1. National 5 Biology Unit 1 Section 6 - Respiration

2. Learning Intentions I will be successful if I can…
State that glucose is a source of energy in the cell.
State that the chemical energy stored in glucose is released by a series of enzyme-controlled reactions called respiration.
State that some energy is released as heat from cells during respiration but most is used for cellular activities such as muscle contraction, cell division, synthesis of proteins and transmission of nerve impulses.
State that energy released from the breakdown of glucose is used to synthesise ATP from ADP and Pi. The ATP can then be used by the cell as an energy source.
State that aerobic respiration yields 38 molecules of ATP per glucose molecule.
State that anaerobic respiration yields 2 molecules of ATP per glucose molecule.
State that aerobic Pathway - breakdown of glucose to pyruvic acid by glycolysis. Further breakdown of pyruvic acid to carbon dioxide and water in presence of oxygen.
State that anaerobic Pathway - breakdown of glucose to pyruvic acid by glycolysis.
State that reversible anaerobic conversion of pyruvic acid to lactic acid in animals.
State that the effect of lactic acid on muscle cells (i.e. muscle fatigue) and subsequent repayment of oxygen debt.
State that the irreversible anaerobic conversion of pyruvic acid to ethanol and carbon dioxide in plants and yeast.
State that glycolysis occurs in the cytoplasm whilst the aerobic stage of respiration occurs in the mitochondrion.
State that anaerobic respiration takes place fully in the cytoplasm

3. Why do Living Organisms need Energy?
Maintain body temperature
Make your muscles work (movement)
Synthesis and degradation of larger molecules
Cells use energy from respiration to…
Carry out chemical reactions
Growth and repair of cells

4. Energy gain What food is made by plants?
How do humans get the energy from the plants?
Glucose formed and changed to starch

5. Energy in food Look at any food or drink wrapper.
What units is energy content measured in?
joules [J] or kilojoules [kJ]

6. Which Foods have the most Energy?
Different types of food contain different amounts of energy.
The three main food groups are:
Carbohydrates
Proteins
Fats

7. Experiment 1 – Measuring the Energy Content of Different Foods
Aim : To measure the energy content of different foods
Dependent Variable:
Independent Variable
Variable to be kept constant:

8. Method 1. Put 20 cm3 of cold water into a boiling tube.
2. Measure the starting temperature with a thermometer.
3. Place boiling tube into a clamp and stand.
4. Place Bunsen onto a heat proof mat and light.

9. Method 5. Hold food in tongs.
6. Set the food on fire and place it underneath the boiling tube until it is completely burnt.
7. Measure the final temperature of the water.
8. Repeat this process using fresh water with the same type of food. .

10. Results Use the following sum to calculate the change in temperature:
final starting = rise in
temperature temperature temperature

11. A Food Calorimeter.
This equipment makes results more reliable because:
Stirrer
Enclosed vessel
Oxygen supply
Chimney

12. Revision What type of energy is in food?
What process allows this energy to be released to be used by cells?
What unit do we use when discussing the energy content of food?
Chemical
Respiration
joules

13. ATP What is Respiration?
A series of chemical reactions in our cells where
energy is released from food
Energy inside
FOOD
(glucose)
Chemical
Reactions
Energy for
the cell to use
ATP

14. The Respiration Equation
Glucose + Oxygen Energy Carbon Water
(ATP) Dioxide
From
Our food
Can be used for
Cell activity eg
Muscle contraction

15. Release of Heat Energy
The source of the energy required to regenerate ATP is the chemical energy stored in food. The cellular process of releasing energy from food is called respiration. Some of the energy released is used to produce ATP. Some of the energy released is lost as heat.

16. ATP
The energy produced during aerobic respiration is stored in a molecule called ATP (Adenosine triphosphate).
Every molecule of glucose that is “burned” in the cell produces 38 ATP molecules.

17. Adenosine Tri Phosphate
ATP
Immediate energy source in a cell
Formed from the energy that was in our food
Adenosine Tri Phosphate
Adenosine Pi Pi Pi
Three inorganic phosphates

18. ADP:
Adenosine Di Phosphate
Adenosine Pi i Pi
Adenosine Pi Pi Pi

19. ATP and Muscle Contraction
Aim: To investigate if ATP or glucose is the source of energy in the
cell used for reactions
Add
ATP
Add
Glucose
Microscope slides
Muscle tissue

20. Decrease in length (mm)
ATP and muscle contraction
Change
Start X
Percentage Decrease:
Solution
Initial length (mm)
Final length (mm)
Decrease in length (mm)
Percentage decrease %
ATP 11 7
Glucose
Conclusion: ATP is used as the energy source for reactions
in the cell and not glucose

21. eg muscle contraction)
The Role of ATP
ENERGY
NEEDED
(comes from
breakdown of food) +
ENERGY
RELEASED
(can be used
for cell activities
eg muscle contraction) Pi

22. The Energy Cycle ATP ADP + Pi Used for ENERGY Cell ENERGY Respiration
Activity
ENERGY
RELEASED
Respiration
Of glucose from food
ENERGY
PUT IN

23. ATP can rapidly convert to _________ and __________ to provide energy for:
Heat (maintaining body temperature)
Nerve impulse
Muscle contractions (movement)
Cell division (synthesis and degradation reactions)

24. Aerobic Respiration Using Oxygen
Breakdown of glucose to release energy in the
presence of oxygen is a two step process:
Glycolysis: Glucose is split in two becoming
pyruvic acid
2. Breakdown of pyruvic acid into simple products

25. This phase takes place in the cytoplasm of the cell.
Stage 1: Glycolysis
This phase takes place in the cytoplasm of the cell.
Glucose
Splitting
Glucose (6C)
2ADP + 2Pi
2ATP
A series of enzyme
controlled reactions
2 x Pyruvic Acid/Pyruvate (3C)

26. Glycolysis
Respiration should be seen as a series of enzyme controlled reactions in which
6-carbon glucose is oxidised (broken down) to form carbon dioxide
this is accompanied by the synthesis of ATP from adenosine diphosphate (ADP) and inorganic phosphate (Pi).
This process takes place within the cytoplasm
does not require oxygen
Glycolysis results in a production of 2ATP.

27. Stage 2: Breakdown of pyruvic acid
Pyruvic acid oxygen
If there is oxygen available ( the normal situation), then the pyruvic acid produced by glycolysis diffuses into an organelle called mitochondrion for further breakdown if oxygen becomes available
enzyme
controlled reactions
carbon dioxide water

28. When is ATP produced? Glucose 2ADP + 2Pi 2ATP Pyruvic Acid + oxygen
carbon dioxide water

29. 2 ATP 36 ATP Total = 38 ATP Glucose Pyruvic Acid + oxygen
carbon dioxide water

30. Mitochondria Structure
This is the site of aerobic respiration.
The inner membrane folds present a large surface area for aerobic respiration takes place.
Sperm, liver, muscle, and neurones in animal cells together with companion cells in plants have large numbers of mitochondria.

31. Structure of a Mitochondrion
Outer Membrane
Inner Membrane
Cristae
Matrix Fluid

32. As a molecule to transfer energy in cells
Glucose +
Oxygen
Carbon Dioxide
Water
Energy
ATP
ADP Pi
e.g. Amino Acids
Protein molecule
RESPIRATION
ENERGY TRANSFER
WORK

33. Anaerobic Respiration
No oxygen
When would this happen to:
An animal?
Over exercising a muscle
A plant?
During a flood the plant gets submerged in water

34. Anaerobic Respiration in Animals
Glucose
same as in
aerobic respiration
Pyruvic Acid
pyruvic acid can’t
be completely
broken down
Lactic acid

35. 2 ATP 0 ATP Total: 2 ATP ATP production Glucose 2ADP + Pi 2ATP
Pyruvic Acid
0 ATP
Total: 2 ATP
Lactic acid

36. Effects of Lactic Acid in Muscle
Glucose
Pyruvic Acid
+ oxygen
heavy exercise
BUILD UP OXYGEN DEBT
recovery period
OXYGEN DEBT REPAID
Lactic acid

37. Total 2 ATP Anaerobic Respiration in Plants and Yeast Glucose
no oxygen
Glucose
2ADP + Pi
2ATP
Total
2 ATP
Pyruvic Acid
No ATP
Ethanol and Carbon Dioxide

38. 3.6 Uses of respiration in yeast
Glucose
Pyruvic Acid
Ethanol and Carbon Dioxide
Bubbles of gas
Make dough rise
(Bread making)
Alcohol
(Beer/Wine making)

39. Yeast Single celled organism Uses glucose for respiration
Can carry out aerobic respiration
Can carry out anaerobic respiration
Both forms of respiration produce
Carbon dioxide bubbles
We use yeast to make dough rise

40. 3.5.3 Comparing aerobic and anaerobic Aerobic respiration
Anaerobic respiration animals
Anaerobic respiration plants
Glycolysis
ATP yield
Products
Yes
Yes
Yes 2 38 2
Carbon dioxide
& water
Ethanol &
Carbon dioxide
Lactic acid

41. Word
Meaning
Adenosine Triphosphate
ATP is an energy rich chemical compound. It is made of adenosine and 3 inorganic phosphates
Aerobic Respiration
Only occurs if oxygen is present. It happens in the mitochondria.
Pyruvic acid  Carbon dioxide + Water + Energy
Anaerobic Respiration
Occurs if there is no oxygen present.
In animals = Glucose Pyruvic Acid  Lactic Acid
In plants = Glucose Pyruvate  Ethanol and Carbon Dioxide
Chemical Energy
Energy stored in chemical compounds that is released when the substance is broken down.
Ethanol
This is an alcohol
Muscle Fatigue
During strenuous activity there is a lack of oxygen so lactic acid builds up and lactic acid is formed
Glucose
6 Carbon sugar molecule required for respiration
Glycolysis
1st stage of respiration where glucose is broken down to pyruvic acid. This generates a net gain of 2ATP. It occurs in the cytoplasm of a cell
Heat Energy
The energy released when a substance is burned in a combustion reaction.

42. Word
Meaning
Kilojoule
(kJ) unit of energy
Lactic Acid
Glucose Pyruvic Acid  Lactic Acid
Produced in animal cells under strenuous exercise when muscle fatigue occurs and an oxygen debt builds up.
Oxygen
Chemical element formula O2
Oxygen Debt
Built up when vigorous muscular activity results in there not being enough oxygen so debt builds up that is “owed back”
Phosphorylation
Addition of a phosphoryl group to a molecule
Pyruvic Acid
3 carbon molecule formed from the breakdown of glucose during glycolysis.