Monday 12 October 2015

Vitamins

Vitamins are organic compounds which cannot be produced by the body and must be supplied in small amount in diet for the normal health, growth and maintenance of body.
Vitamins are essential to us for the normal and proper functioning of the body.  The absence or deficiency of a vitamin can cause specific diseases.

In 1912, Sir H G Hopkins first identified vitamins in milk. The name ‘vitamins’ was given by Casmir Funk.


Vitamins are classified into two types,

  • Water soluble vitamins
  • Fat soluble vitamins


Water soluble vitamins


Vitamin B complex and vitamin c are water soluble.

Fat soluble vitamins



Vitamins A, D, E and K  are fat soluble vitamins.



Sl.No.
Vitamins


Deficiency diseases
1
Vitamin B1
Thiamine (aneurin)

Beriberi
2
Vitamin B2
Riboflavin (lactoflavin)

Chillosis

3
Vitamin B3
Niacin

Pellagra

4
Vitamin B5
Pantothenic acid

Parasthesia

5
Vitamin B6
Pyridoxine

Dermites

6
Vitamin B7
Biotin

Seboria

7
Vitamin B9
Pholic acid

Megaloblastic anemia

8
Vitamin B12
Cyanocobalamin

Pernicias anemia

9
Vitamin C
Ascorbic acid
Scurvy

10
Vitamin A
Retinol

Nightblindness, xerophthalmia, xerosis

11
Vitamin D
Calciferol

Rickets

12
Vitamin E
Tocopherol

Sterility

13
Vitamin K
Phylloquinone
Bleeding


Friday 27 March 2015

POLLINATION


Pollination is the mechanism to transfer  pollen grains from  the anther to the stigma of a pistil is termed pollination.


                                  

                               






KINDS OF POLLINATION


Depending on the source of pollen, pollination can be divided into three.

Autogamy            

Transfer of pollen grains from the anther to the stigma of same flower is called autogamy or self-pollination.



Geitonogamy  

    Transfer of pollen grains from the anther to the stigma of another flower of same plant is called geitonogamy.



Xenogamy     

     Transfer of pollen grains from the anther to the stigma of a different plant is called xenogamy.




AGENTS OF POLLINATION

Pollinating agents are either abiotic (wind and water) or biotic (animals).

Pollination by wind  

Wind pollination is more common amongst abiotic pollination. Wind pollination requires that the pollen grains are light and non-sticky so that they can be transport easily. And the plants have well exposed stamens and large often feathery stigma to easily trap pollen grains.

Pollination by water  

Aquatic plants may have aerial, submerged or floating flowers.   It is quite rare in flowering plants.  And the plants have well exposed stamens and large often feathery stigma to easily trap pollen grains.

Pollination by Animals

              Insect pollination

Flowers are mostly pollinated by insects. When an insect visiting a flower to collect food (nectar) pollen from the stamens sticks to the insect and then it travels to another flower these pollen grains are sticks to stigma of the flower.       

                     




                           









        Bird pollination

Many bird pollinated flowers are bright coloured (red or orange) to attract birds, flowers are large in size and most are tubular so that bird can dip their beaks in. while pollen grains from stamen sticks on birds head and pollination occurs.

                                           



                           




     Mammal pollination

Some types of bats and Australian possum are the important mammal pollinators. They pollinate flowers by feed on nectar and pollen.