Ch.7 Photosynthesis Flashcards
These capture light energy
Chloroplasts
Plants use solar energy to convert CO2 and _____ to sugars and other organic molecules. They release____ as a by product.
H2O
O2
These are “self feeders” that make their own food. They are also the ultimate source of organic molecules for almost all other organisms.
Autotrophs
These are plants and other photosynthesizers that use the energy of light. They are producers of the biosphere and feed consumers
Photoautotrophs
These cannot make their own food and must consume plants or animals or decompose organic material. They are dependent on photoautotrophs for food and O2.
Heterotrophs
_______ are the major sites of photosynthesis in most plants.
Leaves
A light absorbing pigment in chloroplasts that plays a central role in connecting solar energy to chemical energy.
Chlorophyll
A green tissue in the interior of the leaf in which chloroplasts are concentrated.
Mesophyll
A thick fluid within an inner compartment of the chloroplasts is called?
Stroma
This is a tiny opening or pore that carbon dioxide enters and oxygen exits.
Stomata
These are inner connected membranous sacs suspended within the stroma. Built into these membranes are the chlorophyll molecules that capture light.
Thylakoids
How do the reactant molecules of photosynthesis reach the chloroplasts in the leaves?
CO2 enters the leaves through stomata and H2O enters the roots and is carried to leaves through veins.
In plants, H2O is split with hydrogen becoming incorporated into sugar and the o2 released as _____. The O2 released comes from water not ______.
Gas
CO2
Photosynthesis is a ____ process as is cellular respiration.
Redox
In the equation for photosynthesis
6 CO2 + 6 H2O —
C6H12O6
6 O2
When photosynthesis is reduced ____ is added and sugar as electrons are also added.
H+
When photosynthesis is oxidized the reactants lose _____ and _____.
Lose electrons and H+
______ energy of electrons increases as they move from H2O to CO2.
Potential
What provides the potential energy boost during photosynthesis?
The light captured by the chlorophyll in the chloroplasts.
Photosynthesis converts light energy to _____ energy and stores it in the chemical bonds of ______ molecules.
Chemical
Sugar
What is stage one of photosynthesis?
Light reactions
Where do light reactions occur?
In the thylakoids
Describe the process of light reactions.
- Light energy is converted to chemical energy and o2 is released.
- Water is split providing a source of electrons and giving o2 off as a by product.
- Light absorbed by chlorophyll molecules within the thylakoids is used to drive a transfer of electrons and H+ from water to electron acceptor NADP+.
- NADP+ is reduced to NADPH.
What does NADPH store?
Temporarily stores electrons and hydrogen ions and also provides reducing power to the Calvin cycle.
Light reactions absorb solar energy and convert it to chemical energy stored where?
ATP and NADPH
What is the second stage of photosynthesis?
The Calvin cycle.
Where does the Calvin cycle take place?
In the stroma of the chloroplast
Describe the Calvin cycle.
- It requires no light directly for this stage but occurs during daylight.
- Cyclic series of reactions that assembles sugar molecules using CO2 and energy rich products of the light reactions.
This is the incorporation of carbon from CO2 into organic compounds. CO2 then enters the Calvin cycle and are reduced to sugars after.
Carbon fixation
Photosynthesis is a ______ process as is cellular respiration.
Redox
CO2 in photosynthesis becomes _____ to sugars as electrons and H+ are added to it.
reduced
H2O is _____ to O2 as they lose electrons and hydrogen ions.
Oxidized
______ energy of electrons increase as they move from H2O to CO2.
Potential
Light energy captured by ______ in the chloroplasts provide a potential energy boost.
Chlorophyll
Photosynthesis converts light energy to ______ energy and stores it in he chemical bonds of sugar and molecules.
chemical
CO2 enters the Calvin cycle and is reduced to sugars after ____ ____.
Carbon Fixation
What provides the electrons for reducing carbon compounds in the Calvin cycle?
NADPH produced by light reactions
What provides the chemical energy that powers several of the steps of the Calvin cycle?
ATP
Sunlight is electromagnetic energy or _____
Radiation
This is the distance between the crests of electromagnetic waves.
wavelength
This is the full range of electromagnetic wavelengths from short gamma rays to long radio waves.
Electromagnetic Spectrum
What is the wavelength of visible light?
380nm-750nm
These are discrete packets of fixed quantity of energy.
Photons
The shorter the wavelength of light then the _____ the energy of its photons.
greater
These are light absorbing molecules that are built into the thylakoid membranes. They absorb wavelengths of light and reflect and transmit other wavelengths.
Pigments
We see the green wavelength of plants that are not absorbed but are _____ and reflected by the pigment.
transmitted
This absorbs mainly blue violet and red light and reflects green light giving it a blue green color.
Chlorophyll a
This absorbs mainly blue and orange light and reflects ( appears) olive greens.
Chlorophyll b
Chlorophyll b conveys ______ energy to chlorophyll a.
absorbed
This is contained in chloroplasts in various shades of yellow and orange.
Carotenoids
The colors of fall are from longer lasting _____.
Carotenoids
What color of light is least effective at driving photosynthesis? Why?
Green because it is mostly transmitted and reflected not absorbed by photosynthetic pigments.
This consists of a number of light harvesting complexes surrounding a reaction center complex. Within the thylakoid membrane, chlorophyll molecules are organized along with other pigments and proteins into clusters called what?
Photosystems
This contains pigment molecules bound to proteins and function as light gathering antenna. The pigments absorb photons and pass energy from molecule to molecules until it reaches the reaction center.
Light harvesting complex
This contains a pair of special chlorophyll a molecules and a primary electron acceptor.
Reaction center complex
The electron acceptor within a reaction center complex is capable of accepting ______ and becoming reduced.
electrons
Two photosystems connected by an electron transport chain generate_____ and ____.
ATP
NADPH
This is a chemiosmotic production of ATP. As an electron transport chain helps to produce the concentration graident of H+ across the thylakoid membrane synthase thus producing ATP.
Photosynthase
Light reactions take place within the ______.
Thylakoid membrane
ATP and NADPH powers sugar synthase in the _____ ___.
Calvin Cycle
The calvin cycle functions as a sugar factory within the ____.
Chloroplasts
Inputs to the Calvin cycle include what?
- CO2 from the air
- ATP generated from light reactions
- NADPH generated from light reactions
What is the energy source of the Calvin cycle?
ATP
What is the source of high energy electrons for reducing CO2 and sugar in the Calvin cycle?
NADPH
What are the outputs from the Calvin cycle?
- G3P- gylceraldehyde 3
2. Energy rich carbon sugar
Plant cells use the outputs from the Calvin cycle for what?
To make glucose, disaccharide sucrose and other organic molecules.
This is the first step to the Calvin cycle.
Carbon fixation
During the first step of the Calvin cycle the enzyme rubisco combines CO2 with this 5 carbon sugar.
RuBP- ribulose biphosphate
How many times must carbon fixation turn?
3 times
The products split into two molecules of what in the first step of the Calvin cycle?
splits into 2 molecules of 3 carbon organic acid and 3 phosphoglycerate (3-PGA)
For every 3 CO2 entering the Calvin cycle, how many PGA results?
6
This is the second step of the Calvin cycle.
Reduction
What happens during the second step of the Calvin cycle?
A series of 2 chemical reactions uses energy from ATP and electrons donated from the NADPH to reduce 6 molecules of 3-PGA to 6 molecules of the energy rich 3-carbon sugar, G3P.
Describe step 3 of the Calvin cycle.
The release of 1 molecule of G3P as a product. 5 remain in the cycle.
Step 4 of the Calvin cycle is regenerate of RuBP.
The remaining 5 G3P molecules are rearranged using energy from ATP to regenerate 3 molecules of RuBP.
To synthesize one glucose molecule, the Calvin cycle uses __ CO2, ___ ATP and __ NADPH.
6
18
12
Other methods of ___ ___ have evolved in hot dry climates.
carbon fixation
This is the process occurring in the light, consuming O2 and releases CO2. It uses ATP instead of producing it and yields no sugar.
Photorespiration
This type of plant uses CO2 directly from the air and carbon fixation occurs when the enzyme rubisco adds CO2 to RuBP.
C3 plants.
What are examples of C3 plants?
- soybeans
- oats
- wheat
- rice
This plant type conserves water by closing the stomata.
C4 plants
What are examples of C4 plants?
- pineapples
- cacti
- succulents
How do C4 plants conserve water?
By opening its stromata and admitting CO2 only at night and releasing it during the day.
Photosynthesis makes sugar from O2 and H2O providing food and O2 for______.
Almost all living organisms.
This is solar radiation passing through the atmosphere and warms the Earths surface.
Greenhouse effect
What are types of greenhouse gases?
CO2, water vapor and methane
Increasing concentrations of greenhouse gases have been linked to ____ ____ ____.
Global Climate Change
What are some consequences to global climate change?
- Melting polar ice caps
- rising sea levels
- extreme weather patterns
- draughts
- increased extinction rates
- spread of tropical diseases
