1. (Photosynthesis and Respiration)
Energy in cells
(Photosynthesis and Respiration)

2. Photosynthesis
Chemical process that captures light energy and stores it as Chemical Potential Energy, only occurs in autotrophs
Is a series of reactions controlled by enzymes
Occurs in the …
2 Stages
Light phase 1
Dark phase 2

3. Structure of a chloroplast
Granum – stacked thylakoids containing chlorophyll.
Stroma – clear liquid interior
How can you tell which phase occurs where?
How has surface area been maximised?
What is the green colour from?

4. Photosynthesis reaction summary:
The purpose is to capture light energy from the sun and store it as chemical energy in glucose molecules for use inside the plants. It also:
Removes carbon dioxide from the air
Needs water, gained by osmosis from the soil into the root hair cells and up the xylem vessels
Makes oxygen gas for use in respiration in all living organisms
Photosynthesis reaction summary:
Carbon dioxide + water glucose + oxygen + water
CO H2O C6H12O6 + O2 + H20

5. Stages in Photosynthesis
Raw materials
Source of raw materials
Products
(waste)
Location within
Chloroplast
Phase 1. Light or Light Dependent (LD)
Phase 2. Dark or Light Independent (LI)

6. Stages in Photosynthesis
Raw materials
Source of raw materials
Products
(waste)
Location within
Chloroplast
Phase 1. Light or Light Dependent (LD)
Light
Water
ADP
NAPH
Sun
Air
Dark Reaction
ATP
NADPH2
(Oxygen)
Thylakoids of Grana
Phase 2. Dark or Light Independent (LI)
Carbon Dioxide
Light Reaction
Glucose
Stroma

7. Carrier molecules in Photosynthesis
ATP – the energy carrier
ADP (empty)
Transports energy from light phase to dark phase
NADP – the hydrogen carrier
NADPH2 (full)
Transports hydrogen from light phase to dark phase

8. How plants maximise the rate of photosynthesis
See handout and discuss this concept in relation to the leaf model and the chloroplast diagram

9. Factors affecting photosynthesis reaction rate:
Photosynthesis is controlled by enzymes so anything that affects enzymes also affects photosynthesis, including;
Light intensity (can differ for different plants, canopy verses forest floor plants), no photosynthesis in the dark!
Temperature (most plants have an optimum range)
CO2 concentration (substrate concentration)
Low water availability causes the stomata to close and CO2 diffusion to stop so photosynthesis stops as well.

10. Respiration
All living cells must carry out cellular respiration and the purpose is too release the energy stored in food (glucose) and make it available to power all other metabolic reactions (in both autotrophs and heterotrophs)
Occurs in the (name organelle here?)
There are two types (aerobic and anaerobic)

11. Structure of a mitochondria
Cristae are the folded inner membranes. Why are they folded?
The matrix is the liquid inside . What stages take place here?
Mitochrondria are found in all living cells but in general animals cells have more than plants and any cells that need more energy have more e.g. muscle and liver cells have high energy demands so have more….

12. Aerobic Respiration (with O2)
Cellular respiration with oxygen
Also a series of reactions controlled by enzymes
Glucose (food) and oxygen convert to lots of energy (ATP) with waste products of CO2 and H2O
C6H12O6 + 6O2  6CO2 + 6H2O + ATP
glucose oxygen carbon dioxide water energy

13. 4 stages of aerobic respiration
Name
Location in cell
Energy (ATP) produced
Link to equation 1 2 3 4

14. 4 Stages of aerobic respiration (with oxygen)
Glycolysis,
Link reaction ,
Krebs cycle,
Electron transport chain
These stages are linked by carrier molecules in a similar way to photosynthesis reactions…

15. 4 stages of aerobic respiration
Name
Location in mitochondria or cell
Energy (ATP) produced
Link to equation 1
Glycolysis
(breakdown of glucose)
Cytoplasm
2 ATP
Forms Pyruvate
No O2 needed 2
Link reaction
Matrix
none
Forms Acetyl Co enzyme A and CO2 3
Krebs Cycle or Citric Acid Cycle
Produces H2 4
Electron Transfer Chain
Cristae
32 ATP
O2 needed, combines with H2 to produce H2O

16. Carrier molecules in respiration (molecules that link stages of aerobic respiration)
Co-enzyme A – an acetyl carrier
Acetyl co-enzyme A (full)
Transports acetyl group from glycolysis to Krebs cycle
NAD – the hydrogen carrier
NADH2 (full)
Transports hydrogen from Krebs cycle to Electron transport chain

17. Anaerobic respiration (no O2)
Respiration without oxygen
Another series of reactions controlled by enzymes
Stops after glycolysis (stage 1)
Much less energy (ATP) produced
Different waste or by-products produced
Plants
Glucose  carbon dioxide + ethanol + 2ATP
Animals
Glucose  lactic acid + 2ATP

18. Factors affecting respiration
All respiration reactions are controlled by enzymes …so again all things that effect enzymes affect both types of respiration, plus:
Too much toxic product. Too much carbon dioxide (aerobic respiration) and too much ethanol or lactic acid (anaerobic respiration) is toxic. Toxic products must be removed during respiration for it to continue efficiently.

19. See Factors Affecting Enzymes…
Temperature,
pH,
Surface Area,
Substrate (reactant) concentration,
Enzyme concentration,
Co-Factors (enzyme helpers),
Inhibitors (heavy metals, poisons).

20. ATP
Adenosine triphosphate (ATP) is the universal energy carrier in all cells
Cellular respiration is the process of recharging ADP (Adenosine diphosphate) to ATP P P

21. Role of ATP (Energy carrier molecule)
Energy released
from breaking off one
phosphate (-P) from ATP.
Where?
ATP
ADP
Respiration
recharges ADP to ATP using energy and adding one phosphate (+P). Where? +P

22. Energy in cells summary
Photosynthetic Autotroph cells
All Autotroph and Heterotroph cells
Light Energy O2
CO2
and
H2O
P/S
Glucose
ADP
Respiration kJ O2
ATP
H2O
Heat Energy
CO2