Download Section: 3.2 Name:

Section: 3.2
Name:
Opening Activity: What type of energy is absorbed by pigment molecules in plant cells to start
photosynthesis?
Latin Root Word:
Review of Old Information:
ATP then provides the energy needed for our cells to carry out their functions. The following is a review of
what we have learned about ATP so far:
• _______________: adenosine triphosphate
• Made up of adenosine + 3 phosphate groups
• _______________: Adenosine diphosphate
• Cells recycle the ADP to make new ATP to store more energy for future use
• Many proteins have spots where ATP attaches to provide energy for the protein to do its job, then the
ADP is released for recycling
New Information:
Complete the notes on photosynthesis in the spaces below.
Photosynthesis:
•
•
•
•
Process that uses the __________’s energy to make glucose
Carried out by green plants and some bacteria
Purpose is to trap sun’s energy and store it in _______________ (food for the plant or animals)
Photosynthesis occurs in the _______________.
• Thylakoids are green because they contain ____________________.
• Chlorophyll: green _______________ in plants that absorbs light energy.
• _______________: light-absorbing compound
Chemical equation for photosynthesis:
•
6CO
2
(carbon dioxide
+ 6H O
+ light energy

CH O
+ water
+ sunlight

glucose
2
6
12
6
+ 6O
2
+ oxygen)
Steps of photosynthesis:
Step 1: Light Reactions
a. Overall Reaction: Light energy  NADPH and ATP
b. This reaction takes place in the thylakoid membrane!
c. Step 1: _____________________________________________
i. White light is actually a combination of all light
ii. Different pigments in the chloroplast can absorb different types of light
a. Chlorophyll a – absorbs mostly _____________________
b. Chlorophyll b – absorbs mostly _____________________
c. Carotenoids – some ______________________________
d. Step 2: _____________________________________________
i. The absorbed light is used to excite electrons in pigments
ii. These excited electrons and water are used to fuel two biochemical pathways
1. __________________________
a. Every cycles produces one NADPH
2. __________________________
a. Produces ATP
e. Step 3: _____________________________ = makes ATP from H+ that are released by water
REPLACING ELECTRONS
- Pigments that gave up electrons get replacements …from?
-____________________ molecules are split and oxygen is released to the atmosphere. Then…
-H+ go ________________ the thylakoid membrane and _____________ from water are replaced in
photosystem II
Summary: Light reactions (Light-dependent reaction)
This first step of photosynthesis traps sunlight and makes electrons (stored in _______________)
and _______________ to run the dark reactions.
1. Dark reactions (also called “Light-independent reaction” or “_______________ Cycle”)
The second step of photosynthesis uses ATP and electrons from the light reactions and
_______________ _______________ from the air to make _______________.
Activity:
PHOTOSYNTHESIS STARTS WITH
1. Molecules that collect light energy are called _P_ __ __ __ __ __ __ __ .
2. Chlorophyll a and b absorb _B_ __ __ __-_V_ __ __ __ __ __ and _R_ __ __ wavelengths of light
best.
3. _C_ __ __ __ __ __ __ __ __ __ __ is the main light absorbing pigment found in green plants.
4. Plants “look” green because chlorophyll _R_ __ __ __ __ __ __ __ green light.
5. Organisms, like green plants, that can make their own food using energy from the sun are called
_A_ __ __ __ __ __ __ __ __ __.
6. The gel-filled space inside the chloroplast surrounding the thylakoid stacks is called the
_S_ __ __ __ __ __.
7. _P_ __ __ __ __ __ __ __ __ __ __ __ I and II contain chlorophyll and absorb light energy during
the _L_ __ __ __ __ _D_ __ __ __ __ __ __ __ __ reactions.
8. During the light dependent reactions, H+ ions build up in the _T_ __ __ __ __ __ __ __ __ space
when _W_ __ __ __ __ molecules are split.
9. The enzymes for the light dependent reactions are found in the _T_ __ __ __ __ __ __ __ __
_M_ __ __ __ __ __ __ __ , while the Calvin cycle happens in the _S_ __ __ __ __ __.
10. The stacks of thylakoids found inside chloroplasts are called _G_ __ __ __ __ .
11. The light independent reactions are also called the _C_ __ __ __ __ __ _C_ __ __ __ __.
12. Carbon and oxygen from _C_ __ __ __ __ __ _D_ __ __ __ __ __ __ end up as part of a
_G_ __ __ __ __ __ __ molecule following the Calvin cycle.
13. _A_ __ __ and _N_ __ __ __ __ are made during the _L_ __ __ __ __ dependent reactions and
carry energy and high energy electrons that are used during the Calvin cycle to produce
_S_ __ __ __ __ __, like glucose.
14. The O in H2O is given off as_O_ __ __ __ __ __ gas to the atmosphere when water is split during
the light dependent reactions.
15. Proteins in living things that help chemical reactions happen are called _E_ __ __ __ __ __ __ .
16. Electrons are transferred along the membrane from Photosystem II to Photosystem I using the
_E_ __ __ __ __ __ __ __
_T_ __ __ __ __ __ __ __ __ _S_ __ __ __ __ __ .
17. The movement of H+ ions from the thylakoid space, across the membrane, and into the stroma causes
_A_ __ __ _S_ __ __ __ __ __ __ __ to spin and produce ATP,
18. _J_ __ __
to light.
_I_ __ __ __ __ __ __ __ __ __ showed that plants only produce oxygen when exposed
19. Orange and yellow colored pigments called _C_ __ __ __ __ __ __ __ __ __ __ absorb different
wavelengths of light and help chlorophyll use more of the sun’s energy.
20. _T_ __ __ __ __ __ __ __ __ __ __ , amount of _W_ __ __ __ __ , and _L_ __ __ __ __ intensity
are all factors that affect the rate of photosynthesis.