Page 161 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

v Several housekeeping practices should be followed so that water should not be contaminated.

v Sanitation refers to the conditions relating to the health of people, especially the disposal
of waste & provision of clean drinking water.

v Defecating in the open attracts flies & other insects, that carry germs which cause diseases
such as typhoid, cholera, diarrhoea, etc.
v Another cause of spread of the diseases is stagnant water, in which mosquitoes start

breeding , which cause malaria, dengue, etc.
v All places do not have proper sewerage system. To take care of sanitation in such places,

alternative low cost sewage disposal systems are used. These are septic tank, chemical
toilet, composting toilet, vermi-processing toilet & toilets in aeroplanes.

v A septic tank is often installed under the ground in houses or buildings, such as hospitals.
v Chemical toilet has a separate compartment that treats human waste with chemicals &

decreases odour.
v Comporting toilet treats human waste with biological processes.
v Vermi-processing toilet is a toilet in which human excreta is treated using earthworms.

v Airplane toilets use an active vacuum instead of a passive siphon & they are therefore called
vacuum toilets.

v We should take care of sanitation in the public places.
v Dr. Ronald Ross discovered that the salivary gland in mosquitoes was the storage site of the

parasite.
Exercise

A. Tick (3) the correct answer.
1. Sewage refers to wastewater that is released from ...................... .

(a) Homes (b) Industries (c) Offices (d) All of the above

Ans: (d)
2. Harmful growth of toxin-producing algae is called ...................... .

(a) Bacterial bloom (b) Algal bloom (c) Microbial bloom (d) Fungal bloom
Ans: (b)

3. Sewage is mainly ...................... .

(a) Liquid waste (b) Solid waste
(c) Gaseous waste (d) Mixture of solid and gas

Ans: (a)

4. Which of the following is not a source of wastewater?
(a) Sewers (b) Homes (c) Industries (d) Hospitals

Ans: (a)

161