BIO 121 Lecture Notes - Lecture 15: Photosystem Ii, Atp Synthase, Photosystem I

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6 Mar 2017

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Bio 121 - week 9 - lecture 15. Sunlight is absorbed by a chlorophyll molecule in photosystem ii, and its excited electron jumps from one chlorophyll molecule to another (termed resonance) When the electron reaches the reaction center chlorophylls (called p680 in photosystem ii), it is transferred to the primary electron acceptor and trapped in its high-energy state. An electron has now been lost from a chlorophyll molecule of photosystem ii, which is replaced by the oxidation of water. An electron (and hydrogen( are added back to chlorophyll. The trapped, excited electron slowly returns to its ground state as it falls down an electron transport chain connecting photosystem ii to photosystem i. The potential energy of the excited electron is converted to **kinetic energy as it falls down the chain. This kinetic energy is used to pump hydrogen ions (h+) across the thylakoid membrane, against their concentration gradient.

Related Questions

In a thylakoid membrane, absorbed light energy is passed from one chlorophyll molecule to another until it is:

Select one:

a. dissipated as heat.

b. released as fluorescence

c. passed to a reaction center.

Question 2

Protons in a chloroplast flow through an ATP synthase from the:

Select one:

a. cytoplasm to the intermembrane space.

b. stroma to the intermembrane space.

c. thylakoid lumen to the stroma.

d. stroma to the thylakoid lumen.

e. intermembrane space to the stroma.

Question 3

Which of the following are produced directly as a result of the movement of electrons through the photosynthetic electron transport chain?

Select one:

a. oxygen and carbohydrates

b. carbohydrates and ATP

c. ATP and NADPH

d. water and carbohydrates

Question 4

If a mutation occurs such that photosystem II no longer functions as efficiently as it should, what might be most directly affected?

Select one:

a. The amount of H2O produced.

b. The rate at which NADPH is produced.

c. The rate at which protons are transported into the stroma.

d. The rate of ATP synthesis by ATP synthase in the chloroplast.

Phototrophs need an electron source like H₂S orH₂O. Where do the electrons from these sources go?(Assume the organism is growing autotrophically as well astophototrophically.)

	O₂ and CO₂
	O₂ only
	CO₂ only
	Sulfate or oxygen
	Inorganic various molecules, depending on cellular needs.

Which of the following statements about chlorophyll istrue?

	It is a good electron acceptor in its oxidized form.
	It is a good electron donor in its reduced form when energizedby light.
	It contains magnesium.
	It is a tetrapyrrole.
	All of the above

The unifying feature of all photosynthetic organisms isa(n)

	electron transfer chain.
	electron donating system to generate NADPH.
	ATP-generating system.
	light-gathering system.
	All of the above

Evidence suggests that banded iron formations are due to

	chemical oxidation of reduced iron, Fe²⁺.
	aerobic reduction of insoluble ferric iron, Fe(OH)₃.
	anaerobic oxidation of soluble ferrous iron,Fe²⁺.
	Both a and b
	Both a and c

In addition to their ability to harvest light in the 400 to 500nm range, carotenoids also

	eject electrons from the reaction center.
	function as a tetrapyrrole.
	intercept toxic single-state oxygen.
	transfer electrons to ubiquinone.
	raise electrons to a higher energy state.

Ribosomal RNA and other cell features affirm that living cellsshould be divided into three groups called domains.

	True
	False

Microbes have started to evolve recently.

	True
	False

The ________ was essential for the evolution of oxygenicphotosynthesis.

	evolution of cyanobacteria
	development of photosystem I
	ability to extract electrons from CO₂
	ability to extract electrons from H₂O
	ability to use oxygen as the terminal electron acceptor

What do oxygenic phototrophs use as an electron source?

	Oxygen
	Sulfide
	Water
	Organic compounds
	CO₂

10.

Three domains of organisms have been established basedprimarily on size and other structural features of the cells.

	True
	False

fuchsiasea-lion54

The complete set of reactions carried out by an organism is called:

a. anabolism

b. catabolism

c. metabolism

Value: 2

The breakdown of starch is broken down to glucose is an example of:

a. anabolism

b. catabolism

c. metabolism

Value: 3

For the following statement, determine which description best describes the process: DNA is synthesized from free nucleotides.

a. anabolism

b. catabolism

c. metabolism

Value: 4

Fill in the blank: Catabolic reactions result in the synthesis of molecules of .............via cellular respiration. This is then used to power anabolic reactions.

Value: 5

The energy in organic molecules is released in a series of steps because:

a. it is not possible to release it in a single step.

b. more total energy is released in multiple steps than would be released in a single step

c. less total energy is released in multiple steps than would be released in a single step.

d. more energy can be harvested for cellular use in multiple steps than from a single step.

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photosynthesis

1-The light reaction of photosynthesis does not include

a. chemiosmosis

b. oxygen liberation

c. glucose synthesis

d. electron transport

Value: 2

Photosynthesis takes place in the membranes of small sacs called

a. thylakoids

b. photosystems

c. stroma

d. photons

Value: 3

During what stage of photosynthesis is O2 produced?

a. the light-dependent reactions involving photosystems I and II

b. carbon fixation

c. the Krebs cycle

d. O2 is not produced during photosynthesis

Value: 4

The pigment molecules responsible for photosynthesis are located in the

a. mitochondria

b. cytoplasm of the cell

c. stroma of the chloroplast

d. thylakoid membrane of the chloroplast

Value: 5

During what stage of photosynthesis are ATP and NADPH converted to ADP + Pi and NADP+?

a. the light-dependent reactions

b. the light-independent reactions

c. both of the above

d. none of the above

Value: 6

What energy-rich organic compound is produced as a result of the Calvin cycle?

a. ATP

b. NADPH

c. glucose

d. H2O

Value: 7

During photosynthesis, photons raise electrons to higher energy levels. These excited electrons belong to what compound?

a. water

b. ATP

c. chlorophyll

d. electron transport chain

Value: 8

Which of the following statements accurately describes the relationship between photosynthesis and cellular respiration?

a. photosynthesis occurs only in autotrophs; cellular respiration occurs only in heterotrophs

b. photosynthesis uses solar energy to convert inorganics to energy-rich organics; respiration breaks down energy-rich organics to synthesize ATP

c. photosynthesis involves the oxidation of glucose; respiration involves the reduction of CO2

d. the primary function of photosynthesis is to use solar energy to synthesize ATP; the primary function of cellular respiration is to break down ATP and release energy

BIO 121 Lecture Notes - Lecture 15: Photosystem Ii, Atp Synthase, Photosystem I

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