science notes Archives - Page 11 of 32 - Free ZIMSEC & Cambridge Revision Notes

Safety when using chemicals

By garikaib|2025-02-12T09:09:19+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Safe use of chemicals. Image credit montana.edu ZIMSEC Combined Science Notes: Safety when using chemicals

Pesticides are almost always harmful to human beings.
They are graded according to their level of toxicity i.e. how dangerous they are to humans.
There are no safe pesticides all are […]

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Experiment: Do plants release carbon dioxide when they respire?

By garikaib|2025-02-12T09:45:40+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Potted plant. Image credit artificialplantsandtrees.com ZIMSEC Combined Science Revision Notes: Do plants release carbon dioxide when they respire?

Aim: To determine whether all living things, including plants, release carbon dioxide when they respire.

Materials: bell jar or a large container, 3 boiling tubes/flasks glass or rubber tubing, lungs, suction […]

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The circulatory system of mammals

By garikaib|2025-02-12T09:18:59+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

The main parts of the human circulatory system. Image credit organsofthebody.com ZIMSEC O Level Combined Science Notes: The circulatory system of mammals

Mammals also have a transport system just like plants
With this transport system things like food, oxygen,water and other substances […]

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Ecosystems: The soil

By garikaib|2025-02-12T09:39:32+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Soil profile. Image credit nesoil.com ZIMSEC O Level Combined Science Notes: Ecosystems: The soil

Soil is an important part of the ecosystem
It is a critical component of life on earth and agriculture
Soil thickness varies from a few millimeters to a several meters in places
Animals and plants […]

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The nitrogen cycle

By garikaib|2025-02-12T09:03:20+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Nitrogen fixing roots in legumes. Image credit MediaWiki ZIMSEC O Level Combined Science Notes: The nitrogen cycle

Nitrogen makes up 79% of the atmosphere
Animals cannot absorb Nitrogen as a gas
They absorb it indirectly usually as part of food
Recycling of nitrogen is carried out […]

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Experiment: the cooling curve of naphthalene

By garikaib|2025-02-12T09:14:24+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Cooling naphthalene ZIMSEC O Level Combined Science Notes: Experiment: the cooling curve of naphthalene

Materials: test tube, naphthalene, thermometer, hot water, burner, stand, clamp

Be careful as naphthalene vapour is poisonous: you can wear a breathing mask to reduce the risk of you inhaling the vapour

Method

Fill a test tube with naphthalene until […]

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Experiment: Heating metals in air

By garikaib|2025-02-12T09:32:58+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Burning metals in air, Magnesium oxide. Heating metals in air, Magnesium oxide. ZIMSEC O Level Combined Science Notes: Experiment: Heating metals in air

Aim: To heat metals in air and observe and record the process and results

Materials: magnesium, zinc, iron, copper, tongs, burner

Method

Exam the metals and take note of their appearance before heating […]

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Experiment: The properties of acids

By garikaib|2025-02-12T09:00:53+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Universal paper can be used to test the acidity of a solution. Image credit MediaWiki ZIMSEC O Level Combined Science Notes: Experiment: The properties of acids