Page 133 - General and Inorganic Chemistry for Advanced Secondary Schools Students Book Form Five and Six

Biology for Secondary Schools

macroelements and microelements. mineral elements are essential for
The macroelements are those elements normal plant growth and metabolic
that are required by plants in relatively activities. For example, carbon is a
large amounts. They are also known major constituent of plants, hydrogen
FOR ONLINE READING ONLY
as macronutrients. These include is required during photosynthesis and
phosphorus (P), potassium (K), oxygen is required during respiration.
nitrogen (N), sulphur (S), magnesium The essential mineral elements are
(Mg), calcium (Ca), carbon (C), oxygen mainly absorbed by plants from soil.
(O), and hydrogen (H). Among the They usually dissolve in water and

macroelements, some are non-minerals, are absorbed by plants in form of ions.
such as carbon, oxygen and hydrogen, The ions enter the plant through roots
that are obtained from the air. Other and are transported upward through
macroelements are minerals, such the vascular system. Table 6.1 shows

as magnesium, calcium, phosphorus various sources of macroelements in
and potassium. Both non-mineral and plants.

Table 6.1: Sources of different macroelements in plants

Macroelement Sources

Phosphorus Obtained from commercial fertilisers, crop residues, and
manure

Potassium Obtained from soil minerals, organic materials, and
commercial fertilisers

Nitrogen Obtained from commercial fertilisers and from the air.

Rhizobium bacteria in the roots of leguminous plants fix
nitrogen from the air for use by the plants

Sulphur Obtained from rainwater, gypsum, and commercial fertilisers

Magnesium Obtained from soil minerals, organic materials (such as

compost), commercial fertilisers, and lime

Calcium Obtained from lime, gypsum, and commercial fertilisers

Student’s Book Form One Student’s Book Form One 127

15/10/2024 09:24:40
Biology FORM 1 new.indd 127 15/10/2024 09:24:40
Biology FORM 1 new.indd 127