Exam #2 Flashcards
Haiti has a history of overexploited soil..
Spanish colonists planted sugarcane which depleted soil of nutrients
Then, French colonists planted coffee and tobacco, which they cut down forests for. There were fungi living underground in those forests, and when the trees were gone the fungi did not have food and were not Abel os survive. fungi are mutualists with plants
by 2016, only 4% of forests that existed when europeans arrived remain.
Without plant roots to stabilize soil, rain washes soil to sea.
This is sometimes called a deforestation loop.
Soil is not just dirt. What else is in soil?
Bacteria(living), fungi(living), mineral particle(I.e. sand), worms(living), clay particle, water, air, dead organic matter.
Where does a tree get 95% of its mass?
CO2 in the air
Plants require
water, carbon dioxide, nitrogen(makes plants grow strong and healthy), phosphorus(hops plants with photosynthesis, stores and moves energy around the plant using ATP), potassium(helps plant control and use water efficiently)
As the plant takes up water, it also takes up ions dissolved in the soil. CO2 is from the air
What are some examples of macromolecules the plant needs nitrogen and phosphorus to build?
nucleic acids(nitrogenous bases have nitrogen in them); proteins(have an amino end which has nitrogen in it)
phosphate(nucleic acids) have phosphorous in them
How can you tell what mineral a plant is missing. What are these signs?
Not a super important question
- Nitrogen: upper leaves are light green where lower leaves are yellow. Bottom or older places are yellow and shrivelled
Potassium: allowing at th etups and edges, usually in younger leaves. De
FINISH
Soil organisms contribute to plant nutrition. What are two examples of these types of organisms?
Fungi and bacteria
Fungal plant partners(all plants)
Mycorrhizal fungi
Root hairs better Abel to absorb water and minerals(especially phosphorous)
expand root surface area up to 1000 for
Bacterial plant partners(some plants)
- Nitrogen-fixing bacteria(convert nitrogen into a form the plant can use)
convert nitrogen gas from air into ammonia
legumes(like beans) roots are where you usually see bacteria growth
Legumes enrich the soil for other plants because of their bacterial plant partners. Why is this?
The bacteria will leave a lot of valuable nitrogen in the soil that will help other plants
The best way to promote plant growth is to grow legumes in a certain area, harvest them, and then plant other crops in the same soil that the legumes were grown in. Rotating crops works a lot better than just growing the same thing in the same spot over and over
Roots send signals to mutualist partners for colonization.
A signal is sent by the plant, received by the mutualist, and then the mutualist goes towards the plant.
the mutualist can also send messages to the plant.
In exchange for providing water and phosphorus to the plant, what do the mycorrhizal fungi get in return?
products of photosynthesis
carnivorous plants obtain some nutrients(especially nitrogen) by
digesting arthropods(i.e being a predator)
Two parts to the plants vascular system(and what they transport) are
water and solutes –> xylem
sugars–> phloem
do plant cells have cell walls?
yes
What does a plant cell wall contain?
cellulose and chitin
A major component of a plant cell is the
Large central vacuole that is filled with water
Plant cell walls contain cellulose. What molecule strengthens the cell walls of other organisms(bacteria, fungi, diatoms)?
Bacteria: peptidoglycan
Fungi: chitin
Diatoms: silicon
Are cell walls a homologous trait or a homoplastic trait of plants, bacteria, fungi, and diatoms?
Homologous trait: two groups have that same trait because they had a common ancestor that had that trait
Homoplastic trait: two organisms have the same trait ebcuaset he same trait appeared twice in evolution
- because of convergent evolution
cell walls are an example of convergent evolution
Plants have a large central vacuole. What role does it play in the plant cell?
- Provides structure for the plant by pushing against the cell wall and giving the cell structure
- Stores water and nutrients(and sometimes waste)
What is the name of the pressure exerted on the cell wall by the vacuole?
turgor pressure: the pressure exerted by the cell’s fluid content against the cell wall
If a plant is wilting/dried out, it will be droopy and in a placid state because it has low turgor pressure
when a plant has high turgor pressure, it will be in a turgid state
Water(and dissolved moves from the roots up to the leaves through the
xylem
How is water transported through the xylem?
combination of transpiration, tension, and cohesion
- Transpiration of water molecules from the leaves by evaporation.
- Tension in the xylem sap resting from transpiration from the leaves.
- Cohesion of water molecules in the xylem sap, from the leaves to the roots
Evaporation in the leaf causes water to leave the xylem and replenish thirsty mesophyll cells
None of this requires energy on the plants part. The water moves passively through the stomata in the leaf. it’s moving excuse of a difference in pressure. Lots of water in the xylem, and not as much in the mesophyll and outside the leaves. So it will move from high to low concentrations. There are no transport protein that move water molecules towards the leaves. Water molecules. Water molecules in xylem are connected to each other through hydrogen bonding
Plants conserve water by regulating when stomata are open. What are stomata?
Stomata, or pores on the undersides of leaves, regulate gas exchange- they can open or close but the action of the guard cells
Which gases are exchanged by stomata?
Water vapor, CO2, O2
How is transpiration regulated but the stomata?
rewatch this part of the lecture(JOVE video and diagram)
When blue light shines on the cell, then the cell uses ATP(ACTIVE TRANSPORT) to pump protons out of the cell. The membrane now has a difference in charge(more negative charge inside the cell relative to the outside of the cell). This causes two things to happen at the same time. Firstly, potassium moves into the cell due to the charge difference(PASSIVE TRANSPORT). Secondly, some of the protons moved out of the cell is used to pump chloride ions into the cell(ACTIVE TRANSPORT). The water flows into the cell because all the minerals that moved into the cell changed the concentration of water(PASSIVE TRANSPORT)
What causes stomata to open?
Sunlight and ions rushing into guar cells, followed passively by water
How are water and minerals transported in the xylem?
The plant uses energy in the form ATP to pump water out through he stomata in the lead.
Transport proteins in xylem attach to each water molecules and move it up towards the leaves.
Evaporation in the leaf causes water to leave the xylem and replenish thirsty mesophyll cells.
Water molecules in xylem are connected to each other through.
REVIEW DIAGRAM ON SLIDE(2 SLIDES)
Does the opening of stomata require energy? Does the transpiration-cohesion-tension movement of water and minearals through the xylem require energy?
Yes and No
What moves through the phloem
water and sugar/food/photosyntehstic products
Why is there a two way flow in the phloem?
Phloem transports sugar from
sources to sinks
Source: organ that produces or stores sugars(ex. leaf)
sink: consumes sugars for growth and storage(ex. roots, the tip of the shoot where new leaves and flowers come from,
