Photosynthesis and Cellular Respiration 7 th Grade Science Kleb Intermediate School

Photosynthesis  The process of capturing light energy, converting it to chemical energy, storing it by manufacturing sugars  “photo” – light  “syn” – with, together  “thesis” – arranging

Ultimate source of energy  Sunlight Almost everything we eat can be traced back to the sun as the primary energy provider  Plants, algae, and bacteria capture about 1 % of the light energy that reaches the Earth

Chloroplasts  Site of photosynthesis  About ½ million chloroplasts per square millimeter  Pigment is made of a porphyrin ring (light absorbing head) and a hydrocarbon tail Ring - Mg atom encircled by a series of Nitrogen and Carbon atoms

Chlorophyll  Primary pigment involved in photosynthesis  Absorbs mostly red and blue wavelengths  Reflects green and yellow wavelengths causing the plant to look green

Reactants of photosynthesis  Carbon dioxide Enters through the stomata (pores in the leaves)  Water Absorbed into the plant through the roots Products of photosynthesis  3 Carbon sugar  Oxygen gas

Photosynthetic equation  Carbon dioxide plus water in the presence of light yields 3 carbon sugar plus oxygen  3 CO H 2 O  C 3 H 6 O O 2

Factors affecting Photosynthesis  Light  CO 2 concentration  Temperature – enzymes inactivate outside of a certain temperature range

Cellular respiration  Transfers energy from organic compounds to ATP  Heterotrophs obtain organic compounds from feeding  Autotrophs obtain organic compounds as a product from photosynthesis  Takes place in the mitochondria  Known as aerobic respiration since the reactant occurs in the presence of oxygen

Reactants of Cellular respiration  C 6 H 12 O 6 (glucose) Ingested by heterotrophs Produced in photosynthesis  Oxygen gas Produced by splitting water molecules in stage one Heterotrophs must bring in oxygen from the outside

Products of Cellular respiration  CO 2  H 2 O  Energy (ATP) Cellular Respiration equation  Glucose plus oxygen in the presence of enzymes yields carbon dioxide plus oxygen plus energy  C 6 H 12 O O 2  6 CO H 2 O + energy

PNSCR ReactantsCO 2 H 2 O Glucose (sugar) O 2 ProductsSugars O 2 CO 2 H 2 O Driving ForceLightEnzymes OrganelleChloroplastMitochondria PurposeUses ATP to create sugars Uses sugars to create ATP