7

Photosynthesis & Cellular

Respiration

Honors Biology 2009-2010

8-1 Energy and Life

Every living thing needs an input of energy; therefore, every cell needs an input of energy

Autotrophs: make own food; producers

Heterotrophs: consume food to get energy; consumers and decomposers

ADP ATP

Energy

EnergyAdenosine diphosphate (ADP) + Phosphate Adenosine triphosphate (ATP)

Partiallychargedbattery

Fullychargedbattery

Figure 8-3 Comparison of ADP and ATP to a Battery

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Cells don’t keep a lot of ATP around because it doesn’t store a lot of energy. They convert carbohydrates into ATP as needed.

Glucose → ATP (there is more to this equation!)

Van Helmont – tested soil mass increase

Priestley – Found that plants release a substance that keeps a candle burning; we now know this substance is oxygen gas (O2)

Ingenhousz – Concluded that plants need sunlight to produce oxygen

8-2 Photosynthesis: An OverviewEssential Question: When a tiny seed grows into a tree, where does the increase in mass come from? Water? Soil? Air?

Word Equation for Photosynthesis

Chemical Equation for Photosynthesis

8-2 Photosynthesis: An Overview

Plants can then convert glucose (monosaccharide/simple sugar) into more complex sugars like starch or cellulose (polysaccharides/complex sugars)

Photosynthesis takes place in chloroplast of plant cells

Pigments – molecules that absorb light energy

Chlorophyll – plant’s principal pigment (different types); absorbs most colors and reflects green

p. 208: Inside A Chloroplast

9-1 (p. 221-222) Chemical Pathways

Glycolysis

the beginning of the pathway of converting glucose into cellular energy (ATP). Glycolysis only releases a little energy from glucose. IF oxygen is present, glycolysis is followed by additional chemical reactions which release more energy.

occurs in the cytoplasm; this is how prokaryotic cells make energy

Word Equation for Cellular Respiration

Chemical Equation for Cellular Respiration

Overview of Cellular Respiration (p. 222)

Cellular Respiration: process of releasing energy by breaking down food molecules in the presence of oxygen (aerobic respiration).

3 Stages of Cellular Respiration:

1. Glycolysis – cytoplasm; no oxygen needed; little energy produced

2. Krebs Cycle

3. Electron Transport Chain

Both occur in mitochondria; oxygen needed, a lot of energy produced

Both plants and animals do cellular respiration!

Fermentation (anaerobic respiration)

If no oxygen present, ATP will still be made but there is additional waste produced

Alchoholic Fermentation: yeast cells produce ATP anaerobically and produce the waset alchohl; used to make dough, wine, rootbeer!

Lactic Acid Fermentation: some animal cells will produce ATP if oxygen is limited and produce lactic acid waste; occurs during high energy usage (exercise)!