B1 - Bioenergetics Flashcards
Aerobic respiration:
A form of respiration that uses oxygen to release energy
from molecules like glucose - represented by the following word equation: glucose + oxygen —–> carbon dioxide +water
Anaerobic respiration:
A form of respiration that releases energy from molecules
like glucose without using oxygen - represented by the following word equation:
glucose —–> lactic acid
Cellular respiration
An exothermic reaction which is continuously occurring in
living cells
Limiting factor
A factor that limits the rate of a reaction when there is not enough
of it.
Photosynthesis:
An endothermic reaction in which energy is transferred from the
environment to the chloroplasts by light
Oxygen debt:
The amount of extra oxygen the body needs after exercise to
react with the accumulated lactic acid and remove it from the cells.
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 chloroplasts in leaf palisade cells. They contain chlorophyll , a pigment which absorbs light energy
state the word and symbol equation for photosynthesis
1)6CO2 + 6H2O → C6H12O6 + 6O2.
2)Carbon dioxide + water —- (with light energy) —-> glucose + oxygen gas.
is photosynthesis an endothermic or exothermic reaction and why?
endothermic - energy is transferred from the environment to chloroplasts 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
1) broad leaves - maximises surface area
2) thin leaves - short diffusion distance
3)chlorophyll present - trap light energy
4)veins - transport water to leaves via xylem , remove photosynthesis products via phloem
5) air spaces - allow CO2 to enter and 02 to leave
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 particles is increased. The rate decreases past a certain temperature as enzyme become denatured
how does light intensity affect the rate of photosynthesis
increasing the light intensity increases the rate of photosynthesis until another factor becomes limiting
how does carbon dioxide affect the rate of photosynthesis
increasing the carbon dioxide concentration increases the rate of photosynthesis as co2 is required to make glucose
how does the amount of chlorophyll affect the rate of photosynthesis
decreasing the amount of chlorophyll 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
state 5 uses of glucose produced during photosynthesis
1) respiration
2) starch for storage
3) cellulose for strength
4) amino acid and protein synthesis
5)lipids for energy storage in 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 word and symbol equations for aerobic respiration
1)C6H120 +602 —->6C02+6H20
2)Glucose + oxygen → carbon dioxide + water + energy
where does aerobic respiration take place
in the mitochondria
why do organisms require the energy released by respiration
1) synthesis of larger molecules
2)muscle contraction
3)maintenance of body temperature
4) active transport
what is 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 (product for anaerobic respiration builds up in muscles , preventing efficient contraction
what is an oxygen debt
the amount of oxygen needed to convert lactic acid 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
1) aerobic requires oxygen
2) aerobic produces C02 and water; anaerobic produces lactic acid or ethanol
3) aerobic transfers a greater amount of energy
what changes take place when muscular activity increases in the body
1) heart rate increases and arteries dilate - increases flow of oxygenated blood to muscles
2) breathing rate increases and breathing is deeper - increases the rate of gaseous exchange
3) stored glycogen I converted back into glucose
what is metabolism
the sum of all the reaction that take place in a cell or an organism
how do cells use the energy transferred by respiration
to continuously carry out enzyme-controlled processes which lead to the synthesis of new molecules
give examples of metabolism
1)glycerol and fatty acids into lipids
2)photosynthesis
3) respiration
4) glucose and nitrate intno into amino acids
