Chapters 9-10: Bioenergetics Flashcards
What is photosynthesis?
A chemical reaction that takes place in cell chloroplasts and converts water and carbon dioxide into oxygen and glucose using energy from the sun
What is the balanced symbol equation for photosynthesis?
6CO2 + 6H2O => C6H12O6 + 6O2
Where does the majority of photosynthesis take place?
Palisade mesophyll leaf cells as they face the sun and have many chloroplasts
How do gases enter leaves?
They are absorbed from the air into the spaces between the spongy mesophyll cells
How does water enter leaves?
It osmoses into the root hair cells and is transported to the rest of the plant through xylem vessels in transpiration
How is glucose distributed throughout a plant?
It is produced in the leaves and then transported in phloem tissue to other parts of the plant (translocation)
What other organisms photosynthesise?
Algae (uni- and multicellular eukaryotic organisms). Some algae have other photosynthetic pigments that are red or brown
What is a limiting factor?
Anything that reduces or stops the rate of a reaction
What are the 4 limiting factors in photosynthesis?
Low temperatures, CO2 shortage, shortage of light, shortage of chlorophyll
Why do lower temperatures reduce rates of photosynthesis?
The particles have less kinetic energy, so they collide less and react less
What is chlorosis?
When a plant has a magnesium deficiency and can’t produce enough chlorophyll, giving it a yellow appearance
How do plants take in minerals from the soil?
Through active transport (concentrations are lower in the soil than in the plant)
What is yield?
The amount of an agricultural product. Yield can be maximised by growing plants at optimal conditions. When one factor stops being the limiting factor, another factor becomes the limiting factor
What is do plants use their glucose for?
- Producing cellulose for structural growth and making cell walls
- Respiration to release energy for chemical reactions
- They convert it to starch and store it
- making proteins and amino acids for growth
- Converted into fats and oils and stored
How much energy is wasted when one algorithm consumes another?
90%
How would you investigate the effect of light intensity on the rate of photosynthesis using an aquatic organism?
- Cut a piece of pond weed, attach a paperclip to.it to weigh it down and place it into a boiling tube filled with water
- Set up a lamp 50cm from the boiling tube and place a tank of water between them
- Turn off the lights and turn the lamp on for 2 minutes
- Place a thermometer in the boiling tube to ensure the temperature remains constant
- Count the number of bubbles produced in 1 minute, then repeat this 2 more times to get a mean
- Repeat steps 2-6 with 40cm, 30cm, 20cm and 10cm
What is respiration?
An exothermic reaction that takes place in the mitochondria in which glucose and oxygen react to release energy, carbon dioxide and water (which comes out in our breath)
What is the balanced symbol equation for respiration?
C6H12O6 + 6CO2 => 6CO2 + 6H2O (this is the inverse of photosynthesis in plants)
What is this energy converted to?
Thermal energy for keeping the animal warm, a chemical store of energy for reactions and movement
What is anaerobic respiration?
When not enough oxygen is being provided to the cells for aerobic respiration, glucose will be converted into lactic acid, releasing 5% of the energy released in aerobic respiration
What causes muscle cramp?
A buildup of lactic acid preventing the muscle from contracting efficiently
What is oxygen debt?
After a human stops exercising, they will continue to breath heavily to convert the remaining lactic acid into oxygen (lactic acid + oxygen => carbon dioxide + water), releasing 95% of the energy
Where does this process take place?
In the liver (the lactic acid diffuses from a high concentration in the muscles to a lower concentration in the blood. By the time the blood reaches the liver it has a high concentration and diffuses into the liver)
What other organisms respire?
Plants and micro-organisms
What is the equation for anaerobic respiration in micro-organisms such as yeast?
Glucose => Ethanol + carbon dioxide (known as fermentation)
What is this reaction used for?
Making alcoholic drinks and bread (the yeast is killed by heat before it can make too much ethanol, which evaporates away)
What is metabolism?
The sum of all the chemical reactions that take place in the body (they are catalysed by enzymes)
What are breakdown reactions?
Reactions where larger molecules are broken down into smaller ones. These reactions do not require much energy
What happens when proteins are broken down?
They are broken down into amino acids, which diffuse into the liver in the same way as lactic acid, where they are then broken down into urea, which is excreted by the kidneys
What happens to amino acids?
An anime group is removed, creating urea
What are synthesis reactions?
Reactions where smaller molecules are combined to make larger ones. These reactions require more energy
What is glucose synthesised into?
Starch (for storage), cellulose (cell walls in plants), glycogen (for storage in the liver)
How are lipids made?
They are made from 3 molecules of fatty acids and one molecule of glycerol
What are lipids used for?
Chemical store of energy, making cell membranes
How are proteins made?
Glucose and nitrate ions are used to make amino acids. A chain of amino acids are then folded into a specific shape to make a protein
