Carbohydrates are major sources of energy for the body and are found in sugars (fruit, cane sugar, beets) and starches (bread, rice, potatoes, pasta).

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.

A population is a group of organisms of the same species who live in the same area at the same time. A community is a group of populations living and interacting with each other in an area.

The speed of a sound wave will vary with the medium. Sound travels fastest through media that has particles that are very close together, like metal. Thus, it travels faster through water than through air and doesn't travel at all through a vacuum (there are no particles in empty space to vibrate).

A warm front is the boundary between warm and cool (or cold) air when the warm air is replacing the cold air. Warm air at the surface pushes above the cool air mass creating clouds and storms.