5.2.1 Photosynthesis Flashcards
What is the name of the theory that suggests that chloroplast are derived from single celled organisms?
Endosymbiont Theory
What is the endosymbiont theory?
That chloroplast used to be unicellular organisms that, at one time, were taken up by a eukaryotic cell, e.g. cyanobacterium, to provide energy. This stayed in the cell and passed on through asexual reproduction.
Why is photosynthesis important?
It creates a source of energy for nearly all living organisms.
What is the classification of organisms that don’t use light energy get chemical energy?
Chemoautotrophs
What is the classification of organisms that use light energy to produce chemical energy?
Photoautotrophs
Where in the food chain are photoautotrophs found?
Producers in the first trophic level
What is the equasion for photosynthesis?
6CO2 + 6H20 –CHLOROPLAST+PHOTON–> C6H12O6 + 6O2
What is a photon?
A particle of light. Each photon contains an amount of quantum energy
What is the main product of photosynthesis?
A monosaccharide sugar, which can be converted to disaccharides for transport and then to starch for storage.
What is the role of photosynthesis?
Carbon fixation
How does photosynthesis facilitate carbon fixation?
Takes carbon dioxide from the atmosphere and converts it to sugar.
Is carbon fixation endothermic or exothermic?
Endothermic.
This means that energy is required.
How is carbon fixation benificial?
Regulates the concentration of carbon dioxide in the atmosphere and oceans
How does plants rate of respiration change over time?
It doesn’t. Respiration rates stay fairly constant
How does a plants rate of photosynthesis change over time?
Only photosynthesis during daylight
What is the compensation point?
When the rate of photosynthesis and resperation are the same. There is no loss or gain of carbohydrates.
Why is the compensation point important?
Light intensity has to be great enough to allow photosynthesis to take place at the same rate as respiration. This allows it to replenish the carbohydrate stores that are used up during respiration.
What is the compensation period?
The time it takes for a plant to reach the compensation point.
How does the compensation period change with different plants?
Shade plants utilise a lower light intensity so adjust to reach heir compensation point sooner than sun plants which receive a greater light intensity
What is the general structure of a chloroplast?
Disk shaped organelles around 2-10um long.
What is the structure of the membranes of the chloroplast?
A double membrane. The outer membrane is highly permiable.
The intermembrane space (10-20nm) is between the two membranes.
What fills the Chloroplast?
A Fluid-filled matrix called the stroma.
What is found within the stroma?
Grana
What is the role of grana?
The site of the light-dependent stage of photosynthesis.
What is the grana made up of?
Stacks of thilacoids.
What is the structure of thylakoids within the grana?
Stacked together. Stackss can be connected to other thilacoids in other granum by intergranular lamelle (intergranal Thilacoids)
How many thilacoids make up a granum?
up to 100
How are thilcoids adapted to their role?
They have a permiable membrane that are folded into flattened disc like sacks.
How do thilacoids and grana assist with photosynthesis?
With lots of thylakoids in grana and lots of grana in chloroplast and lots of chloroplast in cells, it gives a large surface area for:
* The distribution of photo stems that contain photosystems that trap sunlight.
* Electron carriers and ATP synthase enzymes needed to convert light to ATP
How are photosystems held in place?
Held in the thilacoid membrane by proteins
How does the position of the Grana help the LIS of photosynthesis?
Grana is surrounded by the stroma so products of the LDS can easily pass to the stroma to be used in the LIS.
What is the stroma?
A fluid-filled matrix containing the enzymes needed to catalyse the light Independent Stage of photosynthesis.
What is found within the stroma?
Enzymes,
Starch Grains,
Oil droplets,
Small ribosomes,
DNA
Why is there DNA found in the stroma?
It codes for some of the proteins needed for photosynthesis.
The proteins are assembled in the chloroplast ribosomes.
What are photosystems?
Funnel shaped structures that are found within the thylakoid membranes of chloroplast. They contain photosynthetic pigments.
How do photosystem pigments work?
Each pigment absorbs light of a particular wavelength and reflects the other wavelengths. The colour we see is the colour of the reflected wavelength.
What is the structure of a photosystem?
Funnel shapped with a primary pigment at the base. The walls contain accessory pigments that funnel the light to the primary pigment.
How many types of photosystems are there?
2.
photosystem I and photosystem II
What is chlorophyll?
A mixture of pigments, all with a similar molecular structure consisting of a porphyrin group (ring shape), in which is a magnesium atom, and a long hydrocarbon chain.
What are the two types of chlorophyll?
chlorophyll a and chlorophyll b
What is found in the primary pigment?
chlorophyll a