Unit 3: Respiration & Photosynthesis Flashcards
(18 cards)
C1.2.1
What is the role of ATP
- ATP is the energy carrier molecule of the cell
- Breaking bonds releases energy
- ATP is used to fuel metabolic reactions
C1.2.2
Life processes within cells that ATP supplies with energy
3 examples
Anabolic reactions (synthesizing macromolecules)
- E.g. DNA replication, protein synthesis
Active transport
- Up the concentration gradients
- E.g. Sodium potassium pump
Movement
- E.g. Muscle contractions, movement of cells (mitosis)
C1.2.3
How do we convert ATP –> ADP –> ATP
What is required?
Energy transfers during interconversions between ATP and ADP
- ATP is used to fuel metabolic reactions
- Energy is released when bonds are broken
- ATP’s third phosphate group bond is broken off (hydrolysis) → Forms ADP (adenosine diphosphate), which has less energy
- ATP can be regenerated by forming bonds but energy is required
That energy can come from:
- Cell respiration: the goal is to provide energy to regenerate ATP
- Photosynthesis
- Chemosynthesis
C1.2.4
What is the goal in cell respiration, what is the equation?
Cell respiration: releases energy by using carbon compounds (glucose, lipids) to produce ATP
Requires oxygen and gives off carbon dioxide and water as a byproducts
C1.2.5
What is anaerobic and aerobic cell respiration?
Aerobic: with oxygen
Glucose + Oxygen → CO2 + H2O + ATP
Anaerobic: without oxygen
Yeast → ethanol + CO2
Human → lactate
C1.2.5
What is glycolysis
Glucose is broken down into two pyruvate molecules through glycolysis which produces a small amount of ATP (2 ATP)
It takes place in the cytoplasm
C1.2.5
Differences between anaerobic and aerobic cell respiration** in humans**
When is anaerobic necessary?
Aerobic
- Carbohydrates, lipids, amino acids
- Glycolysis (2 ATP)
- Pyruvate is transported into the mitochondria where it’s broken down into carbon dioxide, water, and a large amount of ATP
- Cytoplasm and mitochondria
- Can produce 30 ATP
In humans:
Anaerobic:
* Only carbohydrates
* Cytoplasm only
* Lactate + 2 ATP –> glycolysis
* It is fast but inefficient and only 2 ATP
When is it necessary?
- Anaerobic is necessary when you need ATP fast but there is no enough oxygen
- Powerlifting, sprinting, working untrained muscles
Lactate buildup = fatigue; clearing it needs extra O₂ (“oxygen debt”).
Body reverts to aerobic as soon as O₂ is restored.
C1.2.6 Variables affecting the rate of cell respiration
How do respirometers work?
What do they measure?
What could be controlled variables when experimenting?
What can you investigate?
Organism will do photosynthesis, consuming oxygen
CO2 absorbents will absorb CO2
So the oxygen concentration will decrease and it will apply less pressure on the liquid so the liquid will rise
Controlled variables:
Temperature
Pressure
What can you investigate?
Different organisms
Different temperatures
Different respiratory substrates (glucose, carbohydrates etc)
C1.3.1
Outline the process of energy transformations in photosynthesis (what types of energies)
Who performs photosynthesis?
Light energy is converted into chemical energy
Chemical energy can be in the form of carbohydrates, lipids, proteins, nucleic acids
Producers do photosynthesis
This is important because they form the base of the food chain
The chemical energy is then passed on to consumers, and even though a little bit of energy is lost at each step, the initial step of energy transfer is vital for most ecosystems.
C1.3.2
What is the equation of photosynthesis?
What is light energy used for in photosynthesis?
Photosynthesis equation : (light energy is used) H2O + CO2 → C6H12O6 + O2
Photolysis: using light energy to split water ( H2O → H+ , e- , O2 )
→ Hydrogen is needed to convert carbon dioxide into glucose
→The oxygen is a byproduct (waste)
C1.3.3
Why is it important to have oxygen as a by-product of photosynthesis?
Oxygen as a by-product of photosynthesis in plants, algae and cyanobacteria
Photosynthesizing organisms is very important for energy conversion, but also for oxygen production
C1.3.4
Separation and identification of photosynthetic pigments by chromatography
Rf value?
Different pigments absorb different wavelengths of light
Plants have multiple pigments
Each pigment has a characteristic Rf value
Calculate the Rf value = distance pigment/distance solvent
C1.3.5
Absorption of specific wavelengths of light by photosynthetic pigments
- Colors are different wavelengths of light
- Pigments absorb certain wavelengths of light
The main pigment in plants is chlorophyll
**Green **wavelengths are reflected, and **Red and blue **are absorbed the most by chlorophylls
BGR
C1.3.6
Similarities and differences of absorption and action spectra
How does the graph look like?
Absorption spectrum: shows the wavelengths of light a pigment absorbs
Action spectrum: photosynthesis rates at different wavelengths
- Oxygen production
- CO2 consumption
C1.3.7
Effect of carbon dioxide, light intensity and temperature on the rate of photosynthesis
How does the graphs look like
For carbon dioxide and light intensity
- When it reaches the maximum rate there is a plateau
Temperature is different because the enzymes will denature
Techniques for measuring the rate of photosynthesis
Using pondweed (an aquatic plant):
* Plants give off oxygen as a byproduct, and that oxygen is going to be oxygen gas
* Oxygen gas when you have it underwater is going to be in the form of bubbles
* As the plant is photosynthesising, it is going to give off oxygen gas bubbles which you can count as a way of measuring the rate of photosynthesis
Key points:
- One independent variable and control the rest
- Must have a reliable way of manipulating the independent variable
- CO2 : sodium hydrogen carbonate
- Light intensity: light further or closer
- Temperature: water bath - Must have reliable way of measuring photosynthesis rates
- Counting oxygen bubbles
- Leaf float time
- Oxygen sensor
- pH sensor
Techniques for measuring the rate of photosynthesis, experiments, just read
Carbon dioxide Concentration:
Boil water, this removes CO2 from water and let it cool
Pour the water from one beaker to another to oxygenate it
Set up the testing apparatus
25C
Lots of light
Count oxygen bubbles (there won’t be a lot)
We start adding more carbon dioxide back to the water, add sodium hydrogen carbonate to increase the CO2 levels
Repeat until the rate of bubble production is the same
At some point, it will reach a plateau meaning that the CO2 concentration is optimal
Light Intensity:
Have a light that is either higher watts, or we can move it further and closer away from the product to vary light intensity
Using leaf discs, (cutting out circles from leaves)
Set up the apparatus
25 degrees
Lots of CO2 (add sodium hydrogen carbonate)
Leaf is gonna have bubbles from the mesophyll layer, and we can use a syringe to suck out all the air bubbles, and then when we put it in some water (the apparatus), it will sink to the bottom
As the plant photosynthesizes it is going to be producing oxygen gas as a byproduct
The oxygen gas is going to alter the buoyancy of the leaf and the leaf should float to the top
We can time how long it takes for the leaf disc to float to the top, and this will be an indicator of photosynthesis rates
The less time it takes, the faster the rate of photosynthesis
We can vary the light intensity until we find the point in which varying the light intensity does not result in a faster rate
Temperature
Set up apparatus in a water bath (with a heater nearby to control the temperature)
Set up the testing apparatus with:
Lots of light
Lots of CO2 (sodium hydrogen carbonate)
Add a culture of algae (or some other plant)
Measure this through either:
An oxygen sensor
Or a pH sensor
How pH sensor works: as the organism is photosynthesising, it will consume carbon dioxide (removing the carbon dioxide from water), this means the water is less acidic, which means the pH should be increasing
Bigger the increase in pH, the higher the rate of photosynthesis
As it gets warmer and warmer, the pH changes more and more until it gets to a certain point, and drops off due to the denaturation of the enzymes necessary for photosynthesis
C1.3.8
Carbon dioxide enrichment experiments as a means of predicting future rates of photosynthesis and plant growth
Hypothesis: Rising CO2 levels will increase photosynthesis rates
FACE experiments
People are trying to control for other factors, but manipulating the amount of carbon dioxide in the air and measuring things like:
- Plant growth
- Looking at other limiting factors of photosynthesis (aside from CO2)
- Looking at other parts of the ecosystem (like other organisms)
