In a controlled experiment, why must all of the variables, except one, be kept constant throughout the experiment

An example of nautural selection is the tail of a male peacock. The female of the species choose to mates based on the colors of the males' tale feathers.

Which factor divides freshwater ecosystems into two main types? a. depth C. water movement b. temperature d. presence of animals

3.2d - 17.88 = - d + 30

Skin does all of the following except: A. absorb water. B. protect from the sun's rays. C. stop bacteria from entering the body. D. keep dirt out.

Muscles make up more than how much of a person's body mass? A. 10% B. 25% C. 40% D. 75%

Can energy be transferred from animal to animal

The more stomata the more water loss?

Why does it take a long time to develop a new variety of tomato? A. Changes in traits happen gradually, over many generations. B. Many plants resist change. C. Tomatoes cannot acquire new traits. D. A species cannot change over time.

Select the one true statement. Vacuoles store nutrients, water, and waste in animal cells. Plant cells can have chloroplasts but do not have a cell wall.

Using water more effectively A. Protects the environment B. Causes the loss of natural pollution filters C. Increases with contamination D. All of the above