Unit 5 Lesson 2: Photosynthesis Flashcards
Your body needs energy to function, but have you ever thought about where that energy comes from? It all begins with the
sun
How does the sun influence eevry human being
Plants convert energy from the sun into food and then the plants are eaten by animals. So, whether you are an herbivore, an omnivore, or a carnivore, the energy that powers your body originally came from the sun.
What is photosynthesis
rocess that transforms light energy into stored chemical energy
What does photosytnehis mean
photosynthesis is the process that transforms light energy into stored chemical energy. The term photosynthesis means taking light (photo) and creating something (synthesis) with it.
Give examlples of things that use phototsyntesis
. Plants, algae and some bacteria use light energy to make sugars. These sugars are where the chemical energy is stored until it can be used.
How to demonstrate photosynthesis
carbon dioxide + water + light energy  yields  sugars + oxygen
How to demonstrate photosynthesis using a chemical equation
6CO2 + 6H2O + light → C6H12O6 + 6O2
What are the reactants and products of photosynthis
Notice that the main input, or reactants, are light, water and carbon dioxide. The outputs, or products, are oxygen and sugars.
Leaves have several layers of cells and little pores called
stomata
Stomata have two main funcations what are they
transpiration and gas exchange.
How does Stomata use gas exchange
they facilitate gas exchange by allowing carbon dioxide to go into a leaf and oxygen molecules to exit the leaf.
How does Stomata use transpiration
They regulate water movement through transpiration.
Stomata have specialized cells called ? along their border.
guard cells
What do guard cells control
Guard cells control whether the stomata opens or closes, as well as the size of the opening. They respond to environmental triggers to determine if the stomata should be open or closed.
How can water vapor leave a plant
Water vapor can also exit the plant through the open stomata.
When do the guard cells open
If the concentration of carbon dioxide in the leaf is low, the guard cells open the stomata, letting in carbon dioxide. Usually, this happens during the daytime, when the plant is photosynthesizing.
How does the oxygen that is produced during phototsytnhies leave
The oxygen that is produced during photosynthesis exits the leaf through the open stomata.
What are the reasons why stomata stays closed a night
At night, when photosynthesis is not occurring, the stomata closes to prevent water loss.
Why does Stomata change in shape
Stomata change in shape and size often, constantly trying to maximize photosynthesis and minimize water loss in a plant.
How has the stomata in plants in hot areas adapt
Some plants, like those in hot, arid regions, have adapted to open their stomata during the night. They take in less carbon dioxide and photosynthesize at a lower level than regular plants, but they conserve water this way.
Where does photosynthesis take place (be exact)
Photosynthesis takes place inside the chloroplasts of plant cells.
What does chloroplast mean
organelle in a green plant cell that conducts photosynthesis
Inside the chloroplast are small, flat, sack-like structures called
thylakoids
What does thylakoid mean
sack-like structure surrounded by a membrane inside chloroplasts where the light-dependent reactions of photosynthesis occur
Thylakoids are stacked into towers called
grana (granum are multiple grana)
Thylakoids are stacked into towers called grana (granum are multiple grana) and are surrounded by a liquid called ?.
Stroma
What is stroma
fluid-filled space that surrounds the stacks of thylakoids inside the chloroplast, within which the light-independent reactions of photosynthesis occur
Thylakoids contain a green pigment called ?, which captures energy from the sun.
chlorophyll
What is chlorophyll
green pigment that captures the energy from the sun
Photosynthesis occurs in two stages:
a light-dependent stage and a a light-independent stage
Where does the light-dependent stage of phototsytnhis occur
a light-dependent stage that occurs in the thylakoid membrane
Where does the light-independent stage of phototsytnhis occur
a light-independent stage that occurs in the stroma.
light-dependent reactions
a series of reactions that take the light energy that is captured by the chlorophyll and convert it into chemical energy in the form of NADPH and ATP; consists of photosystem II, the electron transport chain, photosystem I and hydrogen ion movement and formation of ATP
What do Light-dependent reactions require
light-dependent reactions are processes that require light.
Where do light-dependent reactions take place
Light-dependent reactions take place in the thylakoid membrane.
What is the overall purpose of light-dependent reactions
These reactions take light energy that is captured by chlorophyll and convert it into chemical energy in the form of NADPH and ATP.
What is photosystem II
protein complex where light is absorbed, water is split, hydrogen ions are created, and oxygen is released during photosynthesis
What is the first stage of Photosystem II
In this protein complex, light energy raises some of the electrons in the chlorophyll to a higher energy level.
In the first stage of photosystem II In this protein complex, light energy raises some of the electrons in the chlorophyll to a higher energy level. What are the reacnts and products
Reactants:Sunlight excites electrons ( e−
).
Products:Excited electrons
What is the second stage of photosytem II
The high energy electrons are then passed on to the electron transport chain, a series of molecules that absorb and release the electrons.
What is the electron transport chain
system by which high-energy electrons are moved to photosystem I and hydrogen ions are pumped into the inside of the thylakoid during photosynthesis
In the second stage of photosystem II The high energy electrons are then passed on to the electron transport chain, a series of molecules that absorb and release the electrons. What are the reacnts and products
Reactants:Electrons move along electron transport chain.
Products:Electrons moving along electron transport chain.
What is the 3rd step of Photosystem II
Water molecules are split into their components: two electrons, two hydrogen ions, and one oxygen ion.
What are the reactants and prodcuts of phototsystem II in step 3 Water molecules are split into their components: two electrons, two hydrogen ions, and one oxygen ion.
Reactants: 2H2O
Products:2H2+O2
What is Photosystem I
protein complex where the transfer of hydrogen ions to NADP+ to make NADPH occurs during photosynthesis
What is the first step of photosystem I
As high energy electrons are moved down the electron transport chain to photosystem I, more and more hydrogen ions are pumped into the inside of the thylakoid.
What are the reacnts and prodcuts of Photosystem I step one As high energy electrons are moved down the electron transport chain to photosystem I, more and more hydrogen ions are pumped into the inside of the thylakoid.
Reactants:Electrons moving down electron transport chain.
Products:Hydrogen ions inside thylakoid.
What is the second step of Photosystem I
The electrons lose a little bit of their energy moving the hydrogen ions into the thylakoid.
Waht are the reactants and products of the second step of Photosystem I
The electrons lose a little bit of their energy moving the hydrogen ions into the thylakoid.
Reactants: Electron energy
Products:Movement of H+ into thylakoid.
Wha tis the 3rd step of Photosystem
Pigments in photosystem I take light energy and recharge the electrons before sending them to the outer edge of the thylakoid membrane.
What are the reactns and prodcuts of Photosystem I step 3 Pigments in photosystem I take light energy and recharge the electrons before sending them to the outer edge of the thylakoid membrane.
Reactants:Light energy + pigments
Products:Electrons sent to outer edge of thylakoid membrane.
What is the 4th step of Photosystem I
The electrons and the hydrogen ions are picked up by NADP+ in the stroma and converted into NADPH.
What are the reacnts and products of the 4th step of Photosystem I
Reactants:2e−+H++NADP+
Products:NADPH
What is the 5th stage of Photosystem I
All the remaining hydrogen ions have been pumped into the thylakoid, making the inside very positively charged, especially compared to the stroma. This charge gradient is critical to making ATP. The positive hydrogen ions inside the thylakoid want to cross the membrane to even out the charge gradient.
What are the reactns and products of the 5th stpe of Photosystem I All the remaining hydrogen ions have been pumped into the thylakoid, making the inside very positively charged, especially compared to the stroma. This charge gradient is critical to making ATP. The positive hydrogen ions inside the thylakoid want to cross the membrane to even out the charge gradient.
Reactnats: H+ pumped into thylakoid
Products:Positively charged thylakoid.
What is the 6th step of Photosystem I
However, the hydrogen ions cannot cross the membrane and, instead, must pass through a protein called ATP synthase to exit the thylakoid. ATP synthase rotates every time a hydrogen ion passes through it, similar to a revolving door. As it rotates, it adds a phosphate group to ADP, adenosine di-phosphate to make ATP, adenosine tri-phosphate.
What are the reactions and prodcuts of step 6 in Photosystem I
Reactnas: ADP
Products: ATP
At the end of the light-dependent reactions, light energy and water has been converted to..
oxygen, ATP, and NADPH.
Where does the second stage of phottosyntheissi take place
The second stage of photosynthesis takes place in the stroma of the chloroplast.
light-independent reactions (calvin cycle)
a series of reactions that do not require the presence of light energy and that take the carbon from carbon dioxide and convert it to carbohydrates (glucose), amino acids, and other compounds
When do light-independent reactions (calvin cycle) take place
do not require sunlight and can take place at night.
What happenes during Light indpendent (Calvin cycle) reactions
During the light-independent reactions the plant takes the ATP and NADPH that it made during the light-dependent reaction and uses them to make stable carbohydrates that store the energy for a long time.
How many stages does the Calvin cycle have
3
What happens during the first stage of the Calvin stage
In the first stage, leaves absorb CO2
through tiny holes called stroma. Before the CO2 can be used, it is attached to a sugar called RuBP. After the attachment, it changes to a new compound labeled 3 PGA.
What happens during the second stage of the Calvin stage
In the second stage, ATP and NADPH are used to convert the 3 PGA molecules into glyceraldehyde 3 phosphate, G3P.
What happens during the third stage of the Calvin stage
In the third stage, G3P molecules make glucose and other compounds are recycled to regenerate the RuBP. The regeneration requires ATP and involves a complex network of reactions.
The Calvin cycle has 3 stages.
- Carbon Fixation
- Reduction
- Regeneration
What Stroma
fluid-filled space that surrounds the stacks of thylakoids inside the chloroplast, within which the light-independent reactions of photosynthesis occur
What happens during Carbon Fixation
CO2 enters the leaf via stoma (stomata means multiple stoma), holes in the leaf. The CO2 diffuses into the stroma. The CO2 attaches to the sugar RuBP and changes into the new compound 3-PGA.
What happens during the reduction phase
ATP and NADPH are used to convert the 3-PGA molecules into glyceraldehyde 3 phosphate, G3P.
What happens during the regeneration phase
Some G3P molecules make glucose. Other compounds are recycled to regenerate the RuBP and start the cycle again.
Compare the light-dependent and light-independent reactions in photosynthesis.
Light-dependent reactions take the energy from light and water and convert them into free oxygen that diffuses out of the chloroplast and into the atmosphere, and chemical energy in the form of ATP and NADPH. Light-independent reactions take the carbon dioxide ( CO2
), ATP and NADPH and use them to create a stable sugar ( C6H12O6
), which stores all the energy in its chemical bonds.
The light-independent reactions __________
can only happen in the presence of light
use ATP, NADPH, and CO2 to make carbohydrates
make compounds that store energy in chemical bonds for a long time
take place in the cytoplasm of cells
use ATP, NADPH and CO2 to make carbohydrates
c. make compounds that store energy in chemical bonds for a long time
Explain what ATP synthase does during photosynthesis.
ATP synthase is a protein that spans the thylakoid membrane. It allows hydrogen ions to pass out of the thylakoid and into the stroma. Every time this happens, ATP synthase rotates. Each rotation adds a phosphate group to ADP creating ATP.
Where do the carbons in the carbohydrate that are made during photosynthesis come from?
The carbons come from the carbon dioxide in the air.
What does C6H12O6
represent in the chemical equation for photosynthesis?
Answer
It represents a sugar (carbohydrate, glucose).
What is the chemical equation for photosynthesis?
6CO2+6H2O+light →C6H12O6+6O2
What is light
Light is a form of electromagnetic energy that takes on many different wavelengths, measured in nanometers (nm).
Describe the suns wavelengths
Sunlight is a mix of wavelengths that human eyes can detect called the visible spectrum.
how do people view different colors
Humans see the different wavelengths in the visible spectrum as different colors
Wavelengths of red
620-780 nm
Wavelengths of orange
orange at 585-620 nm,
Wavelengths of yellow
yellow at 570-585 nm
Wavelengths of green
green at 490-570 nm
Wavelengths of blue
blue at 440-490 nm
Wavelengths of indigo
indigo at 420-440 nm
Wavelengths of violet
violet at 400-420 nm
Objects absorb some of these wavelengths and reflect others.
Give an example using the color green
An object that appears green, for example, reflects wavelengths within the green region of the spectrum and absorbs the other wavelengths within the spectrum.
White objects vs black objects
White objects reflect all wavelengths within the visible spectrum and black objects absorb all the wavelengths.
What is chlorophyll
Chlorophyll is the green pigment in the chloroplasts of plant cells that captures light energy.
What is the light energy cpatured by Chlorophyll used for
The light energy is used to change carbon dioxide and water into sugar, which stores the energy in its chemical bonds, and oxygen.
Chlorophyll abosrbs light energy at what part of the specturem
Chlorophyll absorbs light energy at the red and violet ends of the spectrum.
What other pigments do plants have
Plants also contain red, yellow, and orange pigments (like carotene and lycopene) that absorb light in other wavelengths along the visible spectrum.
What is Carotene good for
Carotene has strong cancer-fighting properties.
How do animals take in Carotene
Animals cannot make carotene themselves; they have to get it through their diet.
Where is Carotene found
Carotene is found in fruits and vegetables that are red, yellow, and orange.
What is carotene good for
Carotene acts as an antioxidant in the human body. Antioxidants prevent or slow damage to cells caused by free radicals, which are waste produced by cells in response to environmental and other stressors, such as inflammation, pollution, UV exposure, and cigarette smoke.
Why arent leaves green all the time
In the fall, because of less daylight and cooler temperatures, leaves stop the photosynthesis process. Chlorophyll breaks down and the green color disappears. Yellow and red colors appear due to the different pigments in the leaves’ tissues.
Why is it useful for a plant to have more than one type of pigment?
Each pigment absorbs light at different rates and wavelengths. Having more pigments increases the range of light wavelengths that a plant can absorb allowing it to conduct photosynthesis under a larger array of light conditions.
