General Science GK Questions with Answers – Page 9

All rose plants of one kind belong to a single species, the basic unit of classification. A species is a group of individuals that are alike in their main features and can interbreed in nature to produce fertile offspring.

The English physicist James Prescott Joule showed around 1841 that when a current flows through a conductor, the heat produced is proportional to the square of the current, the resistance of the conductor and the time for which the current flows.

As blood flows through the thin-walled capillaries, part of its plasma, with small proteins and some white blood cells, leaks out into the spaces between cells.

Algae are the predominantly aquatic members of the Kingdom Plantae. They are simple, chlorophyll-bearing organisms with a thallus body that is not divided into true roots, stems and leaves.

A plane mirror is a spherical mirror of infinite radius of curvature, so its focal length f = R/2 is also infinite.

The pituitary releases FSH and LH, and the ovary responds with estrogen and progesterone; together these hormones run the cycle.

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.

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.

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

The thyroid gland needs iodine to make thyroxine, so iodized salt keeps this hormone in supply. Thyroxine (T4) contains four iodine atoms in each molecule, and the thyroid cannot make it without iodine from food.

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

Ultraviolet light is an electromagnetic wave, and all electromagnetic waves are transverse, not longitudinal. In an electromagnetic wave, the electric and magnetic fields vibrate at right angles to each other and to the direction in which the wave travels, which is the mark of a transverse wave.

The word fission is used in two sciences: in biology for splitting of a single-celled organism, and in physics for splitting of a heavy nucleus.

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

Neutrons sit inside the nucleus with protons; it is the electrons that move around the nucleus. The neutron was discovered by James Chadwick in 1932, and he received the Nobel Prize in Physics for it in 1935.

Resistivity is a property of the material and its temperature, not of the wire's shape, so every copper wire has the same resistivity.

Sulphuric acid has two replaceable hydrogen atoms, so its equivalent mass is 98 ÷ 2 = 49 g, and 49 g in one litre makes exactly one gram-equivalent per litre.

Gravitational force varies inversely with the square of the distance, so doubling the distance cuts the force to one-fourth.

Iodine is a non-metal, yet its solid crystals have a shiny, metallic lustre, which makes it the standard exception taught in school chemistry.

The cervix is the narrow lower neck of the uterus and belongs to the female reproductive system. In the male, sperms are made in the testes, which lie in the scrotum outside the body because sperm formation needs a temperature a little lower than body temperature.