Page 10 - Biology Form Two

Biology for Secondary Schools

Mutualism: This is a symbiotic The importance of nutrition
relationship between two species Nutrition is important in various
in which both species are mutually ways. It encompasses the study of the
benefitted. For example, bacteria living relationship between diet, health, and
in the gut of a goat, sheep, or cow get diseases. People who study nutrition are
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their nutrients from the food digested called nutritionists or dieticians. They are
by the animals. The bacteria in turn professionals who advise people on how
help the animals to digest cellulose, by nutrition affects their health and well-
releasing cellulase enzymes that digest being. Through nutrition, an organism
cellulose. can get the necessary nutrients for the
Parasitism: This is a kind of feeding body to produce energy and support

relationship between two species where functioning of various life processes.
Such life processes include growth and
one species benefits while the other is the development of cells, tissues and
harmed. For example, the relationship organs, the repair of damaged parts,
between a tapeworm and a human and movement. Other processes include
being. The tapeworm lives in the ensuring protection against infections
human gut and gets nutrients from the and diseases, maintaining body

human body while the human being is temperature, and reproduction. Through
harmed by getting sick. The organism nutrition the body can also synthesise
that benefits is called a parasite while important chemical substances, such as
the one that is harmed is called a host. enzymes and hormones.
In the human-tapeworm relationship, Moreover, maintaining good nutrition
the human being is a host and the helps to promote general body health so
tapeworm is a parasite. as to reduce the risk of getting chronic

In parasitic mode of nutrition, the diseases such as heart attack, diabetes,
parasites depend on nutrients that are stroke, blood pressure, osteoporosis,
found in the body of their hosts. There and certain types of cancer.
are two types of parasites, namely Exercise 1.1
ectoparasites and endoparasites.
Ectoparasites live outside the body of 1. Using relevant examples, briefly
the host. Examples of ectoparasites explain the following types of
include ticks, lice, fleas, and bedbugs. heterotrophic nutrition:
Endoparasites live and obtain their food (a) holozoic nutrition;
inside the body of the host. Plasmodium (b) saprophytic nutrition; and
sp., Ascaris sp., and tapeworms are (c) symbiotic nutrition.
examples of endoparasites.

4 Student’s Book - Form Two

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