bioenergetics Flashcards
(49 cards)
1
Q
What is the equation for photosynthesis?
A
- carbon dioxide + water -> glucose + oxygen
2
Q
What is the symbol equation for photosynthesis?
A
- 6CO₂ + 6H₂O -> C₆H₁₂O₆ + 6O₂
3
Q
Define photosynthesis
A
- an endothermic reaction in which energy is transferred from the environment to the chloroplasts by light
4
Q
Where does photosynthesis take place?
A
- in the leaves which contain palisade cells that contain the chemical chlorophyll
5
Q
What is the function of chlorophyll and where is it found?
A
- found in chloroplasts
- absorbs the light energy needed for photosynthesis
- energy is transferred from the environment to the chloroplasts via light
6
Q
What are the factors that effect the rate of photosynthesis?
A
- temperature
- light intensity
- carbon dioxide concentration
- amount of chlorophyll
7
Q
What is the effect of light intensity on the rate of photosynthesis?
A
- initially, as light intensity increases, the rate of photosynthesis increases - 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 – light is no longer the limiting factor: temperature or CO₂ is
8
Q
What is the effect of carbon dioxide on the rate of photosynthesis?
A
- initially, as CO₂ concentration increases, the rate of photosynthesis increases - at this point, the CO₂ is the limiting factor
- at one point, the graph flattens out, - CO₂ concentration is no longer the limiting factor (light or temperature is)
9
Q
What is the effect of temperature on the rate of photosynthesis?
A
- initially, as temperature increases, the rate of photosynthesis increases - 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
- once it reaches past the optimum temperature, enzymes denature and the rate of reaction rapidly decreases
10
Q
What is the effect of the amount of chlorophyll on the rate of photosynthesis?
A
- chlorophyll is a chemical needed for photosynthesis - it is how energy is absorbed by light
- a lack of chlorophyll will reduce the rate of photosynthesis (magnesium deficiency)
11
Q
How do we measure the rate of photosynthesis?
A
- light intensity is inversely proportional to distance squared
12
Q
Define limiting factor
A
- An environmental condition which, in low levels, restricts any increase in the rate of photosynthesis
13
Q
Why are limiting factors important?
A
- they’re important in the economics of enhancing the conditions in greenhouses to gain the maximum rate of photosynthesis while still maintaining profit
14
Q
Why is it important that farmers and gardeners know the ideal conditions for photosynthesis?
A
- they can create an environment that maximises the rate of photosynthesis
- this maximises the rate of plant growth, thus crop yield and thus profit
15
Q
Why should a greenhouse be used to maximise the rate of photosynthesis?
A
- conditions can be easily controlled
- easier to keep plants free from pests and diseases
- farmers can add fertilisers to the soil
16
Q
How do greenhouses work to maximise the rate of photosynthesis for temperature?
A
- greenhouses trap heat in from the Sun and ensure temperature isn’t a limiting factor
- if temp is too hot, shades and ventilation by opening windows can cool it down
- electric heaters can be used to keep temp at optimal levels for photosynthesis
17
Q
How do greenhouses work to maximise the rate of photosynthesis for light intensity
A
- artificial light after the Sun goes down to give plants more time for photosynthesis, so rate of growth increases
18
Q
How do greenhouses work to maximise the rate of photosynthesis for CO2 concentrations?
A
- using paraffin heaters
- releases heat and carbon dioxide as a by-product – ensuring CO2 is not limiting
19
Q
How can farmers ensure crop yields are maximised?
A
- farmers can spend more money in creating ideal conditions for photosynthesis
20
Q
What do farmers need to ensure when maximising crop yields?
A
- 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
21
Q
Why must limiting factors be taken into account?
A
- so that plants are only supplied with what they need - there is no money being wasted.
e.g. if they spend lots of money to pump in loads of CO₂ but it isn’t limiting, money is being wasted
22
Q
What are the uses of glucose?
A
- Fats
- Oils
- Respiration
- Starch
- Amino acids
- Cellulose
23
Q
How is glucose used in relation to fat and oil?
A
- fats and oils are ways of storing the energy
- glucose is turned into lipids and used to store energy in seeds and tubers
24
Q
How is glucose used in relation to respiration?
A
- respiration needs glucose in order to release energy needed for metabolic reactions
25
How is glucose used in relation to starch?
* glucose is turned into starch and stored in roots, stems, and leaves - ready to use when photosynthesis isn't happening, can still release energy by respiration (e.g. in the winter)
* starch is insoluble, makes it better for storing than glucose - a cell with lots of glucose would draw in water and swell up
26
How is glucose used in relation to cellulose?
* cellulose is a complex carbohydrate used to strengthen cell walls
27
How is glucose used in relation to amino acids?
* glucose and nitrate ions (absorbed from the soil) are combined to make amino acids
* these are needed for protein synthesis to allow growth
28
Define cellular respiration
* process of transferring energy from the breakdown of glucose
* it is continuously occurring in all living cells
* an exothermic reaction (it releases energy to the surroundings)
* the energy transferred supplies all the energy needed for living processes
29
Name the two types of respiration
* aerobic respiration (using oxygen) - takes place in the mitochondria
* anaerobic respiration (without oxygen) - takes place in the cytoplasm
30
What is the equation for aerobic respiration?
* glucose + oxygen -> carbon dioxide + water
31
What is the equation for anaerobic respiration in muscles?
* glucose -> lactic acid
32
Compare the relative amount of energy transferred in aerobic and anaerobic respiration
* aerobic releases a very large amount of energy because the glucose molecule is fully oxidised
* anaerobic also releases energy, but much less than aerobic respiration - glucose undergoes incomplete oxidation (rather than being fully oxidised like in aerobic)
33
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
34
What is the equation for anaerobic respiration in plant and yeast cells?
* glucose -> ethanol + carbon dioxide
35
What is the significance of anaerobic respiration in plant and yeast cells?
* in yeast cells it is called fermentation
* 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)
36
What do organisms need energy for?
* to build up larger molecules from smaller ones
* movement - allows the muscles to contract
* keeping warm - keep body temp steady
37
What happens during exercise?
* the body needs to react to the increased demand for energy
38
During exercise, what supplies the muscles with more oxygenated blood?
* heart rate
* breathing rate
* breath volume
39
Why does heart rate increase during exercise?
* to get the oxygenated blood around the body faster - to muscles so they respire quickly
* also removes CO₂ more quickly
40
Why does breathing rate increase during exercise?
* get more oxygen into the blood
41
Why does breathing volume increase during exercise?
* get more oxygen in the blood
42
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
* incomplete oxidation of glucose causes a build up of lactic acid, creating an oxygen debt
* during long periods of vigorous activity, muscles become fatigued and stop contracting efficiently
* pulse and breathing rate remain high whilst there are high levels of lactic acid and CO₂
43
What is 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
44
What happens after intense exercise?
* blood flowing through the muscles transports the lactic acid (produced from anaerobic respiration) to the liver
*it is converted back into glucose
45
Why is lactic acid bad?
* it causes fatigue - muscles become tired and do not contract properly
46
How can you investigate the effect of exercise on the body?
* measure breathing rate by counting breathes, and heart rate by taking the pulse
* measure pulse after sitting down, walking, jogging, and running
* plot results in a bar chart - pulse will increase the more intense the exercise
* reduce random error by plotting average pulse rate
47
Define metabolism
* the sum of all the (chemical) reactions in a cell or the body
48
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
49
What does metabolism include?
* 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
