science & technology Online Quiz - 253

The brain itself lacks pain receptors (nociceptors), so brain tissue cannot feel pain. Headaches and brain pain sensations actually come from pain receptors in the meninges, blood vessels, and surrounding structures, not from brain tissue.

Unlike the liver and muscles which store significant glucose as glycogen, brain tissue (neurons) cannot store glucose. The brain depends entirely on continuous blood glucose delivery, though astrocytes can store very small amounts of glycogen.

The tonsure is the practice of shaving or cutting some or all of the hair on the scalp as a sign of religious devotion or humility. It is traditionally associated with monks in various religious traditions, particularly in Christianity (Catholic and Orthodox monasticism).

The atomic number is defined as the number of protons in the nucleus of an atom. This is a fundamental property that determines an element's identity and its position in the periodic table. Atomic mass includes both protons and neutrons.

A neonatologist is a medical doctor who specializes in the care of newborn infants, particularly those who are ill or born prematurely. They work in neonatal intensive care units (NICUs) and treat infants, not adults.

A dust devil is a strong, well-formed, and relatively short-lived whirlwind that forms from surface heating. Unlike tornadoes or cyclones, dust devils are typically small-scale phenomena that occur on clear days when the ground heats the air above it, causing it to rise rapidly.

Troy weight is a traditional system of mass measurement used specifically for precious metals like gold, silver, and platinum. It originated in medieval England and is distinct from avoirdupois weight used for general goods. Liquids are measured by volume, fossil fuels by various weight systems, and medicines use apothecary or metric systems.

Type O blood lacks A and B antigens on red blood cells, making it compatible with all other blood types in transfusions. This is why Type O individuals are called universal donors. Type A can only donate to A and AB, Type B only to B and AB, and Type AB can only donate to AB.

In the liver's urea cycle (ornithine cycle), toxic ammonia (NH₃) combines with carbon dioxide (CO₂) to form urea, which is then excreted by kidneys. This is the primary pathway for nitrogen waste removal in humans. HCl is stomach acid, chromium is a mineral, and ammonium dioxide is not a biological product.

Bats are the only mammals capable of true powered flight. Others like flying squirrels or sugar gliders glide but cannot fly. Owl, pheasant, and pelican are birds, not mammals, and all birds can fly.

Sunspots are dark, cooler areas on the photosphere (visible surface) of the Sun caused by concentrated magnetic fields inhibiting convection. They appear as dark spots against the brighter surrounding photosphere. Black holes are cosmic objects, red giants are star types, and nebulae are gas clouds.

Echography (ultrasound imaging) is used by medical doctors for diagnostic imaging, particularly in obstetrics, cardiology, and abdominal examinations. It uses high-frequency sound waves to create images of internal body structures. Seismologists study earthquakes, astronomers study celestial objects, and geologists study Earth's physical structure.

Cinnabar is mercury(II) sulfide (HgS), the primary ore of mercury. Clay is a sedimentary material used in ceramics, cinnamon is a spice derived from tree bark, and ethanol is an alcohol compound - none are mineral sources of mercury.

Avogadro's number (6.022 x 10^23 mol^-1) represents the number of particles in one mole of a substance. Option A uses an incorrect coefficient (2.066), option B has the wrong exponent (10^32 instead of 10^23), and option C has both incorrect coefficient and formatting.

Calving is the scientific term for when ice chunks break off from a glacier or ice shelf to form icebergs. 'Breaking' is too generic, while 'Borning' and 'Cubing' are not recognized glaciological terms.

The cheetah is the fastest land animal, capable of reaching speeds up to 60-70 mph in short bursts. Lions are fast but not as quick as cheetahs. Zebras are prey animals and 'none' is incorrect.

White blood cells (leukocytes) are the primary cells of the immune system that protect the body from infection and disease. Red blood cells carry oxygen, nerve cells transmit signals, and platelets help with blood clotting (option D is misspelled).

All elements are composed of atoms, which are the smallest unit of matter that retains the chemical properties of an element. Metals, ions, and compounds are not fundamental building blocks of elements.

The Wright Brothers (Orville and Wilbur Wright) invented and flew the first successful airplane in 1903. They are credited with pioneering controlled, sustained flight.

DC (Direct Current) power supply has zero frequency because the current flows in one direction only and does not alternate periodically like AC (Alternating Current).