5.2.1 Photosynthesis Flashcards
What is photosynthesis?
Light energy is transformed into chemical energy - trapped in the bonds of complex organic molecules which can be produced in the process.
What type of organisms perform photosynthesis?
Autotrophs
What is the word equation for photosynthesis?
Carbon dioxide + water -> glucose+ oxygen
What is the symbol equation for photosynthesis?
6CO2 + 6H2O -> C6H12O6 + 6O2
Is photosynthesis endo or exothermic?
Endothermic
What can glucose be converted into by plants?
Glucose combines with nitrogen compounds to form amino acids. Glucose monomers can form large molecules such as starch. Nucleic acids have a sugar portion.
What is a photon?
It is a particle of light. Each photon contains a quantum/amount of energy.
What is the waxy cuticle on a leaf?
It is a non-cellular layer on the surface of the leaf that limits water loss.
What is the upper epidermis on a leaf?
It protects the leaf from injury and reduces water loss, it is transparent. It is the layer below the waxy cuticle.
What are the palisade cells on a leaf?
They are part of the parenchyma tissue making up the internal tissue of a leaf. They contain a large number of chloroplasts and are adapted for efficient photosynthesis.
What is the lower epidermis on a leaf?
Some of the cells of the lower epidermis are modified to form guard cells (stomata) which control the movement of water and gases into and out of the leaf. The lower epidermis also protects the leaf.
What is the spongy mesophyll layer in the leaf?
It forms part of the parenchyma tissue. Contain chloroplasts but are in smaller abundance than palisade cells. Air spaces between the cells play a role in gaseous exchange.
What do photosynthesis and aerobic respiration together in a plant allow?
Cycling of oxygen and carbon dioxide. Products of one process are the raw materials for the next.
What is the compensation point in respiration?
It is where respiration and photosynthesis occur at the exact same rate and there is no net loss or gain of carbohydrate. The time taken to reach this point (where respiration occurs at a faster rate is called the compensation period.
What are thylakoids?
They are pigment-containing flattened discs. The first part of photosynthesis, the light-dependent reaction takes place in the thylakoid membrane.
What are granum?
They are plural grana which is a stack of thylakoids. A single chloroplast can contain around 50 grana. Granum stacks provide the chloroplast with an increased surface area for photosynthesis to occur in limited spaces.
What are the inter-granal thylakoid/lamella?
They are extensions of the membrane that form thylakoids. They connect one granum to another. They are the site of the light-dependent reaction.
What is the stroma?
It is an amorphous, gel-like material. Contains enzymes. The light-independent reaction takes place here using enzymes.
It also contains starch grains to store glucose. Oil droplets to provide raw materials for making new membranes. Small ribosomes to produce the proteins coded for by chloroplast DNA.
What is the double membrane in a chloroplast?
The double membrane or envelope controls molecular traffic into and out of the chloroplast. The inner membrane is extensively folded to form the thylakoids.
What do pigments do in chloroplasts?
They absorb specific wavelengths of light and reflect others.
What does chlorophyll a do in plants?
It is the primary pigment in photosynthesis and absorbs mainly red and blue light and reflects green light. This is why most plants appear green.
What are the accessory pigments in chloroplasts?
Chlorophyll b, carotenoids, xanthrophylls.
What do carotenoids absorb and reflect?
Absorb blue-green light and reflects red, orange and yellow light.
Study the diagram to do with absorbance of wavelenths by pigments
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Where does the light-dependent reaction take place?
The thylakoid membranes.
What is the role of the photosystem?
To absorb light energy of different wavelengths and transfer this energy efficiently and quickly to the reaction centre (RC).
What does the antenna complex of the photosystem consist of?
Carotenoids, chlorophyll a and b and xanthrophyll.
What does the reaction centre consist of?
1 of 2 types of chlorophyll a.
