Biology 2 Lec: test 2 B

Recognize some of the essential plant nutrients.

water
gases
minerals- Micronutrients and trace elements

Review xylem tissue and its primary function

Transport water and dissolved minerals/nutrients upward through the plant

what are the 2 main xylem conducting cell

tracheid’s and vessel element

What are the 2 transport mechanism

Active transport requires energy and a carrier protein
Passive transport-doesn’t require energy

discuss the process of water and mineral absorption

Water and minerals are absorbed by the root hairs
- Root hairs increase surface area
- Minerals enter through carrier protien using active transport/atp water follows

What’s the pathway that water and minerals follow through the root

Root hairs(epidermis)→ cortex→ Endodermis→ vasular tissue

whats the role of the endodermis in transport

-Separates cortex from vascular tissue
- Selectively controls what enters the vascular tissue

What is the Casparian strip

a waxy, selective barrier in the endodermis

What are the 2 different pathway of transportation

Symplast and apoplast

What is symplast pathway

Water/minerals move through the cytoplasm of the cell

What is the apoplast pathway

Water/minerals move through the non-living continuum outside the cytoplasm

what is root pressure

Water accumulating in the roots, creating pressure that forces water up the xylem

What causes root pressure

Active accumulation of ions and roots causes water to enter and accumulate, creating pressure

What is guttation

loss of water in the liquid state from a plant; It is evidence of root pressure

what is xylem sap

watery fluid (water and minerals) moves upward from a plant's roots to its stems and leaves through the Xylem tissue

what is transpiration

Evaporation of water from the leaves of a plant

What is the transpiration-cohesion theory

a column of water is pushed by root pressure and pulled upward by transpiration

What does TACT mean

transpiration, adhesion, cohesion, tension

what does adhesion mean

water stickes to the walls of xylem vessels

what does cohesion mean

water molecules stick to each other through hydrogen bonds

what is tension

The pulling force created when the plant transpires

what is transpirational pull

Pulling of the water column upward as water transpires from the plant leaves

why does xylem transport move only upward

water is being pushed upward due to root pressure and pulled upward by transpiration

what factors affect the rate of transpiration

Structural features- Leaf structure and stomata
environmental factors- humidity, sunlight, wind

how to guard cells open a stomata

1. Guard cells actively accumulate k+

2. water follows

3. turgor pressure increase

4. guard cells swell unevenly

5. stomata open

what is the primary function of phloem

transport organic substances/food in both directions through the plant

what cells make up phloem

Sieve tubes and nucleated companion cells

what is phloem sap

orgainc substances mainly sucrose

what is translocation

The transportation of food(organics) in a plant.

what is the mass flow/pressure flow theory

Food is transported through the phloem from a source to a sink
it is the most widely accepted explanation for phloem transportation

what is a source

a place where sugar is procuded, either through photosynthesis or starch breakdown

what is sink

an organ that consumes or stores sugar

what is phloem loading

Active transport of sugars into phloem cells at the source

what happens to water during phloem loading

Water follows by diffusion

What is phloem unloading

at the sink, sugars are activly transported from the phloem into the sink

In mass flow, where does the phloem sap move

from higher concentration to lower concentration toward the sink

why can phloem transport occur in both directions

• Food moves from source to sink

• Source and sink can be located in different parts of the plant