Bioenergetics Flashcards
Is photosynthesis endothermic or exothermic
Endothermic
It requires energy from the sun to happen so takes in light energy
Why is photosynthesis endothermic
Takes in energy from the sun (light)
Top 5 uses of glucose by plants
Cellular respiration (releases energy)
Converted into insoluble starch for storage
Producing cellulose
Producing amino acids
Producing lipids (fat/ oil)
Top 5 uses of glucose by plants
Cellular respiration (releases energy)
Converted into insoluble starch for storage
Producing cellulose
Producing amino acids
Producing lipids (fat/ oil)
Glucose helps produce cellulose. What is the purpose of cellulose
Strengthens cell walls
Glucose helps produce amino acids in plants. What are the amino acids needed for
Protein synthesis
What else is needed as well as glucose from photosynthesis for plants to produce amino acids
Nitrate ions from soil
Glucose can help produce fats in plant. What is the fat used for
Future energy source
What is meant by inverse square law
As distance of light source from plant increases, light intensity decreases
Relationship between light intensity and distance
Light intensity is Inversely proportional to (1 over) the distance squared
E.g if distance doubles then light intensity quarters
What is meant by a limiting factor (of photosynthesis)
Anything that limits the rate of a reaction when in short supply
3 main limiting factors of photosynthesis (if you’re asked for a 4th then number of chlorophyll is also one)
Light intensity
Temperature
Concentration of carbon dioxide
When drawing a graph to show how limiting factors affect the rate of photosynthesis what goes on each axis
Y axis is rate of photosynthesis
X axis is limiting factor (CO2 concentration/ light intensity/ temperature)
Describe how light intensity (limiting factor) affects rate of photosynthesis
As light intensity increases so does the rate of photosynthesis
However once the light intensity reaches a certain point something else becomes the limiting factor
Therefore after this certain point rate of photosynthesis will remain at a steady rate even as light intensity keeps increasing
Which 2 limiting factors of photosynthesis have similar graphs
CO2 concentration and light intensity
As the factor increases so does rate of photosynthesis up to a certain point where something else becomes the limiting factor so rate of photosynthesis remains constant even as the CO2 concentration/ light intensity keeps increasing
Describe how carbon dioxide (limiting factor) affects rate of photosynthesis
As carbon dioxide concentration increases so does rate of photosynthesis up to a certain point where something else becomes the limiting factor
After this point as CO2 concentration keeps increasing the rate of photosynthesis remains constant
Plateaued meaning
Where the rate of photosynthesis reaches a stage of no change after a period of progress (rate increasing)
This is where as the limiting factor increases, the rate of photosynthesis no longer does but remains the same (as it’s now another limiting factor that affects it)
What is Photosynthesis controlled by
Enzymes
Why at first does rate of photosynthesis increase as temperature increases
The enzymes involved can work more quickly and the molecules can move faster
What happens to rate of photosynthesis after enzymes have reach their optimum temperature
Enzymes start to denature
Active site can no longer bind to substrate
Rate of photosynthesis quickly decreases
Describe how temperature affects rate of photosynthesis
As temperature increases so does rate of photosynthesis as the enzymes can work quickly and the molecules can move faster as they have more kinetic energy
Up to the optimum temperature after which the enzymes denature and the active sites can no longer bind to the substrate so rate of photosynthesis quickly decreases
What can farmers to increase rate of photosynthesis
Grow plants in greenhouses (especially in colder climates) as it traps the sun’s heat to increase temperature
Use artificial light so photosynthesis can occur at night
Use a paraffin heater (releases heat and CO2 as it burns)
Fertilisers (ensure plants have enough essential minerals)
Use pesticides to kill unwanted pests
What is the equation linking light intensity and distance
Light intensity = 1/ distance squared
Is respiration exothermic or endothermic and why
Exothermic
Releases energy
3 ways organisms use energy from respiration
Build larger molecules from smaller ones (e.g proteins from amino acids)
Muscular contraction (for movement)
Maintaining body temperature
Define metabolism
All the chemical processes that occur within a living organism in order to maintain life
What is the most efficient way to transfer energy from glucose
Aerobic respiration
Word equation for anaerobic respiration in muscles
Glucose-> lactic acid
What does glucose produce if there isn’t enough oxygen
Lactic acid
(Anaerobic respiration in muscles)
During anaerobic respiration why is there the incomplete breakdown of glucose molecules
There is no oxygen to oxidise it
(Makes it inefficient as not all energy from glucose molecule is unlocked)
Word equation for anaerobic respiration in plants and yeast
Glucose-> ethanol + carbon dioxide
What is produced from anaerobic respiration in plants and yeast
Ethanol and carbon dioxide
When is lactic aid produced and when is ethanol and carbon dioxide produced in respiration
Ethanol and carbon dioxide- anaerobic respiration in plants and yeast
Lactic acid- anaerobic respiration in muscles
What is fermentation
Anaerobic respiration in yeast
Lactic acid-> ethanol + carbon dioxide
Two uses of fermentation in industry
Use yeast to make bread- produces carbon dioxide to help bread rise
Use yeast to make alcoholic drinks e.g beer and wine- produces ethanol
When we exercise why do we need to carry out more respiration
Exercise requires us to move our muscles more than usual
Muscle contraction requires energy
Energy is released from respiration
More respiration means more energy released needed for this muscle contraction
Why do our muscles need more oxygen during exercise
To carry out more respiration to release more energy for muscle contraction
3 things that increase during exercise
Breathing rate
Heart rate
Breath volume
Which type of respiration involves complete oxidation of glucose
Aerobic
Which type of respiration involves incomplete oxidation of glucose
Anaerobic
If glucose is fully oxidated does this mean more or less energy is released
More
(Aerobic respiration, whereas anaerobic is incomplete oxidation/ breakdown of glucose so not all energy from glucose is used and less energy is produced)
Why does lactic acid build up during exercise
Anaerobic respiration occurs due to lack of oxygen for amount of energy needed
Define oxygen debt
Amount of oxygen needed to react with lactic acid and remove it from the cells
What happens once lactic acid has been oxidated by oxygen
It is converted back to glucose
(Oxidation takes place in liver as lactic acid is transported through blood from muscles)
Once you’ve finished exercising how can your body get rid of the built up lactic acid
Reacting it with oxygen (converted to glucose)
Where does oxidation of lactic acid take place and how does it get there
Liver
Moves from muscles through blood
2 things that happen to muscles during long periods of activity
Become fatigued
Stop contracting efficiently
Give 5 factors that affect metabolic rate
Age
Gender
BMI
Level of exercise
Genetics
When there is a build up of lactic acid in the muscles after long periods of vigorous activity they become f…
Fatigued
When you exercise does the amount of glycogen stored in the muscles increase or decrease
Decrease
When you exercise why does the amount of glycogen stored in muscles decrease
It’s converted to glucose to be used in respiration to release energy for more muscle contraction
Why do athletes ‘carb load’ before a big race
Maximises amount of glycogen stored which can then be converted to glucose for respiration to release more energy for more muscle contraction to help them run faster
Why do birds and mammals have a higher rate of respiration than reptiles and fish
They need to regulate their body temperature and respiration releases the energy for this
Equation of lactic acid reacting with oxygen
Lactic acid + oxygen -> carbon dioxide + water
Chemical formula of lactic acid
C3H6O3
Metabolic processes include the synthesis and breakdown of…
Carbohydrates, proteins and lipids
Metabolic actions include the s… and b… of carbohydrates, lipids and proteins
Synthesis
Breakdown
E.g breakdown of glucose in respiration to release energy
