science notes Archives - Free ZIMSEC & Cambridge Revision Notes

People and Energy

By garikaib|2025-02-12T09:15:19+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Construction workers require a lot of energy. Image credit nehandaradio.com ZIMSEC O Level Combined Science Notes: Experiment: People and Energy

While it is true that everyone needs energy for metabolism and daily activities
Different people have different food needs
Food requirements can […]

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Female Reproductive system

By garikaib|2025-02-12T09:33:12+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Image credit huffpost.com ZIMSEC O Level Combined Science Notes: Female Reproductive system

The diagram below shows the reproductive system of a female

Female reproductive system

Ovaries-there are two ovaries
- Their function is to produce and release ova […]

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Effects of population growth on natural resources

By garikaib|2025-02-12T09:00:15+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Environmental degradation in Epworth. Image credit newsday.co.zw ZIMSEC O Level Combined Science Notes: Population and natural resources

Environmental Effects

Soil erosion
Deforestation
Desertification
Reduced soil fertility

Social Effects

Overcrowding
Criminal activities
Immorality
Poor health services
Poor education facilities
General increase in poverty

To […]

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Light and photosynthesis

By garikaib|2025-02-12T09:39:29+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Potted plant. Image credit hotstyledesign.com ZIMSEC O Level Combined Science: The test for starch

Aim: To test whether light is required for the photosynthesis process.

Materials

A potted plant, cardboard or aluminum foil, scissors, paper clips or tape, equipment for the start test.

Method Image credit [...]
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The enzyme amylase

By garikaib|2025-02-12T09:29:26+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Starch food. Image credit eurofins.com ZIMSEC O Level Combined Science Notes: The enzyme amylase

Energy in cells is obtained by breaking down food molecules during the respiration process.
The chemical reactions involved are carried out by enzymes.
Enzyme molecules also break down food molecules in the digestive system and […]

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Water and ion uptake in plants

By garikaib|2025-02-12T09:39:01+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

The effect of loss and gain of water in plants respectively. Image credit slideshare.net ZIMSEC O Level Combined Science Notes:Water and ion uptake in plants

When plant cells are surrounded by water, the water enters by osmosis […]

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The dispersal of plant seeds

By garikaib|2025-02-12T09:29:56+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Guava fruits are juicy and the seeds are can resist digestion. Image credit plantvillage.org ZIMSEC O Level Combined Science Notes: Reproduction in plants: Reproduction in Plants:The dispersal of plant seeds

The ovary may also become fleshy and […]

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Biological components of the soil

By garikaib|2025-02-12T08:55:49+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Worms are part of the soil's biological components. Image credit wageingenur.nl Worms are part of the soil’s biological components. Image credit wageingenur.nl ZIMSEC O Level Combined Science Notes: Biological components of the soil

In addition to physical components the soil also has biological components as well
These include living plants, animals and […]

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Changes in state

By garikaib|2025-02-12T09:08:59+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Melting ice. Image credit flemox.com ZIMSEC O Level Combined Science Notes: Changes in state

When a solid item is heated the forces of attraction between the particles become weaker

as a result the particles move more quickly

The particles gain more kinetic energy
the solid item melts

[…]

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Deficiency Diseases

By garikaib|2025-02-12T09:16:24+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Iodised salt can prevent iodine deficiency ZIMSEC O Level Combined Science Notes: Deficiency Diseases

A person might suffer from a deficiency disease if their diet lacks certain essential minerals and vitamins
Two essential minerals and vitamins are:
Iodine and
Vitamins

Iodine Goitre is a [...]
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February 2025