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UNIT
2
The nutrition function
PLANT
NUTRITION PROCESSES
Natural Science 2. Secondary Education
UNIT
2
Plant nutrition processes
1. OBTAINING
NUTRIENTS
1c Photosynthesis
2. RESPIRATION
3. SUBSTANCE
DISTRIBUTION
1b Carbon dioxide
(CO2) absorption
4. ELIMINATING
WASTE MATTER
1a The absorption
of water and
mineral salts
Natural Science 2. Secondary Education
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process to
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UNIT
2
Plant nutrition processes
1a. The absorption of water and mineral salts
• Plants absorb water containing dissolved mineral salts from
the soil.
• This is done through cells located at the end of the roots,
called root hairs.
• The mixture of water and minerals absorbed by the roots is
called xylem sap.
Root
hairs
Water and
mineral salts
Natural Science 2. Secondary Education
Xylem sap
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UNIT
2
Plant nutrition processes
1b. Carbon dioxide (CO2) absorption
• Carbon dioxide enters the plant mainly through very small
pores called stomata, which are found on the underside of the
leaves.
CO2
Location of the stomata
on the leaf
Stoma
Natural Science 2. Secondary Education
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UNIT
2
Plant nutrition processes
1c. Photosynthesis
• Photosynthesis takes place in the chloroplasts, which are located in
the green parts of a plant.
• The water and carbon dioxide absorbed by the plant reach the
chloroplasts and, with the energy from sunlight, are transformed into
carbohydrates. Oxygen is produced as a by-product.
• The carbohidrates mix with the water in the leaf and form phloem
sap.
Solar energy
Xylem sap
Water and
carbohydrates
(phloem sap)
Chloroplast
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H2O + CO2
Natural Science 2. Secondary Education
O2
UNIT
2
Plant nutrition processes
2. Respiration
• Plants are constantly respiring. This process is carried out by the
mitochondria.
• The plant absorbs oxygen through the stomata and the root hairs.
• This oxygen reaches the mitochondria, where it is used to get
energy from carbohydrates.
• CO2 and water are released.
Oxygen
Energy
Carbon
dioxide
Carbohydrates
Natural Science 2. Secondary Education
Water
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UNIT
2
Plant nutrition processes
3. Substance distribution
• Substances in the plant are
transported through tube-shaped
vessels which run along the
stem, the branches and the leaf
veins.
Xylem sap
Phloem sap
• Some vessels take the xylem
sap from the roots to the green
parts of the plant.
• Others distribute the phloem
sap throughout the plant.
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UNIT
2
Plant nutrition processes
4. Eliminating waste matter
• Plants eliminate waste in various ways:
• The oxygen from
photosynthesis, the carbon
dioxide from respiration and
excess water are eliminated
through the stomata.
• Plants store waste in the cells
of old leaves and then they
eliminate them.
• They can also release
substances like latex and resin
through cuts in the stem.
Stomata
Water
Carbon
dioxide
Oxygen
Cut
Natural Science 2. Secondary Education
Old leaves
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