Plant Structure (Edexcel GCSE Biology)
Flashcards
1/190Still learning
Know0
- FrontRoot Hair Cells
What is the role of root hair cells?
Enjoying Flashcards?
Tell us what you think
Cards in this collection (19)
What is the role of root hair cells?
Root hair cells absorb water and minerals from the soil.
How are root hair cells adapted to aid the absorption of water and mineral ions?
Root hair cells are adapted for absorption as follows:
they have a large surface area
they contain mitochondria which release energy for active transport
True or False?
Minerals move into root hair cells by osmosis.
False.
Mineral ions move into root hair cells by active transport. Only water can move by osmosis.
Why do root hair cells need energy from respiration?
Root hair cells need energy to fuel the active transport of mineral ions from the soil against a concentration gradient.
How does water move into root hair cells?
Water moves into root hair cells by osmosis.
Minerals, and other dissolved substances, in the cytoplasm of root hair cells lower the water concentration, so water moves into the cells down a water concentration gradient.
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:
lignin strengthens xylem cell walls to prevent breakage of vessels
they are hollow and have no end walls to allow continuous water movement
Define the term phloem.
The phloem is a tissue that transports dissolved sucrose around the plant.
How is phloem tissue adapted for its role?
Phloem tissue is adapted as follows:
phloem tissue contains living cells that supply energy for sucrose transport
it contains elongated tubes along which dissolved sugars can flow
the end walls of cells contain pores to allow passage of dissolved sugars
What is the function of the spongy mesophyll in a leaf?
The spongy mesophyll is the region of the leaf where gas exchange takes place. Gases are exchanged between the cells of the spongy mesophyll layer and the surrounding air spaces.
Some photosynthesis also occurs here.
True or False?
The air spaces in a leaf are an adaptation for gas exchange.
True.
The air spaces increase the surface area of the leaf that is in contact with the air. Gases can diffuse in and out of the spongy mesophyll cells from and into the air spaces.
What is the function of stomata in leaves?
Stomata are small pores present in the epidermis of leaves that allow the movement of gases into and out of leaves by diffusion.
True or False?
Leaves are thin, increasing the diffusion distance for gas exchange
False.
Being thin decreases the diffusion distance for gas exchange in leaves.
What are some adaptations of leaves for gas exchange?
Adaptations of leaves for gas exchange include:
they are thin, reducing the diffusion distance for gases
they are large and flat, increasing their surface area
stomata allow gases to move in and out
air spaces around mesophyll cells increase the contact between cells of the leaf and the surrounding air
True or False?
The role of the waxy cuticle is to reduce water loss from leaves by evaporation.
True.
The waxy cuticle is a waterproof layer that reduces water loss by evaporation from the surface of leaves.
How is the palisade mesophyll layer adapted to maximise photosynthesis?
The palisade mesophyll layer contains tall, thin cells that pack together closely. These cells contain many chloroplasts to maximise light absorption.
Why is it beneficial for leaves to be broad while having a thin cross-section?
It is beneficial for leaves to be broad and thin because:
being broad maximises surface area for light absorption
being thin reduces diffusion distance for gas exchange
How can the leaves of plants be adapted for survival in extreme conditions?
Adaptations for survival in extreme conditions found in leaves include:
reduced surface area
reduced number of stomata
stomata in pits or surrounded by hairs
thickened waxy cuticle
rolled-up leaf shape
What are some adaptations for living in dry conditions shown by the plant in the image?
Adaptations for living in dry conditions shown by the cactus include:
leaves are reduced to spines to reduce water loss by transpiration
thick waxy cuticle reduces water loss by evaporation
extensive roots maximise water absorption from the soil
a thickened stem allows water storage