Chapter 8: Photosynthesis Flashcards
Energy travels to Earth in the form of ______
Light
We perceive different wavelengths of light as _____
colors
Objects absorb every wavelength but _____
One. This one wavelength is being reflected back (which is the color we see).
Ex: red objects reflect red light.
Black/dark colored objects
- absorbs all wavelengths of light equally
- does not reflect any light back
White/light colored objects
reflects all wavelengths of light equally
Apparent color = _______ - _______
Sunlight - wavelengths/colors
Explain the significance of male/female cardinals.
- Feathers of male cardinals are loaded with carotenoid pigments, which absorb some wavelengths of light and reflect others.
Chloroplast
organelle which photosynthesis occurs
Photopigments
Photosynthetic organisms capture energy with sunlight with these photopigments.
- these pigments are light-absorbing molecules
What is the main pigment in plants?
Chlorophyll
Plant pigments include:
- chlorophyll a
- chlorophyll b
- absorb most colors well (reds/blues) except poorly in green (reflects) - carotenoids (which absorb light in other regions of the spectrum reflecting oranges, reds, yellows)
ATP
a compound that cells use to store and release energy
- basic source of energy
What does ATP consist of:
- adenine (base)
- ribose (5-carbon sugar)
- 3 phosphate sugars
ADP
- has 2 phosphate groups
- if a cell has energy available, stores small amounts of energy by adding a phosphate group to ADP
How is energy in ATP released?
by breaking chemical bonds between the 2nd and 3rd phosphate groups.
- ATP releases and stores energy by breaking and re-forming the bonds between its phosphate groups
What is energy in ATP used for?
- Cellular activities
- active transport
- protein synthesis
- muscle contraction
ATP is not good at ______
storing energy for long
True or False: most cells have a large amount of ATP in the cell
FALSE, small amount
All energy on Earth comes from ____.
THE SUN
List 3 photosynthetic organisms.
- plants
- algae (underwater plants)
- cyanobacteria (photosynthesis bacteria)
Write the equation for photosynthesis.
Using sunlight energy, photosynthesis transforms ____ & ______ into ____ and _____.
transforms: carbon dioxide, water
into: oxygen, carbohydrates (glucose)
When is energy transferred to electrons and in which pigments?
in chlorophyll as they absorb sunlight
Chloroplasts are structurally similar to and likely evolved from _____. What is this theory called?
photosynthetic bacteria; endosymbiotic theory (two organelles work together)
Stomata
microscopic pores in which carbon dioxide enters and oxygen exits the leaf (in a LEAF CELL)
Leaf Diagram (memorize!!)
Mesophyll
- the interior tissue of the leaf
- Chloroplasts are found in highest concentrations in cells of mesophyll.
- Mesophyll has 30-40 chloroplasts
Chloroplast Diagram
Thylakoid
Saclike photosynthetic membranes that contain chlorophyll pigments
- light-dependent reactions occur here
Granum
Stack of thylakoids
Stroma
Region outside the thylakoid membrane
- reactions of the Calvin Cycle occur here
- “cytoplasm” of chloroplasts
Chloroplast membrane
Bilayer surrounding the chloroplast
- monitors what enters/exits
Thylakoid membrane
Barrier that surrounds thylakoids; pigments (like chlorophyll) are found here
Chlorophyll
- embedded in the thylakoid membrane
- act like a light “antenna”
- these molecules absorb sunlight energy
What are the 2 parts of photosynthesis?
- light reactions (light dependent reactions)
- Calvin Cycle (light independent reacitons)
Explain the energy collection.
- when chlorophyll absorbs light, light energy is transferred to electrons.
- these high-energy electrons (e-) are needed to start the light-independent reactions.
Oxidation
becomes more positive
Reduction
becomes more negative
Oxidation and Reduction diagram
High-energy electrons
- highly reactive
- require a special “carrier”
NADP+
electron acceptor molecule (only mitten without holding anything)
- accepts high-energy electrons and a hydrogen ion (H+)
NADPH
electron holder molecule (while holding the electrons)
Thylakoids transform light energy into chemical energy of _____.
ATP and NADPH
Why is NADP+/NADPH neccessary?
Plants use electron carriers to transport high-energy electrons from chlorophyll to other molecules.
Explain the effects of NADPH from light dependent reactions and the Calvin Cycle.
The NADPH carries the high-energy electrons from light-dependent reactions (in the thylakoid membrane) to the Calvin Cycle in the stroma of the chloroplast.
What 3 things do plants need? (REV)
- photosynthesis
- light reactions
light (sunlight absorbed by the top of leaves)
H20 (rain absorbed by roots) - Calvin Cycle
CO2 (atmosphere from stomata holes in the bottom of leaf)
Summary of the light reactions
- split H20
- release O2
- reduce NADP+ to NADPH
- generate ATP from ADP by photophosphorylation
Summary of the Calvin Cycle
- the Calvin Cycle forms sugar from CO2, using ATP and NADPH
- the Calvin Cycle begins with carbon fixation (as they incorporate CO2 into organic molecules)
Light (dependent reactions) happen only in ______.
- What is the location of these reactions?
- happen only in SUNLIGHT
- location: thylakoid membrane (which contains chlorophyll)
What are the two parts of light (dependent) reactions?
- Light is absorbed by chlorophyll molecules
- The energy generates molecules of ATP from NADPH.
What are the reactants of light-dependent reactions?
- H20
- light
- NADP+
- ADP
What are the products of light-dependent reactions?
- O2
- NADPH
- ATP
Chemiosmosis
process of joining proton movement (H+ ions) to join ADP and P.
- accomplished by enzymes called ATP synthase/ATPases in the thylakoid membrane.
Photophosphorylation
process of creating ATP using a Proton gradient created by the energy gathered from sunlight.
- (Chemiosis by light energy)
Calvin cycle is located in the _____
stroma
Reactants of the Calvin Cycle
- CO2
- ATP
- NADPH
Products of the Calvin Cycle
- Glucose (C6H12O6)
- ADP
- NADP+
Describe the three phases of the Calvin Cycle
- Carbon fixation (catalyzed by RuBisCo)
- Reduction/Carbohydrate Formation
- Regeneration of the CO2 acceptor (RuBP)
Describe carbon fixation.
- Carbon fixation converts CO2 into different organic forms to be used in the reaction.
- RuBisCo is the enzyme that catalyzes the reaction.
Factors that affect photosynthesis
- Water supply
- Amount of sunlight
- temperature
- carbon dioxide