Multiple choice

1. The least usable form of energy is

A. a calorie. 

B. ATP. 

C. food.

D. heat.

2. The energy used by living organisms on Earth comes from

A. the sun. 

B. fossil fuels. 

C. the oceans.

D. volcanoes.

3. A carbon molecule that has a different arrangement of atoms is known as a/an

A. monomer. 

B. peptide. 

C. isomer.

D. nucleotide.

4. Single-celled organisms that do not have a membrane-bound nucleus are called

A. prokaryotes. 

B. organelles. 

C. Golgi bodies.

D. eukaryotes.