A scientist noticed that the number of salamanders in ponds in the Rocky Mountains was declining. This was a (n)

a. hypothesis.

c. observation.

b. theory.

d. control.

Which of the following is NOT needed in a population in order for natural selection to act? a) genetic variation b) a strong body c) overproduction d) a struggle for existence

Which farming practice causes the least harm to the environment? (1) using natural predators to reduce insect numbers (2) adding chemical fertilizers to all the crops in the area (3) planting the same crop for 1 year on all the fields in the area

What are traces or remains of organisms that lived in the past? A. adaptations B. mutations C. traits D. fossils

A scientist claims that volcanic eruptions caused dinosaurs to become extinct at this location. Decide whether you agree or disagree with the scientist's claim and then explain your decision.

What are two important fuels that comes out of the oil refining process?

Which strain of feminism argues that there are biological differences between men and women and that these differences should be appreciated?

Which of the following processes occurs inside the chloroplast of a plant cell? Choose ALL that are correct. (There will be multiple answers) Carbon dioxide is produced. Oxygen is produced. Sunlight is trapped. Glucose (sugar) is produced.

One turn of the citric acid cycle ultimately generates approximately 20 atp.

During an experiment, the same type of bacteria is grown in two petri dishes. Petri dish A has a diameter of 51 mm and has approximately 40,000 bacteria after 1 hour.

In which phase of the cell cycle are cells most often found?