science & technology Online Quiz - 248

Platelets (thrombocytes) are cell fragments responsible for blood clotting. They form plugs at injury sites and release clotting factors. Red blood cells transport oxygen, white blood cells fight infection, and lymph nodes are immune system organs - none of these handle clotting.

A hurricane is a rotating storm system with winds exceeding 75 mph (119 km/h). The term specifically refers to tropical cyclones in the Atlantic and Northeast Pacific. Tornadoes are different storm types, and 'cyclone' has regional naming conventions. 'Gustnado' is a smaller, short-lived phenomenon.

Hippos are the closest living relatives of whales among land mammals. Both belong to the order Artiodactyla (even-toed ungulates). Genetic and fossil evidence shows whales evolved from early artiodactyls, making hippos their nearest terrestrial cousins. Warthogs are also artiodactyls but more distant.

Proteins are present in every part of your body - muscles, organs, skin, hair, enzymes, hormones, and even bone matrix. They are structural components and functional molecules. Fat is stored in adipose tissue, starch comes from plants, and sugar is mainly in blood - they aren't everywhere.

The pituitary gland is called the 'master gland' because it produces hormones that regulate other endocrine glands like the thyroid, adrenal glands, and reproductive organs. The pineal gland regulates sleep cycles, the pancreas produces insulin and digestive enzymes, and while the brain controls everything, it's not typically called the 'master gland' in endocrine contexts.

The iris is the colored part of the eye that contains muscles to control the size of the pupil, regulating light entering the eye. The cornea is the clear front surface, the pupil is the black opening in the center, and the lens focuses light behind the pupil.

A catheter is a flexible tube inserted into the body to inject fluids (like medication) or withdraw fluids (like urine or blood). It is commonly used in medical procedures for drainage, administration of treatment, or diagnostic purposes.

Momentum is defined as the product of an object's mass and its velocity (p = mv). This is a fundamental concept in physics describing the quantity of motion. Energy, Force, and Acceleration are related but distinct quantities - Energy is 1/2 mv^2 for kinetic energy, Force equals mass times acceleration (F=ma), and Acceleration is the rate of velocity change.

Dietary fiber consists of plant-based carbohydrates that human digestive enzymes cannot break down. Unlike sugars, starches, and proteins that get digested and absorbed, fiber passes through the digestive system largely intact. This is actually beneficial: it adds bulk to stool, promotes regular bowel movements, and supports gut health. 'Inorganic' refers to minerals, not indigestible food components. 'Fibroids' are benign tumors (muscle tissue), not food components. 'Tumors' are abnormal tissue growths, unrelated to nutrition.

The chemical symbol 'Pb' represents lead (atomic number 82). This symbol comes from the Latin word 'plumbum,' which is why lead's chemical symbol is Pb instead of something based on its English name. Plutonium's symbol is 'Pu.' Phosphorus is 'P.' There is no element named 'Bhorium'; this appears to be a distractor mixing 'Bohr' (as in Niels Bohr) with element naming conventions. Lead is a heavy metal known for its density and former use in pipes and paints.

Albert Einstein developed the Theory of Relativity, published in 1905 (Special Relativity) and 1915 (General Relativity). Isaac Newton developed classical mechanics and gravity, not relativity. Marie Curie discovered radioactivity and polonium/radium. Benjamin Franklin was a statesman and scientist known for electricity experiments, not relativity.

Mercury orbits fastest because it's closest to the Sun (about 58 million km vs Earth's 150 million km). According to Kepler's laws, orbital speed decreases with distance. Mercury's average orbital speed is about 47.9 km/s, compared to Earth's 29.8 km/s. Saturn and Uranus are much farther and slower; Mars averages 24.1 km/s.

The liver is the largest internal organ by weight, averaging 1.4-1.6 kg in adults. It performs vital functions including detoxification, protein synthesis, and bile production. The skin is actually the largest organ overall by weight and surface area, but among internal organs listed, the liver dominates. The brain weighs about 1.3-1.4 kg, making it second among internal organs.

For a nut failing due to thread shear, the shear area is calculated as the circumference of the thread (pi x d) multiplied by the thickness of the nut (t). So A_shear = pi x d x t = 3.14 x 12 x 10 mm^2. This represents the cylindrical surface area of the threads that shears. Options A, C, and D use incorrect formulas.

In bolt grading systems like ISO 898, class 12.9 means: 12 = ultimate tensile strength (1200 MPa minimum, first digit × 100), 9 = yield strength ratio (90% of ultimate tensile strength, second digit × 10%). This is standard mechanical engineering notation for bolt strength properties.

Bearing pressure is calculated as load divided by projected bearing area. For a journal bearing, the projected area is diameter times width (not the circular cross-sectional area). So pressure = 40N/(20mm × 30mm) = 40/(20×30) N/mm².

Amazon is an e-commerce platform, not a social networking site. Myspace, Orkut, and Twitter are all social networks where users primarily connect and share content with others. The question asks to identify the exception - Amazon's core purpose is retail transactions, not social interaction.

Gordon E. Moore was indeed one of the original founders of Intel Corporation in 1968, along with Robert Noyce. He is famous for 'Moore's Law' which predicted the exponential growth of transistor density. The other options are founders of other major tech companies: Gates (Microsoft), Yang (Yahoo), and Brin (Google).

Molex connectors are the standard 4-pin power connectors used to supply power to CD-ROM drives, DVD drives, and other internal drives in computers. DB-15 is for video/game ports, PS/2 is for keyboard/mouse, and RJ-11 is for telephone connections. Molex connectors provide the 12V and 5V power rails that optical drives require.