BB ch 7
autotroph
("self-feeders"), make own food; sustain themselves without consuming organic molecules derived from any other organism, producers
granum (plural, grana)
A stack of hollow disks formed of thylakoid membrane in a chloroplast. Grana are the sites where light energy is trapped by chlorophyll and converted to chemical energy during the light reactions of photosynthesis.
Autotroph "Plants, algae, and numerous bacteria are autotrophs."
An organism that makes its own food (often by photosynthesis), thereby sustaining itself without eating other organisms or their molecules.
producer
An organism that makes organic food molecules from CO2, H2O, and other inorganic raw materials: a plant, alga, or autotrophic bacterium.
photoautotroph
An organism that obtains energy from sunlight and carbon from CO2 by photosynthesis.
__________ reacts with ozone to turn it into ____________.
Chlorine; CO2
You are the CEO of a major manufacturing company that decides to use CFCs in production of your products. What are you failing to abide by?
Montreal Protocol
Oxygen is the final electron acceptor for cellular respiration. What is the final electron acceptor in the light reactions of photosynthesis?
NADP+
What do cyclic reactions do in light reactions?
NADP+ turned into NADPH, ATP is transformed, electrons turn back to chlorophyll after going away
In photosynthesis, the electrons come from water and end up in _____.
NADPH
What transports electrons from the light reactions to the Calvin cycle?
NADPH
the process in which a plant adds O2 to RuBP instead of CO2
Photorespiration
Current evidence indicates that the process of photosynthesis arose more than three billion years ago. Its origin had a huge impact on existing organisms and on the physical characteristics of the biosphere. Which major physical change could be attributed to photosynthesis?
Photosynthesis drastically increased the oxygen content of the atmosphere.
You obtain the pigments called carotenoids in your diet when you eat carrots. Why do carotenoids appear yellow and orange?
They absorb blue/green light and reflect yellow and red wavelengths of light.
What is the function of chlorophyll in photosynthesis?
capture light energy
electron transport chain
carries electrons from photosystem II to photosystem I
global warming
changing of aspects of global climate, such as temperature and weather patterns; contributed to by trapped CO2/other gases from fossil fuels; major aspect is global warming
ATP synthesis in both chloroplasts and mitochondria involves the process called _____________.
chemiosmosis
photophosphorylation
chemiosmotic production of ATP in photosynthesis
What are two things that work in conjunction to make CFC'S harmful to ozone?
chlorine and sunlight
A plant's leaves are the primary site of photosynthesis. A plant's leaves would be expected to have a large amount of ____________.
chlorophyll
pigments
chlorophyll a, chlorophyll b, carotenoids, xanthophyll, anthocyanin
What do non-cyclic reactions do in light reactions?
electrons transfer to NADPH
oxygen
comes from the breaking of water during the light reactions
What is an example of a photoautotroph?
corn stalks just before harvest: any plant that is able to produce its own food and act as producers to the biosphere
thylakoids
disk-like, green, interconnected membranous sacs; enclose internal compartment of thylakoid space
wavelength
distance between crests of two adjacent waves
Is the stratosphere moist or dry?
dry
NADP+
electron acceptor in photosynthesis, reduced to NADPH
In both cellular respiration and photosynthesis, a(n) ________ _________ _______ built into a membrane pumps H+ across the membrane as electrons are passed from one electron carrier to the next in a series of redox reactions.
electron transport chain
Photosynthesis is an __________ process in which carbon is __________, whereas cellular respiration is an __________ process in which carbon is __________.
endergonic : reduced : exergonic : oxidized
When a pigment absorbs a photon of light, if a substance somehow kept the boosted electron from falling back to its ground state, would light and hear still be released in the same amount?
energy would not be given off as light and heat at that time
Incoming photons of light energy initiate photosynthesis by _____.
exciting electrons in pigment molecules within the photosystems, raising them to a higher energy level
thylakoid space
fills up with hydrogen ions and creates a concentration gradient
light reactions
first step in photosynthesis; convert light energy to chemical energy, release O2; occur in thylakoids
photon
fixed quantity of light energy
C4 plants
fixes carbon in two different cells, (mesophyll and bundle sheath)
What is the function of RuBP?
fixes/binds to CO2
What are benefits of photosynthetic products to humans?
food, fuel, removal of CO2 from the atmosphere
electromagnetic spectrum
full range of electromagnetic wavelengths from very short gamma rays to very long-wavelength radio waves
primary electron acceptor
gets electrons from p680 or p700
Which parts of the visible light spectrum do plants reflect?
green
mesophyll
green tissue in interior in leaf, most concentrated in cells on leaf
photosystem
group of light-harvesting complexes surrounding reaction-center complex
CFCs
hairspray
Where does photosynthesis take place?
in the chloroplast
carbon fixation
incorporation of carbon from CO2 into organic compounds in Calvin cycle, fixes CO2 into usable organic molecule
What is the equation that represents photosynthesis?
6CO2 + 6H2O → C6H12O6 + 6O2
heterotrophs
(hetero, "other"); organisms that consume organic material, consumers; organisms that decompose organic material, decomposers
What are the differences between C4 and CAM plants in photosynthesis?
*C4*: stomata closed, conserves water, 4 carbon compound (fix CO2), ex. corn, sugarcane *CAM*: open stomata at night to bank CO2 at night and release it during the day, ex. ferns, pineapple, cacti, aloe, jade *Same*: minimize photorespiration, maximize photosynthesis, hot and dry climates, ways to cool down the cell without stopping sugar production, stores water
What are two additional pigments that can be found in plants?
*carotenoids*: help absorb extra light that could damage. Interacts with oxygen to form a reactive oxidative molecule. various shades of yellow and orange *xanthophylls*
What are the two types of chlorophyll found in plants?
*chlorophyll a*: participates directly in light reactions, absorbs mainly blue-violet and red light. Looks blue-green *chlorophyll b*: broadens the range of light that a plant can use by conveying absorbed energy to chlorophyll a. Absorbs blue-orange light and reflects olive green
What are the differences between photosystem I and photosystem II?
*photosystem I*: occurs second, produces NADPH *photosystem II*: happens first, produces ATP, splits water *same*: cooperate in light reactions, characteristic reaction center complex, special pair of chlorophyll a molecules with a particular primary electron acceptor, thylakoid membrane, drives flow of electrons from water to NADPH, light excites the electrons, 2 complexes of pigments linked by the electron transport chain
A student has been shrunk to fit inside the thylakoid space of a granum. How many layers of phospholipids would he or she need to cross through to get completely out of the mesophyll cell?
8 layers- 8 layers of phospholipids
photon "The shorter the wavelength of light, the greater the energy of a photon."
A fixed quantity of light energy.
chlorophyll
A green pigment located within the chloroplasts of plants, algae, and certain prokaryotes. It can participate directly in the light reactions, which convert solar energy to chemical energy.
photosystem
A light-capturing unit of a chloroplast's thylakoid membrane, consisting of a reaction center complex surrounded by numerous light-harvesting complexes.
C4 plant
A plant that prefaces the Calvin cycle with reactions that incorporate CO2 into four-carbon compounds, the end product of which supplies CO2 for the Calvin cycle.
CAM plant
A plant that uses an adaptation for photosynthesis in arid conditions in which carbon dioxide entering open stomata during the night is converted to organic acids, which release CO2 for the Calvin cycle during the day, when stomata are closed.
C3 plant
A plant that uses the Calvin cycle for the initial steps that incorporate CO2 into organic material, forming a three-carbon compound as the first stable intermediate.
stoma (plural, stomata) "A plant conserves water when its stomata are closed."
A pore surrounded by guard cells in the epidermis of a leaf. When stomata are open, CO2 enters a leaf, and water and O2 exit.
What summarizes the inputs and outputs of the Calvin cycle?
ATP + NADPH + 3CO 2 → G3P
What links the two stages of photosynthesis with each other?
ATP and NADPH
What two molecules are produced by the light reactions and used to power the Calvin cycle?
ATP and NADPH
Briefly, explain what would happen to the levels of NADPH and ATP within the stroma is the passage of electrons to the primary electron acceptor of photosystem I were inhibited.
ATP production would stop- cell would die because it needs energy. Halt production of NADPH, no NADP+ going through cycle
What connects the two photosystems in the light reactions?
An electron transport chain
In __ plants, the first product of carbon fixation is the three-carbon compound 3-PGA formed in the Calvin cycle.
C3
In __ plants, CO2 is first fixed into a four-carbon compound, which moves into bundle-sheath cells and releases CO2 to the Calvin cycle.
C4
In ___ plants, stomata are open at night, and CO2 is first fixed into a four-carbon compound, which releases CO2 to the Calvin cycle during the day.
CAM
Which gas contributes to both global warming and the deterioration of the ozone layer?
CFCs
The carbon in glucose comes from what source?
CO2
The oxygen in glucose comes from what source?
CO2
A toxin is found to inhibit the uptake of CO2 into plant leaves. This toxin would most directly affect the ____________ ____________.
Calvin Cycle
What substance provides the majority of the atoms that make up the sugar produced by photosynthesis?
Carbon Dioxide
What provides the carbon atoms that are incorporated into sugar molecules in the Calvin cycle?
Carbon dioxide (CO2)
How is the primary electron acceptor reduced in light reactions?
Electrons are supplied to chlorophyll P680 as it reduces the primary electron acceptor.
What is the final product of the Calvin Cycle?
G3P
In both respiration and photosynthesis, the potential energy of a(n) __ ____________ _______ is tapped to drive the phosphorylation of ADP to ATP. As H+ diffuses back through ___ _______ (an enzyme complex embedded in the membrane), ATP is produced.
H+ concentration gradient; ATP synthase
What provides electrons for the light reactions?
H2O
photorespiration "Photorespiration produces no sugar molecules or ATP."
In a plant cell, the breakdown of a two-carbon compound produced by the Calvin cycle. The Calvin cycle produces the two-carbon compound, instead of its usual three-carbon product G3P, when leaf cells fix O2, instead of CO2.
global climate change
Increase in temperature and change in weather patterns all around the planet, due mostly to increasing 苔tmospheric CO2 levels from the burning of fossil fuels. The 虹ncrease in temperature, called global warming, is a major aspect of global climate change.
What is the potential benefit of photorespiration in plants?
It allows plant cells to reduce the buildup of oxygen gas without opening stomata.
A botanist discovers a new plant species in the Amazon rainforest that has blue leaves. Briefly explain what can be inferred about the pigments in the leaves of this plant
It contains lots of Chlorophyll A and participates directly in light reactions
When such plants close their stomata on hot, dry days to conserve water, __ builds up in the leaf and is added to RuBP in place of CO2. A two-carbon product of this reaction is broken down to CO2, consuming ATP and generating no sugar.
O2
thylakoid "A stack of thylakoids is called a granum."
One of a number of disk-shaped membranous sacs inside a chloroplast. Their membranes contain chlorophyll and the enzymes of the light reactions of photosynthesis.
Where was the thinning of ozone initially discovered?
Over the Antartic
One of the important waste products of photosynthesis is oxygen gas. Where does this oxygen gas come from?
Oxygen is released when water is broken down to extract electrons and protons for use in the light reactions.
Hydrogen is a likely candidate in the search for a replacement for petroleum. However, removing hydrogen from water requires the investment of a great deal of energy. Why are plants considered to be one step ahead in the utilization of hydrogen as an alternative fuel source?
Plant cells possess water-splitting enzymes.
Why is the Calvin Cycle Cyclic?
RuBP is regenerated in the final chemical reactio
Although the reactions of the Calvin cycle are not directly dependent on light, they usually do not occur at night. Why?
The Calvin cycle depends on products of the light reactions.
wavelength
The distance between crests of adjacent waves, such as those of the electromagnetic spectrum.
electromagnetic spectrum
The entire spectrum of radiation ranging in wavelength from less than a nanometer to more than a kilometer.
light-dependent reactions
The first of two stages in photosynthesis; the steps in which solar energy is absorbed and converted to chemical energy in the form of ATP and NADPH. The light reactions power the sugar-producing Calvin cycle but produce no sugar themselves.
stroma "Sugars are made in the stroma by the enzymes of the Calvin cycle."
The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water.
mesophyll
The green tissue in the interior of a leaf; a leaf's ground tissue system; the main site of photosynthesis.
greenhouse effect
The warming of the atmosphere caused by CO2, CH4, and other gases that absorb infrared radiation and slow its escape from Earth's surface.
carbon fixation
The incorporation of carbon from atmospheric CO2 into the carbon in organic compounds. During photosynthesis in a C3 plant, carbon is fixed into a three-carbon sugar as it enters the Calvin cycle. In C4 and CAM plants, carbon is fixed into a four-carbon sugar.
photosynthesis
The process by which plants, autotrophic protists, and some bacteria use light energy to make sugars and other organic food molecules from carbon dioxide and water.
photophosphorylation
The production of ATP by chemiosmosis during the light reactions of photosynthesis.
Calvin cycle/reactions
The second of two stages of photosynthesis; a cyclic series of chemical reactions that occur in the stroma of a chloroplast, using the carbon in CO2 and the ATP and NADPH produced by the light reactions to make the energy-rich sugar molecule G3P.
A red chemical dye known as phenol red changes to yellow when CO2 is present. A small green plant seedling is placed in phenol red and then placed in the dark. Which of the following is most likely to occur?
The solution is red to begin with, and it will turn yellow because respiration is occurring.
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 before you left, the plant stored energy in the form of sugars or starch, and it was able to derive energy from those during your vacation.
chlorophyll
a light-absorbing pigment in the chloroplasts; plays a central role in converting solar energy to chemical energy
ATP Synthase
a transport protein that attaches P to ADP
rubisco
an enzyme that fixes a carbon onto RuBP
photoprotection
biochemical process that helps organisms cope with molecular damage caused by sunlight; ex: carotenoids
Which parts of the visible light spectrum do plants absorb?
blue, red, orange
Where is carbon dioxide used?
calvin cycle
In photosynthesis, _____ ______ drives electrons from a low-energy state in water to a high-energy state.
light energy
The two complexes of pigments that constitute a photosystem include ________ __________ _____________ and the _________ __________.
light harvesting complex; reaction complex
The thylakoid membranes bring together the components necessary to carry out the _____.
light reactions
Where is light used?
light reactions
Where is oxygen made?
light reactions
Where is water used?
light reactions
Where are enzymes used?
light reactions and the calvin cycle
What are the two primary reactions in photosynthesis?
light reactions, calvin cycle
What is the purpose of enzymes in photosynthesis?
lower the energy needed to make chemical bonds
Can the light reactions take place in the dark? Why?
no- need light to function
The Calvin Cycle is also referred to as the referred to the light-independent reactions. Briefly explain why referring to the chemical reactions of the Calvin cycle as the light-independent reactions is only partially accurate.
none of the steps in the Calvin Cycle may require light directly but the reaction usually occurs in daylight because it depends on the products from light reactions which are light-dependent
photoautotrophs
organisms that convert solar energy to chemical energy, use sunlight (such as plants)
Cellular respiration and photosynthesis are similar in that both involve _____.
oxidation-reduction (redox) reactions
In respiration, the electrons come from the oxidation of organic molecules, and ______ is the final electron acceptor.
oxygen
The light reactions produce _____.
oxygen, NADPH, and ATP
p680 and p700
pairs of chlorophylls that lose their electrons
How can ultraviolet rays cause sunburn and skin cancer?
photons of wavelengths that are shorter than those of visible light have enough energy to damage molecules suck as proteins and nucleic acids
CAM plants
plants adapted to very dry climates; conserves water by opening stomata at night to take in CO2; fixes CO2 into four-carbon compound, releases 3-carbon sugar during day, stores water; ex: pineapple, cactus
C4 plants
plants that fix CO2 into four-carbon compound before entering Calvin cycle, closes stomata when hot but can continue photosynthesis normally using pathway and enzyme with high affinity for CO2; ex: sugarcane
C3 plants
plants where first product of carbon fixation is three-carbon compound 3-PGA; close stomata when hot but cannot continue photosynthesis properly, thus dehydrating
photorespiration
process in which O2 builds up in leaf, rubisco adds O2, instead of CO2, to RuBP, two-carbon product broken down in cell; consumes O2 and releases CO2
photosynthesis
process in which plants convert CO2 and H2O to their own organic molecules (such as glucose); release O2 as by-product
What is the function of water in photosynthesis?
replace electrons lost by photosystem II
In all three types of plants, the enzyme _______ brings CO2 into the Calvin cycle.
rubisco
Calvin cycle
second step in photosynthesis; cyclic series of reactions assembling sugar molecules, inputs CO2 and outputs sugar (glucose)
What is the function of the electron transport system?
shuttle electrons during redox reactions to create ATP
stomata
small pores in which carbon dioxide enters and oxygen leaves the leaf
grana
stacks of thylakoids
What do plants do with excess glucose produce?
store it
The rate of photosynthesis depends of what 3 conditions?
sunlight, CO2, water
What eliminated the use of CFC's by all participating countries?
the Montréal Protocol of 1987
What links photosystem I with photosystem II?
the electrons passing between the two photosystems
Glucose
the end product of the metabolic pathway we call photosynthesis
Redox
the nickname for Oxidation-Reduction Reaction
If a scientist removes the pair of cholorophyll a molecules from the reaction-center complex, then what consequence would be likely to occur?
the transfer of energy from the light-harvesting complex to the reaction center complex would stop
What is the definition of photosynthesis in words?
the use of solar energy transformations to be stored to chemical energy; the making of glucose
A new bacterium is discovered in Lake Superior. Scientists are able to determine that these bacteria produce oxygen gas. What is likely to be true about these organisms?
they are photoautotrophs that undergo photosyntheses
stroma
thick fluid in inner membrane of chloroplast
The light reactions take place in the _________ and the Calvin cycle takes place in the _________.
thylakoids; stroma
What does a plant use the products of the Calvin Cycle for?
to make starch, cellulose, and molecules used in protein synthesis
chlorophyll a
type of pigment in chloroplasts; participates directly in light reactions; absorbs mainly blue-violet and red light
Both mitochondria and chloroplasts _____.
use an H+ gradient to produce ATP
You are a graduate student studying the effects of global warming on photosynthesis. What are some different methods that you could think of to measure the rate of photsynthesis in a plant?
use small growth chambers to carefully measure changes to make sure you have control!
What is the function of PGAL (G3P)?
used to make glucose
The hydrogen in glucose comes from what source?
water
The oxygen plants give off comes from what source?
water
What molecule is broken down in the Light reactions?
water
What is the overall effect of increased CO2 levels on poison ivy growth?
weeds that are becoming poisonous are beginning to harm people more easily than ever before... putting people and animals in harms way
Reduction
when a molecule gains an electron
Oxidation
when one molecule loses an electron
phosphorylation
when one molecule, such as ATP, gives energy to another molecule by transferring a phosphate group
Why is the greenhouse effect not necessarily bad?
without the greenhouse effect, Earths average air temperature would be -18ºC which is too cold for many types of life
