Chapter 7.1 Summary

Sunlight powers life

• All organisms need food
• Autotrophs: make their own food by converting inorganic molecules into organic molecules
• Photosynthesis: using the sun's energy to convert water and carbon dioxide into sugars
• Producers = autotrophs
• Heterotrophs: obtain food by eating producers or other consumers
• Consumers = heterotrophs
• Harvest energy from food through cellular respiration
• Cellular respiration: a chemical process that converts chemical energy into ATP using oxygen
• ATP is the main energy supply for plants and animals
• Photosynthesis and cellular respiration recycle water, carbon dioxide, oxygen, and organic compounds like glucose
• Photosynthesis uses water and carbon dioxide to produce glucose and oxygen
• Cellular respiration uses oxygen to produce carbon dioxide and water

Concept Check 7.1

1. Define autotroph and heterotroph, and give an example of each.

An autotroph is an organism that produces its own food and a heterotroph is an organism that gets its food by consuming autotrophs or other heterotrophs. An example of an autotroph is a dandelion while an example of a heterotroph is a hippopotamus.

2. Explain the role of food (glucose) in both photosynthesis and cellular respiration.

Glucose is where the energy comes from. Photosynthesis is a process that creates glucose while cellular respiration is a process to convert the energy from glucose into ATP.

3. Explain how life on Earth depends on the sun.

Life on Earth depends on the sun because consumers depend on producers for sustenance. Producers need the sun's energy to get food through the process of photosynthesis. So without the sun, producers would perish which, in turn, would cause the consumers to starve to death.