Transport in Flowering Plants

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  • Created on: 06-03-14 16:08
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Transport in Flowering Plants - Gabrielle Abrahams
Transport in Flowering Plants
Plants are defined as `multicellular photosynthetic eukaryotes' as include mosses, ferns,
conifers, and flowering plants.
All flowering plants (angiosperms):
Develop from embryo protected by the tissues of the parent plant (seed inside a
parent)
Have starch as their main storage compound
Have cell walls made from cellulose
Are vascular plants, they have a transport system. The veins that you can see in
leaves and stems are specialised tissues called xylem and phloem that transport
substances around the plant
Two classes of flowering plants:
Monocotyledons (Monocots) Dicotyledons (Dicots)
Smaller percentage Larger percentage
Petals in multiples of 3 Petals in multiples of 4 or 5
Adventitious roots Tap roots
One cotyledons Two cotyledons (these leaves are
not like other leaves
Veins are parallel Netlike veins
Scattered vascular bundle Vascular bundles are arranged
Herbaceous plants have a short life cycle. Tree shrubs are not supported by turgidity of
tissue so it has the adaptation of wood (bark) which is reinforced xylem that isn't in use,
for strength
Plants have three tissue types:
Ground - bulk of plant body

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Transport in Flowering Plants - Gabrielle Abrahams
Dermal - outer covering on herbaceous - as it has no wood there is no support
structure, epidermal cells are able to secrete a waxy cuticle
Vascular - xylem, phloem, cambium, parenchyma - transport
Water
and
minerals from the soil enter the plant through the root hair cells. They are carried up the
plant in the xylem vessels.…read more

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Transport in Flowering Plants - Gabrielle Abrahams
exchange occurs, a little water vapour may be lost here.
As a result of transpiration, water moves through the plant from roots to leaves and is lost
into the air as water vapour. This is known as the transpiration stream. 98% of the water
entering the leaf is lost to the air in transpiration. It contributes enormously to the water
cycle as this water vapour forms clouds leading to rain.…read more

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Transport in Flowering Plants - Gabrielle Abrahams
Internal factors affecting transpiration
Leaf surface area - the larger the surface area the faster the transpiration rate
o There is more surface with stomata that is exposed to the air
Distribution of stomata - the more large stomata the faster the transpiration rate
o If leaves have more stomata, or larger stomata the water vapour is lost more
quickly.…read more

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Transport in Flowering Plants - Gabrielle Abrahams
Rolled leaves - Leaf rolls so lower epidermis is not exposed to atmosphere and
water vapour is enclosed in the leaf. Protects stomata from the wind
Measuring transpiration
A potometer measures water uptake and estimates the rate of transpiration. A potometer
can be set up by:
1. Cut a leafy shoot under water to stop water
from entering the xylem
2. Fill a capillary tube with water
3.…read more

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Transport in Flowering Plants - Gabrielle Abrahams
The apoplast pathway - water passes along the cellulose cell wall as its structure has no
resistance to water. Water continues to pass through cell walls until it reaches the
endodermis. The cell wall of the endodermis contains a casparian strip, which is a
waterproof barrier made of suberin. Water cannot cross this barrier as is diverted into the
cytoplasm. This is therefore called an apoplast block, as it blocks the apoplast pathway.…read more

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Transport in Flowering Plants - Gabrielle Abrahams
form a continuous tube once the end walls of each cell break down. There is
therefore no barrier to the movement of water and minerals from the roots to the
top of a plant. The loss of cell contents means more empty space for water and
less resistance. Lignin is deposited in the cellulose cell walls, providing strength
which prevents the vessel collapsing when pressure inside falls, makes the vessel
waterproof.…read more

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Transport in Flowering Plants - Gabrielle Abrahams
Translocation in the phloem - the mass flow hypothesis
Translocation is the movement of solutes from place to place. For
example, sucrose, produced during photosynthesis, is translocated from
the leaves to other parts of the plant in the phloem. Phloem is involved
in the translocation of organic solutes within a plant. The solutes carried
include sucrose and amino acids, which, being soluble, are carried in
solution through the phloem sieve tubes.…read more

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