bioenergetics Flashcards
photosynthesis equation
carbon dioxide + water -> glucose + oxygen
define photosynthesis
an endothermic reaction in which energy is transferred from the environment to the chloroplasts by light
where does photosynthesis take place
in the leaves which contain palisade cells that contain the chemical chlorophyll
function of chlorophyll and where it’s found
it is found in chloroplasts and absorbs the light energy needed for photosynthesis; energy is transferred from the environment to the chloroplasts via light
4 main factors that affect the rate of photosynthesis
temperature, light intensity, carbon dioxide concentration and the amount of chlorophyll
effect of light intensity on the rate of photosynthesis
- initially, as light intensity increases, the rate of photosynthesis increases
- this is because, at this point, light intensity is the limiting factor (light intensity is what is stopping the rate from increasing)
- at one point, the graph flattens out and, as we increase the light intensity, the rate of photosynthesis does not change – showing that light is no longer the limiting factor: temperature or carbon dioxide is
effect of carbon dioxide on the rate of photosynthesis
- carbon dioxide is a reactant in photosynthesis so it makes sense that it is a limiting factor for the rate of photosynthesis (it has a similar graph to light intensity)
- initially, as carbon dioxide concentration increases, the rate of photosynthesis also increases because, at this point, the carbon dioxide was the limiting factor
- at one point, the graph flattens out, showing that CO2 concentration was no longer the limiting factor and something else is limiting the rate from increasing (light or temperature)
effect of temperature on the rate of photosynthesis
- initially, as temperature increases, the rate of photosynthesis increases because particles have more kinetic energy so react faster
- at a certain point, it reaches a maximum then rapidly decreases; this is because photosynthesis is an enzyme-controlled reaction so, once it reaches past the optimum temperature, the rate of reaction will rapidly decrease due to the denaturation of enzymes
effect of amount of chlorophyll on the rate of photosynthesis
- chlorophyll is a chemical needed for photosynthesis because it is how energy is absorbed by light
- a lack of chlorophyll will thus reduce the rate of photosynthesis
why are limiting factors important
they’re important in the economics of enhancing the conditions in greenhouses to gain the maximum rate of photosynthesis while still maintaining profit
why is it important that farmers and gardeners know the ideal conditions for photosynthesis
they can create an environment that maximises the rate of photosynthesis, which maximises the rate of plant growth, thus crop yield and thus profit
why should a greenhouse be used to maximise the rate of photosynthesis
this is the best way, because conditions can be easily controlled
how do greenhouses work to maximise the rate of photosynthesis for temperature
- naturally, greenhouses trap heat in from the Sun and ensure temperature isn’t a limiting factor
- if the temperature is too hot, shades and ventilation by opening windows can cool it down
- we can also use electric heaters in the greenhouses to keep temperature at optimal levels for photosynthesis
how do greenhouses work to maximise the rate of photosynthesis for light intensity
we can have artificial light that turns on when the Sun goes down to give plants more time for photosynthesis, so rate of growth increases
how do greenhouses work to maximise the rate of photosynthesis for CO2 concentrations
carbon dioxide concentration can be kept high using paraffin heaters, which release heat and carbon dioxide as a by-product – again ensuring CO2 is not limiting
how can farmers ensure crop yields are maximised
farmers can spend more money in creating ideal conditions for photosynthesis
what do farmers need to ensure when maximising crop yields
the increased cost of conditions must be justified by the increase in crop-yield to ensure that the conditions created are cost-effective and help increase profit
why must limiting factors be taken into account
so that plants are only supplied with what they need, and not more, so that there is no money being wasted. e.g., if they spend lots of money to pump in loads of CO2 but carbon dioxide isn’t even limiting, money is being wasted
uses of glucose (remember the acronym!)
FORSAC:
- Fats
- Oils
- Respiration
- Starch
- Amino acids
- Cellulose
how is glucose used in relation to fat and oil
fats and oils are ways of storing the energy and are used to store energy in seeds and tubers
how is glucose used in relation to respiration
respiration needs glucose in order to release energy needed for metabolic reactions
how is glucose used in relation to starch
we need to store insoluble starch so that, when the plant is not photosynthesising, it can still release energy by respiration by converting the starch back into glucose when needed
how is glucose used in relation to cellulose
cellulose is a complex carbohydrate used to strengthen cell walls
how is glucose used in relation to amino acids
amino acids are produced by combining glucose and nitrate ions absorbed from the soil; these are needed for protein synthesis to allow growth
define cellular respiration
an exothermic reaction (because it releases energy to the surroundings) which is continuously occurring in all living cells. the energy transferred supplies all the energy needed for living processes
two types of respiration
respiration in cells can take place
- aerobically (using oxygen)
- anaerobically (without oxygen)
to transfer energy
equation for aerobic respiration; explain the relative amount of energy transferred
glucose + oxygen -> carbon dioxide + water
- this chemical reaction releases a very large amount of energy because the glucose molecule is fully oxidised
compare aerobic and anaerobic respiration in relation to oxygen
AEROBIC - takes place in the presence of oxygen
ANAEROBIC - only takes place when there is insufficient oxygen
equation for anaerobic respiration in muscles; explain the relative amount of energy transferred
glucose -> lactic acid
- this chemical reaction also releases energy, but releases much less than aerobic respiration, because the glucose undergoes incomplete oxidation (rather than being fully oxidised like in aerobic)
equation for anaerobic respiration in plant and yeast cells
glucose -> ethanol + carbon dioxide
significance of anaerobic respiration in plant and yeast cells
it is called fermentation, and has economic importance in the manufacture of bread (the carbon dioxide produced allows bread to rise) and the manufacture of alcoholic drinks (ethanol produced can be used in them)
organisms need energy for:
- building larger molecules
- movement
- keeping warm
- respiration
what happens during exercise
the body needs to react to the increased demand for energy
during exercise, what supplies the muscles with more oxygenated blood
heart rate, breathing rate and breath volume all increase during exercise
what happens if insufficient oxygen is supplied during exercise
anaerobic respiration takes place in the muscles; the body is unable to supply the cells with sufficient oxygen, so the incomplete oxidation of glucose causes a build up of lactic acid and creates an oxygen debt. during long periods of vigorous activity, muscles become fatigued and stop contracting efficiently
define 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 happens after intense exercise
blood flowing through the muscles transports the lactic acid (produced from anaerobic respiration) to the liver, where it is converted back into glucose
define metabolism
the sum of all the (chemical) reactions in a cell or the body
how are new molecules synthesised
the energy transferred by respiration in cells is used by the organism for the continual enzyme controlled processes of metabolism that synthesise new molecules
metabolism includes: (the examples that u need to know)
- converting glucose into cellulose in plants
- converting glucose into starch in plants
- converting glucose into glycogen in animals
- forming lipid molecules from a molecule of glycerol and three molecules of fatty acids
- the use of glucose and nitrate ions to form amino acids which in turn are used to synthesise proteins
- respiration
- the breakdown of excess proteins to form urea for excretion
why is the build-up of lactic acid bad
it causes fatigue
