Photosynthesis

How many turns does it take of the Calvin cycle for one g3p to exit?

3

Photosynthesis chem equation

6CO2 + 6H2O ------> C6H12O6 + 6O2

Which of the following explains what happens to oxygen produced by the light-dependent reactions? KA

A It is used in the Calvin cycle. B It is released into the atmosphere. C It combines with NADPH to produce water. D It is recycled as a reactant in another light-dependent reaction. CORRECT ANSWER B

Photosynthesis can be divided into two steps: the light-dependent reactions and the Calvin cycle. Which of the following correctly describes the overall process of the Calvin cycle? KA

ATP and NADPH produced by the light reactions are used by the Calvin cycle to make carbohydrates. In the first step of photosynthesis, ATP and NADPH are produced using the light-dependent reactions. The ATP is used to provide energy to the Calvin cycle, where carbon is reduced to make carbohydrates.

Calvin cycle equation

ATP and NADPH to G3P glucose precursor

If there is a bald spot underneath a tree where grass does not grow, what is the best explanation as to why?

Area does not receive enough sunlight

Which compounds are produced in the light-dependent reactions? KA

NADPH and ATP: During the light-dependent reactions, the energy from sunlight is absorbed by chlorophyll and converted into chemical energy, synthesizing ATP and NADPH.

When oxygen is released as a result of photosynthesis what is the by product?

Oxidation of water

Reactants of photosynthesis KA

Oxygen and glucose (G3P)

Which of the following reactions occurs during the Calvin cycle? KA

RuBP regeneration: Some G3P molecules that are produced go on to make glucose, and others must be recycled to regenerate the RuBP acceptor for the Calvin cycle to continue. AND Carbon fixation Carbon dioxide is fixed and reduced in order to form G3P AND Carbon reduction. carbon dioxide is fixed and reduced in order to form G3P G3PG, 3, P.

Photosynthesis can be divided into two steps: the light-dependent reactions and the Calvin cycle. Which of the following is true regarding these two steps? KA

The light-dependent reactions take place in the thylakoid membrane, and the Calvin cycle takes place in the stroma.

NADPH and ATP from light reactions are used to TBR

convert 3pg to g3p

Function of light reactions TBR

convert light energy into usable form of chem energy

Examples of photosynthetic organisms

cyanobacteria, plants, algae. they have the ability to synthesize carbohydrates to feed themselves

What does chemiosmosis do? TBR

depends on -complexes in thylakoid membrabe -electromagnetic gradient -difference h+ concentration between thylakoid space and stroma AND RESULTS IN ATP FORMATION

What are thylakoids?

different membrane system within stroma forming flattened sacks. multiple stacked thylakoids are called granum

What is a stroma?

fluid inside of chloroplasts. energy rich solution where co2 first attached to organic compound then reduced by a carbohydrate.

What contains the most stored energy?

glucose

absorption of chlorophyll is TBR

not same as carotenoids, approximates action spectrum of photosynthesis, explains why chlorophyll pigment is green, shows some colors of light are more absorbed than others

What is ATP triphosphate?

nucleotide sharing chemical energy in bonds between 2 and 3 phosphates.

Light reactions equation

solar energy to chem energy (ATP and NADPH)

What is the stomata?

where carbon dioxide enters the leaf through (small openings)

Products of photosynthesis KA

Carbon dioxide and water

How does ATP provide chemical energy?

In the form of chemical bonds

What do excess of protons (H+) in the thylakoid space do?

Make more ATP (move through ATP synthase channel)

What is the final acceptor of electrons during noncyclic electron pathway is? TBR

NADP+

What do roots of a plant do?

absorb water

What is a carbohydrate?

an organic molecule: most efficient way to store short term energy and can be used to make ATP

Electron transport chain TBR

passage of electrons along series of carrier molecules from higher to lower energy level: energy released used for ATP synthesis

What do thylakoids contain?

photosynthetic pigments such as chlorophyll a and b which absorb solar energy

Photosytstem TBR

photosynthetic unit where solar energy is absorbed and high energy electrons are generated contains antenna complex and electron acceptor

Sequence of Calvin cycle

Carbon fixation (enzyme rubisco captures co2 from atmosphere and attaches it to 5c molecule called RUBP), resulting 6C molecule unstable and splits into 2, 3C molecules, Reduction by NADPH or reduction of GP to G3P where ATP loses phosphate becoming G3P, 6 atp molecules used in process. Regeneration. Some G3P molecules go to make glucose, while others must be recycled to regenerate the RuBP acceptor. Regeneration requires ATP and involves a complex network of reactions.

What does a leaf of a flowering tissue contain?

mesophyll tissue where cells are specialized for photosynthesis

Photosynthesis:

process of converting solar energy into chemical energy of a carbohydrate. (process produces an enormous amount of carbohydrate)

Which of the following are true regarding photosynthesis and cellular respiration? KA

A Photosynthesis and cellular respiration are near-opposite processes. B Photosynthesis produces carbon dioxide, and cellular respiration uses carbon dioxide C Both photosynthesis and cellular respiration occur in the chloroplasts of a cell. D Photosynthesis and cellular respiration are performed by all plants and animals. CORRECT ANSWER: A: Photosynthesis and cellular respiration are almost reciprocal reactions, meaning that the reactants for one are the products for the other. They only differ in the type of energy absorbed or released.

A scientist suspects that a particular plant contains chloroplasts that lack photosystem II (PSII), even though it is able to live.How could the scientist determine if PSII is missing from the plant's chloroplasts? KA

A Test for the fixation of CO2 in the dark B Test for the presence of sugar C Test for the presence of oxygen in light D Test for thylakoid presence in the chloroplasts CORRECT ANSWER: C : Test for the presence of oxygen in light Oxygen is released in PSII, so if PSII is missing from the chloroplasts, no oxygen will be found.

The thylakoid membrane becomes damaged, causing the inside of the thylakoid to mix with the stroma. Which of the following processes is likely to be most affected by this damage? KA

A The reduction of NADP+ to NADPH B Sunlight absorption by the chloroplasts C The movement of electrons from photosystem II (PSII) to photosystem I (PSI) D ATP synthesis CORRECT ANSWER A: The leaking membrane would cause the diffusion of protons into stroma, destroying the proton gradient. Because ATP synthesis relies on the proton gradient, the damage prevents ATP from being produced.

Calvin cycle reactants and products KA

CO2 is a reactant. G3P is a product and reactant, ATP is a reactant, NADPH is a reactant. The Calvin cycle uses CO2 and ATP, along with NADPH made from the light-dependent reactions to produce 3-carbon sugars called G3P.Some of the G3P exits the cycle to make glucose, and the rest gets used up in the Calvin cycle to regenerate RuBP. Thus, G3P is both a reactant and a product of the Calvin cycle.

Appearance of O2 and beginning of aerobic life was made possible by what?

Development of PSII

Light reactions notes

Excitation of electrons occurs when chlorophyll absorbs photon of particular energy in PS II. Oxidation of water replaces lost electrons. ETC passes off electrons giving off energy. Photo excitation reoccurs in PSI resulting in NADP+ becoming NADPH. As electrons pass through ETC overtime moves through protein pumps H+ inside thylakoid space/ membrane from stroma. H+ goes through atp synthase making atp.

oxidation of water equation

H2O becomes 2H+ and 1/2 O2

Light reactions KA

Light absorption in PSII. When light is absorbed by one of the many pigments in photosystem II, energy is passed inward from pigment to pigment until it reaches the reaction center. There, energy is transferred to P680, boosting an electron to a high energy level. The high-energy electron is passed to an acceptor molecule and replaced with an electron from water. This splitting of water releases oxygen which is released into atmosphere. ATP synthesis. The high-energy electron travels down an electron transport chain, losing energy as it goes. Some of the released energy drives pumping of H+ ions from the stroma into the thylakoid interior, building a gradient. H+ ions from the splitting of water also add to the gradient.) As H+ ions flow down their gradient and into the stroma, they pass through ATP synthase, driving ATP production in a process known as chemiosmosis. Light absorption in PSI. The electron arrives at photosystem I and joins the P700 special pair of chlorophylls in the reaction center. When light energy is absorbed by pigments and passed inward to the reaction center, the electron in P700 is boosted to a very high energy level and transferred to an acceptor molecule. The special pair's missing electron is replaced by a new electron from PSII (arriving via the electron transport chain). NADPH formation. The high-energy electron travels down a short second leg of the electron transport chain. At the end of the chain, the electron is passed to NADP+ to make NADPH.

What factors can and can't affect photosynthesis?

Too much sun CAN affect photosynthesis. too little oxygen and glucose DO NOT affect photosynthesis.

Photosynthetic reactions in relation to redox terms

Water is oxidized because it loses electrons when splits. (becomes H+ and o2), NADP+ reduced and becomes NADPH

Chlorophyll a and b absorb what colors of light best?

blue, violet, red. since green light is transmitted and reflected by chlorophyll plant leaves appear green to us.

What do autotrophs and heterotrophs have in common?

both use organic molecules from photosynthesis as building blocks for growth and repair as a source of chemical energy.

Cyclic vs noncyclic phosphorylation

cyclic photophosphorylation exists to provide energy for the calvin cycle and involves only p680 in photosystem ll and its product is ATP. Non-cyclic photophosphorylation is carried out using p700 in photosystem l and p680 in photosystem ll and it produces nadph and atp.

Which of the following equations correctly summarizes the process of photosynthesis? KA

carbon dioxide + water ⟶ glucose + oxygen

Under what conditions might plants use the cyclic electron pathway instead of the noncyclic pathway? TBR

low co2 levels

What is chemiosmosis ?

method of producing atp in light reactions

What are chloroplasts?

organelles that carry on photosynthesis: double membrane surrounds chloroplasts

What is an autotroph/ producer?

organism able to convert solar energy to chemical energy stored in chemical bonds

What is absorption spectrum?

pigments found in chloroplasts capable of absorbing various portions of visible light

What does a photosystem consist of? TBR

pigments, reaction center, electron acceptor