B4 - Bioenergetics Flashcards
How does photosynthesis produce glucose?
By using light
Give the word equation for photosynthesis
carbon dioxide + water –light –> glucose + oxygen
Where does photosynthesis occur?
In the chloroplasts in green plant cells
Chlorophyll is a green pigment, but how does it help photosynthesis?
It absorbs light
Photosynthesis is exothermic. True or false?
False - it is endothermic, so energy is transferred from the environment
Give the symbol equation for photosynthesis
6 CO2 + 6 H2O –light–> C6H12O6 + 6 O2
WHat are the 5 main ways that plants use glucose?
1) For respiration - transfers energy from glucose, enabling the plant to convert the rest of the glucose into otehr useful substances
2) Making cellulose - for making strong cell walls
3) Making amino acids - glucose combined with nitrate ions in soil, then the amino acids create proteins
4) Stored as oils or fats - lipids for storing in seeds
5) Stored as starch - Stored in roots, stems & leaves, ready to use when photosynthesis isn’t happening (like in winter)
Why do plants store glucose as starch instead?
Because starch is insoluble - a cell with lots of stored glucose in would draw in lots of water and swell up
What are the limiting factors of photosynthesis?
Light
Temperature
CO2 concentration
(Amount of chlorophyll)
What affect would these environmental conditions have on the rate of photosynthesis?
a) If its night
b) If its very warm
c) If there isn’t much CO2
a) Slower rate of photosynthesis
b) Faster rate of photosynthesis
c) Slower rate of photosynthesis
What can affect the amount of chlorophyll in a plant?
Disease (e.g. tobacco mosaic virus)
Environmental stress (e.g. lack of nutrients)
These can cause chloroplasts to get damaged or not make enough chlorophyll, so less absorbtion of light so reduced rate of photosynthesis
Fill the graph ^Rate of photosynthesis | | | | | | | |\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_>Light intensity
^Rate of photosynthesis | | | | r------------------------------------------------ | / | / | / |/\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_>Light intensity
It always levels out eventually because then the CO2 or the temperature is the limiting factor, not light
Fill the graph ^Rate of photosynthesis | | | | | | | |\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_>% Level CO2
^Rate of photosynthesis
|
|
|
| r————————————————
| /
| /
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|/_____________________________>% Level CO2
When it levels out, this means that the level of CO2 is no longer the limiting factor
Fill the graph ^Rate of photosynthesis | | | | | | | |\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_>Temperature
^Rate of photosynthesis | | | r-----\ | / \ | / \ | / \ | / \ |/\_\_\_\_\_\_\_\_\_\_\_\_\_\\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_>Temperature There are enzymes needed for photosynthesis, so at around 45 degrees the graph is y=0, as the enzymes needed for photosynthesis and its other reactants will be damaged
Can one graph show the effect of more than one limiting factor of photosynthesis?
Yes - plotted rate of photosynthesis = y, light intensity=x, then there are 2 lines labelled with different temperatures and/or CO2%. the lowest line shows a limiting factor
What practical can be used t show the rate of photosynthesis?
Counting the bubbles produced off a plant, as oxygen production shows the rate of photosynthesis
Reorder these instructions of the practical used to show how the distance of light affects the rate of photosynthesis:
1) The whole experiment is repeated with the light source at different distances
2) The pond weed is left to photosynthesise for a set amount of time. As it photosynthesises, the oxygen released will collect in the capillary tube
3) For this experiment, any variables need to be controlled - temperature, time, colour and distance of light
4) A source of white light is placed at a specific distance from the (Canadian) pond weed
5) At the end of the experiment, the syringe at the end of the capillary tube is used to draw the gas bubble alongside a ruler, and the length of the bubble is measured. This is proportional to the volume of oxygen produced
6) The experiment is repeated more times with everything the same, then a mean is calculated
4) A source of white light is placed at a specific distance from the (Canadian) pond weed
2) The pond weed is left to photosynthesise for a set amount of time. As it photosynthesises, the oxygen released will collect in the capillary tube
5) At the end of the experiment, the syringe at the end of the capillary tube is used to draw the gas bubble alongside a ruler, and the length of the bubble is measured. This is proportional to the volume of oxygen produced
3) For this experiment, any variables need to be controlled - temperature, time, colour and distance of light
6) The experiment is repeated more times with everything the same, then a mean is calculated
1) The whole experiment is repeated with the light source at different distances
How can the practical used to see how the distance of light affects the rate of photosynthesis be used to measure the affect of temperature or CO2 on photosynthesis?
E.g. The test tube of the pond weed can be put into a water bath at a set temperature
Or a measured amount of sodium hydrogencarbonate can be dissolved in the water (which gives off CO2).
The experiment can then be repeated with different temperatures/ concentrations if sodium hydrogencarbonate
Light intensity is directly proportional to the distance of the light in photosynthesis. True or false?
False - light is inversely proportional to the square of distance - this is the inverse square law
What does the inverse square law mean? (use the photosynthesis example of light is inversely proportional to the square of the distance of the light)
If you halve the distance, the light intensity will be 4x greater.
If you third the distance, the light intensity will be 9x greater.
If you double the distance, the light intensity will be 4x smaller
If you treble the distance, the light intensity will be 9x smaller
How do greenhouses help artificially create ideal conditions for farming?
Greenhouses help to trap the sun’s heat, and make sure that temperature isn’t a limiting factor.
However, this can be damaging to the plants enzymes in summer, so shades and ventilation may be used to cool it down.
But in winter, heaters can also be used in the greenhouse
How can commercial farmers give plants more photosynthesis time in a greenhouse?
By supplying artificial light when the sun goes down
How can farmers and gardeners increase the level of CO2 in their greenhouses?
E.g. using a parafin heater - as it burns, CO2 is a by-product created
What are the benefits of keeping plants in an ENCLOSED environment (such as a greenhouse)?
Easier to keep away pests and diseases
The farmer can easily add fertilisers to the soil too, providing all the minerals needed for healthy growth
Fill the blanks:
Sorting out greenhouses requires a lot of money, but if the farmer can keep the conditions just right for ______________, the plants will grow much ______ and a decent crop can be harvested ____ _____, which are then ____. It’s important that the farmer supplies just the right amounts of ____, _____, etc - enough to make the plants ____, but not more than the plants ____, as this will just _____ _____.
Photosynthesis Faster More often Sold Heat Light Grow Need Waste money
Give a definition of respiration
“It is the process of transferring energy from the breakdown of glucose, which goes on in every cell continuously.”
IT IS NOT BREATHING, as it involves many important reactions to transfer the energy cells need to act.
Respiration is exothermic. True or false?
True - it transfers energy to the environment
Give 3 examples of how organisms use the energy transferred by respiration
1) To build larger molecules from smaller ones (like proteins from amino acids)
2) In animals, it is used to allow the muscles to contract
3) In mammals and birds, the energy is used to keep their body temperature steady in colder surroundings (unlike other animals, mammals and birds keep their bodies constantly warm)
What is metabolism?
It is ALL the chemical reactions in an organism
What controls the chemical reactions happening all the time in a cell?
Enzymes
What are enzymes?
Biological catalysts
Using:
reactant -enzyme-> product -enzyme-> product -enzyme-> product
Talk about how larger molecules are made from smaller ones, with glucose
Lots of small glucose molecules are joined together in reactions to form starch (a storage molecule in plant cells), glycogen (a storage molecule in animal cells) and cellulose (plant cell walls)
What are lipids made from?
One molecule of glycerol and 3 fatty acids
Glucose is combined with what to make amino acids?
Nitrate ions. Amino acids are then made into proteins
Glucose is broken down during what process?
Respiration - which then transfers energy to power all the reactions in the body that make molecules
What happens to excess protein?
It is broken down to produce urea, which is then excreted in the urine
What is the sum of all reactions that happen in a body or a cell called?
Metabolism
Aerobic respiration needs lots of oxygen
Anaerobic respiration occurs when there is a lack or carbon dioxide
True or false?
False -
Aerobic respiration is respiration using oxygen (so it does need plenty of oxygen)
Anaerobic respiration occurs when there isn’t enough oxygen
Most of the reactions in aerobic respiration occurs where?
In the mitochondria - constant in both plants and animals
Give the balanced symbol equation of aerobic respiration
C6H12O6 + 6 O2 —> 6 CO2 + 6 H2O
Give the word equations of:
a) Anaerobic respiration (animals)
b) Aerobic respiration
c) Anaerobic (plants & yeast)
a) glucose —> lactic acid
b) glucose + oxygen —> carbon dioxide + water
c) glucose —> ethanol + carbon dioxide
What is fermentation?
Anaerobic respiration in yeast cells
What is fermentation used for?
As it is anaerobic respiration in yeast cells, so it produces ethanol + CO2, it is used to make bread and alcoholic drinks
The CO2 created is what makes the bread rise
Complete the sentence:
When you exercise…
You respire more
OR
Your body responds in different ways to get enough energy to our cells
Why do you respire more when exercising?
Because your muscles have to contract more frequently than normal, so they need more energy, so you respire more
An increase in respiration in your cells means what?
That they need more oxygen, so your breathing rate and breath volume increase to get more oxygen into the blood, and your heart rate increases to get this oxygenated blood around the body faster, removing CO2 faster at the same time
If you do very vigorous exercise, what happens in your body?
Your body can’t supply oxygen to the muscles fast enough, so they start respiring anaerobically, which is BAD as lactic acid builds up, causing pain
What can long periods of exercise cause?
Muscle fatigue - the muscles get tired and then stop contracting efficiently
What breaks down lactic acid?
Oxygen
Oxygen+ lactic acid —> CO2 + water (harmless)
How is lactic acid formed in fancy words?
Formed from the incomplete oxidation of glucose
Anaerobic respiration leads to what?
Oxygen debt, and you will have to stop exercising
What is an oxygen debt?
The amount of extra oxygen your body needs to react with the build up of lactic acid and remove it from the cells.
This means you have to keep breathing hard even when you stop, and your pulse and breathing rate stay high whilst there are high levels of lactic acid and CO2
How can you investigate the effect of exercise on the body?
How can you reduc the effect of any errors?
By measuring the breathing rate or heart rate of yourself when doing different exercises
Plot this in a bar chart
Do it in a group and plot the average pulse rate
Exercise suggestions - sitting for 5 mins, after 5 mins walk, after 5 mins jog, after 5 mins run
The more intense your exercise is, what will happen?
The more your pulse rate & breathing rate will increase as your body needs more oxygen to take to the muscles and to take CO2 away from the muscles
