Respiration
Think, pair, share
• The word equation for respiration.
• Where aerobic respiration takes place
in the cell.
• Why do cells need energy?
Energy in Cells
Cells need energy for;
Cell division, growth, muscle contraction
and synthesising large molecules.
Where does this energy come from?
Energy in Food
How do you know that there is energy
present in the malteser?
The Respiration Equation
Glucose +
Oxygen
From
Our food
Energy +
(ATP)
Carbon + Water
Dioxide
Can be used for
Cell activity e.g.
Muscle contraction
Respiration
Respiration is a series of enzyme
controlled reactions that releases the
chemical energy stored in glucose.
ATP
• The energy from glucose is used to form ATP
by making a bond between ADP (adenosine diphosphate) and Pi (inorganic phosphate).
Energy from glucose
ATP
• ATP carries the energy to a cell which needs
energy and breaks down into ADP and Pi.
Energy released from ATP
The energy released from the bond can be used in
cell division, muscle contraction and making
proteins.
The Energy Cycle
ATP
ENERGY
PUT IN
Respiration
Of glucose
ENERGY
RELEASED
ADP + Pi
Used for
Cell
Activity
Quick Questions
1. What is respiration?
2. What is the equation for respiration?
3. What form does the energy take when it is
released from food?
4. What does ATP stand for?
5. What can ATP be used for?
Aerobic Respiration
Using Oxygen
Breakdown of glucose to release energy in the
presence of oxygen is a two step process:
1. Glycolysis:
Glucose is split in two becoming
pyruvic acid
2. Breakdown of pyruvic acid into simple products
Stage 1: Glycolysis
Glucose
Splitting
Glucose (6 carbons)
enzyme
controlled reactions
Pyruvic Acid (3 carbons)
How many molecules of pyruvic acid come from 1 molecule of glucose?
Stage 2: Breakdown of pyruvic acid
Pyruvic acid
+ oxygen
enzyme
controlled reactions
carbon dioxide +
water
When is ATP produced?
Glucose
2ADP + 2Pi
2ATP
Pyruvic Acid
+ oxygen
How many molecules of ATP are
produced from 1 molecule of
pyruvic acid?
36 ADP + 36 Pi
36 ATP
carbon dioxide +
water
ATP production
Glucose
2 ATP
Pyruvic Acid
+ oxygen
36 ATP
carbon dioxide +
water
Total = 38 ATP
Anaerobic Respiration in Plants and Yeast
no oxygen
Glucose
2ADP + Pi
2ATP
Total
2 ATP
Pyruvic Acid
No ATP
Ethanol and Carbon Dioxide
Effects of Lactic Acid in Muscle
Glucose
Pyruvic Acid
+ oxygen
heavy exercise
recovery period
BUILD UP OXYGEN DEBT
OXYGEN DEBT REPAID
Lactic acid
3.5.3 Comparing aerobic and anaerobic
Aerobic
Anaerobic Anaerobic
respiration respiration respiration
animals
plants
Glycolysis
ATP yield
Products
Yes
Yes
Yes
38
2
2
Carbon dioxide
& water
Lactic acid
Ethanol &
Carbon dioxide
Produce a graph using the information below:
Time (mins) Force (Newtons)
0
400
5
380
7
390
10
350
18
330
20
290
22
300
25
290
26
270
30
240
Explain why the force used by the muscle is
decreasing.
Questions
1. Define the term anaerobic respiration.
2. Explain why lactic acid builds up in the
muscles.
3. Identify 2 conditions necessary for the
oxygen debt to be repaid.
4. Give 3 differences between the
breakdown of a glucose molecule in a root
cell which respires in;
a) well aerated soil.
b) anaerobically in flooded soil.