General Science Questions (MCQs) for Competitive Examinations

Notes:
A heart attack occurs when blood flow to a part of your heart is blocked for a long enough time that part of the heart muscle is damaged or dies. The medical term for this is myocardial infarction. Most heart attacks are caused by a blood clot that blocks one of the coronary arteries. The coronary arteries bring blood and oxygen to the heart. If the blood flow is blocked, the heart is starved of oxygen and heart cells die.

Notes:
During hibernation in winter, toads or frogs spend the time tucked away deep in the soil, in the mud underwater or hidden amidst foliage or rotting plants. Outside of times of hibernation, they usually take in oxygen via the air, employing their lungs. However, during hibernation, they receive their necessary oxygen through their permeable skin. This is referred to as cutaneous gas exchange.

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:
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:
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:
Black soil is most suitable for the cultivation of cotton. The deep and medium black lava soil of the Deccan and Malwa plateaus is considered ideal, though it can be grown on alluvial and red soil as well. The black cotton soil is also known as regur.

Notes:
The Rock Dove (Columba livia) or Rock Pigeon, is a member of the bird family Columbidae (doves and pigeons). In common usage, this bird is often simply referred to as the “pigeon”. The species includes the domestic pigeon (including the fancy white pigeon).

Notes:
DPT refers to a class of combination vaccines against three infectious diseases in humans: diphtheria, pertussis (whooping cough), and tetanus. The vaccine components include diphtheria and tetanus toxoids and killed whole cells of the organism that cause pertussis (wP).

Notes:
When a DNA solution is heated enough, the double-stranded DNA unwinds, and the Hydrogen bonds that hold the two strands together weaken and finally break. The process of breaking a double-stranded DNA into single strands is known as DNA denaturation, or DNA melting. The hyper-chromicity of DNA occurs when the DNA duplex is denatured.

Notes:
Ethanol fermentation, also called alcoholic fermentation, is a biological process which converts sugars such as glucose, fructose, and sucrose into cellular energy, producing ethanol and carbon dioxide as by products. It is an anaerobic process since Yeasts perform this conversion in the absence of oxygen.