Exam 3 Material Flashcards
What is the word that describes the movement of water and mineral nutrients from soil to atmosphere in plants?
Transpiration
When do we say water evaporates from leaf cells?
When the relative humidity is less than 100 percent.
What is the term that describes the landscape-level movement of water from the soil to the atmosphere?
Evapotranspiration
Stoma are usually open during the day but are closed at night. Why?
Because photosynthesis needs to occur during the day, so the stomata are closed at night to prevent water loss.
When guard cells are open, it means they are…
When guard cells are closed, it means they are…
Turgid
Flaccid
What is the name for the plant that has adapted to dry environments and typically uses CAM photosynthesis meaning they open their stomata at night?
Xerophytes
What are some of the adaptations and functions of those adaptations that plants in drier environments use?
- Smaller leaves - less surface area less chance of water escaping
- Sunken Stomata - often surrounded by hairs that trap moisture in
- Thick, waxy cuticle - prevent water loss
- Less stomata - same
- CAM photosynthesis - CO2 is stored as an acid stomata open at night
What does the transpiration cohesion theory state?
That water has cohesive properties and adhesive properties (cell wall) due to hydrogen bonds
How does water get from soil to a root epidermal cell?
What changed?
soil :
(solute potential) -0.1 + (pressure potential) 0.0 = (Total water potential) -0.1
epidermal cell:
(solute potential) -0.3 + (pressure potential) 0.1 = (Total water potential) -0.2
The solute potential and pressure potential = water potential is lower in the epidermal cell.
How does water get from a root epidermal cell to a parenchyma cell?
What changed?
epidermal cell:
(solute potential) -0.3 + (pressure potential) 0.1 = (Total water potential) -0.2
parenchyma cell:
(solute potential) -0.4 + (pressure potential) 0.1 = (Total water potential) -0.3
The solute potential is lower in the parenchyma cell = lower water potential.
How does water get from a root parenchyma cell to a
functional xylem cell?
parenchyma cell:
(solute potential) -0.4 + (pressure potential) 0.1 = (Total water potential) -0.3
xylem cell:
(solute potential) -0.01 + (pressure potential) -0.4 = (Total water potential) -0.41
xylem cell has more negative water potential because of the negative pressure in xylem cells.
How does water get from a functional xylem cell to a leaf mesophyll (parenchyma) cell?
xylem cell:
(solute potential) -0.01 + (pressure potential) -0.4 = (Total water potential) -0.41
mesophyll cell:
(solute potential) -0.6 + (pressure potential) 0.1 = (Total water potential) -0.5
mesophyll cell has more negative water potential because of the lower solute potential.
What is the main function of potassium in plant cells?
To regulate stomata closure
What does the increase in K+ ion movement into the vacuoles of guard cells during the day do?
Water moves in via osmosis and turgor pressure increases.
What are the two ways that water can move into a plant cell?
- Root hairs
- Mycorrhizal fungi (extensions)
How did pioneers kill trees?
They peeled the bark back from trees which is called girdling which exposes the xylem preventing the sugar transport that needs to happen to the roots.
What are the 6 mineral nutrients that plants need and why?
- N - amino acids, ATP, DNA
- K - stomata closure regulation
- P - phospholipids, ATP
- Mg - chlorophyll function
- S - amino acids that contain it
- Ca - needed for cells wall
Are C, O, H considered mineral nutrients?
Why do plants need them?
Because they are needed for sugars.
and No
What is the process of using plants to remove contamination of soil water and sediments?
Phytoremediation
Where does the translocation of sugars in plants occur?
In the living phloem sieve tube members
Sugars move from a source like….
To a sink like…
Source - leaves or photosynthetic stems
Sink - roots or phloem
What are the two plants that produce all of the sugar in the world?
- Sugar cane
- Sugar beets
How much of the radiant energy from the sun is utilized in photosynthesis?
40%
What wavelengths of light can plants use?
Visible spectrum - 400 to 700 nm
What are the primary photosynthetic pigments in green plants?
What do they do?
They donate electrons.
Cholorphyll a P680 or P700
What are the accessory pigments a part of?
The light harvesting system
- rest of chlorophyll a
- chlorophyll b
- carotenoids - carotene (orange) and xanthophylls (yellow)
What is the difference between chlorophyll a and b?
The R group in A is CH3 and the R group in B is CHO
Describe the spectrum of absorption for the pigments.
A - works best near 420 and 680
B works best near 480 and 640
Carotenoids - works best near 480 and 500
Why are chlorophyll A and B broken down in the fall but not the carotenoids?
Because the A and B contain Nitrogen and Mg that needs to be reabsorbed by the plant, while the carotenoids just have stuff that is in sugars.
Describe the funneling of light energy to chlorophyll A in the reaction center.
It hits the carotenoids, then the B and then A
Explain the light dependent reactions.
In the light reactions of photosynthesis, water is split by Photosystem II (PSII), releasing oxygen, protons (H⁺), and electrons. The electrons are picked up by plastoquinone and move through a chain of proteins, including the cytochrome b6f complex. As they move, more protons are pumped into the thylakoid lumen, creating a buildup of H⁺ (a pH gradient). This gradient is later used to make ATP. The electrons continue to Photosystem I (PSI), where they get re-energized by light, then pass to ferredoxin and finally to an enzyme called FNR, which uses them to turn NADP⁺ and H⁺ into NADPH. In the end, water provides electrons, and light energy powers the production of both ATP and NADPH, which are needed for the Calvin Cycle to make sugars.
What does rubisco stand for?
Ribulose bisphosphate carboxylase/oxygenase
What is photorespiration?
Rubisco catalyzes the fixation of O2 to RuBP (oxygenase activity)
What is it called when Rubisco fixates CO2 on RuBP?
Carboxylation
In what type of plants is the C4 cycle found?
warm-season prairie grasses, maize, corn, sugarcane
What are two advantages and 1 disadvantage of the C4 cycle?
Advantages
- Increases the CO2 concentration in the bundle sheath cells
- Reduces photorespiration
Disadvantages
1 Uses ATP and is even less efficient when the environment is not hot and dry
What are the common monosaccarides?
- glucose
- Fructose
- Galactose
What are the common disaccharides?
- Sucrose
- Maltose
- Lactose
Why is cellulose considered a fiber?
Can’t break it down - no enzymes
What are the soluble forms of fiber?
- Pectin
- mucilage
What are the insoluble forms of fiber?
- Lignin
- Cellulose
