Nutrition is the process of acquiring energy and carbon. Organisms
need energy for synthesis of substances for growth and repair. Ex: Protein
synthesis, active transport of substances into and out of cells against concentration gradient (Sodium-Potassium
pump), electrical transmission of nerve impulses, mechanical contraction of
muscle and beating of cilia and flagella. lets find out more about nutrition.
Different modes of nutritional patterns in the living world:
• Living organisms can be
grouped on the basis of their source of energy or source
of carbon
• Organisms which have an
inorganic source of carbon such as
carbon dioxide are
described as autotrophic
• Organisms having an organic
source of carbon are described as heterotrophic
• Organisms using light energy
are described as phototrophic
• Organisms using chemical
energy are described as chemotrophic
• Autotrophs
synthesize their own organic
requirements from simple inorganic
materials
• Autotrophic nutrition is of
two types:
• Photoautotrophic – Energy
source is sunlight and carbon source is
carbondioxide.eg: cyanobacteria,
green bacteria ,green plants
• Chemoautotrophic- energy
source is chemical substances and carbon source is
Carbondioxide eg; nitrifying
bacteria like Nitrobacter, Nitrosomonas
• Heterotrophic organisms feed
on an organic source of carbon. All
animals and
fungi and majority of bacteria are heterotrophic
• Modes of heterotrophic
nutrition
• There are three types:
• Saprotrophic
• Holozoic
• Symbiotic
Saprotrophic nutrition
Organisms
which feed on dead or decaying organic matter are called
saprotrophs.
eg: Many fungi and bacteria. Saprotrophs secrete enzymes on
to the dead
organic matter and digest. Soluble end products of this
extracellular
digestion are then absorbed and assimilated by the saprotrophs
Holozoic nutrition
Most animals
are holozoic. They ingest food into their alimentary canal.
This mode of
nutrition consists of five main steps ;
Ingestion,
digestion, absorption, assimilation and ejection.
Symbiosis
Two different
species of organisms living together. It is divided into three
groups.
• Mutualism
• Parasitism
• Commensalism
• Mutualism
It is a
close association between two living organisms of different
species,
which is beneficial to both partners. e.g., Legume root nodules
and Rhizobium
• Parasitism
It is a close
association between two living organisms of different
species,
which is beneficial to one (parasite) and harmful to the other
(host)
,
e.g., Plasmodium Necator americanus,Cuscuta
• Commensalism
It is a
close association between two living organisms of different
species
which is beneficial to one and does not affect the other. e.g., Sea
anemone and
hermit crab, epiphytes (orchids)
• Insectivorous plants
This is a special type of nutrition. These plants capture insects
passively or actively
and obtain specially their
nitrogen requirements by digesting them.
e.g., Nepenthes, Drosera,
Utricularia
No comments:
Post a Comment