1. Chapter 2 lesson 4 TB. Pg. 69-72 Prepared by Ms. Uzma Grade 7 Science
Cellular Respiration
Chapter 2 lesson 4 TB. Pg
Prepared by Ms. Uzma
Grade 7 Science

2. Cellular Respiration
Cellular Respiration is a series of chemical reactions that convert the energy in food molecules into usable form of energy called ATP.
Occurs in two steps:
step 1. Reactions in the cytoplasm-Glycolysis
step 2. Reactions in the mitochondria

3. Glycolysis
Glycolysis is a process by which glucose, a sugar, is broken down into smaller molecules.
It produces some Adenosine triphosphate (ATP) molecules

4. Reactions in the Mitochondria
This step of cellular respiration requires oxygen
Smaller molecules made from during glycolysis are further broken down and large amounts of ATP-usable energy-are produced.
Two waste products water and carbon dioxide are given off during the second step.

5. Fermentation Occurs in the cell’s cytoplasm
Is a reaction that eukaryotic and prokaryotic cells can use to obtain energy from food when oxygen levels are low.
Fermentation makes less ATP than cellular respiration does.
There are two types of fermentation:
a. alcoholic fermentation
b. lactic acid fermentation

6. Lactic-Acid Fermentation
In alcoholic fermentation glucose is converted into ATP and a waste product called lactic acid.
Some fungi and bacteria help produce cheese yoghurt and sour cream using lactic acid fermentation.
Glucose (C6H12O6) ATP + Lactic acid
In a Muscle cell: Lactic Acid is produced by muscles during rapid exercise when the body cannot supply enough oxygen.

7. Alcoholic fermentation
Alcoholic fermentation is done by yeasts and some types of bacteria.
It produces an alcohol called ethanol and & Carbon Dioxide
Yeast cells
Glucose (C6H12O6) energy(ATP) +CO2 + Alcohol

8. Photosynthesis
Photosynthesis is the process during which a light energy, water carbon dioxide combine and make sugars. In plants, photosynthesis occurs only in cells with chloroplasts. The chemical reaction for photosynthesis is: (light energy)
6 H2O (water) + 6CO2 ( CO2 ) O2 (oxygen gas) + C6H12O6) (glucose)

10. Energy & Exercise
Quick energy – Lactic Acid fermentation is used to get quick energy and gives off lactic acid as a by product, thus the muscle pain.
Long-Term Energy – Use cellular respiration to produce energy. Exercising or activities that last for at least 15 to 20 minutes. Best form for weight control.
6O2 + C6H12O6  6CO2 + 6H2O + Energy
Oxygen + Glucose  Carbon Dioxide + Water + Energy

11. Comparing Photosynthesis & Respiration
Cellular Respiration
Function
Energy Storage
Energy Release
Location
Chloroplasts
Mitochondria
Reactants
CO2 and H2O
C6H12O6 and O2
Products
Equation
6CO2 + 6H2O  C6H12O6 + 6O2
C6H12O6 + 6O2
6CO2 + 6H2O