bioenergetics Flashcards
what is photosynthesis?
The process by which plants synthesise glucose using light energy from the Sun.
Light energy is converted into chemical energy
where does photosynthesis take place?
Within chloroplast in leaf Palaside cells. They contain chlorophyll, a pigment which absorbs light energy.
State the equations for photosynthesis
6co2 + 6H2o —-> C6H12O6 + 6O2
Is photosynthesis an endothermic or exothermic reaction and why?
Endothermic energies transferred from the environment to the chloroplast by light
How can you show that a plant gives off oxygen during photosynthesis?
using a water plant, collect gas bubbles produced during photosynthesis. The gas will relight a glowing splint as it contains oxygen
Give examples of leaf adaptations which maximise the rate of photosynthesis
broadleaves – maximise surface area
Fin leaves – short diffusion distance
Chlorophyll present – trap light energy
Veins – transport water to leaves via xylem, remove photosynthesis products by phloem
airspaces– allows CO2 to enter an O2 to leave
Guard cells – control opening of stomata for gaseous exchange preventing water loss 
what are the four main factors that affect the rate of photosynthesis?
Temperature, light intensity, carbon dioxide concentration, amount of chlorophyll
how does the temperature affect the rate of photosynthesis?
Increasing the temperature increases the rate of photosynthesis as the kinetic energy of the particles is increased. The rate decreases past a certain temperature as enzymes become denatures.
how does light intensity affect the rate of photosynthesis?
Increasing the light intensity increases the rate of photosynthesis until another factor becomes limited
how does carbon dioxide concentration affect the rate of photosynthesis?
Increasing the carbon dioxide concentration increases the rate of photosynthesis ( until another factor becomes limiting ) as CO2 is required to make glucose

How does the amount of chlorophyll affect the rate of photosynthesis?
decreasing the amount of chlorophyll(eg due a to lack of magnesium) decreases the rate of photosynthesis as chlorophyll is required to absorb light energy
what is a limiting factor?
An environmental factor which can restrict the rate of photosynthesis
eg light intensity
explain how you can calculate the rate of photosynthesis by measuring oxygen production
set up a bubble potometer apparatus (pondweed in a sealed tube of water, attached to a capillary tube and a gas syringe )
Oxygen gas produced causes the bubbles in the capillary tube to move the distance moved by the bubble is used to calculate the volume of oxygen produced 
How can farmers use their knowledge of limiting factors to increase their profits?
They can control temperature, light intensity and CO2 concentration to achieve the fastest possible rate of photosynthesis, leading to greater yield
State the law which describes the relationship between the distance of light source from a plant and light intensity
State five uses of glucose produced during photosynthesis
Respiration
Starch for Storage
Cellulose for Strength
Amino acid and protein synthesis (combined with nitrates)
Lipids for energy storage and seeds
What is aerobic respiration?
An exothermic reaction in which glucose reacts with oxygen to release energy which can be used by cells
what are the equations for aerobic respiration?
C6H12O6 + 6O2 ———> 6CO2 + 6H2O
where does aerobic respiration take place?
Mitochondria
Why do organisms require the energy release by respiration?
synthesis of larger molecules
Muscle contraction
Maintenance of body temperature
Active transport
What is an anaerobic respiration?
An exothermic reaction in which glucose is broken down to release energy in the absence of oxygen
what is the equation for anaerobic respiration?
glucose —-> lactic acid (+energy)
Why is anaerobic respiration less efficient than aerobic respiration?
Glucose is not completely broken down, so less energy is transferred
why can anaerobic respiration lead to muscle fatigue?
Lactic acid buildup in muscles, preventing efficient contraction
What is an oxygen debt
The amount of oxygen needed to convert lactic acid into back into glucose after anaerobic respiration
what is fermentation?
A type of anaerobic respiration that occurs in yeast cells
what is the equation for fermentation?
glucose —-> ethanol + carbon dioxide (+energy)
why is the fermentation reaction important?
It is used in the production of bread and alcoholic drinks
What are the differences between aerobic and anaerobic respiration?
aerobic requires oxygen; anaerobic does not
Aerobic produces CO2 and water: anaerobic produces lactic acid or ethanol and CO2
Aerobic transfers, a greater amount of energy
how do muscles store glucose?
As glycogen
What changes take place when muscular activity increases in the body?
heart rate increases in arteries dilate – increases flow oxygenated blood to the muscles
Breathing rate increases and breathing is deeper – increases the rate of gaseous exchange
stores glycol is converted back into glucose
How is lactic acid transported away from the muscles?
blood flow through the muscles transports lactic acid to the liver, where it is oxidised back to glucose
What is metabolism?
The sum of all the reactions that take place in a cell or an organism
How do cells use energy transferred by respiration?
To continuously carry out enzyme controlled processes which lead to the synthesis of new molecules
give examples of metabolic reactions
Glucose into starch/glycogen/cellulose
Glycerol and fatty acids into lipids
Glucose and nitrate ions into amino acids
Photosynthesis
Respiration
Breakdown of excess proteins into urea
