Why are index fossils good indicators of geologic time? A. They are rare.

B. They lived during a short period of geologic time.

C. They lived during a long period of geologic time,

D. They lived with humans,

True or false: (a) the strings of little red dots represent carbohydrates. (b) the model is called a bilayer because there are two main types of molecules present, lipids and proteins. (c) the many black lines represent amino acid tails. (d) this model shows membrane transport. (e) the blue ovals are hydrophobic. (f) the blue ovals represent phospholipid heads.