Scientific investigations most often start from observations of the natural world and which of the following?

A) model

B) computers

C) variable

D) questions

Genes which code for transcription factors can have a large influence on gene expression. Mutations in genes that control gene expression can have large and sudden effects on the evolution of species.

How many cell we have in human body

Animal cells and bacterial cells both may have all of the following cell structures except a. mitochondria. b. DNA. c. plasma membrane. d. flagella.

Because the Earth's orbit around the Sun is elliptical, A) Earth is not round in shape, but slightly dented near the poles. B) the distance between the Sun and Earth does not remain the same all the time. C) Earth's axis is tilted 23.

When looking at the clouds, you can usually make out different shapes and figures with what?

Contamination of food items by other living organisms is a known as

Minerals are naturally occurring, inorganic solids that have a crystalline structure and a definite chemical composition. True or False

What does it mean for an organism to be anaerobic? a. It is poisoned by water. b. It lives in salty environments. c. It is poisoned by oxygen. d. It produces large amounts of oxygen.

Chorionic villi sampling (CVS) is a test to determine whether fetal cells have genetic abnormalities and can be performed as early as 8 weeks. Chorionic villi cells are removed using a small tube that is passed through the cervix.

The largest carbon source is