Module 3 chapter 9 Flashcards
What are the 2 types of plants
- Monocotyledons
- Dicotyledons
What is an example of a Monocotyledon
Corn
What is an example of a Dicotyledon
Pea peanut
What makes a plant a monocotyledon
If their petals are a multiple of 3
Makes seeds that contain 1 cotyledon
What makes a plant a Dicotyledon
2 cotyledons
What is the waters role in plants
- Photosynthesis
- Transports mineral ions
- Keeps plant cool when H2O is lost by evaporation
- Turgidity
- solvent
- reactions
What is the equation of respiration
Glucose+oxygen–>water+energy+carbon dioxide
What are plants who have a specialized transport systems known as
Vascular plants
What does the Xylem transport
Water + dissolved substances
What does the Phloem transport
Sugars + hormones + water
What is the amino acid structure
H
¦
NH2 -- C = COOH
¦
R groupWhat minerals do plants exchange and transport
- Water
- Inorganic ions
- Organic minerals
What are the 2 transport systems in plants
- Transpiration system
- Translocation system
What type of Transport system is passive
Transpiration
What type of Transport system is Active
Translocation
Which type of transport system doesn’t require energy
Transpiration system
Where is H2O taken up by the plant
Root hair cell
What has a higher Water potential the root hair cell or the soil
Soil
What is the casparian strip’s function
Prevents H2O from moving along the cell wall and forces it into the symplast
What is the symplast
the inner part of the cell
Is it quicker for H2O to diffuse through the cell wall or the symplast
Cell wall
Why is it quicker for H2O to diffuse through the cell wall
In the symplast it has organelles which slow down the movement of H2O as they require substances
Which factors causes an increase in transpiration rate
- low humidity
- windy day
- light intensity
- temperature
How does the plant cool its self down
By transpiration
What are the 6 different areas of a root
- Epidermis
- Cortex
- Endodermis
- casparian strip
- pericycle
- Xylem
What does the plasmodesmata allow
H2O to travel through the symplast
What is root pressure
Large influx of H2O through the roots
What do the pits in the lining of the Xylem vessel allow H2O to do
If there’s a bend in the plant it gives it an alternate root
What are the 3 reasons plants need transport system
- metabolic demands
- Size
- SA:V ratio
What do the cells of the green parts make their own of
- Glucose
- oxygen
How do plants make glucose and oxygen
Photosynthesis
How do the roots and internal parts of the plant get mineral ions and nutrients
They need O2 and glucose transported to them
How do the roots and internal parts remove waste products
use transportation system
Where do mineral ions need to be transported to
All cells
Why do mineral ions need to be transported to cells
To make proteins
Why does a plant need to make proteins
For enzymes and structure of the cell
Why do large plants need a transport system
To move substances up and down the plant
What area of the plant is adapted to have a large surface area to volume ratio
The leaves
Why do leaves need a large SA:V ratio
For gaseous exchange
What 3 areas of the plant have a low SA:V ratio
- Stem
- trunks
- roots
What can’t the Stem, trunks and roots rely on
Diffusion to supply their cells
What are the 2 main functions of the Xylem
- transport of water and mineral ions
- support
What is the direction flow of the xylem
From the roots to the shoots and leaves
What is the xylem made from
columns of cells fusing together end to end
What is the 2nd wall of the xylem lined with
Lignified secondary walls
What does the secondary wall of the xylem do
Provide extra mechanical strength
What does the secondary wall of the xylem not do
Transport water
What are the different ways lignin can be found in the xylem
rings
spirals
solid tubes
If the lignin is found in solid tubes in the xylem what feature will it have to allow water to move in and out
small undignified areas called border pits
What does the phloem do
transports the plants “food”
What is a plants “food” in the form of
Organic solutes
Where are the Organic solutes made
In the plants leaves
How are the Organic solutes made
Photosynthesis
What does the phloem supply the cells with
sugars and amino acids
What do the plants cells need sugars and amino acids for
Cellular respiration
synthesis of all other useful molecules
What direction can the flow of the phloem move in
Up and down the plant
What are the main transporting vessels of the phloem
Sieve tube elements
What are sieve tubes made out of
many cells joined end to end
What do sieve tubes form
Long hollow structures
Are the phloem tubes lignified
No
What happens in areas between the cells of the phloem
walls form sieve plates
What do sieve plates allow
The phloem contents flow through
Do mature phloem cells have a nucleus
NO
What’s linked to sieve tube elements
Companion cells
What link the companion cells and sieve tube
Plasmodesmata
What connects the symplast pathway
the plasmodesmata
How does water move through the symplast
By osmosis
How does the root hair cell having a high water potential than the next cell along help
water can diffuse in from the soil making the cytoplasm more dilute
What happens when water leaves the root hair cell by osmosis
Water potential of cytoplasm falls again
How does the water potential of the cytoplasm falling help maintain
it maintains a steep water potential gradient
Where does water move through in the apoplast pathway
Cell walls and intercellular spaces
What is the casparian strip
A band of waxy material
Where is the casparian strip found
around each of the endodermal cells forming a waterproof layer
What does the casparian strip do
Forces water from the 1 pathway into the symplast pathway
What are the 5 factors affecting transpiration
- Light intensity
- relative humidity
- Temperature
- Air movement
- Soil-water availability
How does light intensity affect transpiration
Opens up the stomata which increases the rate of water vapor diffusing out
Does a higher or lower light intensity increase transpiration rate
Higher light intensity
Does a higher or lower relative humidity increase transpiration rate
Lower relative humidity
How does having a lower relative humidity increase transpiration rate
It increases the water vapour potential gradient between the inside of the leaf and the outside air
Does a higher or lower temperature increase transpiration rate
Higher temperature increases transpiration rate
How does temperature affect the kinetic energy inside the plant
increases kinetic energy of H2O molecules
How does increasing the kinetic energy of the H2O molecules affect transpiration
increases evaporation from the spongy mesophyll cells into the air spaces of the leaf
How does an increase in temperature affect the concentration of water vapor
It increases the concentration of water vapour that the external air can hold before it becomes saturated
How will dry soil affect transpiration
It’ll put the plant under water stress reducing the rate of transpiration
How do the hairs on the leaf affect transpiration
water that diffuses out of the leaf accumulates in the hairs
What happens to the water vapour potential gradient when the water vapour accumulates around the hairs
It increases around the stomata
How will still air affect transpiration
Reduce transpiration
What is the main way the plant controls transpiration rate
Opening and closing of stomatal pores
What happens to the guard cell when the turgor is low
the asymmetric configuration of the guard cell wall closes the pores
How does the guard cell pump its solutes when in “good” conditions
by active transport
What happens to the guard cells turgor when being pumped by active transport
increases their turgor
What prevents the cells from swelling in width
Cellulose hoops
What causes the guard cell to being bean shaped
The inner wall is less flexible than the outer wall
What can trigger turgor loss from the guard cell
Hormonal signals from the roots
What happens to the guard cell when there is turgor loss
The pores close
Why do the pores close when there is turgor loss
To conserve water
What does a plant need for respiration
glucose
What is glucose converted into for transport
sucrose
What 3 things could happen to sucrose when it reaches the cells
- converted back into glucose for respiration
- converted into starch for storage
- any other cellular functions
What is translocation
transport organic compounds in phloem from sources to sink
Is translocation an active or passive movement
Active (requires energy)
What are the products of photosynthesis that are transported known as
assimilates
What is the main assimilate
sucrose
What is the percentage of sucrose in the cell sap
0.5%
What is the percentage of sucrose in the phloem sap content
20-30%
What are the 3 main sinks in a plant
- Growing roots
- meristems that are actively dividing
- any part that is laying down food sources
What are the main sources of assimilates in a plant
- green leaves and stems
- food stores in seeds
- storage organs
2 examples of storage organs
tubers and tap roots
How much sucrose can a large tree transport down its trunk
250 KG
What speeds do substances get transported around in a large tree
0.15-7m/Hour
By what process do soluble products from photosynthesis move into the phloem
an active process
What makes sucrose more efficient than glucose
it isn’t used in metabolism as much so isn’t going to be used by during transportation
What are the 2 ways assimilates are loaded into the plant phloem
- symplast route (largely passive)
- Apoplast route (Active)
Where do the assimilates travel in the apoplast route
- Through the cell walls
- Inner cell spaces of companion cells
How is sucrose moved into the cytoplasm from the companion cells
across the cell membrane in an active process
Where are H+ ions pumped out of (plants)
companion cell
Where are the H+ ions pumped into from the companion cell
surrounding tissue
What molecule is used to pump the H+ ions from the companion cell to the surrounding tissue
ATP
How do the H+ ions return to the companion cell
Via the co-transporter protein
What molecule is co-transported with the H+ ion
Sucrose
Why is co-transporting sucrose with H+ ions important
Increases the sucrose concentration
Where does the sucrose concentration increase via the co-transporter
- companion cell
- sieve elements
- plasmodesmata
Due to the increase in sucrose in the companion cell and sieve tube element what also moves in
Water by osmosis
Water moving into cells leads to a build up of what
Turgor pressure
What causes the turgor pressure increase in the cells apart from water
The rigid cell walls
What does solute accumulation in the source phloem lead to
An increase in turgor pressure
What does the increase in turgor pressure in the phloem force
forces sap to regions of lower pressure in the sinks
What pressure does the phloem create
2MPa
When does phloem unloading occur
Anytime it’s needed
By what process does phloem unloading occur
Diffusion
What does sucrose turn into when unloading
Glucose
Why does sucrose turn into glucose when going through phloem unloading
To maintain the sucrose concentration gradient
What does a loss of solutes from the phloem lead to
rise in the water potential of the phloem
What happens to some of the water that carried the solute into the sink
Drawn into the transpiration stream in the xylem
Looking at evidence of translocation
How can we tell by mitochondria
If the mitochondria cell is poisoned translocation stops
Looking at evidence of translocation
How can we tell by microscopes
allows us to see adaptations of the companion cells for active transport
Looking at evidence of translocation
How can we tell by the flow of sugars
The flow of sugars is 10,000x faster than it would be by diffusion
What does the flow of sugars being 10,000x faster suggest
active process is driving the mass flow
Do all solutes move at the same rate in the phloem
No
Does sucrose move at the same rate in the phloem
Yes
What affects how fast a substance moves through the phloem
the concentration at the sink
What is a negative of having a large SA:V ratio
increases the risk of water loss by transpiration
What are the 3 adaptations of a plant to conserve water
- Waxy cuticle
- Stomata
- roots
How does the waxy cuticle conserve water
reduces transpiration from the leafs surfaces
Where are the stomata mainly found
The underside of the leaf
How do the stomata conserve water
open and close to prevent the loss of water vapour
How do the roots conserve water
Grow down to the water in the soil
What are plants that live in places with low water availability called
Xerophytes
Xero-phytes
3 examples of xerophytes
- Conifers
- marram grass
- cacti
Where is marram grass found
sand dunes
coastal areas
What other types of conditions can xerophytes live in
very cold and icy conditions
What are the 8 adaptations of xerophytes to help conserve water
- Thick waxy cuticle
- sunken stomata
- reduced stomata
- reduced leaves
- hairy leaves
- curled leaves
- succulents
- leaf loss
What percentage of water loss is through the waxy cuticle
up to 10%
What does having a thick waxy cuticle help with
Reduced water loss
What type of plants commonly have a thick waxy cuticle
evergreen plants
Where do xerophytes have their sunken stomata
In the pits
How does having your stomata located in the pits help conserve water
- reduces air movement
- produces micro-climate of still humid air
What does a micro-climate do
reduces the water vapour potential gradient and transpiration
What plants are micro-climates found
xerophytes
