B4 - Bioenergetics Flashcards
What is the word equation for photosynthesis?
Carbon dioxide + water → oxygen + glucose
What is the balanced symbol equation for photosynthesis?
6CO2 + 6H2O → C6H12O6 + 6O2
What are the reactants of photosynthesis?
What are the products?
Reactants:
Water and carbon dioxide
Products:
Oxygen and glucose
Where in plants does photosynthesis take place? Why?
In all the green parts of the plant.
Because chlorophyll, which is used for light absorption, in the chloroplasts produce a green colour.
Why are leaves adapted to be broad and flat?
To give a large surface area which help to absorb lots of sunlight.
Why are leaves adapted to have lots of chloroplasts?
Chloroplasts have chlorophyll to absorb lots of sunlight.
How do plants use the glucose created from photosynthesis?
C - glucose is converted into cellulose which strengthens cell walls
R - glucose is broken down through respiration to release energy
O - glucose is turned into lipids (oils or fats) and store in seeds
P - glucose is combined with nitrate ions to create amino acids which then are made into protein
S- glucose is turned into starch and stored for when there is no photosynthesis happening
What is a limiting factor?
Any environmental variable that may limit the rate of photosynthesis if it is in short supply.
How is the rate of photosynthesis affected by light intensity?
Light intensity is needed for energy in photosynthesis.
As light intensity increases energy increases. This means the rate of photosynthesis increases until light intensity is no longer a limiting factor.
How is the rate of photosynthesis affected by concentration of carbon dioxide?
CO2 is a raw material needed for photosynthesis.
As the concentration of CO2 increases the rate of photosynthesis increases until the concentration of CO2 is no longer a limiting factor.
How is the rate of photosynthesis affected by temperature?
The right temperature is a needed for the enzymes to work in photosynthesis.
As temperature increases the rate of photosynthesis increases until the temperature is too high.
(This will denature the enzymes needed for photosynthesis)
Pondweed practical
How does oxygen production show the rate of photosynthesis?
There are bubbles in the water
This is oxygen gas
Which is released when photosynthesis occurs
In the limiting factors practical, what is the independent variable?
Light intensity - the distance between the lamp and pondweed
In the limiting factors practical, what is the dependant variable?
Rate of photosynthesis- the number of bubbles produced
What is the inverse square law?
Light intensity decreases in proportion to the square of the distance
Light intensity ∝ 1/distance^2
How are greenhouses used to create the ideal conditions for photosynthesis?
So that temp is not a limiting factor:
• Greenhouses help trap suns heat
• Use heater in winter
• Use shades & ventilation in summer
So that light is not a limiting factor:
• Artificial light used after sunsets
• More time for photosynthesis
So that CO2 is not a limiting factor:
• Paraffin heater
For healthy growth:
• Enclosed greenhouse keeps away pets and diseases
• Fertilisers to provide all minerals
Explain how photosynthesis is an endothermic reaction?
Energy is transferred from the environment in the process
What is respiration?
The process of transferring energy from glucose, which goes on in every cell.
Explain how respiration is an exothermic reaction?
Energy is transferred to the environment
How and why is glucose used during respiration?
The glucose is broken down using oxygen to provide energy for the cells.
Where does respiration take place?
In the mitochondria in the cell cytoplasm.
What is aerobic respiration?
The breakdown of glucose to make energy using oxygen.
What is the word and symbol equation for aerobic respiration?
Glucose + oxygen → carbon dioxide + water
C6H12O6 + 6O2 → 6CO2 + 6H2O
What is anaerobic respiration?
The breakdown of glucose to make energy without using oxygen.
As the oxidation of glucose is incomplete, lactic acid is formed.
What is the word equation for anaerobic respiration in muscle cells?
Glucose → lactic acid
What is the word equation for anaerobic respiration in plants and yeast cells?
Glucose → ethanol + carbon dioxide
What is fermentation?
What is fermentation used for?
Fermentation is anaerobic repetition in yeast cells.
In bread-making, it’s the carbon dioxide from fermentation that makes bread rise.
In beer and wine-making, it’s the fermentation process that produces alcohol.
Why do you respire more when you exercise?
Muscles need energy from respiration to contract. When you exercise you need more energy because your muscles contract more frequently.
Why does anaerobic respiration occur when exercising?
During exercise respiration in cells increases and they need more oxygen. Eventually your body will not supply oxygen to your muscles quickly enough so they start anaerobic respiration.
This builds up lactic acid in the muscles, which is painful.
What are the two ways lactic acid is removed from the muscles?
- Oxygen reacts with the lactic acid to form carbon dioxide and water.
- The blood that enters your muscles transports the lactic acid to the liver where it is converted back to glucose.
What is an oxygen debt?
The amount of extra oxygen your body needs to react with the build up of lactic acid and remove it from the cells.
This means you have to keep breathing for a while after you stop, to get more oxygen into your blood, which is transported to the muscle cells.
During exercise, why does heart rate increase?
• Blood is pumped around faster
• Respiration occurs faster
• More oxygen needs to be supplied
• More glucose needs to be supplied
• More CO2 needs to be removed
• More lactic acid needs to be removed
During exercise, why does rate and depth of breathing increase?
Respiration occurs faster to release energy for muscle contraction
More oxygen is supplied to respiring cells
More carbon dioxide is removed
During exercise, why do arteries dilate?
To supply more blood to the muscles
What is the pulse?
What is metabolism?
The sum of all the reactions that happen in a cell or the body.
What are the 2 types of metabolic reactions?
Anabolic = synthesis reactions
• endothermic
• controlled by enzymes
• join smaller molecules to create larger molecules
Catabolic = breakdown reactions
• exothermic
• break down larger molecules into smaller molecules
What are examples of anabolic reactions in both plants & animals?
Anabolic = synthesis reactions
• endothermic
• controlled by enzymes
• join smaller molecules to create larger molecules
Examples:
• glucose to form cellulose (plants)
• glycogen to form starch
• glycerol + 3 fatty acids to form lipids
• glucose + nitrate ions to form amino acids
• amino acids to form proteins
What are examples of catabolic reactions in both plants & animals?
Catabolic = breakdown reactions
• exothermic
• break down larger molecules into smaller molecules
Examples:
• (in digestion) proteins to amino acids
• (in respiration) glucose to energy
• excess amino acids to urea (excreted as urine)
