Photosynthesis Flashcards
(144 cards)
1
Q
the source of energy
A
the sun
2
Q
autotrophs
A
organisms that can make their own food
all green plants, some bacteria, some protists
3
Q
what form of energy do autotrophs use to produce food
A
light energy from the sun
4
Q
what form is light energy produced as food
A
glucose or sugar
5
Q
heterotrophs
A
organisms that cannot make their own food
all animals and all fungi
6
Q
how do heterotrophs gain energy
A
by consuming food
7
Q
what form does energy enter the ecosystem
A
sunlight
8
Q
what do plants use the suns energy to make
A
glucose
9
Q
photosynthesis
A
- converting radiant energy (from the sun) into chemical energy (as glucose)
- convert water & carbon dioxide into high-energy sugar molecules
10
Q
Name & Energy Level
ATP
A
- Adenosine Triphosphate
- Energy Rich
11
Q
Name & Energy Level
ADP
A
- Adenosine Diphosphate
- Energy Poor
12
Q
Structure of ATP
A
- Adenine, a nitrogen base
- Ribose, a 5-carbon sugar
- A chain of three phosphate groups
13
Q
ADP -> ATP
A
Adding a phosphate
* when a cell has energy available it can store small amounts by adding a phosphate group
14
Q
Storing Energy
A
Add a phosphate
15
Q
ATP -> ADP
A
Removing a phosphate
* when a cell needs energy, the third phosphate will be removed
16
Q
Releasing Energy
A
Removing a phosphate
17
Q
What does ATP power?
A
- Photosynthesis
- Protein Synthesis
- Muscle Contractions
- Active Transport
18
Q
Basic Energy Source
A
ATP
19
Q
How much ATP is consumed & regenerated in a second?
A
10,000,000
20
Q
waste product of photosynthesis
A
oxygen
21
Q
What is life on earth dependent on photosynthesis for?
A
food & oxygen
22
Q
The Photosynthesis Equation
A
6CO2 + 6H2O + Sunlight = C6H12O6 + 6O2
23
Q
How do plants take in CO2?
A
Through their leaves
24
Q
How do plants take in H2O?
A
Through their roots
25
What does photosynthesis require?
* water
* carbon dioxide
* light energy
* chlorophyll
26
electromagnetic spectrum
the range of energy radiated outward from the sun
27
what does the atmosphere act as?
a selective window that allows visible light to pass through while screening out a substantial fraction of other radiation
28
What drives photosynthesis?
the visible light from radiation
29
the colors of the visible spectrum are
red, orange, yellow, green, blue, indigo, violet
30
pigment
any substance that absorbs light
31
how do plants absorb the suns energy?
via pigments (light absorbing)
32
different pigments...
...absorb light of different wavelengths
33
what happens to the absorbed wavelengths?
they disappear
34
is there an alternate to absorbing wavelengths?
yes, reflecting them
| the colors we see are being reflected by a pigment
35
principal photosynthetic pigment
chlorophyll
36
chlorophyll
a green pigment contained in chloroplasts
37
What can chlorophyll absorb?
All colors of the visible spectrum except for green. It reflects green.
| So, its green to us
38
What wavelengths of light are best absorbed by chlorophyll?
~425nm and ~660nm
39
What wavelengths of light are least absorbed by chlorophyll?
~450nm and ~650nm
40
chlorophyll-a
blue-green
41
chlorophyll-b
yellow-green
42
what happens when chlorophyll absorbs light?
energy transfers directly to electrons
| these high-energy electrons make photosynthesis work
43
major organ of photosynthesis
leaves
44
what are leaves the major organ of
photosynthesis
45
how many chloroplasts per sqmillimeter of leaf?
~500,000
46
Cuticle
A waxy covering on the upper & lower surface of a leaf that helps prevent water loss
47
Mesophyll
* central middle area
* contains palisade cells & spongy cells (both of many chloroplasts)
* the palisade layer is the primary photosynthetic layer
48
Stomata
* pores in the leaf (for CO2 to enter and oxygen to exit)
* the opening into the leaf
* guard cells found on either side (they're like the doors)
* source of water loss
* usually found on the lower surface (to help reduce water loss)
49
vascular bundles
* contains xylem and phloem
* xylem carries water up the plant, brings water to the leaf
* phloem carries food down the plant, glucose will exit through the phloem and get carried to other parts of the plant
50
chloroplast membrane
double membrane - there is a space between them
51
thylakoids affect on the chloroplast
* make a third membrane system
* big stacks of thylakoids are called grana
* they contain chlorophyll
52
What is surrounding of the thylakoid?
a dense solution called, the stroma
53
What are Thylakoids
the structural unit of photosynthesis
54
what form do thylakoids take
the form of flattened sacs or vesicles
55
What molecules are built into the thylakoid membrane
chlorophyll molecules
56
what do chlorophyll molecules do?
capture light energy
57
where does photosynthesis take place??
in the chloroplast
58
What happens to pigments in the thylakoid membrane?
They are clustered together
59
What are clusters of pigments called?
Photosystems
60
Photosystems
* clusters of pigments
* light collecting units
61
what is the light collecting unit of the chloroplast?
photosystems
62
what happens when sunlight hits chlorophyll
the electrons in chlorophyll become very excited
63
excited electrons
electrons that have a LOT of energy
64
what do high energy electrons need?
a carrier
65
an electron carrier
a compound that can accept a pair of high energy electrons
| without draining the electrons energy
66
electron carriers are also known as
the electron transport chain
67
what is the process of transporting high energy electrons called?
electron transport
68
example of an electron carrier
NADP+
69
NADP+
accepts and holds 2 high energy electrons alongside a hydrogen ion
| when that happens NADP+ becomes NADPH
70
NADPH
NADP+ when it has 2 high energy electrons and a hydrogen ion
71
where do the high energy electrons go?
elsewhere in the chloroplast for chemical reactions & to build glucose molecules
72
where do light dependent reactions occur?
thylakoid membranes
73
where do light INdependent reactions occur?
in the stroma - region outside of the thylakoids
74
example of a light independent reaction
calvin cycle
75
Which photosystem comes first?
Photosystem II
76
What is a photosystem?
a collection of pigment molecules that serve as the light collecting unit
| embedded in the thylakoid membranes
77
what do pigments in photosystem II do?
absorb light
78
what does the light energy absorbed by the electrons do?
increase their energy level
79
what happens when electrons are lost?
they get replaced
80
what do enzymes break apart in the thylakoid membrane?
water molecules into 2 electrons, 2 H+ ions, and 1 oxygen atom
81
what is considered a waste product?
| photosystems
oxygen
82
what is responsible for nearly all the oxygen in our atmosphere?
the splitting apart of water
83
what ion is released into the thylakoid?
hydrogen
84
protein molecules use the energy from high-energy electrons to create what?
ATP
85
what does chlorophyll do in photosystem I?
absorb energy and use it to re-energize the electrons
86
What is the purpose of light dependent reactions?
produce ATP and NADPH for the light independent reactions
87
Where do light dependent reactions take place?
Thylakoid membrane
88
What do light dependent reactions do?
pass electrons from water to NADPH
89
The two photosystems work together to produce what?
ATP and NADPH
90
Where are thylakoids found?
inside the chloroplasts
91
what are big stacks of thylakoids called?
grana
92
what are grana?
big stacks of thylakoids
93
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what is the thylakoid space
the middle of the thylakoid
95
what is in the middle of the thylakoid?
the thylakoid space
96
what is a collection of chlorophylls and carotenoids called?
pigments
97
what do pigments do?
absorb light energy from the sun
98
what strikes the surface of the leaf?
sunlight
99
what increases the energy level of electrons in chlorophyll?
light energy
100
What is the energy from high energy electrons used for?
to transport hydrogen ions from the stroma into the thylakoid space
101
what gets released inside the thylakoid
hydrogen ions
102
what gets released into the air?
oxygen
103
what does photosystem I receive from photosystem II?
electrons
104
What is the energy absorbed from the sun by chlorophyll molecules in photosystem I used for?
re-energizing electrons
105
What does NADP+ join with in light dependent reactions?
1 hydrogen atom and 2 electrons
106
NADPH is formed when?
NADP+ joins with 1 hydrogen ion and two electrons
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108
what is the area outside the thylakoid called?
the stroma
109
what is the stroma?
a dense liquid surrounding the thylakoids
110
111
from where to where do hydrogen ions move in the chloroplast?
flow from high concentration (in the thylakoid) to low concentration (in the stroma)
112
what is hydrogen flowing through?
ATP synthase, a protein enzyme
113
What does ATP synthase do when hydrogen flows through it?
Rotates like a turbine
114
What does ATP synthase do while rotating?
Binds a phosphate to ADP (forms ATP from ADP)
115
How does the concentration of hydrogen stay high inside the thylakoid?
Hydrogen ions are actively pumped back into it
116
What is formed for use in the Calvin Cycle?
NADPH & ATP
117
What is the purpose of light dependent reactions?
Produce high-energy compounds
118
What are high-energy compounds?
ATP & NADPH
119
What are high-energy compounds used for?
Calvin Cycle
120
The Calvin Cycle is also known as...
the Light Independent Reactions
121
Where does the Calvin Cycle occur?
In the Stroma
122
What is the purpose of the Calvin Cycle?
to take *CO2 and high-energy products* of the light dependent reaction *to make* **glucose**
123
How does the Calvin Cycle obtain CO2?
via the atmosphere
124
What does CO2 enter leaves through?
the stomata
125
5-carbon sugar called
RuBP or ribulose biphosphate
126
carbon fixation
carbon (from CO2) combining with 5-carbon sugar (RuBP)
127
What does Carbon Fixation form?
An unstable 6-carbon compound
128
What does the unstable 6-carbon compoud break apart into?
2 molecules of PGA (a three-carbon compound)
129
how does PGAL form?
a series of reactions involving ATP & NADPH convert PGA into PGAL
130
What could happen to the PGAL?
1. the two PGAL molecules combine and form glucose
2. the PGAL is converted into RuBP for the reaction to occur again
131
What is the number one problem land plants face?
Dehydration
132
Why is dehydration a problem?
Plants must open their stomata, to let in CO2, which causes excessive water loss
133
What do plants do on a hot dry day?
Close the stomata to conserve water
134
Consequences of having the stomata closed?
Slows down photosynthesis
135
What are the 2 pathways for carbon fixation?
1. the four-carbon pathway
2. the CAM pathway
136
What is special about the C4 Pathway?
Prefaces the Calvin Cycle with an additional step
137
Additional step of C4 Pathway
converts CO2 into a 4-carbon compound to save it until it is needed
| REVERSABLE
138
C4 Plant Examples
Corn, Sugar Cane, Crab Grass
139
What is special about the CAM pathway?
Stomata is only open at night
140
CAM Pathway Plant examples
Cacti & Pineapples
141
What is REQUIRED in light dependent reactions?
water
| ...and light
142
how is water obtained for photosynthesis?
via the roots of plants
143
what does a shortage of water do?
slow or stop photosynthesis
144
what is done to prevent water loss?
plants are covered with a waxy cuticle
