chapter 7, bio test 3
Photosynthesis equation
6CO2 + 6H2O + light energy --> C6H12O6 + 6O2 -reverse of cellular respiration -endergonic -H20 oxidized to O2, -C02 is reduced to C6H1206
What products of the light reaction (phototrophy) are required for the dark reaction (Calvin cycle) to operate? H2O O2 ATP NADPH CO2
ATP NADPH
IMPORTANT info on calvin cycle and citric acid cycle
Calvin Cycle: anabolic, regenerative molecule is RuBP Citric Acid Cycle: catabolic, regenerative molecule is Oxaloacetate
Which of the following statements is NOT true about Rubisco? It is more likely to pick up oxygen than carbon dioxide if the oxygen level are too high in a cell. It is present in all organisms that use the Calvin cycle to fix CO2. It catalyzes the addition of CO2 to ribulose 1,5-bisphosphate (RuBp). It is the "pick up molecule" that is regenerated as the Calvin cycle is completed
It is the "pick up molecule" that is regenerated as the Calvin cycle is completed
how are autotrophs able to produce their own food?
Most autotrophs use a process called photosynthesis to make their food. In photosynthesis, autotrophs use energy from the sun to convert water from the soil and carbon dioxide from the air into a nutrient called glucose. Glucose is a type of sugar. The glucose gives plants energy.
Which of the following is not one of the steps of the Calvin cycle. Regeneration of the Rubisco enzyme Carbon fixation Regeneration of ribulose 1,5-bisphosphate (RuBp) Reduction
Regeneration of the Rubisco enzyme
non-cyclic electron flow
The combined action of photosystem II and photosystem I in which electrons flow in a linear manner to produce NADPH , as well as ATP and oxygen
carbon fixation
The initial incorporation of carbon into organic compounds. - CO2 from atmosphere is attached to RuBP (5 Carbon) - Results in 6-carbon molecule that splits to form two molecules of PGA (3 carbon) - 3 RuBP + 3 CO2 → 6 PGA
In plants, most photosynthesis occurs in the mesophyll cells of the leaves. True False
True
explain the significance of RuBP carboxylase enzyme to photosynthesis
catalyzes the conversion of atmospheric CO2 into organic compounds.
In what organelle does photosynthesis take place?
chloroplast
Photosystem
contains pigment complex, reaction center, and electron acceptor -located in thylakoid membranes to capture solar energy
photosynthesis
converts solar energy into chemical energy
what cell type does photosynthesis take place?
mesophyll
anatomy of a plant leaf
mesophyll tissue = cells are specialized for photosynthesis stomata = small openings for carbon dioxide to enter leaf chloroplasts = organelles that carry out photosynthesis
CAM plants
only open stomata at night to pick up CO2, the stored CO2 is used in the calvin cycle during the day, when CO2 is used and when CO2 is obtained is separated (temporal separation) -cacti, pineapple
In the reaction, 6CO2 + 6H2O →C6H12O6 + 6O2, carbon dioxide is being reduced oxidized phosphorylated released hydrolyzed
reduced
Photorespiration
series of reactions that occur in plants when carbon dioxide levels are depleted but oxygen continues to accumulate RuBP fixes O2 instead of CO2
regeneraion
- 5 molecules of G3P are used to reform 3 molecules of RuBP - One molecule of G3P given off (three cycle turns required) - The G3P released can be used to form glucose (takes 2), fatty acids, or amino acids - 5 G3P + 3 ATP → 3 RuBP + 3 ADP+ P
reduction
- Each of the two PGA molecules undergoes reduction to G3P - Two steps involving ATP and NADH (from light reactions) - 6 PGA + 6 ATP + 6 NADPH → 6 G3P + 6 ADP+ P + 6 NADP+
Light Reaction : Photosystem I
- Electrons gained from photosystem II - Pigment complexes absorb solar energy and energized electrons leave the reaction center and are captured by electron acceptors - Electrons are passed to NADP+ molecules which are reduced to form NADPH - NADPH to be used in calvin cycle - Input: NADP+, solar energy, electrons - Output: NADPH
Light Reaction : Photosystem II
- H2O is oxidized and split to give off electrons and oxygen - Pigment complex absorbs solar energy until reaction center is formed - Electrons in reaction center become energized and move to electron acceptor molecules - Electrons move down ETC and create H+ gradient - ATP produced through H+ gradient by ATP synthase - ATP to be used in calvin cycle - Input: H2O, solar energy, ADP + P - Output: O2, ATP
components of chloroplast
- stroma = semifluid interior, carbohydrates form here - thylakoids = flattened sacs, absorb solar energy - granum = stacked thylakoids - chlorophyll = green pigment that absorbs sunlight & drives photosynthesis, found in thylakoid membrane
two stages of photosynthesis
1) Light Reactions (photo) -PS1 AND PS2 -occur in the thylakoid membrane 2) Calvin Cycle = Light Ind. Reaction (synthesis) -occur in the stroma
Explain how different ways of achieving photosynthesis allow plants to adapt to particular environments.
C3 plants most adapted to: -cold temperatures (below 25c) -high moisture C4 plants most adapted to: -high light intensities -high temperatures -limited rainfall CAM plants most adapted to: -extreme aridity -dry environments
Photorespiration is the process by which light is used to break down stored carbohydrate molecules to release the energy needed to perform work in plant cells. True False
False
Plants do not need to perform cellular respiration to make ATP because they can make all the ATP they need through photosynthesis. True False
False
Through the process of photosynthesis, carbon dioxide (CO2) is oxidized to produce glucose and water is reduced to form oxygen (O2) which is released from the plant. True False
False
Photoautotrophs
Organisms that use light as a source of energy to synthesize organic substances. -plants, algae, prokaryotes, bacteria
What would happen if the stomata of a leaf remained closed all day? Select all that apply. Oxygen in the air spaces would increase. Carbon dioxide in the air spaces of the leaf would decrease. The amount of water within the air spaces would decrease. Photorespiration would increase in CAM plants. Photorespiration would increase in C3 plants
Oxygen in the air spaces would increase. Carbon dioxide in the air spaces of the leaf would decrease. Photorespiration would increase in C3 plants
How might a plant cope with the fact that the Calvin cycle uses more ATP than NADPH? Electron flow rate can be increased, increasing both ATP and NADPH production. Photosystems can convert from non-cyclic to cyclic electron flow, producing more ATP than NADPH. Increase the electrochemical gradient for H+ across the thylakoid membrane, producing more ATP but not NADPH. More pigment can be rapidly created for greater photosynthetic capacity, producing equal amounts of ATP and NADPH. Plants often increase the amount of NADP reductase, thereby increasing NADPH production to match ATP output.
Photosystems can convert from non-cyclic to cyclic electron flow, producing more ATP than NADPH.
what is the role of photosynthetic pigments in harnessing solar energy ?
Pigment molecules absorb wavelengths of light, but only some pigments absorb certain lights, so they either reflect or transmit other wavelengths.
why do plants carry out both cellular respiration and photosynthesis?
Plants use both photosynthesis and cellular respiration because have to make their food with photosynthesis then use cellular respiration to turn their food into usable energy
heterotrophs
are the consumers of the biosphere -typically depend on phototrophs for food and O2 -can NOT use inorganic carbon to build their own organic molecules -consume other organisms
autotrophs
are the producers of the biosphere organisms that can use inorganic sources of carbon like carbon dioxide and build their own organic molecule like sugar
Steps of the Calvin Cycle
carbon fixation, reduction, regeneration
phototrophs
those that use light as their energy source
C4 plants
unique leaf anatomy, avoid photorespiration by separating where carbon fixation and the calvin cycle occurs (spatial separation) -sugarcane, corn, and grasses
cyclic electron flow
uses only photosystem I and produces ATP, but not NADPH