Flashcards
2.9 Photosynthesis
Cards in this deck (17)
- 1Explain methods that can be used to measure the rate of photosynthesis.[5]measure production of oxygen;
because oxygen is a by-product of photosynthesis;
example of technique for measuring oxygen production (count
bubbles/use sensors/other);
measure uptake of carbon dioxide;
because carbon dioxide is used during photosynthesis;
example of technique for measuring carbon dioxide production
(sensor, aquatic pH shift);
measure biomass of (batches of) plants;
increase in biomass gives (indirect) measure of rate of photosynthesis;
Since the command term is explain, reasons must be given to
receive full marks. - 2Outline the role of chlorophyll and the effects of temperature, light intensity and carbon dioxide concentration on the rate of photosynthesis. [6]chlorophyll is composed of a number of pigments;
absorb different colours of light;
mainly red and blue absorbed;
green light reflected;
temperature increases rate;
up to a point where enzymes denature;
light intensity increases rate;
up to a point where maximum absorbance can occur;
carbon dioxide increases rate;
up to a point where fixation is at a maximum; - 3Outline how light energy is used and how organic molecules are made in photosynthesis. [6]chlorophyll is the (main) photosynthetic pigment;
absorbs (mainly) red and blue light;
green light is reflected;
light energy absorbed is converted into chemical energy;
ATP produced;
water split;
to form oxygen and hydrogen;
ATP and hydrogen used to fix carbon dioxide to make organic molecules; - 4Photosynthesisproduction of carbon compounds in cells using light energy.
Carbon dioxide + water + light energy -> glucose + oxygen - 5Plants use the Pigment Chlorophyll to Absorb Light Energy- The vast majority of plant leaves appear green to our eyes because they contain chloroplast that are actually green.
- Plants contain a variety of pigments in chloroplasts.
- The photosynthetic pigment that dominates in the most plant species is the molecule chlorophyll.
- Plants make use of the same part of the electromagnetic spectrum that our eyes are able to see = visible light portion of the electromagnetic spectrum. - 6Regions chlorophyll absorbs light energyred end, green middle of the spectrum, blue end of the spectrum
- 7When substances are struck by a particular wavelength,- absorb that wavelength
- reflect that wavelength - 8Why is the leaf green?- As chlorophyll is a green pigment, they reflect green light and absorb other wavelengths (red and blue) of the visible light spectrum.
- 9Absorption spectrum
- 10Action spectra
- 11Photosynthesis Occurs in Two Stages1. First set of reactions in photosynthesis trap light energy and convert it to ATP (light independent reaction
1) Chlorophyll (and other photosynthetic pigements) absorb light energy and convert that energy to a form of chemical energy, specifically ATP.
2) Light energy is also used to photolysis water, where a water molecule is spit into its component elements: hydrogen and oxygen.
3) The oxygen that is split away due to the photolysis of water is typically released from the plant leaf as a waste product as the leaf only needs ATP and hydrogen for photosynthesis.
2. Set of reactions in which ATP is used to help bond carbon dioxide and water molecules together to create glucose (light independent reactions).
1) ATP and hydrogen are used as forms of chemical energy to convert carbon dioxide and water into useful organic molecules for the plant.
2) The carbon fixation (above reaction) requires energy and it comes from the ATP and hydrogen created in the first stage. - 12Measuring the Rate of Photosynthesis- At any given time of year, any one plant has a fairly consistent rate of cell respiration, not only throughout the day and night but also in a low level. This is because plants need ATP far less than animal needs even though they use it for biochemical processes.
- But the rate of photosynthesis is not consistent. The photosynthetic rate is highly dependent on many environmental factors, including the light intensity, air temperature, and amount of CO2.
- Methods of measuring photosynthetic rate: (1) production of oxygen or carbon dioxide intake (2) keeping track of the change in biomass of experimental plants. - 13The effects of changing light intensity on the rate of photosynthesis
- 14The effects of increasing temperature on the rate of photosynthesis
- 15The effect of increasing CO2 concentration on the rate of photosynthesis
- 16Steps in Chromatography1. tear up a leaf into small fragments
2. grind pieces of leaf with sharp sand and propanone to extract the leaf pigments.
transfer sample of extra to a watch glass.
4. evaporate to dryness with hot air from a hair-dryer.
5. add a few drops of propanone to dissolve the pigments.
6. build up a concentrated spot of pigment 10mm from the end of the strip of paper.
7. suspend the strip in a tube with the base dipping into running solvent.
8. remove the strip from the tube when the solvent has nearly reached the top.
9. calculate Rf values for each pigment spot. - 17Rf valuedistance moved by the spot/ distance moved by the solvent.
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- Biology (Topic 2 :: Molecular Biology) Flashcards on 2.9 Photosynthesis, created by Jianna Park on 20/02/2019.
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