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IGCSE UNIT 6 PLANT NUTRITION 2015-16
Transcript of IGCSE UNIT 6 PLANT NUTRITION 2015-16
Provide the nitrates, phosphates & potassium that plants need to grow and increase the yield. (MINERAL REQUIREMENTS)
6 PLANT NUTRITION
6.6 LIMITING FACTORS
TRANSVERSE SECTION OF A LEAF
waxy layer secreted by the cells in the epidermis. Prevents water evaporation.
6.4 USES OF GLUCOSE
The glucose molecules produced by photosynthesis can be used for different purposes:
5.6 Mineral Requirements
Nitrogen: in the form of nitrate/nitrite/ammonium ions are needed for protein synthesis. Nitrogen deficiency means the plant will be small and will grow slowly.
: process by which plants manufacture carbohydrates from raw materials using energy from light.
6.2 PHOTOSYNTHESIS (cont)
BALANCED AND WORD EQUATION:
An increase in light intensity speeds up photosynthesis, but only up to a limit where all available chloroplasts are occupied in light absorption.
There is only a 0.03 per cent of carbon dioxide in the air. An increase in carbon dioxide concentration (like in greenhouses) allows a faster rate of photosynthesis
An increase in temperature also speed up photosynthesis as this is a process in which enzymes are involved and they work faster at higher temperature.
Limiting factor: is something present in the environment in such short supply that it restricts life processes, such as photosynthesis
In greenhouses to increase the crop yield, farmers control the limiting factors: a CO2 enrichment, an optimum temperature (thermostatically controlled) and a high light intensity.
thin layer of cells (w/o chloroplasts). Protects the cells below.
layer of elongated cells full of chloroplasts for photosynthesis. They are close to the top of the leaf so they get a lot of light.
layer of irregular cells that create air spaces to allow gases to diffuse. They have fewer chloroplasts.
layer of protective cells on the bottom,
in it there are
little holes that can open and close thanks to
vascular bundle (veins)
with xylem an phloem. Provides transport and support. Xylem vessels carry water and phloem tubes carry away substances made by the plant.
Broad and flat surface.
Position and arrangement.
Large surface area.
Leaf Adaptations to obtain CO , HO and sunlight
IGCSE OFFICIAL EXAM JUNE 2011
For a maximum light absorption
1)FOR ENERGY: by the process of RESPIRATION glucose is broken to drive anabolic chemical reactions.
2)STORAGE: the spare sugar is converted to starch and stored in grains, tubers or seeds.
Magnesium: is needed for chlorophyll synthesis. Magnesium deficiency means plant lacks chlorophyll so leaves turn yellow.
Phosphorus: in the form of phosphates are needed for DNA.
The overuse of fertilisers can lead to
, which is when the fertiliser is transported by rain and leaches into some water e.g. a pond.
Questions 6.16-6.19 in p. 65
6.1 TYPES OF NUTRITION
TAKING IN USEFUL SUBSTANCES
TO MAKE NEW PARTS
TO REPAIR OLD PARTS
TO RELEASE ENERGY
ANIMALS AND FUNGI
They cannot make their own food
FEED ON ORGANIC SUBSTANCES
Make their own food
FEED ON INORGANIC SUBSTANCES
Carbon dioxide, water and minerals.
Carbs, lipids, proteins and vitamins
Sunlight: provides the energy to drive the reactions.
The green pigment that makes plants look green.
Absorbs sunlight energy and converts it into chemical energy available for the formation of carbohydrates.
6.plant nutrition (11-17 in the animation
From the midrib branches a network of veins which deliver water and salts and carry away the food made in the leaves.
The leaf stalk continues into the leave as a MIDRIB.
The LEAF BLADE or LAMINA is broad to receive sunlight.
Attached to the stem by a STALK or PETIOLE.
TRANSVERSE SECTION OF THE LEAF:
TRANSVERSE SECTION OF A LEAF
Leaf Adaptations to obtain CO , HO and sunlight (cont)
For an efficient gaseous exchange:
Large surface area of the leaf.
Leaves are very thin.
Air spaces in spongy mesophyll
The branching network of veins provides a good water supply to the photosynthesizing cells
To expose as much of the leaf to sun (and air)
There are many chloroplasts in the palisade cells and arranged broadside on
Thin and transparent epidermal cells
So sunlight penetrates
To expose chlorophyll to sunlight
To obtain water:
Questions 6.4-6.9 in p. 62
Questions 6.10-6.15 in p.63
NOT IN THE SYLLABUS P.69-70
Carbon dioxide is the molecule used to make sugar (in combination with the water).
Glucose is not a good storage molecule because it is reactive and soluble water.
3) SYNTHESIS OF OTHER SUBSTANCES. Sugars can be used to build up:
Sucrose for transport. It is small and soluble but less reactive than glucose.
Chlorophyll: they need N and Mg . Its deficiency produces yellow leaves.