Photosynthesis & Cellular Respiration

Photosynthesis The process by which a cell captures energy in sunlight and uses it to make food. The process by which a cell captures energy in sunlight and uses it to make food. Nearly all living things obtain energy directly or indirectly from the sun. Nearly all living things obtain energy directly or indirectly from the sun. Autotrophs-An organism that makes its Autotrophs-An organism that makes its own food. Heterotrophs- An organism that cannot Heterotrophs- An organism that cannot make its own food.

Two Stages of Photosynthesis Stage 1- Capturing the Sun’s Energy- This happens inside the chloroplast! Stage 1- Capturing the Sun’s Energy- This happens inside the chloroplast! Plants use energy from the sun to convert CO 2 (carbon dioxide) and H 2 O (water) into O 2 (oxygen) and sugars. Plants use energy from the sun to convert CO 2 (carbon dioxide) and H 2 O (water) into O 2 (oxygen) and sugars. Pigments-Compounds that absorb Pigments-Compounds that absorb light. In plants these are green! Chlorophyll- The main photosynthetic Chlorophyll- The main photosynthetic pigment, found inside chloroplasts.

Stage 2 Using energy to make food- The cell needs H 2 O and CO 2 for this stage. Using energy to make food- The cell needs H 2 O and CO 2 for this stage. The roots of the plant absorb The roots of the plant absorb water. Then H 2 O moves to the chloroplasts. CO 2 enters the plant through CO 2 enters the plant through small openings in the leaves called stomata, then moves to the chloroplasts.

Photosynthesis Equation 6 CO 2 + 6H 2 O –light energy----  C 6 H 12 O O 2 6 CO 2 + 6H 2 O –light energy----  C 6 H 12 O O 2 H 2 O & CO 2 with energy from the sun, go through complex chemical reactions to make O 2 & sugars. H 2 O & CO 2 with energy from the sun, go through complex chemical reactions to make O 2 & sugars.

Respiration Respiration is the process by which cells obtain energy from glucose (sugar). Respiration is the process by which cells obtain energy from glucose (sugar). During respiration, cells break down simple food molecules and release energy. During respiration, cells break down simple food molecules and release energy.

The Two Stages of Respiration Step 1- Takes place in the cytoplasm, occurs without oxygen, and only a little energy is released. Step 1- Takes place in the cytoplasm, occurs without oxygen, and only a little energy is released. Step 2- Takes place in the mitochondria, requires oxygen, and release a lot of energy. Step 2- Takes place in the mitochondria, requires oxygen, and release a lot of energy.

The Respiration Equation C 6 H 12 O O  6 CO H 2 O + Energy C 6 H 12 O O  6 CO H 2 O + Energy The raw materials (or reactants) for respiration are sugar and oxygen. The raw materials (or reactants) for respiration are sugar and oxygen. The process of cellular respiration produces CO 2, H 2 O, and energy! The process of cellular respiration produces CO 2, H 2 O, and energy!

Comparing Photosynthesis and Respiration How do the equations for photosynthesis and respiration relate to each other? How do the equations for photosynthesis and respiration relate to each other?

Review Questions Why do living things need energy? Why do living things need energy? What is the primary source of energy for all living things? What is the primary source of energy for all living things? What are the substances needed for cellular respiration? What are the substances needed for cellular respiration? What substances are produced during photosynthesis? What substances are produced during photosynthesis? Explain why cellular respiration adds carbon dioxide to the atmosphere, but photosynthesis does not. Explain why cellular respiration adds carbon dioxide to the atmosphere, but photosynthesis does not.