Unit 3: Ch. 7 Flashcards
Define autotroph.
Autotrophs- “self feeder”
auto=self troph=feeder
Define phototrophic autotrophs.
What are they responsible for?
Phototrophic autotrophs- use carbon dioxide as carbon source (using suns energy to make complex molecules)
photo= light feeder self feeder
Obtain energy from the sun
Ultimately responsible for the survival of nearly all other organisms (humans)
Solar energy+carbon+water=carbon dioxide and glucose
6CO(2)+6H(2)O+light energy=C(6)H(12)O(6) + 6O(2)
Describe the chloroplast structure.
Structure of Chloroplasts:
Chloroplast: site of photosynthesis
Double membrane wrapped around a fluid filled interior called the stroma
Inner membrane forms disks called grana (single is granum)
- inner membrane and grana form the thylakoid membrane system
What are the properties of light? (2)
Properties of Light:
Light travels as packets of energy called photons in waves
Wavelength (distance between crests or troughs) determines amount of energy
Short wavelength=most energy
Long wavelength=least energy
Electro Magnetic Spectrum:
Longest and shortest wavelengths
Most and least energy wavelengths
red=longest wavelength and least energy
orange=
yellow=
green=
blue=
indigo=
violet=shortest wavelength and most energy
absorption spectrum?
Pigments absorb various wavelengths of visible light
what light does chlorophyll absorb?
Chlorophyll a-
Chlorophyll b-
what lights do carotenoids absorb and reflect?
what lights do phycobilins reflect?
absorb violet, blue, and red light
- main photosynthesis pigment
- and other pigments absorb light energy and transfer it to chlorophyll a
- absorb violet and blue wavelengths and reflect red, orange, and yellow
- reflect red and blue
The light dependent reactions
What do they require?
Where do they occur?
What’s absorbed and given up?
What’s formed to run the light-independent reactions?
Where do they get replacement electrons
The light dependent reactions
Require light
Occur in the grana of the chloroplast
Pigments absorb light and give up electrons
ATP and NADPH are formed to run the light-independent reactions
Pigments that give up electrons get replacement electrons from water
Light-independent reactions
What kind of pathway?
where and what energy is used from light-dependent reactions?
where do they occur?
What is carbon dioxide fixed into? (3 things)
Light-independent reactions:
Aka calvin cycle, C3 pathway
Do not require light
- get energy (ATP, NADPH) from light dependent reactions
Occur in the stroma of chloroplasts
Fixes carbon dioxide into PGAL (G3P) and then into glucose and other organic molecules (amino acids, fatty acids)
Photosystems:
How do they work?
hundreds of pigment molecules
Absorb photons and this causes their electrons to become boosted to higher energy levels
ATP Production:
What’s it produced by?
What happens?
Atp produced by chemiosmosis
When h20 is split, hydrogen ions in thylakoid space flow into stroma through ATP synthase and ATP is produced
C3 Plants: light independent, calvin cycle,
First intermediate is a 3-carbon PGA compound
Stomata on leaves are site of O2 and CO2 exchange
On hot days, stomata close to conserve water and CO2 cannot diffuse into leaves
Oxygen builds up in leaves and photorespiration occurs (use oxygen instead of carbon dioxide)
Less ATP is made and therefore less glucose
C4 Plants:
first intermediate is a 4-carbon compound (oxaloacetate)
Double carbon fixation
Mesophyll cells fix C)2 into oxaloacetate
Oxaloacetate is transferred to bundle sheath cells around leaf veins, CO2 is released and fixed again in the C3 pathway
More efficient at CO2 fixation
Evolved in regions of higher temperatures where stomata must be closed to save water
CAM Plants: crassulacean Acid Metabolism
These plants found in deserts and dry environments
Open stomata and fix CO2 at night
Intermediate is stored in central vacuole and used in photosynthesis the next day
