Plant organisation Flashcards
what is the purpose of the ‘Large surface area’ leaf adaptation? feature or structural of leaf?
To absorb more light
-feature
what is the purpose of the ‘Thin’ leaf adaptation? feature or structural of leaf?
Short distance for carbon dioxide to diffuse into leaf cells
-feature
what is the purpose of the ‘Chlorophyll’ adaptation? feature or structural of leaf?
Absorbs sunlight to transfer energy into chemicals
-feature
what is the purpose of the ‘Network of veins’ leaf adaptation? feature or structural of leaf?
To support the leaf and transport water and sugar
-feature
what is the purpose of the ‘stomata’ leaf adaptation? feature or structural of leaf?
Allows carbon dioxide to diffuse into the leaf and oxygen to diffuse out
-feature
state the layers of the internal structure of a leaf? (7)
-waxy cuticle
-upper epidermis
-palisade mesophyll
-spongy mesophyll
-air space
-lower epidermis
-guard cells (with stomata in between)
what is the internal structure of a leaf adapted to do?
to promote efficient photosynthesis
why is the Epidermis thin and transparent ?
To allow more light to reach the palisade cells
why is the Thin cuticle made of wax?
To protect the leaf from infection and prevent water loss without blocking out light
why is the Palisade cell layer at top of leaf?
To absorb more light and increase the rate of photosynthesis
what is the purpose of the spongy layer?
Air spaces allow carbon dioxide to diffuse through the leaf
why does the Palisade cells contain many chloroplasts
To absorb all the available light
what are the two types of transport tissue within a plant?
xylem and phloem
what are leaves also involved in?
-state how this process works out (what is going on)
gas exchange
- carbon dioxide enters the leaf and oxygen and water vapour leave the plant through the stomata
what are the stomata surrounded by?
-what do they do?
guard cells, which control their opening and closing.
why are palisade mesophyll cells arranged closely together?
so that a lot of light energy can be absorbed.
explain what the xylem and phloem transport within a cell: (2)
xylem transports water and mineral ions
phloem transports substances (such as sucrose and amino acids)
what process do plants absorb water and mineral ions by? (2)
water = osmosis
mineral ions = active transport
how are root hair cells adapted for taking up water and mineral ions?
by having a large surface area to increase the rate of absorption.
how are root hair cells adapted for active transport? (2)
-contain lots of mitochondria, which release energy from glucose during respiration
-in order to provide the energy needed for active transport.
what are the stomata and what do they do?
what do they allow in and out of the leaf?
tiny holes found in the underside of leaves.
-control water loss and gas exchange by opening and closing.
-allow water vapour and oxygen out of the leaf and carbon dioxide into the leaf.
what do plants growing in drier conditions tend to have a small number of? where?
-why?
stomata and only on their lower leaf surface,
-to reduce water loss.
describe what happens to guard cells in bright light and low light conditions
-In bright light the guard cells take in water by osmosis and become plump and turgid.
-In low light the guard cells lose water and become flaccid, causing the stomata to close.
when do the guard cells only normal close in? why?
the dark when no carbon dioxide is needed for photosynthesis.
what is the size of the stomatal opening is used by the plant to do? + therefore limit what?
control the rate of transpiration
-limit the levels of water loss from the leaf
what does the xylem consist of?
dead cells
describe how the dead cells making up the xylem are adapted for their function. (2)
-lose their end walls so the xylem forms a continuous, hollow tube.
-become strengthened by a substance called lignin.
what does lignin do?
gives strength and support to the plant.
what is the difference between the xylem and phloem in terms of direction?
xylem = upwards only
phloem= upwards and downwards
describe transpiration and translocation?
transpiration: movement of water and mineral ions via the xylem
translocation: movement of substances (e.g sucrose) via the phloem
