustments in order to maintain balance. Through its input from vestibular receptors and proprioceptors, it modulates commands to motor neurons to compensate for shifts in body position or changes in load upon muscles. So, it controls the maintenance of posture, balance and equilibrium.

Notes:
When cells are exposed to sunlight, radiant energy can damage the DNA. For example, ultraviolet irradiation causes covalent bond formation between adjacent thymines on the same strand of DNA.

Notes:
Proper storage of seed is vital to conserving its vigour and vitality. Seeds can last from a few years to centuries, depending on the species and the storage conditions. In general, most seeds stored in cool, dry conditions will survive longer than seeds stored in a wet, warm environment.

Notes:
Alpha-rays have high ionizing power but it is difficult for them to penetrate matter thoroughly. This is because alpha particles are likely to ionize the first thing they come into contact with; thus, they hold a small range of penetrating power. Beta rays have intermediate; while, Gamma Rays and X-Rays have maximum penetrating power.

Notes:
Wisdom teeth are vestigial third molars that human ancestors used to help in grinding down plant tissue. Their presence indicate the origin of human from one time ruminants.

Notes:
The word ‘comose’ means ‘hairy’ in Latin. It refers to certain seeds (such as cotton) having a tuft or tufts of hair. The seeds of plants like Calotropis, Gossypium, etc, possess a large number of hair which enable them to float in air. Such seeds with hair are described as comose.