Chapter 8.1 Assessment

1.C. Explain how ADP and ATP are each like a battery. Which one is "partially charged" and which one is "fully charged?" Why?

ADP and ATP are like batteries because they store energy in the chemical bonds they contain. ADP has only two phosphate groups (and fewer bonds), so it's like a par- tially charged battery. ATP has three phos- phate groups, so it is like a fully charged battery and has more bonds available for energy storage.

1.A. What is ATP and what is its role in the cell?

ATP is an abbreviation for the compound adenosine triphosphate. Cells use ATP to store and release energy.

1.B. How does the structure of ATP make it an ideal source of energy for the cell?

ATP can easily release and store energy by breaking and re-forming the bonds between its phosphate groups.

2.B. How do heterotrophs obtain energy? How is this different from how autotrophs obtain energy?

Heterotrophs obtain energy by feeding on other living things. Autotrophs, by contrast, make their own food.

2.A. What is the ultimate source of energy for plants?

Sunlight.

2.C. Why are decomposers, such as mushrooms, considered heterotrophs and not autotrophs?

Decomposers consume the remains of living things for energy and cannot make their own food.