PHOTOSYNTHESIS CH 8

I. How organisms obtain food Without the ability to obtain and use energy, life would cease to exist

Autotrophs – Producers – Make glucose by photosynthesis – Plants, algae, some bacteria Heterotrophs – Consumers – Consume food – Animals, fungi, most bacteria

II. Food and Energy A. Energy Ability to do work 2 forms – Potential energy Stored energy – Kinetic energy Energy used for work

Thermal energy: a form of kinetic energy where energy is lost as heat Chemical energy: a type of potential energy where energy is stored in molecules

B. Using Chemical Energy 1. Energy and Molecules Where in a molecule is energy stored?

2. 2 types of chemical reactions:

Exergonic reactions: – Break down large molecules releasing energy – Cell respiration is exergonic – Catabolic reactions are exergonic Endergonic reactions: – Build up large molecules using energy – Photosynthesis is endergonic – Anabolic reactions are endergonic

C. ATP: The Energy Molecule of Cells The ATP cycle:

Bond between the last 2 phosphates is high energy When that bond is broken, energy is released When that bond is made, energy is absorbed

What does cell use ATP for? o/3421/ATP-cycle h?v=AhuqXwvFv2E

II. Overview of Photosynthesis 6C H 2 0 → C 6 H 12 O 6 + 6O 2

Requires: – Light – Co2 – Water Produces: – Oxygen – Sugar Occurs in 2 stages: – Light dependent reaction – Light independent reaction

What is the purpose of the light dependent reactions? What is the purpose of the light independent reactions?

1. Light Light is a mixture of different wavelengths. How come only 1% of solar energy is used in photosynthesis?

Which wavelengths of light supply the energy for photosynthesis? Why do plants appear green?

2. Chloroplasts and chlorophyll

Structure of chloroplast: – Double membraned – Contain stacks of thylakoids where light dependent reaction occurs – Has stroma where light independent reaction occurs

III. The Process of Photosynthesis Photosynthesis is a series of energy transformations from solar energy to energy the cell can use Is endergonic, anabolic reaction Occurs in 2 stages: – Light dependent reaction – Light independent reaction

A. The Light Dependent Reaction Transfers solar energy to ATP and NADPH

Photosystems contain clusters of chlorophyll Solar NRG is captured by chlorophyll and transferred to e- e- is captured by ETC and NRG is used to actively transport protons As protons diffuse thru ATP synthase, NRG is used to make ATP Another boosted e- is transferred to NADP to make NADPH

Role of water How is oxygen produced What is role of electron from 1 st photosystem What is role of electron transport chain What is role of light What is role of electron from 2 nd photosystem What is the role of the H+ ions What is role of ATP synthase What is role of ATP and NADPH

B. The Light Independent Reaction

Uses energy in ATP and NADPH as well as CO2 from atmosphere to produce sugar Occurs in the stroma of the chloroplast

factorEffect on photosynthesisexplanation Increase in temperature Decreased Light intensity Shortage of water Decrease in CO2