Crop Plants: Fertiliser (Edexcel IGCSE Biology (Modular)): Revision Note
Exam code: 4XBI1
Crop Plants: Fertilisers
Modern technology has increased food supply substantially
One of the key ways this has been achieved is with the use of fertilisers
Fertilisers increase the amount of key nutrients in the soil for crop plants, meaning that they can grow larger and are more healthy, which increases yields
Using fertilisers to increase crop yields
Plants require a range of mineral ions in order to grow well
As crop plants take up these mineral ions from the soil, the mineral ions need to be replaced if crops are grown repeatedly in the same field (i.e. year after year)
Fertilisers are used to replace these mineral ions
They can make crops grow faster and bigger so that yields are increased
Fertilisers can be in the form of organic fertiliser or chemical fertiliser
Organic fertilisers commonly used by farmers include farmyard manure and compost
Chemical fertilisers are often applied to the soil as dry granules or can be sprayed on in liquid form
Two mineral ions plants require for growth are magnesium ions and nitrate ions
Mineral ion | Function in plants | Sign of deficiency |
|---|---|---|
Magnesium ions | needed for chlorophyll | yellowing of leaves |
Nitrate ions | needed for amino acids (the building blocks of proteins) | weak growth and yellowing of the leaves |
There are other mineral ions that plants require:
Mineral ion | Function in plants | Sign of deficiency |
|---|---|---|
Phosphate ions | needed for ATP, DNA, RNA | poor root growth, dark green or purple-tinged leaves, stunted growth |
Calcium ions | needed for cell walls and cell membranes | deformed new leaves, stunted growth |
Potassium ions | needed for stomatal opening | yellowing at leaf edges |
Examiner Tips and Tricks
The specification only requires you to know that magnesium ions are needed for chlorophyll and nitrate ions are needed for amino acids, so be sure to learn the functions of these two ions.
It's important to spell 'nitrate' correctly in the exam! Plants require nitrate ions, NOT nitrites or nitrogen.
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