PHOTOSYNTHESIS

Pregunta	Respuesta
Which part of the plant is the main photosynthetic structure?	The leaf
What is the name of the cellular organelles within the leaf where photosynthesis takes place?	Chloroplasts
The leaf has many adaptations that make it suited to photosynthesis. One of these is a ______ surface area that collects as much sunlight as possible	Large
Also, the arrangement of the leaves on the plant minimises ____________ and avoids the shadowing of one leaf by another	Overlapping
How is the fact that leaves are thin make them well adapted for photosynthesis?	Most light absorbed in the first few millimetres Diffusion distance kept short
A transparent _______ and epidermis that let light through to the photosynthetic mesophyll cells beneath	Cuticle
Long, narrow upper mesophyll cells packed with ____________ that collect ________	Chloroplasts that collect sunlight
Numerous _______ for gaseous exchange	Stomata
Stomata that open and close in response to _____ _________	Light intensity
Many ___ _______ in the lower mesophyll layer to allow diffusion of carbon dioxide and oxygen	Air spaces
A network of _____ that brings water to the leaf cells	Xylem
______ that carries away sugars produced by photosynthesis	Phloem
What are the three main stages to photosynthesis?	1. Capturing of light energy 2. The light dependent reaction 3. The light independent reaction
In the light DEPENDENT reaction, light energy is converted into what type of energy?	Chemical energy
In the light INDEPENDENT reaction, the protons from the LD are used to _______ carbon dioxide to produce sugars and other organic molecules	Reduced
What are the two distinct regions with a chloroplast?	Grana Stroma
What are the grana?	Stacks of disc like structures called thylakoids
What stage of photosynthesis takes place in the grana?	Light-dependent
Within the thylakoids is the photosynthetic pigment called...	Chlorophyll
What is the stroma and what stage of photosynthesis takes place there?	A fluid filled matrix where the independent stage of photosynthesis takes place
What other structures may be found in the stroma?	Starch grains
In how many ways is the light energy captured used in the light dependent reaction?	2
What are these ways?	- To add Pi to ADP making ATP - To split water into H+ ions and OH- ions
What is used to split the water?	Light
What name is given to this process?	Photolysis
When a substance is combined with oxygen it is called _________	Oxidation
When a substance is oxidised it loses ________	Electrons
When a substance is ________ it gains electrons	Reduced
In how many ways can something be oxidised/reduced?	3
Reduction	1. Gain of electrons 2. Gain of H+ 3. Loss of oxygen
Oxidation	1. Loss of electrons 2. Loss of H+ 3. Gain of oxygen
What happens when a chlorophyll molecule absorbs light energy?	It boosts the energy of a pair of electrons within the chlorophyll, raising them to a higher energy level
These electrons are said to be in an ________ _____	Excited state
In fact, the electrons become so energetic that they...	Leave the chlorophyll molecule
What are these electrons taken up by?	An electron carrier molecule
The chlorophyll molecule has become _________	Oxidised
The electron carrier has been _______	reduced
The electrons are now passed along a chain of electron carriers in a series of _________-_________ reactions	Oxidation-reduction
Where is this transfer chain located?	The membrane of the thylakoid
Why do electrons lose energy as they travel down the chain?	Each new carrier is at a slightly lower energy level
What is this energy used to do?	ADP + Pi ---> ATP
The loss of electrons when light hits the chlorophyll molecule leaves it short of electrons. What does this mean needs to happen?	The electrons need to be replaced if the chlorophyll molecule is to continue absorbing light energy
Where are these electrons provided from?	Water molecules that are split using light energy
What does this photolysis of water also produce?	H+ (protons)
What is the equation for the photolysis of water?	2H20 ---> 4H+ + 4e- + O2
What are the protons taken up by?	NADP
What does NADP then become?	Reduced NADP
What does reduced NADP enter?	The light independent reaction
Why is the reduced NADP important for the plant?	It is a further source of chemical energy
What happens to the oxygen by-product of the photolysis of water?	- Used in respiration - Diffuses out as a waste product
The chloroplasts are adapted for their function in catching sunlight and carrying out the LD reaction. How? (1. surface area)	Thylakoid membranes provide a large s.a for the attachment of enzymes, chlorophyll and electron carriers
How does the network of proteins in the grana make the chloroplasts well adapted?	They hold the chlorophyll in a very precise manner that allows maximum absorption of light
The granal membranes have _________ attached to them, which help manufacture what?	Enzymes that help manufacture ATP
Chloroplasts contain both ___ and _________ so they can quickly and easily manufacture some of the proteins needed for the LD reaction	DNA and ribosomes

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