General Science Questions (MCQs) for Competitive Examinations

Notes:
Cyanobacteria, also known as blue green algae, are single-celled and belong to the family of Prokaryotes. That means, they do not have a well defined cell nucleus. The ability of cyanobacteria to perform oxygenic photosynthesis is thought to have converted the early reducing atmosphere into an oxidizing one, which dramatically changed the composition of life forms on Earth by stimulating biodiversity and leading to the near-extinction of oxygen-intolerant organisms.

Notes:
Enzymes are defined as biological catalysts. Chemically all enzymes are globular proteins. Each enzyme catalyses only one chemical reaction. Protein part of enzyme is known as Apoenzyme. It forms an active enzyme system by combination with a coenzyme and determines the specificity of this system for a substrate.

Notes:
Bacteriophage refers to any of a group of viruses that infect bacteria. Bacteriophages were discovered independently by Frederick W. Twort in Great Britain (1915) and Felix d’Herelle in France (1917). D’Herelle coined the term Bacteriophage, meaning “bacteria eater”.

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:
Vermicomposting is the process of using worms also called red worms and micro-organisms to turn kitchen waste into black, earthy-smelling, nutrient-rich humus. Vermicompost is an excellent, nutrient-rich organic fertilizer and soil conditioner.

Notes:
Cotton is the most popular of the BT crops. In BT cotton, BT gene was isolated and transferred from a bacterium Bacillus thurigiensis to American cotton. The American cotton was subsequently crossed with Indian cotton to introduce the gene into native varieties. The BT cotton variety contains a foreign gene obtained from Bacillus thuringiensis. This bacterial gene, introduced genetically into the cotton seeds, protects the plants from bollworm (A. lepidoptora), a major pest of cotton.

Notes:
The process of breaking down large molecules into simpler one in the presence of enzyme is called fermentation. Alcoholic fermentation is a complex biochemical process during which yeasts convert sugars to ethanol, carbon dioxide, and other metabolic byproducts that contribute to the chemical composition and sensorial properties of the fermented foodstuffs.

Notes:
Motor skills are needed to control the movements of the different muscles in the human body. The frontal lobe plays a large role in voluntary movement. It houses the primary motor cortex which regulates activities like walking. The frontal lobes are also involved in problem solving, spontaneity, memory, language, initiation, judgement, impulse control, etc.

Notes:
The eustachian tube is a canal that connects the middle ear to the nasopharynx. It controls the pressure within the middle ear, making it equal with the air pressure outside the body. The cochlear nerve is also known as the acoustic nerve. It transfers auditory information from the cochlea (auditory area of the inner ear) to the brain. The malleus transmits the sound vibrations from the eardrum to the incus, and then to the stapes.

Notes:
Herbivorous animals have longer intestines than that of carnivorous animals. This is because their diet is grass and plants, made up of fibre and cellulose which are hard to digest. As a result, the herbivorous animals need a longer digestive track to digest their foods completely.