c1.3 photosynthesis Flashcards
(34 cards)
What is photosynthesis?
Photosynthesis is the transformation of light energy to chemical energy where carbon compounds are produced.
What is the photosynthesis reaction equation?
6CO2 + 6H2O –light energy–> C6H12O6 + 6O2
What is chemical energy?
Chemical energy is the energy between the bonds in molecules (e.g., when they break), it can then be used as an energy source to make ATP.
What is photosynthesis used for?
This transformation of energy supplies most of the chemical energy needed for life processes in ecosystems. Energy is passed along through food chains/webs as organisms eat other organisms. Every food chain starts with a producer (something that can produce glucose - usually plants). Photosynthesis creates a chemical store of energy in the form of carbohydrates. Photosynthesis occurs in plants, algae, and cyanobacteria.
What are stomata?
Stomata are the small holes on the underside of the leaf that let gases in and out. Carbon dioxide diffuses in for photosynthesis, oxygen made in photosynthesis diffuses out, and water vapour diffuses out. Stomata can be opened and closed by guard cells.
How does photosynthesis occur?
It goes through two steps; light dependent and light independent reactions. The conversion of carbon dioxide to glucose in photosynthesis is done by using hydrogen obtained by splitting water.
What is a chloroplast?
The chloroplast is a membrane-bound organelle found in plant and algae cells which is responsible for photosynthesis.
What is a granum?
A stack of thylakoids.
What is a thylakoid?
A tiny, membrane-bound compartment inside a chloroplast where photosynthesis takes place. A thylakoid membrane is where the first part of photosynthesis takes place, for a light dependent reaction. They are important for capturing sunlight and transporting electrons for the conversion of light energy to chemical energy.
What is the stroma?
The fluid in chloroplast. It is where the second part of photosynthesis takes place, for the light independent reaction.
What is chlorophyll?
Green pigment in the chloroplasts of plant cells. Absorbs light energy and enables it to be used to drive the reactions of photosynthesis (photo-pigment). The main photo-pigment in plants (although there are others). Found within the chloroplasts of leaves.
What are the steps of a light dependent reaction for photosynthesis?
Occurs in the grana (pl) granum (sing.) (stacks of thylakoids - thylakoid membrane) of the chloroplast. Solar energy is required. Light energy is used to split water (called photolysis) into hydrogen and oxygen ions. Some ATP is produced as well. Oxygen is a waste product and is released through holes in the bottom of leaves called stomata. The hydrogen ions go to the next step, the light independent reaction.
What are the steps of a light independent reaction for photosynthesis?
Occurs in the stroma (the liquid part of the chloroplast). Light energy is not required. Uses the hydrogen ions from the previous stage as well as carbon dioxide from atmosphere. ATP from the previous stage supplies energy to this process. The carbon dioxide is ‘fixed’ - this means it is combined with other carbon-based molecules. Goes from inorganic form (CO2) to organic form (CH2O). End product is glucose. Glucose can be used for cellular respiration in the plant, or stored as starch.
What wavelengths of visible light does chlorophyll absorb the most effectively?
Chlorophyll absorbs red and blue light most effectively and reflects green light more than other wavelengths.
What does the absorption spectra show?
Shows the wavelengths of light that are absorbed by the photosynthetic pigments. Pigments absorb a certain wavelength of light because the energy levels of the electrons in the pigment match the energy level of the photons of those wavelengths.
How is the absorption spectra created?
Created by separating the amount of light absorbed by each photo-pigment.
What colours are absorbed by chlorophyll?
Orange-red light and blue light are absorbed. Green light is reflected or transmitted.
What are carotenoids?
Carotenoids are a class of mainly yellow, orange or red fat-soluble pigments.
What pigments are on the absorption spectra graph?
Chlorophyll a, chlorophyll b, carotenoid.
What does the action spectra show?
Shows the effectiveness of different wavelengths of light on driving the process of photosynthesis. Shows the rate of photosynthesis at different wavelengths. Shows which wavelengths are used more irrespective of the degree to which they are absorbed.
How is the action spectra created?
Created by using the sum of all wavelengths absorbed by all photo pigments.
What are similarities of the action and absorption spectra?
On the action spectra, the highest rates of photosynthesis occur at the blue and red wavelengths, while the lowest is at the green. This corresponds to the absorption spectra of the photosynthetic pigments in their ability to absorb light energy that allows photosynthesis to occur.
How is the rate of photosynthesis measured and what are the three different ways?
It is measured by calculating the change over time, this could be through three ways: 1. Oxygen production - count/measure bubbles given off, uses oxygen probe. 2. Carbon dioxide uptake - measure changes in pH, uses carbon dioxide probe. 3. Change in biomass - measure change in mass, uses scale.
What are limiting factors?
Factors that can affect the rate of photosynthesis.
