Unit 5 - Energy transfers in and between organisms

what is the word equation for photosynthesis?

carbon dioxide + water —> glucose + oxygen

what is the balanced equation for photosynthesis?

6CO2 + 6H2O —> C6H12O6 + 6O2

what are the main stages of photosynthesis?

capturing of light energy by pigments such as chlorophyll
the light dependent reaction, where light energy is converted into chemical energy
the light independent reaction, where sugars and other organic molecules are produced

what is the role of ATP in organisms?

ATP is a molecule that temporarily stores and quickly releases energy for various cellular processes

what is the relationship between respiration and photosynthesis?

the products of photosynthesis, glucose and oxygen can be used as reactants in respiration to synthesise ATP
the products of respiration, carbon dioxide and water can then be used as reactants in photosynthesis

how are plant leaves adapted for photosynthesis?

large surface area to absorb sunlight
minimal overlapping to avoid shadowing
thin to keep diffusion distance short
transparent cuticle and epidermis to allow light to enter the leaves
chloroplasts packed into mesophyll cells to carry out photosynthesis
stomata for gas exchange taking in and out gases
xylem and phloem to transport reactants and products of photosynthesis between the leaves and the rest of the plant

what is the role of photosynthetic pigments?

absorb energy from certain wavelengths of light

what is the stroma?

is a fluid filled matrix in a chloroplast where the light-dependent stage of phtosynthesis takes place 

what are the grana, thylakoids and lamellae?

grana are stacks of flattened sacs called thylakoidsand they are jooined by membranes called lamellae

do chloroplasts have a single membrane or a double membrane?

a double membrane

what is the main function of chloroplasts and where are they usually found?

chloroplasts are the site of photosynthesis they are found in plant cells and they are mainly in the mesophyll tissues in leaves

what is the main pigment in photosynthesis?

chlorophyll

what is the site of the light dependent reaction and how is this region adapted for this function?

it takes place in the thylakoids

these are well adapted for light dependent reactions because 

1 they have a large surface area for chlorophyll and electron carriers in the electron transport chain 

2 they contain ATP synthase channels 

3 they are selectively permeable, allowing a proton gradients to be esablished for ATP production 

what are oxidation and reduction?

oxidation is when a substance loses electrons or gains oxygen

reduction is when a substance gains electrons or loses oxygen

what is the main reactants of the light dependent reaction?

water and light energy

what are the products of the light dependent reaction?

for non cyclic photophosphorylation are ATP, reduced NADP and oxygen

but in cyclic photophosphorylation is just ATP

what are the key stages of the light dependent reaction?

absorption of light by pigments
release of electrons from pigments
electron transfer along the electron transport chain
photolysis of water to provide protons and electrons
chemiosmosis 
production of ATP and reduced NADP

what is the role of chemiosmosis in photosynthesis?

is the diffusion of protons across the partially permeable thylahoid membrane down their gradient, through the ATP synthase channel

what is the role of the electron transport chain in the light dependent reaction?

it transfers the excited electrons from photosynthetic pigments to electron carriers, this transfer releases energy which is used to pump protons across the thylakoid membrane 

what is the equation for the photolysis of water?

2H2O + light energy —> 4H+ +4e- + O2

how is photolysis useful in photosynthesis?

photolysis produces electrons to replace these lost pigments, it produces that help set up the proton gradient that drives ATP synthesis, the protons and electrons are used to reduce NADP and produces oxygen

how is ATP produced in the light dependent reaction, including reference to ATP synthease and NADP?

ATP synthase catalyses the production of ATP from ADP and Pi this uses the energy from the flow of protons down their concentration gradient from the thylakoid space into the stroma through ATP synthase channels the protons are taken up by NADP in the stoma and along with the electrons produce reduced NADP

what are the products of the light dependent reaction?

ATP, reduced NADP and oxygen