Define the term xylem .

Xylem are vessels that transport water and mineral ions from the roots to the upper parts of plants.

True or False? Xylem vessels provide structural support to plant stems.

True. Xylem vessels are strong to enable them to transport water without breaking; this means that they also contribute to structural support within plant stems.

Define the term phloem .

The phloem is a tissue that transports sucrose and amino acids around plants.

How are xylem vessels adapted to carry out their function? ( Extended Tier Only )

Xylem vessels are adapted to their function as follows: Cell walls strengthened with lignin No cell contents No end walls

What is the role of a root hair cell ?

The role of a root hair cell is to absorb water and mineral ions from the soil.

How are root hair cells adapted to aid their function?

Root hair cells are adapted for absorption of water and minerals as follows: They have a large surface area They contain mitochondria which release energy for active transport

True or False? A piece of celery stem placed in food colouring can be used to show the location of phloem tissue in celery.

False. Placing a celery stem in food colouring and allowing it to absorb the dye allows the location of the xylem to be seen.

Define the term transpiration .

Transpiration is the loss of water vapour from the leaves of plants by evaporation .

What is the role of the spongy mesophyll cells in transpiration?

The spongy mesophyll cells are involved in transpiration as follows: water vapour evaporates from the surface of spongy mesophyll cells and enters the leaf air spaces water vapour diffuses from the air spaces out of the leaf

By what process does water vapour exit the leaf air spaces ?

Water vapour exits the leaf air spaces by the process of diffusion through the stomata .

Name the piece of equipment used to measure transpiration rate in a plant shoot.

The piece of equipment used to measure transpiration rate in a plant shoot is known as a potometer .

Describe how a bubble potometer works to measure transpiration rate.

A bubble potometer works to measure transpiration rate as follows: a bubble is introduced into a tube containing a cut plant stem as the plant transpires water is pulled up the stem, causing the bubble to move the distance the bubble moves in a given time indicates the transpiration rate

How can a potometer be set up to ensure that the system is airtight ?

An airtight potometer system can be ensured as follows: a potometer can be set up underwater to prevent entry of air bubbles petroleum jelly can be used to seal any joins

How could you investigate the effect of wind speed on transpiration rate using a potometer?

The effect of wind speed on transpiration rate can be investigated by setting up a fan or hairdryer blowing air over the plant shoot at different speeds .

Give three environmental variables that should be kept the same when investigating the effect of temperature on transpiration rate.

Environmental variables that should be kept the same when investigating the effect of temperature on transpiration rate include: wind speed light intensity humidity type/species of plant shoot surface area of plant shoot / number of leaves that the plant shoot has

How does the structure of the spongy mesophyll layer aid transpiration? ( Extended Tier Only )

The structure of the spongy mesophyll layer aids transpiration as follows: the spongy mesophyll layer contains air spaces where the surface of spongy mesophyll cells come into contact with the air there is a large internal surface area where this cell-air contact occurs the large surface area increases the rate at which water vapour evaporates from the surface of spongy mesophyll cells

What is the relationship between number of stomata and transpiration rate ? ( Extended Tier Only )

The relationship between number of stomata and transpiration rate is as follows: the more stomata , the faster the rate of transpiration (and vice versa)

Define the term transpiration pull . ( Extended Tier Only )

Transpiration pull occurs when water is drawn up the xylem to replace the water that is lost from the surface of spongy mesophyll cells by evaporation .

How do forces of attraction between water molecules enable transpiration pull? ( Extended Tier Only )

Forces of attraction between water molecules enables transpiration pull because: each water molecule pulls on the water molecule below the water molecules move upwards in a continuous column

True or False? Transpiration rate increases at higher temperatures due to the increased kinetic energy of molecules. ( Extended Tier Only )

True. At higher temperatures water molecules have more kinetic energy and are more likely to diffuse out via the stomata.

Why does transpiration occur faster on a windy day ? ( Extended Tier Only )

Transpiration is faster on a windy day because wind blows water vapour away from the surface of leaves, maintaining a water vapour concentration gradient between the inside and the outside of leaves.

True or False? Increasing humidity levels will increase the rate of transpiration. ( Extended Tier Only )

False. Increasing humidity levels will decrease the rate of transpiration . This is because humid conditions decrease the water vapour concentration gradient between the inside and outside of the leaf.

Define the term water vapour concentration gradient in the context of transpiration. ( Extended Tier Only )

The water vapour concentration gradient is the difference in water vapour concentration between the inside and the outside of a leaf.

Why do plants wilt ? ( Extended Tier Only )

Plants wilt when they lose water and cannot replace it with water from the soil. The water loss causes the plant cells to lose their rigid structure and the cell walls no longer provide support to the plant.

Define the term translocation . ( Extendend Tier Only )

Translocation is the movement of sucrose and amino acids through phloem tissue from sources to sinks .

Define the term source in the context of plant transport. ( Extended Tier Only )

A source is a part of the plant that produces or releases sucrose or amino acids.

Define the term sink in the context of plant transport. ( Extended Tier Only )

A sink is a part of a plant that uses or stores sucrose or amino acids.

True or False? Sources and sinks can be found in different parts of plants at different times of year. ( Extended Tier Only )

True. Sources and sinks can be in different parts of plants depending on whether plants are photosynthesising or relying on stored sucrose .

Why does phloem transport not always occur in the same direction? ( Extended Tier Only )

Phloem transport occurs in different directions depending on the time of year: During early spring sucrose will be transported upwards , from storage organs in the roots towards growing leaves and flowers During summer sucrose will be transported downwards , from photosynthesising leaves towards storage organs in the roots

IGCSEBiologyCambridge (CIE)Flashcards8. Transport in PlantsTransport in Plants

Transport in Plants (Cambridge (CIE) IGCSE Biology)

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Define the term xylem.
Xylem are vessels that transport water and mineral ions from the roots to the upper parts of plants.
True or False?
Xylem vessels provide structural support to plant stems.
True.
Xylem vessels are strong to enable them to transport water without breaking; this means that they also contribute to structural support within plant stems.
Define the term phloem.
The phloem is a tissue that transports sucrose and amino acids around plants.
True or False?
The image below correctly shows the distribution of vascular tissue in a root.
True.
The xylem tissue forms a cross shape in the centre of roots, and the phloem surrounds the xylem tissue.
Which colour (green or pink) represents the xylem tissue in this stem cross-section diagram?
Xylem tissue is represented by pink regions in the diagram. This is because phloem is on the outside of the vascular bundles in a stem, while xylem is on the inside.
Which types of plant tissue are represented by letters A and B in the diagram?
The types of plant tissue represented by A and B are:
- A = xylem
- B = phloem
The diagram shows a leaf cross section. Xylem tissue is closer to the upper surface of leaves while phloem is closer to the lower surface.
How are xylem vessels adapted to carry out their function? (Extended Tier Only)
Xylem vessels are adapted to their function as follows:
- Cell walls strengthened with lignin
- No cell contents
- No end walls
What cell type is shown in the image below?
The cell type shown in the image is a root hair cell.
What is the role of a root hair cell?
The role of a root hair cell is to absorb water and mineral ions from the soil.
How are root hair cells adapted to aid their function?
Root hair cells are adapted for absorption of water and minerals as follows:
- They have a large surface area
- They contain mitochondria which release energy for active transport
Write a flow diagram to describe the pathway taken by water as it travels across the root, up the stem, and out of the leaves of plants.
The pathway taken by water as it travels across the root, up the stem, and out of the leaves of plants is:
Root hair cells $\to$ root cortex $\to$ xylem vessels $\to$ spongy mesophyll cells
True or False?
A piece of celery stem placed in food colouring can be used to show the location of phloem tissue in celery.
False.
Placing a celery stem in food colouring and allowing it to absorb the dye allows the location of the xylem to be seen.
Define the term transpiration.
Transpiration is the loss of water vapour from the leaves of plants by evaporation.
What is the role of the spongy mesophyll cells in transpiration?
The spongy mesophyll cells are involved in transpiration as follows:
- water vapour evaporates from the surface of spongy mesophyll cells and enters the leaf air spaces
- water vapour diffuses from the air spaces out of the leaf
By what process does water vapour exit the leaf air spaces?
Water vapour exits the leaf air spaces by the process of diffusion through the stomata.
Name the piece of equipment used to measure transpiration rate in a plant shoot.
The piece of equipment used to measure transpiration rate in a plant shoot is known as a potometer.
Describe how a bubble potometer works to measure transpiration rate.
A bubble potometer works to measure transpiration rate as follows:
- a bubble is introduced into a tube containing a cut plant stem
- as the plant transpires water is pulled up the stem, causing the bubble to move
- the distance the bubble moves in a given time indicates the transpiration rate
How can a potometer be set up to ensure that the system is airtight?
An airtight potometer system can be ensured as follows:
- a potometer can be set up underwater to prevent entry of air bubbles
- petroleum jelly can be used to seal any joins
How could you investigate the effect of wind speed on transpiration rate using a potometer?
The effect of wind speed on transpiration rate can be investigated by setting up a fan or hairdryer blowing air over the plant shoot at different speeds.
Give three environmental variables that should be kept the same when investigating the effect of temperature on transpiration rate.
Environmental variables that should be kept the same when investigating the effect of temperature on transpiration rate include:
- wind speed
- light intensity
- humidity
- type/species of plant shoot
- surface area of plant shoot / number of leaves that the plant shoot has
How does the structure of the spongy mesophyll layer aid transpiration? (Extended Tier Only)
The structure of the spongy mesophyll layer aids transpiration as follows:
- the spongy mesophyll layer contains air spaces where the surface of spongy mesophyll cells come into contact with the air
- there is a large internal surface area where this cell-air contact occurs
- the large surface area increases the rate at which water vapour evaporates from the surface of spongy mesophyll cells
What is the relationship between number of stomata and transpiration rate? (Extended Tier Only)
The relationship between number of stomata and transpiration rate is as follows:
- the more stomata, the faster the rate of transpiration (and vice versa)
Define the term transpiration pull. (Extended Tier Only)
Transpiration pull occurs when water is drawn up the xylem to replace the water that is lost from the surface of spongy mesophyll cells by evaporation.
How do forces of attraction between water molecules enable transpiration pull? (Extended Tier Only)
Forces of attraction between water molecules enables transpiration pull because:
- each water molecule pulls on the water molecule below
- the water molecules move upwards in a continuous column
True or False?
Transpiration rate increases at higher temperatures due to the increased kinetic energy of molecules. (Extended Tier Only)
True.
At higher temperatures water molecules have more kinetic energy and are more likely to diffuse out via the stomata.
Why does transpiration occur faster on a windy day? (Extended Tier Only)
Transpiration is faster on a windy day because wind blows water vapour away from the surface of leaves, maintaining a water vapour concentration gradient between the inside and the outside of leaves.
True or False?
Increasing humidity levels will increase the rate of transpiration. (Extended Tier Only)
False.
Increasing humidity levels will decrease the rate of transpiration.
This is because humid conditions decrease the water vapour concentration gradient between the inside and outside of the leaf.
Define the term water vapour concentration gradient in the context of transpiration. (Extended Tier Only)
The water vapour concentration gradient is the difference in water vapour concentration between the inside and the outside of a leaf.
Why do plants wilt? (Extended Tier Only)
Plants wilt when they lose water and cannot replace it with water from the soil. The water loss causes the plant cells to lose their rigid structure and the cell walls no longer provide support to the plant.
Define the term translocation. (Extendend Tier Only)
Translocation is the movement of sucrose and amino acids through phloem tissue from sources to sinks.
Define the term source in the context of plant transport. (Extended Tier Only)
A source is a part of the plant that produces or releases sucrose or amino acids.
Define the term sink in the context of plant transport. (Extended Tier Only)
A sink is a part of a plant that uses or stores sucrose or amino acids.
True or False?
Sources and sinks can be found in different parts of plants at different times of year. (Extended Tier Only)
True.
Sources and sinks can be in different parts of plants depending on whether plants are photosynthesising or relying on stored sucrose.
Why does phloem transport not always occur in the same direction? (Extended Tier Only)
Phloem transport occurs in different directions depending on the time of year:
- During early spring sucrose will be transported upwards, from storage organs in the roots towards growing leaves and flowers
- During summer sucrose will be transported downwards, from photosynthesising leaves towards storage organs in the roots