Bio Topic 7 Flashcards
What do xylem vessels transport?
Water and minerals.
What do phloem vessels transport?
Sucrose and amino acids.
In which direction is water transported in a plant?
From roots to leaf.
In which direction are sucrose and amino acids transported in a plant?
From source to sink.
Which plant transport vessel transports sucrose and amino acids?
Phloem.
Which plant transport vessel carries water and minerals?
Xylem
What is a source?
Area of Production
What is a sink?
The place of need (e.g. storage, use)
What is the most common source of sucrose for a plant in summer?
Leaves
What is the most common source of sucrose for a plant in winter?
The plant’s roots.
Define transpiration.
The movement of water and minerals from the roots to the leaf (diffuse out through stomata).
Define translocation
The movement of sucrose and amino acids from source to sink in the phloem vessel.
What is the name of the process by which sucrose and amino acids are transported from source to sink in the phloem?
Translocation.
What is the name of the process by which water and minerals are transported from roots to leaves in xylem?
Transpiration.
What is the function of a root hair cell?
To absorb water and ions.
What is the name of the plant cell that absorbs water from the soil?
Root hair cell.
Why do root hair cells have a large surface area?
To increase rate of absorption of water and ions.
What enables root hair cells to increase the rate of absorption of water and ions?
Large surface area
Why do root hair cells have no chloroplasts?
They are underground, thus does not receive sunlight, meaning no need of chloroplast.
Which structure usually found in plant cells is absent from a root hair cell?
Chloroplasts.
Name the four tissues in a plant root, working from the outside inwards.
Root hair, Root cortex, Phloem, Xylem.
What is the first cell a water molecule enters, when it is absorbed by a plant?
Root hair cell
After leaving the root hair cell, through which tissue does water travel to get to the xylem vessels?
Root cortex.
After leaving the xylem vessels, through which part of a leaf does water travel?
spongy mesophyll.
Through which part of the lower epidermis does water evaporate from a leaf?
Stomata
Name the four factors that affect the rate of transpiration.
Temperature, humidity, light intensity, wind speed
Describe how increasing humidity affects the rate of transpiration.
Decreases water potential gradient, hence rate of osmosis is decreased.
Describe how increasing temperature affects the rate of transpiration.
Temperature increase => transpiration rate increase
Describe how increasing light intensity affects the rate of transpiration.
a
Describe how increasing air movement affects the rate of transpiration.
Increased air movement => increased rate of transpiration
Explain why increasing humidity decreases the rate of transpiration, using the term ‘concentration gradient’.
Humidity decreases the concentration of water molecules between the atmosphere and inside the leaf, decreasing the rate of transpiration.
Explain why increasing temperature increases the rate of transpiration.
Increasing temperature increases the rate of evaporation as more water particles with higher energy escape the upper epidermis’s surface.
Explain why increasing light intensity increases the rate of transpiration.
a
Explain why increasing air movement increases the rate of transpiration using the term ‘concentration gradient’
More air movement = removal of more water vapor => allows more water to diffuse out of plant and thus increasing the concentration gradient.
Describe how xylem and phloem are arranged in the root of a plant.
Xylem in a ‘X’ shape at the center.
Phloem in a circle around the xylem.
Describe how xylem and phloem are arranged in the stem of a plant.
In vascular bundles
Describe how xylem and phloem are arranged in the leaves of a plant.
a
What is a vascular bundle?
a
Which parts of a plant contain vascular bundles?
Stem
What is cohesion?
Cohesion refers to the attraction of water particles to other water particles.
What is the name of the forces that cause water molecules to stick together?
Cohesion
How does cohesion allow transpiration to occur?
a
How can water loss from leaves be measured?
The percentage change in mass.
What can be measured by the percentage change in mass of a leaf?
The rate of transpiration (loss of water)
