Exam 2 Flashcards
Photosynthesis and Plants
What are the steps of photosynthesis?
-light transfers energy to photopigments in PSII, which become excited and pass that energy to split a H2O molecule, which donates an electron to the electron acceptor.
-electron acceptor goes down the electron transport chain and creates ATP as a byproduct
-photoreceptors in PSI get excited and pass that electron through to the electron receptor, turning it into NADPH
-that NADPH and ATP goes into the Calvin cycle, which makes them into NADP+ and ADP, as well as sugar
How are the light reactions connected to the Calvin Cycle?
Light reactions are the prerequisite for the Calvin Cycle, and provide the ATP and NADPH that is used. The light cycles also use the ADP and NADP+ that the Calvin Cycle produces.
Where do the light reactions occur? Where does the Calvin Cycle occur?
Light reactions occur in the thylakoids, the calvin cycle occurs in the stroma
How do the photosystems operate?
Photosystems II and I (680 and 700) capture light energy in the photopigments and pass the energy around in the form of an excited state/electron
What is the photosynthesis equation?
6 CO2+12 H2O = C6H12O6+6 O2+6 H2O
What is photophosphorylation?
A phosphate group is added to ADP to make ATP
What is the difference between primary and secondary growth?
Primary growth= growth in length
Secondary growth= growth in width
What is xylem? What is phloem?
Xylem and Phloem are part of the vascular system of a plant that help move materials through the plant body
what are the steps of bulk flow?
-sugar and solutes loaded into sieve tube
-osmosis occurs
-pressure builds in sieve tube, at source end
-Bulk flow occurs in sieve tube down pressure gradient
-Sugars and other materials are unloaded into the sink
What is compression?
Positive water pressure
What is tension?
Negative water pressure
Explain bulk flow
The mass movement of water, sugars and minerals through the Xylem and Phloem
What are the three phases of the Calvin Cycle?
Carbon fixation, catalyzed by Rubisco
Reduction
Regeneration of the CO2 acceptor
What is photorespiration?
In the Calvin cycle, Rubisco adds O2 instead of CO2, and this O2 gets consumed to produce CO2 without synthesizing sugar or ATP
What is the difference in the Calvin Cycle processes in C3, C4, and CAM plants?
C3- “regular” cycle
C4- CO2 is fixed into 4 carbon compounds (malate) by PEP carboxylase. These only have PSI, so they use cyclic production only
CAM- temporarily separate Light and Calvin cycles to fix carbon at night
What happens in leaf mesophyll cells?
Photosynthesis begins here
What kind of growth occurs at the apical meristem?
Primary growth (growth in length)
What kind of growth occurs at the cork cambium?
Secondary growth where epidermis is replaced with periderm, this makes bark
What kind of growth occurs at the vascular cambium?
Growth of the secondary xylem (inwards) and the secondary phloem (p for pbark=outwards)
What is cotransport?
Where two molecules pair together to go through a channel that is specific to one of the molecules.
What is an ion channel?
A channel that moves ions down their concentration gradient, also cotransport
What is solute potential?
Directly proportional to solutes molarity. Has a negative relationship with water potential because water forms hydration shells around solutes and rendering those water molecules irrelevant
What is positive pressure?
Has a positive relationship with water potential, pushes water/puts physical pressure on it
What roles do pressure gradients and hydrogen bonds play in bulk flow?
Pressure gradients are shifted to move sugar and materials to the lower side. Moves things around! Hydrogen bonds are important because that’s how water sticks to itself and other things, and moves itself and the stuff its transporting
What is transpiration and why is it important to plants?
Helps draw water from roots to leaves, cools the plant down, keeps it hydrated with available water
What is Translocation?
the movement of sugars around the plant body, from a sugar source to a sugar sink
What is a sugar source?
A plant organ that synthesizes sugar through photosynthesis
What is a sugar sink?
A plant organ that uses sugar as a resource
How does pressure move phloem sap through the plant body?
Pressure is increased/decreased in order to move phloem sap (usable resources) through the plant body
(Increase in pressure = resource goes away, decrease=resource goes towards)
How do plants move sugars against a concentration gradient?
Proton pump! (Aka, active transport)
What is abscisic acid?
A plant hormone produced in response to dehydration that causes stomata to close
What is the apoplastic pathway?
Through the cell wall
What is the symplastic pathway?
Through the plasmodemata (the cell itself)
What is soil?
A complex ecosystem of living and nonliving organisms that gives rise to basically everything else on land
What is the difference between micronutrients and macronutrients?
The quantity that (plants) require them in. Macro: large quantities, micro: small quantities
What aspect of soil affects the availability of soil nutrients?
The composition of soil, I.e. its makeup of inorganic (mineral) and organic (chemical) compounds, including pH
What is cation exchange?
Where cations are displaced from their attachment to soil particles by other cations (especially those released by roots) these cations enter the soil to be taken in by other roots
What is the rhizosphere?
The layer of soil directly on the roots of a plant which contains a LOT more bacteria (decomposers and nitrogen fixers) than the rest of the soil
What are rhizobacteria?
The bacteria that lives in the rhizosphere that can enter the roots, they can produce hormones, antibiotics, absorb toxins, make nutrients more available to roots
What is the nitrogen cycle?
Nitrifying bacteria oxidize NH3 to Nitrite, to Nitrate, which can then be used by plants for growth. Some of this nitrogen is returned to the soil when the plant decomposes
What are nodules and why are they useful for legumes?
Nodules are little “infections” of Rhyzobium bacteria, which is nitrogen fixing and helps make nitrogen easily available to the plant
What are arbuscular mychorrhizae?
Mychorrhizal bonds where the fungus hyphae penetrate the root and form arbuscules
What are ectomycorrhizae?
Mychorrhizal relationships where the hyphae do not penetrate the root, but instead form a dense sheath over the root
Why are some plants carnivorous?
Because they’re metal asf
(They also live in nitrogen poor areas and need extra nitrogen to live, hence, eat some guy!)
What are the main steps of the nitrogen fixation cycle?
-Nitrogen fixing bacteria fixes N2 from the atmosphere
-bacteria bonds N2 with the ammonia from ammonia fixing bacteria to make ammonia.
-Add H+ from the soil to make ammonium.
-Nitrifying bacteria makes the ammonium into nitrate
Both the remaining ammonium and the nitrate are taken in by the plant roots
