Biology MCQs

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Alzheimer’s disease is a progressive neurologic disease of the brain leading to the irreversible loss of neurons and the loss of intellectual abilities, including memory and reasoning. These with time become severe enough to impede social or occupational functioning. Alzheimer’s disease is also known as simply Senile Dementia.

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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.

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The small intestine, the part of the gastrointestinal tract between the stomach and the large intestine, is the main digester and absorber of food. The small intestine has three distinct regions – the duodenum, jejunum, and ileum–that carry out the absorption of nutrients and minerals from food. It converts the food into a semi-solid mass.

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The largest invertebrate is Mollusc. With over 80,000 species, molluscs form the second largest phylum of animals on Earth and range from tiny snails to giant squid and octopuses.

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Plants and photosynthetic organisms utilize this solar energy in fixing large amounts of CO2 while amounts consumed by human beings are relatively small representing only 10% of the energy converted during photosynthesis. The process of photosynthesis in plants involves a series of steps and reactions that use solar energy, water, and carbon dioxide to produce organic compounds and oxygen.

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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 causes pertussis.

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The presence of air bubble in blood, known as air embolism, occludes blood vessels. The flow of blood is obstructed causing strokes, heart attacks, pulmonary complications. An arterial air embolism is far more dangerous than a venous embolism since it prevents oxygenated blood from reaching the target organ and cause ischemia. It can even lead to heart attack or stroke leading to death.

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Parietal cells (also known as oxyntic cells), are the epithelial cells that secrete hydrochloric acid (HCl) and intrinsic factor. These cells are located in the gastric glands found in the stomach. They contain an extensive secretory network from which the HCl is secreted by active transport into the stomach.

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Acid rain is caused mainly due to oxides of sulphur and nitrogen mixing with rain water making rain water acidic. When calcium carbonate of white marble reacts with acidic water, it results into its corrosion. This is known as “marble cancer”. Our heritage monuments, like the Taj Mahal, are threatened by stone cancer called marble cancer.

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Copper is involved in normalized function of many enzymes, such as cytochrome oxidase, which is complex IV in mitochondrial electron transport chain, These enzymes catalyze reactions for oxidative phosphorylation, iron transportation, antioxidant and free radical scavenging and neutralization, and neurotransmitter synthesis, respectively.