Chapter 7.1 Sunlight Powers Cells

Obtaining Food

Autotrophs self-feeders They make their own food from chemicals and the sun. Autotrophs are always producers and create sugars. Plants and algae are the best examples.

Autotrophs use photosynthesis to make their sugars.

heterotrophs! Heterotrophs Heterotrophs need to eat organisms to get their energy. They are always consumers. Humans are…? heterotrophs!

HARVESTING ENERGY IN FOOD

Cellular respiration is a chemical process where sugar is broken into chemical energy. ATP (adenosine triphosphate) is a molecule that holds the energy. ATP is then used as an energy source. Producers and consumers use ATP.

Photosynthesis and cellular respiration use common chemicals: water carbon cioxide oxygen organic compounds like glucose

Active Activity Squeeze a tennis ball as many times as you can for one minute. How did your hand feel at the beginning? How did your hand feel at the end?

What is happening to the muscles in your hand? The muscles are requiring more oxygen than the blood can deliver (oxygen debt). As oxygen levels decrease, the muscle cells form lactate, which causes discomfort or pain.

How do swimmers overcome lactate buildup as they near the end of a race? Initially, creatine phosphate powers the muscles during the race. However, near the end of the race, the swimmer uses rapid breathing to restore the oxygen supply to the muscles. The lactate diffuses out of the muscles and into blood where it be carried to the liver for conversion to glucose. The glucose is transported back to the muscle cells for cellular respiration to synthesize ATP which is used to regenerate creatine phosphate.

Another Perspective glucose ATP Which is easier to spend? Which do you usually have to “break” to use it?

Solar-Powered Life Is my life solar-powered too? On paper, draw a diagram tracing the energy stored in the egg I ate for breakfast back to the sun.

sunlight corn hen egg me light energy from sun chemical energy in the molecules due to photosynthesis hen Chemical energy in the molecules due to eating corn egg Chemical energy due to coming from the hen me Energy to dance due to energy from egg

Answer with a partner: Define autotroph and heterotroph and give an example of each. Explain the role of food (glucose) in both photosynthesis and cellular respiration. Explain how life on Earth depends on the sun.