(a) Complete the table below; Disease Causative... | WAEC SSCE - Biology - 2020 (Objective)

Question 1 Report

(a) Complete the table below;

Disease	Causative organism	Vector	Control
Cholera
	Trypanosome
		Female Anopheles mosquito
Ringworm		None

(b) Explain briefly the biological basis of preserving foods using each of the following methods;

(i) salting (ii) irradiation (iii) smoking

Answer

(a) Completed table

Disease	Causative organism	Vector	Control
Cholera	Vibrio cholerae (a bacterium)	Housefly / contaminated water	Provide clean water and good sanitation; proper sewage disposal; vaccination
Sleeping sickness (trypanosomiasis)	Trypanosome (Trypanosoma species)	Tsetse fly	Clear bushes; destroy tsetse fly breeding sites; treat patients with drugs
Malaria	Plasmodium (a protozoan)	Female Anopheles mosquito	Destroy mosquito breeding sites; use insecticide-treated nets; take antimalarial drugs
Ringworm	Fungus (Tinea / Microsporum)	None (spread by contact)	Maintain personal hygiene; apply antifungal ointment; avoid sharing clothing

(b) Biological basis of food preservation

(i) Salting

Adding salt creates a very concentrated (hypertonic) medium around the food. Water is drawn out of the micro-organisms by osmosis, dehydrating them so they cannot grow, multiply or spoil the food. The dry, salty condition also removes the water that microbes need.

(ii) Irradiation

Food is exposed to ionising radiation (such as gamma rays). The radiation destroys or damages the cells and DNA of bacteria, fungi and other micro-organisms (and inactivates enzymes), killing them so they can no longer cause spoilage.

(iii) Smoking

Smoking dries the food by heat, removing water that micro-organisms need. In addition, the smoke deposits antimicrobial chemicals (such as phenols and creosote) on the food surface which inhibit the growth of bacteria and fungi.

Read lesson note on Microorganisms: Man And Health (WAEC)

Read lesson note on Biology And Food Industry - Food Additives (WAEC)

Answer Details

(a) Completed table

Disease	Causative organism	Vector	Control
Cholera	Vibrio cholerae (a bacterium)	Housefly / contaminated water	Provide clean water and good sanitation; proper sewage disposal; vaccination
Sleeping sickness (trypanosomiasis)	Trypanosome (Trypanosoma species)	Tsetse fly	Clear bushes; destroy tsetse fly breeding sites; treat patients with drugs
Malaria	Plasmodium (a protozoan)	Female Anopheles mosquito	Destroy mosquito breeding sites; use insecticide-treated nets; take antimalarial drugs
Ringworm	Fungus (Tinea / Microsporum)	None (spread by contact)	Maintain personal hygiene; apply antifungal ointment; avoid sharing clothing

(b) Biological basis of food preservation

(i) Salting

(ii) Irradiation

(iii) Smoking

Read lesson note on Microorganisms: Man And Health (WAEC)

Read lesson note on Biology And Food Industry - Food Additives (WAEC)

Microorganisms: Man And Health

Biology And Food Industry - Food Additives

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(a) Complete the table below; Disease Causative organism Vector Control Cholera Trypanosome Female Anopheles mosquito Ringworm None (b) Explain briefly the ...

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(a) Complete the table below; Disease Causative organism Vector Control Cholera Trypanosome Female Anopheles mosquito Ringworm None (b) Explain briefly the ...

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