General Science Mixed Quiz: Set 127

Cells made by the meristem lose the ability to divide and take on a fixed shape, size and job, and this change is called differentiation.

The liver weighs about one and a half kilograms and is both the largest gland and the largest internal organ of the body; it secretes bile, stores glycogen, iron and vitamin A, converts ammonia into urea and detoxifies drugs and poisons.

Argon is chemically inert, so the hot tungsten filament does not react with it, and its presence also slows the evaporation of tungsten, which is why bulbs are filled with argon, sometimes mixed with nitrogen, instead of being left as a vacuum.

The 2011 FSSAI labelling rules made the list of ingredients, nutrition information and the vegetarian or non-vegetarian mark compulsory, but not medical advice on allergies.

Red blood cells are produced in the red bone marrow, lose their nucleus on maturing and survive roughly four months, after which they are broken down in the spleen, which is accordingly called the graveyard of red blood cells; the iron released from their haemoglobin is used again.

Meiosis halves them in the gametes, and fertilisation restores them in the offspring. Each parent makes gametes by meiosis, so a human egg or sperm carries 23 chromosomes instead of 46.

Mitochondria carry their own small, circular DNA and their own ribosomes. Mitochondria are the powerhouses of the cell, where aerobic respiration makes ATP.

A hydrogen bomb, also called a thermonuclear bomb, works in two steps. A fission explosion of uranium or plutonium produces the temperature of millions of degrees needed to force light nuclei together, and the fusion of those nuclei then releases far more energy than the fission stage alone.

When an electric discharge is passed through neon at low pressure it glows a bright reddish orange, which is why the tubes of advertising signs and warning lights are filled with it, and the name neon sign has stuck to such tubes whatever gas they now contain.

Dolly was a sheep produced at the Roslin Institute in Scotland in 1996 by the technique of somatic cell nuclear transfer, in which the nucleus of an udder cell of one sheep was placed in an egg whose own nucleus had been removed, so the lamb carried the genes of…

The Austrian scientist Karl Landsteiner discovered the A, B and O blood groups in 1901 and received the Nobel Prize for Physiology or Medicine in 1930 for the work; he was also associated with the discovery of the Rh factor, named after the rhesus monkey.

In a class 3 lever the effort is applied between the fulcrum and the load, so the effort always sits nearer the fulcrum and its arm is the shorter of the two.

Carbon dioxide reacts with lime water, a solution of calcium hydroxide, to form insoluble calcium carbonate, whose fine white particles make the liquid look milky; if more of the gas is passed the milkiness disappears as soluble calcium bicarbonate is formed, and that second step is often the harder half…

The pinna is the outer, visible flap of the ear, and its funnel shape collects sound from the surroundings. Sound gathered by the pinna travels down the ear canal to the tympanic membrane, or eardrum, which starts to vibrate.

The cerebellum lies behind and below the cerebrum and coordinates voluntary muscular activity, so it keeps the body balanced and the posture steady; damage to it causes a staggering walk even though the muscles are strong.

When cells are joined in parallel all their positive terminals are connected together and all their negative terminals together, so each cell is across the same two points and the voltage of the combination is the voltage of one cell, that is 12 volts.

In the Haber process nitrogen from the air and hydrogen are combined under high pressure at a few hundred degrees Celsius over a catalyst of finely divided iron, and the ammonia so made is the starting point of nitrogenous fertilisers such as urea and of nitric acid.

The islets of Langerhans are patches of endocrine tissue in the pancreas, and their beta cells secrete insulin, which lowers the level of glucose in the blood by helping cells take it up and by storing the surplus as glycogen; a lack of insulin causes diabetes mellitus.

Compressed natural gas is mainly methane, the simplest hydrocarbon, and biogas from a gobar gas plant is also mostly methane along with carbon dioxide, produced by the anaerobic decay of organic matter; methane is also called marsh gas because it bubbles up from waterlogged ground.

Each kidney contains about a million nephrons, and each nephron consists of a Bowman's capsule enclosing a knot of capillaries called the glomerulus, followed by a tubule in which useful substances are reabsorbed; together they filter the blood and form urine.