Photosynthesis 3.2 Flashcards
What is the equation for photosynthesis?
6CO2+ 6H2O C6H12O6 + 6O2
What is the definition of photosynthesis?
Photosynthesis is the process by which green plants are able to use light energy to convert carbon dioxide into carbohydrates.
Why do plants get rid of their leaves in the winter?
As the leaves aren’t receiving much sunlight so they would take the plants nutrition.
What characteristic of the leaf allows it to absorb as much sunlight as possible?
Thin and large surface area allows sunlight to penetrate the leaf as much as possible.
What characteristic allows the leaf to diffuse carbon dioxide?
Stomatal pores, air spaces in spongy mesophyll and spaces between the palisade cells.
What is needed for the light dependent stage of photosynthesis to occur?
Light energy my be harvested by the plant.
Where are chlorophylls and carotenoids found?
The thylakoid membranes of the chloroplast.
What are groups of chlorophylls and carotenoids called?
An antenna complex.
What is a photon?
A quantum of light energy.
What are the two stages of photosynthesis?
Light dependent and light independent.
What is the light dependent stage?
The stage that requires light.
What is the light independent stage?
The stage that is able to take place in the dark.
Where does the light stage take place?
The internal membranes of the chloroplasts-thylakoids.
What are the functions of the light stage?
Production of reduced NADP using hydrogen obtained by splitting water.
Synthesis of ATP.
What is the first reaction of the light dependent stage?
Splitting water molecules by light (photolysis), to produce hydrogen ions and electrons. Oxygen is produced as a waste product.
What is the second reaction of the light dependent stage?
Synthesis of ATP from ADP and Pi. This type of phosphorylation is known as photophosphorylation as light energy is involved.
What is the third reaction of the light dependent stage?
The combination of hydrogen ions and electrons with NADP to produce NADPH2.
What are the two ways phosphorylation can occur?
Non-cyclic processes – both ATP and NADPH2 are made.
Cyclic processes – only ATP is made.
Why is light harvested?
To energy levels of the electrons.
What is non-cyclic phosphorylation?
The phosphorylation of ADP to ATP using the energy from sunlight called photophosphorylation.
Where does non-cyclic phosphorylation take place?
In both photosystems I and II.
Where does cyclic phosphorylation take place?
In photosystem I.
How many ATP molecules are formed in non-cyclic phosphorylation?
1
How many NADPH2 molecules are formed in non-cyclic phosphorylation?
2
What is the Calvin cycle?
A metabolic pathway.
What is the main purpose of the Calvin cycle?
To convert carbon dioxide into carbohydrates- glucose, fructose…
Describe the structure of a chloroplast.
Double membrane, grana connected by intergranal lamellae and stroma.
Where are chloroplasts located in an angiosperm leaf?
Mesophyll layers.
What is a photosynthetic pigment?
A molecule present in chloroplasts that absorbs certain wavelengths.
Examples of photosynthetic pigments:
Chlorophyll a and b, beta carotene and xanthophyll’s.
What is an absorption spectra?
A graph showing the wavelengths of light absorbed by a pigment.
What is an action spectra?
A graph of the rate of photosynthesis against each wavelength of light absorbed by a pigment.
What is an action spectra?
A graph of the rate of photosynthesis against each wavelength of light absorbed by a pigment.
What is photolysis?
The splitting of a molecule of water in the presence of light that occurs during the light dependent stage of photosynthesis. This produces protons, electrons and oxygen:
H2O–>2H+ + 2e- + 1/2O2
What happens to the products of photolysis?
Hydrogen is used in proton pumping and to reduce NADP, e- replaces electrons lost from chlorophyll a in photosystem II and oxygen is a by-products which is used for respiration or diffuses out of the leaf as waste gas.
How does the electron transfer chain result in the production of reduced NADP?
NADP acts as a final electron acceptor and is subsequently reduced.
What is a limiting factor?
A variable that limits the rate of a particular reaction.
Factors that limit the rate of photosynthesis.
Light intensity- light dependent stage
Light wavelength- absorption by chlorophyll
CO2 levels- light-independent stage
Temperature- enzyme-controlled reactions
pH- enzyme-controlled reactions.
What does nitrogen deficiency in plants cause?
Stunted growth and chlorosis (yellowing of the leaves)
Describe the role of magnesium in plant metabolism.
Synthesis of chlorophyll.
What does magnesium deficiency in plants cause?
Chlorosis.
