Ch 10

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Endosymbiont theory
The original chloroplast was a photosynthetic prokaryote that lived inside ancestor of eukaryote cells
Chloroplasts are
The sites of photosynthesis
Chloroplasts are mainly found in
Mesophyll- tissue in the interior of the leaf
Stomata
Microscopic pores in which carbon dioxide enters the leaf and oxygen exits
Leaves also use veins to
Export sugar to the roots and other non photosynthetic parts to a plant
Mesophyll cell has
About 30-40 chloroplasts
A chloroplast has an envelope of two membranes surrounding a dense fluid called
Stroma
Suspended in the stroma are
Sacs called thylakoids
Thylakoid stacks/columns
Grana/granaum
Chlorophyll
The green pigment that gives leaves their color. (In thylakoids)
In the presence of light the green parts of plants produce
Organic compounds and oxygen from carbon dioxide and water
Photosynthesis is a
Redox reaction
Photosynthesis requires energy meaning
It's endergonic
There are 2 stages of photosynthesis
Light reactions and the Calvin cycle
Light reactions are the steps when
Solar energy is converted to chemical energy
The light reactions use solar energy to reduce
NADP+ to NADPH
The light reaction generates
ATP using chemiosmosis
Carbon to organic molecules is
Carbon fixation
The Calvin cycle makes sugar with the help of
NADPH and ATP (produced by light reactions)
Calvin cycle occurs in
The stroma
Light is a form of energy known as
Electromagnetic energy or electromagnetic radiation
The distance between the crests of electromagnetic waves is
Wavelength
Visible light is the light
That can be detected by the human eye
A quantum or discrete quantity of light that behaves as if it were a particle
Photon
The shorter the wavelength of the light
The greater the energy of each photon of light
Substances that absorb light are
Pigments
Spectrophotometer
An instrument that can measure various wavelengths of light
2 types of pigments
Chlorophyll a, chlorophyll b
Chlorophyll a
A pigment that participates directly in the light reactions that convert solar energy to chemical energy
Chlorophyll b
An accessory photosynthetic pigment that transfers light to chlorophyll a
Photosystems
When chlorophyll molecules are organized along with other small organic molecules and proteins into complexes
A photosystem is composed of a
Reaction center complex
Photosystem (in thylakoid) 2 types
Photosystem I (PSI) and photosystem II (PSII)
Linear reaction flow(during the light reactions of photosynthesis)
A route of electron flow that involves both photosystems and produces ATP, NADPH, and O2
Cyclic electron flow(alternative path)
A route of electrons during the light reactions of photosynthesis that involves only 1 photosystem and ply produces ATP
Calvin cycle is
Anabolic (consumes energy)
Glyceraldehyde 3-phosphate (G3P)
The 3 carbon carbohydrate that is a product of the Calvin cycle
Photorespiration produces
No sugar
2 types of photosynthetic cells
Bundle-sheath and mesophyll cells
Bundle sheath
Cell arranged into tightly packed sheaths around the veins of a leaf
Pep carboxylase
An enzyme that adds CO2 to PEP to form oxaloacetate in mesophyll cells of c4 plants (prior to photosynthesis)
CAM plants
A plant that uses crassulacean acid metabolism, an adaptation for photosynthesis in arid conditions.
The Calvin cycle uses
ATP and NADPH to produce sugar from carbon dioxide
50% of the organic material made by photosynthesis is
Consumed as fuel for cellular respiration in plant cell mitochondria
The light reactions of photosynthesis occur in the __________.
thylakoids
The light reactions of photosynthesis generate high-energy electrons, which end up in __________. The light reactions also produce __________ and __________.
NADPH; ATP; oxygen
Why are most autotrophs referred to as the producers of the biosphere?
They are the ultimate sources of organic compounds for all nonautotrophic organisms.
The Calvin cycle could not occur without the light reactions. Which of the following statements describes why this is the case?
ATP and NADPH produced in the light reactions provide the energy for the production of sugars in the Calvin cycle.
Where does the Calvin cycle of photosynthesis occur?
Stroma
Carbon dioxide and oxygen enter and exit a leaf by diffusion. Which structure(s) on a leaf allow(s) this process to happen?
Stomata
During the Calvin cycle, what happens during the carbon fixation phase?
The Calvin cycle incorporates each CO2 molecule, one at a time, by attaching it to a five-carbon sugar named ribulose bisphosphate.
In the light reactions of photosynthesis, ATP is produced by photophosphorylation. Which of the listed processes is most similar to photophosphorylation?
Oxidative phosphorylation in cellular respiration
During which process is molecular oxygen produced in photosynthesis?
The light reactions by linear electron flow
Which of the following processes occurs during the second phase, the reduction phase, of the Calvin cycle?
G3P production
Both mitochondria and chloroplasts __________.
use chemiosmosis to produce ATP
The reactions of the Calvin cycle are not directly dependent on light, but they usually do not occur at night. Why?
The Calvin cycle requires products only produced when the photosystems are illuminated.
You have a large, healthy philodendron that you carelessly leave in total darkness while you are away on vacation. You are surprised to find that it is still alive when you return. What has the plant been using for an energy source while in the dark?
While it did have access to light, the plant stored energy in the form of sugars or starch, and it was able to derive energy from the stored molecules during your vacation.
The most important role of pigments in photosynthesis is to __________.
capture light energy
Which of the following statements correctly describes the difference in carbon fixation between C3 and C4 plants?
The first product of carbon fixation in C4 plants is a four-carbon compound instead of a three-carbon compound.
What property of the pigment chlorophyll makes it appear green?
Chlorophyll absorbs all of the visible spectrum of light except green, which it reflects.
Of the following, which occurs during the Calvin cycle?
CO2 is reduced.
The source of the oxygen produced by photosynthesis has been identified through experiments using radioactive tracers. The oxygen comes from __________.
Water
When chloroplast pigments absorb light, __________.
their electrons become excited
How does carbon dioxide enter the leaf?
Through the stomata
Metabolic pathways are typically redox processes. In photosynthesis, what molecule is oxidized and what molecule is reduced?
Water is oxidized and carbon dioxide is reduced.
Where do the electrons entering photosystem II come from?
Water
The energy used to produce ATP in the light reactions of photosynthesis comes from __________.
movement of H+ through a membrane
Light reactions
Convert light energy to chemical
Calvin cycle (dark or carbon reactions)
Uses the products if the light reactions to produce sugar
C4 plants have
Anatomical adaptations that concentrate chloroplasts into 4-carbon carbon dioxide (increases flow of CO2 and decreases water loss)
CAM plants
Slowest and most inefficient in converting suns energy into glucose. Most water efficient (found in deserts) adapt to harsh conditions
C3 plants
Most energy efficient
Stage I photosynthesis happens
Only in grana
Stage II in photosynthesis happens
In the stroma