Chapter 17 Flashcards
Why do plants have a need for energy
Plants need energy for active transport photosynthesis and cell division
What is photosynthesis
Photosynthesis is the process where light energy is used to make glucose from water and carbon dioxide
6CO2 + 6H2O → C6H12O6 + 6O2
What is respiration
The process by which organic molecules are broken down into smaller inorganic molecules to synthesise ATP
C6H12O6 + 6O2 → 6CO2 + 6H2O
How are photosynthesis and respiration linked
The raw materials of photosynthesis are the products of respiration and vice versa
Draw a diagram of a chloroplast
Checking notes should include stroma outer membrane thylakoid DNA lamela granum and inner membrane
What is a pigment
Molecules absorb specific wavelengths of light contained in chloroplasts EG chlorophyll a chlorophyll b, xanthophyll and carotenoids
What is a photosystem and draw a diagram
Photosystem is a protein complex involved in the absorption of light and electron transfer in photosynthesis
Has primary pigments at the centre known as the reaction centre where electrons are excited
Has accessory pigments surrounding it which are the light harvesting system which transfer energy to the reaction centre
How can you separate photosynthetic pigments
1) grind up leaves with anhydrous sodium sulfate and propanone
2) add petroleum ether
3) add some liquid from the top layer to a pencil line on the bottom of a TLC play and build up of concentrated spot
4) putting a beaker with the solvent and add a lid
5) when the solvent reaches the top Mark the front and calculate the RF values to identify
Explain the process of non cyclic phosphorylation in the light-dependent stage of photosynthesis
1) light is absorbed by photosystem II and excited electrons in the chlorophyll
2) the electrons move to a higher energy level and along the electron transport train to photosystem one by chemosmosis
3) photolysis- light energy splits water into H+ ions electrons and oxygen to replace the electron lost in photosystem 1
4) energy is used to transport protons into the thylakoid from the electron so they lose energy down the train
5) this creates a proton gradient so protons and move down the gradient via ATP synthase which combines ADP and inorganic phosphate to make ATP
6) light energy absorbed by photosystem 1 excite electrons which are transferred with a protein to nadp to form reduced nadp
What is cyclic phosphorylation
Cyclic photophosphorylation only uses photosystem 1 electrons are recycled and don’t produce nadp or O2
Explain the process of the light independent stage of photosynthesis
1) fixation-
Carbon dioxide enters and combines with ribulose bisphosphate catalyzed by ribulose bisphosphate carboxylase to give an unstable 6 carbon compound which breaks down into two glycerate-3- phosphate molecules
2) reduction-
Glycerate 3 phosphate is converted into triose phosphate by ATP and H+ ions from reduced nadp
3) regeneration-
5 of every 6 triose phosphates are used to regenerate ribulose bisphosphate
One makes carbohydrates lipids and amino acids
How does light intensity affect photosynthesis
Light intensity is needed for the light dependent stage so reducing it reduces the rate of the light-dependent stage which reduces ATP and nadp needed to convert glycerate 3 phosphate to triose phosphate to the concentration of glycerate 3 phosphate will rise and triosephosphate and ribulose bisphosphate will fall
How does temperature affect photosynthesis
Temperature affects the rate of enzyme controlled reactions and can cause denaturation as all reactions in the Calvin cycle are catalysed the lower temperature will decreased ribulosebis, glycerate-3-phosphate and triose phosphate
How does carbon dioxide concentration affect photosynthesis
Carbon dioxide is needed for carbon fixation in the Calvin cycle so at low concentrations there will be less glycerate 3 phosphate and triose phosphate but ribulose bisphosphate will increase
Does water stress affect photosynthesis
Underwater stress stomata on plant leaves will clothes to avoid water lost by transpiration this also stops the diffusion of carbon dioxide which reduces the rate of the light independent reaction
