• MEANING OF PLANT NUTRIENTS
    AGRICULTURAL SCIENCE

    PLANT NUTRIENTS

    Plants require nutrients or elements obtained from the soil for good growth and healthy development. These elements or nutrients are classified into two main groups which are: Macro-Nutrients: Macro-nutrients are mineral elements or nutrients required by crops in large quantities. Examples of macro-nutrients are nitrogen, phosphorus, potassium, magnesium, calcium and sulphur. Micro Nutrients or Trace Elements: Micro nutrients are mineral elements or nutrients required by crops in small quantities. Examples of micro-nutrients are zinc, copper, boron, molybdenum, iron, chlorine and manganese. The functions and deficiency symptoms of these elements or nutrients are summarised below: a) Nitrogen Functions It aids plants’ growth and reproduction because it is an essential constituent of…

  • AUXINS
    BIOLOGY

    AUXINS

    Auxins help primarily in influencing cell elongation and enlargement hence sometimes referred to as growth hormones. Actions of auxins are to stimulate or inhibit growth hence they are regarded as growth regulators. The most abundant natural auxin manufactured in plants is indoleacetic acid (IAA), IAA is secreted most abundantly in the tips of shoots, developing leaves, flowers, fruits, cambial cells and root tips. Auxins have been artificially synthesised. An example of a synthetic auxin is Dichlorophenoxy ethanoic acid (2,4-D).   The roles of auxins Phototropism of shoot: When light shines on one side of the shoot of a plant, the auxin on that side is reduced, and consequently the growth…

  • GROWTH
    BIOLOGY

    GROWTH

    Growth is defined as an irreversible or permanent increase in size, dry mass or weight due to the addition of living protoplasmic materials in organism. In other words, Growth is defined as an irreversible increase in size and complexity of an organism brought about by the synthesis of new protoplasm. For growth to occur, the rate of synthesis or building up of materials (anabolism) must exceed the rate of breaking down (catabolism).   Differences Between Plants and Animals Growth   Growth in plants Mainly restricted to place growing regions/ body/ apical meristem. Continuous throughout life (in growing regions). Indefinite number of parts.   Growth in animals Diffuse/takes in all parts…

  • MICRO-ORGANISMS IN ACTION
    BIOLOGY

    MICRO-ORGANISMS IN ACTION

    GROWTH OF MICRO-ORGANISMS Micro-organisms, like all living things, do increase in size and multiply in number of cells using either the culture medium provided or any suitable surface such as moist bread as source of food. Microorganisms can also increase in mass. Such an increase in size, mass or number of cells is regarded as growth in micro-organisms. If environmental conditions of growth such as food, adequate temperature and humidity are favourable, such an increase in mass, size and number of cells of the colony is an index of growth of micro-organisms.   Ways of Measuring Growth in Microorganisms There are two major ways of measuring growth in micro-organisms. These…

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