The biosphere is the global ecological system integrating all living beings and their relationships. This includes their interactions with the lithosphere (the rigid outer part of the earth, consisting of the crust and upper mantle), hydrosphere (all surface water), and atmosphere (the envelope of gases surrounding the planet).

Radiation occurs when electromagnetic waves transmit heat. An example is the heat from the Sun as it travels to Earth.

An element is matter than cannot be separated into different types of matter by ordinary chemical methods.

Convection is the transfer of heat by the circulation or movement of the heated parts of a liquid or gas.

Reproductive (haploid) cells known as gametes have half as many (23) pairs of chromosomes as normal (diploid) cells. When the male gamete (sperm) combines with the female gamete (ovum) through meiosis to form a zygote, each gamete supplies half the chromosomes needed to form the normal diploid cells.