True or False?
Leaves are plant organs.
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True or False?
Leaves are plant organs.
True.
Leaves contain multiple tissues that work together to carry out photosynthesis.
Where is epidermal tissue located in the leaves of plants?
Epidermal tissue is present on the upper and lower surfaces of leaves; the upper surface is the upper epidermis and the lower surface is the lower epidermis.
What is the role of palisade mesophyll tissue?
The role of palisade mesophyll tissue is to carry out photosynthesis.
True or False?
Spongy mesophyll tissue contains some chloroplasts for photosynthesis.
True.
Spongy mesophyll cells do contain chloroplasts. While most photosynthesis occurs in the palisade mesophyll tissue, some takes place in the spongy mesophyll layer.
How is spongy mesophyll tissue adapted for gas exchange?
Spongy mesophyll tissue is adapted for gas exchange by the presence of air spaces between cells. This increases the surface area of the cells that comes into contact with the air, so enabling faster gas exchange.
True or False?
Xylem is the only type of vascular tissue found in plants.
False.
Xylem and phloem are both types of vascular tissue found in plants.
What is the role of guard cells in leaves?
Guard cells control whether the stomata in leaves are open or closed; this allows plants to reduce water loss via the stomata when water availability is limited.
Where would meristem tissue be found in plants?
Meristem tissue is found in the growing tips of plant shoots and roots.
True or False?
The roots, stem and leaves together form a plant organ system.
True.
The organ system that comprises the roots, stem and leaves enables the transport of substances around a plant.
What is the role of root hair cells?
Root hair cells absorb water and minerals from the soil.
True or False?
Water is taken up from the soil by active transport.
False.
Water is absorbed from the soil by osmosis while minerals are absorbed by active transport.
How are root hair cells adapted to aid their function?
Root hair cells are adapted for absorption as follows:
They have a large surface area
They contain mitochondria which release energy for active transport
Define the term xylem.
Xylem are vessels that transport water and mineral ions from the roots to the upper parts of plants.
How are xylem vessels adapted to transport water around plants?
Xylem vessels are adapted for water transport as follows:
they are hollow and have no end walls to allow continuous water movement
lignin strengthens xylem cell walls to prevent breakage of vessels
Define the term phloem.
The phloem is a tissue that transports dissolved sugars (sucrose) from the leaves to the rest of the plant (after photosynthesis).
How is phloem tissue adapted for its role?
Phloem tissue is adapted as follows:
it contains elongated tubes along which dissolved sugars can flow
the end walls of cells contain pores to allow passage of dissolved sugars
Define the term transpiration.
Transpiration is the loss of water vapour from the leaves of plants by evaporation.
Describe the structure of stomata.
The stomata are pores in the leaf surface, surrounded by two guard cells.
What is the role of the stomata and guard cells in transpiration?
The stomata and guard cells allow plants to regulate the volume of water lost during transpiration. When water availability is low the guard cells can close, reducing transpiration.
Which four factors can affect the rate of transpiration in plants?
Four factors that affect the rate of transpiration are:
Temperature
Humidity
Wind speed / air movement
Light intensity
What happens to transpiration rate as light intensity increases?
As light intensity increases the transpiration rate increases.
True or False?
Transpiration rate increases at high light intensity because the stomata close.
False.
Transpiration rate increases with light intensity because the stomata open at high light intensities to enable gas exchange for photosynthesis.
What happens to transpiration rate as temperature decreases?
As temperature decreases the transpiration rate decreases.
True or False?
Transpiration rate increases at higher temperatures due to the increased kinetic energy of molecules.
True.
At higher temperatures water molecules have more kinetic energy and are more likely to diffuse out via the stomata.
True or False?
Transpiration rate increases as wind speed increases.
True.
As wind speed increases the transpiration rate increases.
Why does transpiration occur faster on a windy day?
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.
How will putting a plant inside a plastic bag affect its rate of transpiration?
Putting a plant inside a plastic bag will decrease its rate of transpiration. This is because the bag will trap water vapour and raise humidity levels, decreasing the water vapour concentration gradient between the leaf and the surrounding air.
True or False?
Increasing humidity levels will increase the rate of transpiration.
False.
Increasing humidity levels will decrease the rate of transpiration.
Define the term translocation.
Translocation is the movement of dissolved sugar molecules through phloem tissue.