How many insect species are there in 2017?

There are at least 900,000 species, but many more probably have yet to be discovered. Insects all have bodies consisting of a head, a thorax of three segments, usually three pairs of legs and often one or two pairs of wings. Their heads have compound eyes and long antennae that are sensitive to touch and smell.

this age may represent the age of the earth's accretion, of core formation, or of the material from which the earth formed. this dating is based on evidence from radiometric age-dating of meteorite material and is consistent with the radiometric ages of the oldest-known terrestrial and lunar samples.

b tumor cells have a cell wall instead of a membrane

explanation:

tumor cells different from normal cells because tumor cells have a cell wall instead of a membrane.