4.2.3 Plant tissues, organs and systems Flashcards
(15 cards)
What tissues does the leaf organ contain
Epidermis
Palisade mesophyll
Spongy mesophyll
Xylem
Phloem
Guard cells
What is the function of guard cells
Control the openings and closing of the stomata according to the water content of the plant
How is epidermal tissue adapted for its function
Waxy cuticle which helps reduce water loss from the leaf surface
How is palisade mesophyll tissue adapted for its function
Contains lots of chloroplast which allows photosynthesis to progress at rapid rate
How is the spongy mesophyll adapted for its function
Has lots of air space which allows gases to diffuse in and out
How is the xylem adapted for its function
Made up of dead cells which form a continuous hollow tube-allows the movement of water and minerals ions from the roots to the leaves
Strengthen by lignin-makes it waterproof
How is the phloem adapted for its function
Cells have seive plates that connect them together
Cell sap can move through into other cells
How are stomata adapted for their function
Stomata allow the control of gaseous exchange and water loss from the leaf
More stomata on the base of the leaf minimize the water loss as the side is cooler and shaded
Have guard cells which j control their opening and closing
What is transpiration
Is evaporation of water vapour from the surface of the plant
How does transpiration work
water evaporates from the leaf structure by the stomata
Water molecules coheed together more water is pulled up the xylem in an unbroken column
More water is taking up from the soil creating a continuous transpiration stream
What is the relationship between light intensity and transpiration rate?
Higher light intensity increases transpiration. Light stimulates the opening of stomata to facilitate photosynthesis, allowing more water vapor to escape from the leaf surfaces.
How does increased air movement influence transpiration in plants?
Increased air movement enhances transpiration. Wind removes the humid air layer around the leaf surface, maintaining a steep concentration gradient for water vapor, which promotes more rapid diffusion of water out of the leaf.
What is the effect of high humidity on plant transpiration?
High humidity decreases the rate of transpiration. When the surrounding air is moist, the gradient for water vapor diffusion from the leaf to the atmosphere is reduced, slowing down water loss.
How does increasing temperature affect the rate of transpiration in plants?
Increasing temperature raises the rate of transpiration. Higher temperatures provide water molecules with more kinetic energy, leading to faster evaporation from leaf surfaces and a steeper water potential gradient between the inside and outside of the leaf.
