plant transport (Part 1)

what do shoots acquire above ground?

Sunlight and Co2, which is used for photosynthesis

what do roots acquire below ground?

Water from the ground and dissolved minerals

what dissolved minerals do roots collect? (and what are they needed for?)

nitrogen, phosphorus, and potassium

• they are needed for many cell functions

what are nutrients important components of?

Nutrients, such as proteins and nucleic acids, are important components of organic compounds

what affects light capture?

• A stems length and branching pattern

• A leaves size, arrangement, and orientation

what occurs as a plant grows taller?

they avoid shading and gain better access to sunlight

what does branching in a plant improve?

It improves sunlight interception, with more branching and more leaves increasing sunlight interception

what benefit do large leaves have? (what is the trade off?)

they have more surface area to capture more sunlight, but the trade off is that it has more potential for water lose

• the bigger the leaf, the more water it loses

what are two different ways leaves can be?

They can be opposite or alternate; arranged along one plane or separate

what are vertical planes?

a plane that includes leaves that can be either opposite and have 2 leaves per node or be alternate and have 1 leaf per node

what does a leaf having 2 or more planes allow for?

For more sunlight interception

what ways can leaves be oriented?

vertically or horizontally

how can some plants track sunlight daily?

With leaf orientation

• Examples of plants that do this: sunflowers, beans, buttercups

what can shoots open/close on a daily basis?

their stomata

what does the stomatal density of a shoot affect?

the uptake of CO2 and leaf size

what is lost through the stomata?

water is lost as the trade-off between water loss and photosynthesis

What percent of water is lost through the stomata?

about 95% of plant water

what control is stomatal density under?

under both genetic and environmental control

what is an example of stomatal density under genetic control?

plants that are adapted to dry environments having fewer stomata

what is an example of stomatal density under environmental control?

low CO2 levels during leaf development increasing

what is the opening/closing of the stomata controlled by?

By guard cells, which are modified epidermal cells

How do guard cells open the stomata?

They are filled with water, causing them to get swollen and open the stomata

How do guard cells close the stomata?

Water is released from the guard cells, causing the stomata to close

what triggers the opening/closing of the stomata?

the accumulation of potassium in vacuoles and water following along with it

what are the three primary cues for the opening/closing of the stomata?

• light at dawn

  • the sun being out causes the stomata to open

• CO2 depletion in air spaces of cell

  • causes the need to let CO2 in for photosynthesis

• Internal circadian clock

what is another cue for the opening/closing of the stomata?

Water deficiency

How does water deficiency in plants affect the stomata?

Plants losing too much water under water stress, such as a drought, can cause the stomata to close in order to conserve water

what do plants sometimes have to chose between?

Between growing taller or branching off more

• while others have a fixed trade off to invest in growing taller or branching off more

what affects water and mineral uptake in roots?

The root length and depth, branching patterns and root hair density

how can roots maximize nutrients uptake?

by responding to local soil conditions

• such as by branching out more into pockets containing high nitrate (aka nutrient rich areas)

• or by extending deeper when the water table is low

what type of roots do monocots typically have? (what does it allow for?)

They typically have fibrous roots that spreads out more horizontally, allowing for access to water that is closer to the surface

what type of roots do eudicots typically have? (what does it allow for?)

they typically have taproots, allowing for access to deeper water resources

what are the two major transport continuums?

Apoplast and symplast

what is apoplast?

Its everything external to a living cell plasma membrane

• includes: cell wall, extracellular spaces, interiors of dead cells, and water conducting cells of xylem

what is symplast?

Its everything internal to a living cell plasma membranes

• includes: the protoplasm (aka the cell membrane and its contents)

what is the transmembrane route?

A route that goes through the apoplast and symplast, crossing from one membrane to another through the protoplasm

what is short distance transport?

A transport that is at the cellular level

• Ex: moving substances into or out of the cell

how is short distance transport controlled?

Mostly by the membrane permeability

what are the two types of short distance transport?

Passive and active

what are the features of passive transport?

• doesnt need energy input from the cell

• Substances move along its concentration gradient or something similar

• Includes diffusion and osmosis

what are the features of active trasnport?

• Does need energy input from the cell in the form of ATP

• Moves substances against its concentration gradient

• includes pumps and transport proteins