Which is a function performed by stem cells in the skin?

a. growing new organsb. making cells for the intestines

c. differentiating into brain cells

d. replacing lost skin cells

How do humans increase the natural amount of carbon dioxide in the atmosphere

What is the dark crumbly high organic part of soil?

Which of the following is true about cells? A. In general, prokaryotic cells do not have a true nucleus or membrane-bound organelles, whereas eukaryotic cells contain both a nucleus and organelles enclosed by membranes. B.

All living organisms are composed of A. only one cell. B. at least three cells. C. at least 100 cells. D. one or more cells.

Missense, nonsense, and silent mutations are examples of which type of mutation? A) substitution B) insertion C) deletion D) replication

How does science works

Of the following, which is NOT characteristic of vascular plants? A cell walls B roots C Limited range in height D xylem

What causes the phases of the moon?

Dolphins lack vocal cords, nevertheless creating aounds: a complicated system of whistles, squeaks, moans, trills, and clicks are produced by

Which diagram correctly labels the four layers of the earth