Unit 3: Plants Flashcards
Overall equation for photosynthesis…
Carbon dioxide + water + energy —> glucose + water
What are the two reactions of photosynthesis?
Light dependent reactions:
- using photons of light (sun)
Light independent reactions:
- synthesizing carbohydrates
(Dark)
The reactants in the photosynthesis requisition come from?
Sunlight, atmosphere, cellular respiration
The products of photosynthesis are used by…
Taken up by organism for food and breathing (cellular respiration)
What part of the plant is responsible for photosynthesis?
Leaves (chloroplast)
Parts of a leaf…
Cuticle: waxy outside layer
Upper epidermis: rectangular structures under cuticle
Mesophyll cells: (solar panels) long structures in the middle of the leaf
Leaf vein: (xylem and phloem) vein like structure under the mesophyll cells
Stomata: the hole like structure at the bottom of the leaf
Guard cells: the 2 structures surrounding the stomata
What is the chloroplast?
The organelle in each of the mesophyll cells that carries out photosynthesis
The number of chloroplast per mesophyll cells…
40-200
Structures of the chloroplast…
Outer membrane: very outside Inner membrane Stroma: aqueous space Thylakoid: each round structure (pancake) Granum: a stack of thylakoids
Plants and animals…
Animals use cellular respiration (in the mitochondria)
Plants use cellular respiration (in the mitochondria) and photosynthesis (in the chloroplast)
Relationship between cellular respiration and photosynthesis…
- equations are flipped
- products of one are needed for the reactants of the other
What are pigments?
- located in the thylakoid membrane
- have the unique property of being able to absorb certain wavelengths of light, which reflecting all other wavelengths
What is the wavelength of red light?
About 700 nm
Properties of blue / violet light…
Shortest wavelengths, greater energy
Properties of red light…
Longest wavelengths, least amount of energy
Chorophyll a and b and light…
- reflects green and yellow back to our eyes
- absorbs the shortest (purple / blue) and longest (orange / red)
Carotenoids and light…
- absorbs blue an green
- reflects yellow, red and orange
(Don’t break as quickly in the fall so therefor they are seen once chlorophyll are broken down)
What are photons?
- a package of energy made up of absorbed light energy
- photons of red light contain less energy than photons of blue light
- unit of measurement
What does the stomata let in and out of the cell?
Carbon dioxide in and oxygen out
What is the light dependent reaction?
Occurs in the thylakoid membrane and uses chlorophyll to split water to hydrogen ions and oxygen
What is a photo system?
- a complex of clusters of pigments and proteins
- two in every chloroplast
What does the light dependent reactions use?
- sunlight (photons of sunlight)
- water
- NADP
What does the light dependent reaction makes?
- ATP
- H+ , oxygen (g)
- NADPH, H+
What is the photo system process
of electron transport chain one?
- a photon of light is absorbed by the pigments in the photosystem and gets passed along until it reaches the reaction center in the photosystem (an enzyme), where an electron used that energy to jump to a higher state
- the electron is then picked up by a different molecule, an electron acceptor
- from there, it travels down one of two electron transport chains
- the energy from the electron is used to pump hydrogen ions from the stroma to the thylakoid, creating a concentration gradient, which powers ATP synthase to add inorganic phosphate to ADP, producing ATP (in electron transport chain one)
What is involved in photosystem twos pathway (electron transport chain 1)?
- water molecules are split resulting in hydrogen and electrons to go through the chain and a byproduct of oxygen, the hydrogen ions (protons) are electrons are passed along the first electron transport chain (splitting of water is done in order to replace the lost electrons
What is involved in photosystem ones pathway (electron transport chain two)?
The electrons that are passed along the chain are used to reduce NADP to NADPH, H+ through the addition of two electrons and one hydrogen to NADP
What is photosystem 2?
- discovered second
- reaction centre absorbs light with the wavelength 680 nm (orange red)
- known as P680
What is photosystem 1?
- discovered first
- reaction center absorbs light with the wavelength of 700 nm (red) (longer wavelength)
- known as P700
Overall equation for aerobic respiration…
Glucose + oxygen —> carbon dioxide + water + energy (ATP)
What is the light independent reaction?
Occurs in the stroma of the chloroplast and involves turning carbon dioxide into carbohydrates (glucose) by using energy from ATP and NADPH made during the light dependent reactions. This set of reactions is called the Calvin cycle
What does the light independent reactions use?
- carbon dioxide
- ATP
- NADPH
What does the light independent reaction make?
- ADP
- NADP
- glucose
What is rubisco?
An enzyme that helps stick carbons together, including those of carbon dioxide and RuBP
How many cycles does it take to make one glucose molecule?
6
What are C3 plants?
Plants that make G3P through the Calvin cycle. They are only about 3% efficient when using photosynthesis in nature. Rubisco contributes to this inefficiency because oxygen is a competitive inhibitor to this enzyme, so it will bind with carbon dioxide, preventing rubisco to bind with it and therefore reducing production
Explain why chlorophyll appears green?
We see light that bounces off of objects, reflected light. Chlorophyll absorbs the longest wavelengths (red) and the shortest (blue / violet), but is not good at absorbing green and is therefore reflected by this pigment back to our eyes resulting in is seeing green.
How does the amount of energy in light change as the wavelength increases?
As wavelength increases, the amount of energy decreases. This, violet light, which has the shortest wavelength, has more energy than red light (which has a longer wavelength)
Which colours of light are most effective for photosynthesis? Explain.
Chlorophyll a and b are pigments found in chloroplast that absorb and reflect certain wavelengths of light. These specific pigments absorb light most effectively in the blue and violet range and the orange and red range. Since violet and blue wavelengths have the most energy in the visible light range (due to their shorter wavelengths) they can provide the maximum energy for photosynthesis
What happens to water molecules in the light reaction?
Water molecules are split to give electrons, H+ ions and oxygen gas
What photosynthesis waste product is formed in the light reaction?
Oxygen gas
What products of the light reactions are used up in the Calvin cycle, the dark reaction?
ATP and NADPH
What does the Calvin cycle do to carbon dioxide molecules?
Carbon dioxide molecules are combined with each other (carbon fixation) and with the electrons and hydrogen from NADPH to form glucose
In what form is the glucose formed in photosynthesis stored?
Starch
What is the source of energy in cellular respiration compared to photosynthesis?
Cellular respiration = bond energy in food
Photosynthesis = sunlight (visible wavelength)
Which process is an overall reduction reaction?
Photosynthesis
Which process is an overall oxidation reaction?
Aerobic cellular respiration
What does the enzyme rubisco do?
Carbon fixation in the dark reactions
Is photosynthesis anabolic or catabolic?
Anabolic because is sticks carbons together to form glucose (forming of a larger molecule from monomers)
