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60 Cards in this Set

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(autos = self, trophe = nutrition)

Plants are considered to be what?

Autotrophs (Photoautotrophs)

Why are plants photoautotrophs?

They use the energy from light to produce organic molecules with which they build their cells and store energy

Organic molecules

Compounds associated with living organisms with carbon atoms.

Inorganic compounds

Lifeless minerals dug up from the ground

Organic molecules that a plant produces must be (5 things)

1. Storable in plant

2. Capable of being broken back down

3. Reasonable compact

4. Transportable

5. Stable and non-toxic


Photoautotrophs rely to capture that light energy and to produce carbon based organic molecules. The carbon comes from carbon dioxide in the atmosphere.

Photosynthesis is said to "fix" carbon. What does this mean?

To secure or sequester carbon

Removal of carbon dioxide from the atmosphere by planting trees is a method of what?

Carbon sequestration

Carbon credits

Industries that discharge CO2 purchase credits from organizations whose activities (like tree planting) sequester carbon.

5 Characteristics of Light

1. Travels in waves

2. Wavelength differs for each color

3. Within visible wavelengths, red is longest. Outside of visible wavelengths, infrared and radio are even longer

4. Shorter wavelengths (like blue) are not visible

5. Light has a particulate nature (photons)


Provide energy that drives photosynthesis

Photosynthesis equation

water + carbon dioxide -> oxygen, water and simple sugars


12H20 + 6CO2 -> 6O2 + 6H2O + C6H12O6

Glucose/Fructose formula


Two reactions that make up photosythesis

1. Light Reaction (LR)

2. Light Independent Reaction (LIR)

Light Reaction (LR)

Requires light - uses energy to split water which transforms energy from sun into hydrogen ions and electrons

Light Independent Reaction (LIR)

Does not require light - uses energy to grab carbon from CO2 and build simple sugars, second part of photosynthesis, takes place in stroma

LIR (Larry Intelligent Ramstad) is a kid that wants candy bars on a rainy day

Two chlorophyll pigments that absorb light

Chlorophyll a

Chlorophyll b

True or False: High absorbance at a particular wavelength means that pigment is collecting those waves to harvest energy. Low absorbance means that the plant is reflecting that light back to us and we see that color.


High absorbance

Pigment is collecting waves to harvest energy

Low absorbance

Plant is reflecting light back, we see it

Chlorohpyll absorbs blue and red and reflect what color?


Accessory Pigment example



Assist chlorophyll in light capture and energy transfer and also contribute to regulation of excessive excitation of pigment molecules during intense sunlight.

Carotenoids absorb/reflect what colors

Absorb: Green

Reflect: red and yellow

What type of cell in the leaf has the highest concentration of chloroplasts?

Palisade mesophyll cells


Interior of chloroplast


Coin-like objects in the stroma


Stacks of Thylakoids

Thylakoid membrane

Surrounds thylakoids

Antenna Complex

Captures and routes energy from sunlight down to the reaction center (collector)

What pigments are embedded in the thylakoid membranes?

Cartinoid and xanthophyll pigments

Thylakoid membranes are arranged in a structure known as what?

Antenna complex

True or False: When light hits a pigment molecule in the antenna complex, the energy from the light photon demotes (pushes down) an electron in one of the pigment's atoms to a lower orbital.

FALSE: When light hits a pigment molecule in the antenna complex, the energy from the light photon promotes (pushes up) an electron in one of the pigment's atoms to a higher orbital.


Released energy passed to another pigment molecule

True or False: Electrons can stay in higher orbitals forever.


Splitting water

Light reaction (light dependent reaction), first major chemical reaction in photosynthesis. Requires light.

How is water split?

When the reaction center grabs electrons from water, separating water into electrons, oxygen gas and hydrogen ions.

Steps to photosynthesis

1. Light captured by antenna complex

2. Electrons in chlorophyll jump to higher orbital

3. Electron drops back

4. Energy transferred to adjacent atom (resonance)

5. Resonance energy travels down antenna

6. Water is split to oxygen gas, electrons and hydrogen ions

Layers of antenna complex

1. Cartenoids

2. Chlorophyll b

3. Chlorophyll a

(then comes the reaction center)

Light Reaction Portion of the Photosynthesis Equation

12H2O -> 6O2 + 24e- + 24H+

Where do Light Independent Reactions take place?

In the stroma of the chloroplast

In Light Independent Reactions, what compounds carry energy from light that was transformed into hydrogen ions and electrons?


Calvin Cycle

NADPH, ATP and carbon dioxide enter, energy is used to fix carbon into G3P.

Calvin Cycle requires help from what protein? What does that protein even do?

It requires rubisco, which catalyzes the step in the process where carbon is incorporated into an organic molecule.

Rubisco is most abundant in what?


True or False: Rubisco might just be the most abundant protein in the world.


G3P (triose phosphate)

Produced by the carbon fixation process (Calvin Cycle), 3-carbon sugar with phosphorous and oxygen

Why is sucrose important?

It is the sugar that is transported by the phloem throughout the plant to provide energy for other organic molecules (like starch/cellulose)

Light Independent Reaction portion of the Photosynthesis Equation

24H+ + 24e- + 6CO2 -> C6H12O6 + 6H2O


Regions of photosynthesis and sugar production

True or False: Leaves are not the main source within the plant that is where most photosynthesis takes place.

False! It is.


Regions that do not support photosynthesis but still need organic molecules to survive (roots)


Movement of solutes like sucrose from source to sink through the phloem

Sucrose can be broken down into glucose and frucose. What can glucose and frucose then build?

Useful organic compounds (starch and cellulose)


Key storage compound in plant cells


Main constituent of cell wall and structural integrity

1,4 linkage

Bonds between carbon #1 and carbon #4

Big difference between starch and cellulose

Alpha bond between glucose molecules results in starch

Beta bond between glucose molecules produces cellulose

Essentially, bond angle determines whether it will be starch or cellulose

Humans cannot digest cellulose but can digest starch. Why?

Because plants use starch for nutrient storage while they use cellulose for structure (it's the difference between eating potatoes and sawdust)