Page 73 - Biology - XII

Common Disease-Causing
6 Common Disease-Causing
Organisms
Organisms

EXPERIMENT - 13

Objective
To identify common disease-causing organisms like—ascaris, entamoeba, plasmodium, and fungus causing
ringworm through permanent slides or specimens. Comment on symptoms of diseases that they cause.

Principle/Theory
Many diseases in human beings is caused due to external factors such as some disease-causing
organisms. These organisms are called pathogens. Thus, the diseases are categorised as pathogenic
diseases. At times these diseases can be fatal, too. Hence, they need to be treated after pathogenic
study. The size of pathogens range from microscopic to macroscopic.

Materials Required
Specimens/Permanent slides and compound microscope

Procedure
1. Observe the specimens.
2. Compare the comments mentioned.

3. Draw the diagram in your record fi le and write comments for each spot.
SPOT - 1

Comments
1. Systematic position
Phylum – Nematoda Mouth
Class – Chromadorea

Type – Ascaris lumbricoides Excretory pore
Common name – Roundworm
2. It is Ascaris lumbricoides (roundworm), Mouth Gonopore
an endoparasite of human intestine. Excretory pore
3. Children are the most susceptible to
infections of this worm. Lateral line
4. The infection of ascaris to the individual
is called ascariasis.
Disease—Ascariasis
The symptoms of this disease are— Penial setae cloaca

(a) Constipation, diarrhoea, and anaemia. Male Anus
(b) The patient turns anaemic and pale and shows weakness. Female
(c) The patient may even die in severe case of infection. Fig. 13.1: Ascaris

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