Light Reactions Flashcards
What does Redox mean?
Reduction-Oxidation
What is oxidation-reduction (redox) reactions?
The redox reactions involve electrons passing from one molecule to another
Oxidation is the _____________ of electrons while Reduction is the ______________ of electrons
loss; gain
What are the tasks of ATP?
- Chemical work: ATP is used for building macromolecules
- Transport work: ATP is used for transporting ions membranes
- Mechanical work: ATP is used for mechanical processes such as muscle contraction, cilia movement
How do plants harness light energy to manufacture food?
Photosynthesis
How do living organisms harness energy from food?
Cellular Respiration
Formula of Photosynthesis
6CO2 + 6H20 -> C6H12O6 + 6O2
Formula of Cellular Respiration
C6H12O6 + 6O2 -> 6CO2 + 6H20
Plants are ____________. This term means “self-feeders” in Greek.
Autotrophs
Autotrophs make their own food and thus sustain themselves without?
Eating other organisms or even organic molecules
Plants are referred to as the ____________ of the biosphere
Producers
Plants are not only the producers certain ________, _______, and ________ also make food molecules from inorganic materials
Bacteria, Archaea, Protists
All organisms that use light energy to make food molecules are called?
Photosynthetic Autotrophs
______, _____, and _____________________ all use light energy to drive the synthesis of organic molecules from carbon dioxide and water
Plants; Algae; Photosynthetic Bacteria
All green parts of a plant have ____________ and can carryout photosynthesis
Chloroplasts
In most plants, what part of the plant has the most chloroplasts?
The leaves
The green color in plants comes from where?
Chlorophyll pigments in chloroplasts
Chloroplasts are concentrated in the cells of the _________.
Mesophyll
What is the definition of Mesophyll?
Mesophyll is defined as the green tissue in the interior of the leaf
Carbon dioxide enters the leaf and the oxygen exits by way of tiny pores called?
The Stomata
The chloroplasts’s inner membrane is filled with?
Stroma
What is Stroma?
- It is a thick fluid
- It is where sugars are made from carbon dioxide and water
What is Thylakoid?
- It is suspended in the air
- It is a system of dislike membranous sacks
Grana are __________ that are concentrated in stacks
Thylakoids
The thylakoid membranes house much of the machinery that converts _____ energy to ________ energy
Light; Chemical
Sunlight is a type of energy called _________ or _________________________
Radiation; Electromagnetic Energy
The distance between the crests of two adjacent waves is called?
Wavelength
Light-absorbing molecules called pigments in the membranes of a granum absorb what color wavelengths?
Mainly Blue Violet and Red Orange
Chlorophyll A absorbs mainly?
Violet and Red Orange light
Does Chlorophyll A participate directly in the light reactions?
Yes
Chlorophyll B absorbs mainly?
Blue and Orange light
Does Chlorophyll B participate directly in the light reactions?
No
Chloroplasts contains a family of yellow-orange pigments called ___________, which absorbs mainly blue-green light.
Carotenoids
Carotenoids has a protective function that does what?
It absorbs and dissipates excessive light energy that would otherwise damage the chlorophyll
What color of light is least effective in driving photosynthesis?
Green
A ______ is a fixed quantity of light energy, and the shorter the wavelength, the greater the energy
Photon
What happens when a pigment molecule absorbs a photon?
One of the pigment’s electrons gains energy and the electron has been raised from a ground state to an excited state.
When illuminated, the chlorophyll emits heat and photons of light that produce a reddish after glow as electrons fall from excited state to the ground state. What is this afterglow called?
Fluorescence
What are the two types of Photosystem?
Photosystem I and Photosystem II
What is the reaction center in Photosystem I?
P700
What is the reaction-center of Photosystem II?
P680
Light reactions use ________ in order to initiate electron transfer
Sunlight
Light reactions are used to?
Form ATP through phosphorylation
Key events of the light reactions of photosynthesis are?
- Absorption of Light Energy
- Excitation of Electrons by Light Energy
- Formation of ATP and NADPH using energy made available by the cascade of energized electrons down the electron transport chains
What is the waste product of the light reactions?
O2
What are the products of the light reactions?
NADPH, ATP, O2
The synthesis of ATP is driven by what process?
Chemiosmosis
There is a flow of electrons from ____________ molecules to _____________, which is reduced to __________, the source of
electrons for sugar synthesis in the _________________ cycle.
Water, NADP+, NADPH, Calvin
The chemiosmosis production of ATP is referred to as?
Phosphorylation
Protons “want” to diffuse back
down the gradient into the stroma, and their only route of passage is through the enzyme?
ATP Synthase
Why does Cyclic Electron Flow exist?
- When CO2 concentration is less in the atmosphere
- When need for ATP outweighs the need for NADPH
