bioenergetics Flashcards
what is photosynthesis
the process by which plants synthesis glucose using light energy from the sun, light energy is then converted into chemical energy
where does photosynthesis take place?
within chloroplasts in leaf palisade cells, they contain chlorophyll, a pigment that absorbs light energy
word equation for photosynthesis
carbon dioxide + water - glucose + oxygen
symbol equation for photosynthesis
6co(2) + 6h(2)o - c(6)H(12)o(6) + 6o(2)
is photosynthesis an endothermic or exothermic reaction
endothermic
why is photosynthesis an endothermic reaction
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 that maximise the rate of photosynthesis
broad leaves - maximize surface area
thin leaves - short diffusion distance
chlorophyll present - trap light energy
veins present - transport water to leaves via the xylem, remove photosynthesis products via the phloem
air spaces - allow co(2) to enter and o(2) to leave
guard cells present - control opening of stomata for gas exchange and prevent water loss
what are the 4 main factors that affect the rate of photosynthesis
- temp
- light intensity
- carbon dioxide concentration
- amount of chlorophyll
how does temp affect the rate of photosynthesis?
increasing the temp increases the rate of photosynthesis as the kinetic energy of particles is increased. the rate decreases past a certain temp as enzymes 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 concentration 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
explain how you can calculate the rate of photosynthesis by measuring oxygen production
set up bubble photometer apparatus
oxygen gas produced causes the bubble 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 temp, light intensity, and Co2 concentration to achieve the fastest possible rate of photosynthesis, leading to greater yield.
state 5 uses of the glucose produced during photosthesis
- respiration
- starch for storage
- cellulose for strength
- amino acid and protein synthesis
- 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 is the equation for aerobic respiration
glucose + oxygen = carbon dioxide + water (+energy)
where does aerobic respiration take place
in the mitochondria
why do organisms require the energy released by respiration
- synthesis of larger molecules
- muscle contraction
- maintenance of body temp
- active transport
what is anaerobic respiration
an exothermic reaction in which glucose is broken dow 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 builds up in muscles, preventing efficient contraction
what is an oxygen dept
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 anaerobe respiration
aerobic requires oxygen, anaerobic does not
aerobic produced carbon dioxide and water, anaerobic produces lactic acid or ethanol and carbon dioxide
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 and arteries dilate - increases flow of oxygenated blood to muscles
breathing rate increases and breathing is deeper - increases the rate of gaseous exchange
stored glycogen is converted back into glucose
how is lactic acid transported away from the muscles
blood flow through the muscles transport 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 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 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
