General Science Mixed Quiz: Set 198

Using v² = u² − 2gh with final velocity zero at the top, u = √(2gh) = √(2 × 10 × 20) = √400 = 20 m/s. A ball thrown straight up slows down under gravity until its velocity becomes zero at the highest point.

Syngamy is the fusion of a male and a female gamete, and since each gamete is haploid, their union gives a diploid zygote.

Rearranging Newton's law of gravitation gives G = F r² / (m₁ m₂), so its unit is newton × metre² ÷ kilogram².

The antibodies, mainly of the IgA class, come ready-made in the first milk, the colostrum, and the child's own immune system does no work, which is why the protection begins at once and lasts only a few months; antibodies of the IgG class reach the foetus through the placenta in…

Sound is a mechanical wave, so it needs a medium, and in air its particles vibrate along the direction of travel.

Isoenzymes, also called isozymes, are different molecular forms of an enzyme that speed up the same chemical reaction but differ in their amino acid sequence.

The human body conducts electricity because its fluids contain dissolved salts that break up into ions, and these ions carry current.

A geostationary satellite is placed in a circular orbit about 35,786 kilometres above the equator, where its period of revolution equals the period of rotation of the earth about its axis, and it moves from west to east like the earth, so it appears to stay over the same point…

Valency is the combining capacity of an atom, and it is decided by the valence electrons it gains, loses or shares to complete its outer shell.

It is the only surviving species of its order, has remained almost unchanged for many millions of years and is known from fossils of the age of the dinosaurs, which is why it is called a living fossil; it is a gymnosperm with fan-shaped leaves, grown widely as an ornamental…

Functional group isomers have the same molecular formula but different functional groups. Alkyl halides such as C2H5Cl can only contain the halogen group, so no other functional group can be built from the same formula; they show chain and position isomerism instead.

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.

These two organelles carry their own circular DNA and their own small (70S) ribosomes, so they can make some of their own proteins.

By mass, an adult human body has the most oxygen, then carbon, hydrogen and nitrogen. Oxygen makes up about 65 percent of body mass, carbon about 18 percent, hydrogen about 10 percent and nitrogen about 3 percent.

Amphibians and most reptiles have a heart with three chambers: two atria and one ventricle. In frogs and toads, oxygen-rich blood from the lungs and oxygen-poor blood from the body both reach the single ventricle, so some mixing takes place.

Bombyx mori is the mulberry silkworm, the insect reared in sericulture, whose larva spins the cocoon from which mulberry silk is reeled, and the word mori refers to the mulberry on whose leaves it feeds.

Estrogen, made mainly by the ovaries, brings about the female secondary sexual characters at puberty. At puberty the pituitary releases FSH and LH, which stimulate the ovaries to secrete estrogen.

Vitamin K is needed by the liver to make prothrombin and other clotting factors, without which blood does not clot properly.

A disease that stays constantly present at a steady baseline level in a particular area, without being brought in from outside, is called endemic.

Analogous structures do the same job but evolved separately, and the wings of birds and bats are a standard example.