General Science Questions (MCQs) for Competitive Examinations

Notes:
Chlorargyrite is the mineral form of silver chloride (AgCl). It is also known as cerargyrite and, when weathered by desert air, as horn silver. Silver chloride is formed by the disappearance of the initial silver oxide layer.

Notes:
Chemical weapons are called “poorman’s bomb”. These cause catastrophic damage, and are easy to produce. Sarin is a colorless and odourless agent, and is extremely potent. It was used in Damascus in 2013. Mustard Gas is possibly the most commonly used chemical agent and gets its name from the distinctive odour of rotten mustard. It is less potent and usually only 5 to 10 percent people exposed to it usually die. It was widely used during Second World War. VX is a nerve agent which is odourless and appears as brownish oily substance.

Notes:
Sublimation describes a phase transition where a substance changes from a solid directly to a gas, bypassing the liquid state. This physical transformation is distinct from chemical changes like oxidation or reduction. Sublimation happens under certain combinations of pressure and temperature. Examples include dry ice (solid CO2), which sublimates at room temperature, and solid water, or ice, which sublimates under low pressure conditions.

Notes:
Milk is a poor source of ascorbic acid (Vitamin C). It contains about 1 mg ascorbate per 100 g. Even the little Vitamin C is usually destroyed when the milk is heat treated. Milk as a complete food contains most of the esential nutrients except are vitamin C and iron.

Notes:
A virus has a simple structure. It has no internal cellular structure, no cell wall or cell membrane, just the protein coat that holds the string of nucleic acid. It is made only of a nucleic acid + a protein coat. A cell wall is a layer located outside the cell membrane found in plants, fungi, bacteria, algae, and archaea.

Notes:
Ecological succession is unidirectional progressive process of development in an ecosystem or biome. Grass ecosystems are an early stage of succession in regions where the mature ecosystems are forests. However, grass ecosystems are climax ecosystems in grassland regions, where there is not enough rainfall to support a forest. Due to limiting factors such as water scarcity and forest fire, a grassland ecosystem changes to a desert ecosystem. The ecological succession of grassland is desert.

Notes:
These types of mechanism have been termed seismonastic movements. The movement occurs when specific regions of cells lose turgor pressure, which is the force that is applied onto the cell wall by water within the cell vacuoles and other cell contents.

Notes:
Bacillus Calmette–Guérin (BCG) vaccine is a vaccine primarily used against tuberculosis. The vaccine was originally developed from Mycobacterium bovis which is commonly found in cows. It is on the World Health Organization’s List of Essential Medicines, the most effective and safe medicines needed in a health system.

Notes:
Anaerobic reactions involve break down of glucose into pyruvic acid, which then reacts to produce lactic acid. As muscle metabolism shifts from aerobic to anaerobic ATP production, lactic acid begins to accumulate in muscles and to appear in the bloodstream. This leads to muscle fatigue with changing pH of muscle cells. C6H12O6 —> 2C3H6O3 + 2ATP

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.