Upgrade to remove ads
Only $2.99/month

Honors Biology- Photosynthesis

Terms in this set (50)

autotrophs
organisms that use energy from sunlight or from chemical bonds in inorganic substances to make organic compounds (plants)
photosynthesis
process that converst light energy from the sun into chemical energy in the form or organic compounds, primarily carbohydrates
heterotrophs
organisms that get energy from food instead of directly from sunlight or inorganic substances (humans).
biochemical pathway
a series of chemical reactions linked how the product of one reactions is consumed in the next (photosynthesis and cellular respiration)
2 types of photosynthesis
1. Light reaction
2. Calvin Cycle
light reaction
1st stage of photosynthesis that begin with the oabsorption of light in chloroplasts (thylakoid)
chloroplastt
organielles found in the cells of plants and algae that contain chlorophyll
thylakoid
arranded as flattened saccs in the chloroplast where light reactions occur
grana
stack of thylakoids
stroma
stuff surrounding the grana (solution)
pigment
compounds that absorb light
chlorophyll
colored pigments located in the chloroplast
carotenoids
compounds found in the thylakoid membrane that function as accessory pigments;
photosystem
Consists of a pigment complex (chlorophyll a, chlorophyll b and carotenoids) and electron acceptor molecules within the thylakoid membrane.
2 types of photosystems
Photosystem 1
Photosystem 2
primary electron receptor
the acceptor of the electrons lost from chlorophyll a is a molecule in the thylakoid called the primary electron receptor
electron transport chain
a series of molecules that transfer electrons from one molecule to the next
chemiosmosis
a process that occurs in chloroplasts and mitochandria where protons move down their concentration gradient across a membrane and is coupled to the synthesis of ATP
Calvin Cycle
series of enzyme-assisted chemical reactions that produces a three-carbon sugar
carbon fixation
incorporation of CO2 into organic compounds
stomata
small pores that plants can rapidly lose water through during hot seasons
CAM Pathway
water-conserving pathway that was first discovered in plants of the family Crassulaceae such as the jade plant
The Light reactions do what? Calvin Cycle?
1. energy is absorbed from sunlight and converted into chemical energy which is temporarily stored in ATP and NADPH
2. CO2 and the chemical energy stored in ATP and NADPH are used to form organic compounds
Monocot
(one cotolydon)
Cotolydon
embryodic leaf- parlell venition
What are examples of Monocots?
corn, grass, lillies, tulips
Dicot
have reticulate venition; examples are oak tree, magnolia, rosebush,
Photolysis
A reaction taking place in the thylakoid membranes of a chloroplast during light-dependant reactions where two molecules of water are split to form oxygen, hydrogen ions, and electrons
Formula?
CO2 + H2O--energy--> C6H12O6 + O2
How are the electrons energized?
-- the solar power that goes into the chlorophyll excites the electrons, causing them to be move down the electron transport chain, and energy is captured and later used for ATP production (Photosystem II)
--- they are also taken up by NADP to produce NADP+H+ from the photolysis of water
What does Photosystem I do?
When PS I complex absorbs solar energy, the electrons leave the reaction center and are captured by different electron acceptors.
The electron acceptors in PS I pass their electrons to NADP+. Each one accepts two electrons and an H+ to become NADPH+H+(chemiosomosis-where a concentration gradient of H+ is produced to form movement)
What is needed for a light dependent reactioN?
Chlorophyll
ETS
ADP + independent P
NADP
Sun
water
What is produced from a light reaction?
Oxygen as waste
ATP
NADPH +H+
What powers the Calvin cycle that occurs in the stroma?
NADPH+H+ and ATP
Calvin Cycle
A series of reactions that produce carbohydrate before returning to the starting point once more. The series of reactions uses Carbon Dioxide.
3 processes of the Calvin Cycle
Carbon fixation
Carbon dioxide reduction (add H)
Regeneration of RuBP
What is an alternative pathway?
Plants that live in hot, dry regions have a problem because they must open their stomates to let carbon dioxide in and oxygen out but in the process will also let water out.

A low Carbon dioxide level and a high oxygen level will inhibit photosynthesis. This occurs when stomates are left closed.
Photorespiration
A process when a plant fixes oxygen instead of carbon dioxide. The process in non-productive and no glucose is produced.
C-4 Pathways
compound is made into a 4-carbon molecule
- Plants such as corn, sugar cane, and crab grass partially open their stomates so lose less water

They have an enzyme that can fix carbon dioxide into 4 carbon compound in bundle sheath cell of the mesophyll region of the leaf (photosynthesizing region)
Where does Photosynthesis occur?
mesophyll
Difference between C-4 and CAM pathways
C-4 plants have carbon fixation separated structurally from the Calvin Cycle(bundle sheath)

CAM plants separate carbon fixation from the Calvin cycle at different times. Night versus day.
What 4 factors affect Photosynthesis?
Light intensity: rate of photosynthesis increases as light intensity increases. More electron excitement with more light. There is a maximum amount of excitation however.
Carbon dioxide level: Increase carbon dioxide leads to increased photosynthesis until maximum level is reached.
Temperature: increased temperature increases photosynthesis. The rate peaks when the enzymes denature due to too high a temperature. Also the stomates begin to close because of water loss. At high temperatures, photosynthesis will decrease.
High Oxygen levels: This will lead to photorespiration.
CAM Pathway
second adaptation to deal with arid conditions in succulent plants such as cacti, pineapples, and certain other plants(jade, bromeliads)

Plants that open their stomates at night and close them during the day

They store the organic acids they make during the night in their vacuoles until light reactions supply ATP and NADPH for the Calvin cycle
What reduces photorespiration and produces the same amount of glucose with less water?
Carbon dioxide being attached to PEP by PEP carboxylase
What happens to light when it strikes an object?
it can be:

reflected
transmitted
absorbed
Why does a plant appear green?
Chlorophyll A absorbs less blue light but more red light than Chlorophyll B. Because neither abseorb green pigment, plants contain a green pigment called chlorophyll
chlorophyll
pigment that absorbs light in plants
How is an electron exciteD?
light energy forces electrons to a higher energy level, causing them to be excited
ETS
accepts energy from carriers in the matrix and stores it to a form that can be used to phosphorylate ADP. Two energy carriers are known to donate energy to the ETS, namely (NAD) and (FAD).
What does PHotosystem 2 do?
absorbs solar energy, electron gets excited in chlorophyll molecule and leaves molecule
The electron goes to the ETS and is passed from carrier molecule to carrier molecule releasing energy with each transfer.
ATP synthase is able to use the energy to build ATP from ADP and Pi (independent phosphate)
THIS SET IS OFTEN IN FOLDERS WITH...