Science - Biology - Bioenergetics - B4 Flashcards
1
Q
what is photosynthesis ?
A
photosynthesis is the process that produces ‘food’ in plants
2
Q
what is the food produced from photosynthesis that plants need ?
A
glucose - a sugar
3
Q
what are the reactants in photosynthesis ?
A
- water
- carbon dioxide
4
Q
what are the products of photosynthesis ?
A
- glucose
- oxygen
5
Q
where does photosynthesis take place ?
A
in the chloroplasts in green plant cells
6
Q
what do the chloroplasts contain ?
A
a pigment called chlorophyll which absorbs light
7
Q
what type of reaction is photosynthesis ?
A
an endothermic reaction
8
Q
what is an endothermic reaction ?
A
a reaction where energy is transferred from the environment in the process
9
Q
how does carbon dioxide leave the leaf cell, and oxygen enter ?
A
diffusion
10
Q
how does water reach the cell ?
A
through the xylem
11
Q
what is the word equation for photosynthesis ?
A
carbon dioxide + water - light - glucose + oxygen
12
Q
what is the symbol equation for photosynthesis ?
A
6CO2 + 6H20 - light - C6H12O6 + 6O2
13
Q
what are the main things that glucose is used for ?
A
- respiration
- making cellulose
- making amino acids
14
Q
what is respiration ?
A
a process which occurs in all living organisms, where energy is released from the breakdown of glucose
15
Q
what is the energy released from glucose, respiration used for ?
A
- to convert the rest of the glucose into other useful substances
16
Q
what is cellulose used for ?
A
making strong cell walls to strengthen and support the cells
17
Q
what are amino acids ?
A
the building blocks which make up proteins
18
Q
what is combined with glucose to make amino acids ?
A
nitrate ions
19
Q
how can glucose be stored ?
A
in -
- starch
- lipids
20
Q
give an example of how glucose is stored in lipids
A
sunflower seeds
21
Q
why is glucose stored as starch ?
A
so its ready to use when photosynthesis isn’t happening as much, like in the winter
22
Q
give an example of how glucose is stored in starch
A
- in roots
- in stems
- seeds
- leaves
23
Q
why is starch good for storing glucose ?
A
it is insoluble
24
Q
what does the rate of photosynthesis depend on ?
A
- intensity of light
- volume of carbon dioxide
- temperature
25
what is a limiting factor ?
the factor which is stopping photosynthesis from happening any faster
26
give an example of when light is a limiting factor for photosynthesis
- at night there's much less light than there is during the day, so light intensity is usually the limiting factor at night
27
give an example for when temperature is a limiting factor for photosynthesis
- in winter it is usually cold, so a low temperature is often the limiting factor
28
give an example of when the volume of carbon dioxide is a limiting factor for photosynthesis
- if it's warm enough and bright enough, the amount of carbon dioxide is usually limiting
29
give an example of how chlorophyll is a limiting factor of photosynthesis
the amount of chlorophyll in a plant can be affected by disease or environmental stress. These factors cause chloroplasts to become damaged or not to make enough chlorophyll, so photosynthesis is limited as they can't absorb as much light
30
describe the graph showing how light intensity affects the rate of photosynthesis
the rate increases with light intensity, then the line goes straight
31
why does the line in the light intensity graph stop increasing ?
the rate stops increasing because the temperature or volume of carbon dioxide then becomes the limiting factor, not light
32
describe the graph showing how carbon dioxide level affects the rate of photosynthesis
the rate steadily increases, then stops because the light or temperature becomes the limiting factor
33
describe the graph showing how temperature affects the rate of photosynthesis
it increases, reaches the optimum temperature, then decreases
34
why does the graph showing how temperature affects the rate of photosynthesis decrease after increasing ?
if the plant gets too hot, the enzymes it needs for photosynthesis and its other reactions will become damaged
35
what temperature becomes too hot for photosynthesis ?
45 degrees and above
36
what are enzymes, and how do they link to photosynthesis ?
enzymes are proteins which increase the speed of chemical reactions in living things, so enzymes increase the rate of photosynthesis in plant cells, the speed at which enzymes work is affected by temperature
37
how does having a low temperature, affect a plants ability to photosynthesize ?
the enzymes needed for photosynthesis work more slowly at low temperatures
38
what is the control variable ?
the thing you keep the same
39
what is the dependent variable ?
what you measure
40
what is the independent variable ?
what you change
41
give one way/experiment you can do to investigate the rate of photosynthesis
by using an aquatic plant, like pondweed and the rate at which the pondweed produces oxygen corresponds to the rate of oxygen production the faster the rate of photosynthesis
42
describe the experiment for investigating the rate of photosynthesis
- a source of white light is placed at a specific distance from the pondweed
- the pondweed is left for a couple of minutes to adjust to the new light intensity
- pondweed is left to photosynthesize for a set amount of time
- as it photosynthesizes the oxygen released will collect in the capillary tube
- at the end of this experiment the syringe is used to draw the gas bubble in the tube up alongside a ruler and the length of the gas bubble is measured, which is proportional to the volume of oxygen produced
43
what is the dependent variable with the rate of photosynthesis experiment ?
the amount of oxygen produced - the size of the oxygen bubble
44
give an example of the control variables in the rate of photosynthesis experiment
- if your plant's in a flask, keep the flask in a water bath to help keep the temperature constant
45
how do you calculate the rate of photosynthesis in the rate of photosynthesis experiment ?
divide the total length of the bubble by the time taken to produce it
46
what is the inverse square law ?
the inverse square law means that if you halve the distance, the light intensity will be 4 times greater, and if you third the distance, the light intensity will be 9 times greater, likewise if you double the distance, the light intensity will be 4 times smaller e.t.c
47
how is the inverse square law written out ?
light intensity - 1/distance (d2)
48
what are the different ways you can control plant growth ?
- storing them in greenhouses
- temperature
- light
- carbon dioxide concentration
- general health of plants
49
how can greenhouses maximize plant growth ?
greenhouses are made so it has ideal conditions for photosynthesis, which then maximizes the rate of plant growth
50
why do people use greenhouses ?
commercial farmers often grow large quantities of plants in commercial greenhouses
51
how is temperature kept in greenhouses?
greenhouses help to trap the suns heat, and make sure that the temperature doesn't become limiting
52
how can temperature be controlled, other than with a greenhouse ?
- in winter, farmers may use a heater in their greenhouse to keep the temperature at an ideal level
- in summer, greenhouses could get too hot so farmers might use shades and ventilation to cool things down
53
how can greenhouses control the light ?
farmers often use artificial light after the sun goes down to give their plants more quality photosynthesis time
54
how can greenhouses control the carbon dioxide concentration ?
farmers can increase the carbon dioxide by using a paraffin heater to heat the greenhouse, as the paraffin burns, it makes carbon dioxide as a by product
55
how can greenhouses help keep plants healthy ?
- by keeping plants enclosed in a greenhouse also makes it easier to keep them free from pests and diseases, the farmer can also add fertilizers to the soil as well
56
what is respiration ?
the process of transferring energy from glucose which goes on in every cell
57
what type of reaction is respiration ?
exothermic, it transfers energy to the environment
58
what is an exothermic reaction ?
where it transfers energy into the environment
59
what is aerobic respiration ?
respiration using oxygen
60
where does aerobic respiration happen in the cell ?
mitochondria
61
who does aerobic respiration happen to?
plants and animals
62
what is the word equation for aerobic respiration ?
glucose + oxygen - carbon dioxide + water
63
what is the symbol equation for aerobic respiration ?
C6H12O6 + 6CO2 - 6CO2 + 6H20
64
what do organisms use the energy for respiration for ?
- organisms use energy to build up larger molecules from smaller ones ( proteins from amino acids )
- animals use energy to allow their muscles to contract - which then allows them to move
- mammals and birds use energy to keep their body temperature steady
65
what is anaerobic respiration ?
respiration that doesn't require oxygen, it's the incomplete breakdown of glucose making lactic acid
66
why is anaerobic respiration used ?
when you do vigorous exercise and your body can't supply enough oxygen to your muscles
67
what is the word equation for anaerobic respiration ?
glucose - lactic acid
68
why doesn't anaerobic respiration transfer as much energy as aerobic respiration ?
glucose isn't fully oxidized so anaerobic respiration is only useful in emergencies
69
what is oxygen debt ?
the amount of extra oxygen your body needs after exercise, so you have to repay the oxygen you didn't have to get to your muscles in time because your lungs, heart and blood couldn't keep up with the demand earlier on
70
what does the oxygen that's being repaid react with in the muscles to stop the cramps ?
lactic acid
71
give another way your body has of coping with the high level of lactic acid
the blood that enters your muscles transports the lactic acid to the liver and the lactic acid is converted back to glucose
72
in anaerobic respiration for plants and yeast, what is produced instead of lactic acid ?
ethanol and carbon dioxide
73
what is the word equation for anaerobic respiration in plant and yeast cells ?
glucose - ethanol + carbon dioxide
74
what is fermentation ?
anaerobic respiration in yeast cells
75
why is fermentation by yeast important?
it is used to make bread and alcoholic drinks, helps the bread rise, and produces alcohol
76
what does regular physical activity do to your breathing rate and heart rate ?
- increases your breathing rate, and breath volume to meet the demand for extra oxygen
- increases your heart rate to make your blood flow more quickly, delivering more oxygen and glucose to cells for respiration, and taking more carbon dioxide away
77
what can long periods of exercise cause?
muscle fatigue
78
what is the recovery period ?
when your breathing rate is higher than usual after anaerobic exercise due to oxygen debt being repaid
78
what is muscle fatigue ?
when the muscles get tired and stop contracting efficiently
79
what do enzymes control ?
the chemical reactions happening in a cell, many reactions are linked together to form bigger reactions
80
what is metabolism ?
all the chemical reactions that happen in a cell or the body
