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41 Cards in this Set
- Front
- Back
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Where does the light dependant reaction occur? |
In the thylakoid membranes of the chloroplast. |
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What does the light dependant reaction require? |
Light from the sun. |
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What is the three main stages of the LDR reaction? |
1. Photoionisation of chlorophyll. 2. Photolysis 3. Chemieosmosis and the production of NADPH |
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What occurs during photolysis? |
Bonds between water molecules are broken by absorbing photons of light into protons and electrons. Some of the electrons are replaced by those lost from the chlorophyll molecule. |
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Describe briefly the process of chemiosmosis. |
1. The electrons (from photolysis) travel down the electron transport chain releasing energy through a series of redox reactions. 2. The energy is used to transport protons across the thylakoid membrane, this creates an electrochemical gradient. 3. Because of this gradient, a proton motive force is generated and proton are pushed through an ATP synthase enzyme, allowing it to spin and generate ATP. |
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What is the LIR also known as. |
The light independent reaction is also known as the Calvin Cycle. |
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Where does the LIR occur? |
In the stroma of chloroplasts. |
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Describe the process of the light independent reaction. |
1. Ribulose biphosphate is fixated with carbon dioxide, through the use of a rubisco enzyme. 2. Glycerate-3-phosphate is created. This is then reduced through the use of ATP (produced by LDR). 3. Two molecules of triose phosphate are made. One of the six carbons is used towards creating an organic substance such as glucose, the other five are used to regenerate ribulosebiphosphate. |
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How many turns of the Calvin Cycle produces a hexose sugar? |
Six turns. |
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Limiting factors of photosynthesis. |
1. CO2 concentration. 2. Temperature. 3. Light intensity. 4. Water availability. |
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What are the four main stages of respiration and where do they occur? |
Glycolysis - cytoplasm. Link reaction - mitochondrial matrix. Krebs cycle - mitochondrial matrix. Oxidative phosphorylation - mitochondrial membrane. |
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What is the anaerobic stage of respiration? |
Glycolysis, it doesn’t require oxygen. |
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Describe the process of glycolysis. |
1. Glucose is first phosphorylated into hexosebiphosphate through the usage of 2 ATP molecules. 2. This compound is unstable and so splits into two molecules of triose phosphate. 3. Triose phosphate is then converted into pyruvate by oxidation using NAD (that is made into NADH) and releases two ATP molecules each. 4. Overall there is a net gain of 2x NADH and 2x ATP |
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Describe the process of the link reaction. |
1. Pyruvate is converted into acetate through the usage of NAD and the release of carbon dioxide.
2. Acetate then combines with coenzyme A to form acetyl coenzyme A, this then goes into the krebs cycle. |
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Describe the process of the Krebs Cycle. |
1. Acetyl coenzyme A combines with a four carbon compound (oxaleacetic acid) to form a six carbon compound (citrate) and the coenzyme A is released and goes back to the link reaction. 2. A few redox reactions occur and the final products are: 6x NADH 4x CO2 2x ATP 2x FADH2 per glucose molecule. |
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Describe the process of oxidative phosphorylation. |
1. NADH and FADH2 loose their hydrogen atom, thissplits into a proton and an electron. 2. The electrons travel down the electron transportchain, loosing energy at each level.3. This energy lost is used to move protons fromthe matrix of the mitochondria to the intermembrane space. A gradient iscreated, and protons move through the ATP synthase enzyme to convert ADP and Piinto ATP. 4. When electrons travel down the ETC, they areaccepted by the oxygen molecule and combine with the protons to form water. Theoxygen is known as the terminal electron acceptor. |
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What happens during anaerobic respiration and why is it important in continuing glycolysis? |
The pyruvate made is reduced into lactate by oxidizing the NADH molecules to form NAD and so glycolysis can continually occur and produce ATP even without oxygen. |
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Why is anaerobic respiration not sustainable. |
A build-up of lactate can cause muscle fatigue, this is not sustainable. Lactate is also acidic, meaning it can denature enzymes used in respiration.
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In aerobic respiration, how does pyruvate from glycolysis enter the mitochondrial matrix? |
Via active transport across the mitochondrial membrane. |
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What is biomass? |
The mass of carbon (dry mass of tissue per given area. |
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What is NPP? |
Net primary production, its the chemical energy stored in plants after respiratory losses have been taken into account. |
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What is GPP? |
Gross primary production, the chemical energy store in a plants biomass per given volume. |
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What is the equation for net primary production? |
N = I - (F+R) I -> Ingested energy. F -> Energy excreted through fecal matter. R -> Respiratory losses. |
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What are the units for rate of productivity.
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kj ha^-1 year^-1 (can be hectre or m^-2) |
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Justify the units for the rate of productivity. |
kj -> Unit for energy. Ha -> Using area to standardise and make comparisons as different systems will vary in size. year -> To take into account the seasonswhich will vary in productivity due to changes in light, CO2 and other factors. This is also to standardise. |
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Why is phosphorus an important molecule. |
Used in DNA, RNA, ATP and phospholipid bilayer of cells. |
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What are mycorrhizae and what is their relationship with plants? |
Fungal associations between plants, the relationship is mutalistic. |
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What benefits do mychorizae provide? |
They increase surface area for water and mineral absorption. They hold water for the plant and make them more drought resistant. |
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What do michorrizhae get in return? |
Sugars and other organic molecules to aid their growth. |
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Outline the phosphorus cycle. |
1. Weathering and erosion can cause for the release of phosphate ions into the soil and water ways. 2. Plants assimalate these phosphorus ions and use them for growth to create sugars. 3. Animals then eat the plants, uptaking some of the phosphorus ions to create their own organic material. 4. Animals then die and the phosphate ions are returned to the soil where they are broken back down by bacteria. 5. The ions then reenter the water ways to be assimilated by plants once again. |
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One advantage and one disadvantage of using natural fertiliser? |
- Cheaper and comes from farmers own livestock. - Exact concentration of minerals cannot be strictly controlled. |
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One advantage and one disadvantage of using artificial fertiliser? |
- Has exact concentrations of minerals. - More water soluble and therefore can cause leaching and lead to eutrophication. |
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Nitrogen containing compounds? |
Proteins, ATP, DNA, RNA. |
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Four stages of nitrogen cycle (just names)? |
1. Nitrogen fixation 2. Ammonification 3. Nitration 4. Denitrification |
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Why is energy lost along a food chain?
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- Not all glucose made by producers is stored as starch or used to build biomass, as certain parts are lost in respiration (As heat)
- Not all the stored energy in the plant is transferred to primary consumers as parts of the plant may be inedible and indigestible. |
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Effect of energy loss on a food chain? |
Places a limit on the length of the food chain as the higher trophic levels would not be able to obtain enough energy from the food it consumes. |
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Adaptations of plants for photosynthesis. |
- Many stomata for gas exchange. - Large leaves for large surface area for light absorption. - Thin leaves for short diffusion distance for CO2. - Air spaces in spongy mesophyll to support gas exchange. - Pallisade cells. |
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Adaptations of palisade cells. |
- Large surface area for light absorption. - Many chloroplasts to increase rate of photosynthesis. - Thin cell wall for a short diffusion distance of CO2. - Large vacuole pushing chloroplasts closer to light. |
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Effect of limiting light on Calvin Cycle? |
- RuBP decreases as it is not being resynthesised from triose phosphate due to low ATP levels (from independent reaction) - GP increases as it is not being converted into triose phosphate as there is no ATP. |
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Effect of limiting CO2 on Calvin Cycle? |
- RuBP increases as no CO2 for the carboxylation and conversion of RuBP into GP. - GP decreases as less GP is being made but it's still being converted into triose phosphate. |
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What is the role of sapriobionts in the ecosystem? |
The saprobionts digest and decompose the organic material of organisms extracelularlly, converting DNA/amino acids/RNA/urea into ammonium ions. |
