Page 265 - Biology_F5
P. 265
Chapter
Five
Nutrition
FOR ONLINE READING ONLY
Introduction
Living organisms require energy in order to accomplish various metabolic activities.
The main source of energy for organisms in all ecosystems is the sun. Organisms
obtain their food in different ways. In this chapter, you will learn about physiology
of photosynthesis which include mechanism of light reaction and dark reaction in C3
and C4 plants. You will also carry out anatomical and physiological investigations
related to digestive system in mammals. The competences developed will enable you
to improve human health and agricultural practices.
namely; autotrophs and heterotrophs. All
Think organisms that can make their own food
from simple inorganic substances, such
The world without knowledge on plant as water and carbon dioxide are called
and animal nutrition. autotrophs. Autotrophs, such as plants, green
algae, and some bacteria, have the green
5.1 Concept of nutrition pigment (chlorophyll) used to synthesise
their own food through the process known
Task 5.1
From biology books and internent as photosynthesis. Some other autotrophs
sources, search for information on the use the process known as chemosynthesis
concept of nutrition. to make their own food. Sulphur bacteria,
for example, use inorganic sulphur as the
source of energy for synthesising their food,
There are different modes of nutrition by and Methanobacterium sp. (bacteria living
which living organisms obtain food in in deep oxygen-depleted oceans) obtain their
order to obtain energy and nutrients that energy from conversion of organic substrate
are required for survival and for different such as alcohol and esters to methane as
metabolic activities. Nutrition entails a a source of energy. Other organisms that
process by which living organisms take cannot make their own food but depend
in food and use it for metabolic activities,
such as growth, and body repair. Based on on other organisms for food and energy are
their modes of nutrition, living organisms called heterotrophs. These include animals,
are categorised into two main groups, fungi and some bacteria.
258