February 2025

The structure of the leaf and photosynthesis

By |2025-02-12T08:56:55+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

The external structure of the leaf. Image credit passmyexams.co.uk The external structure of the leaf. Image credit passmyexams.co.uk ZIMSEC O Level Combined Science Notes: The structure of the leaf and photosynthesis

  • The leaves are the main organs of photosynthesis.
  • Their structure is adopted for the process of photosynthesis.
  • Veins-vein networks support the physical structure […]
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The respiratory system and gaseous exchange

By |2025-02-12T09:34:21+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Human respiratory system. Image credit anatrik.org Human respiratory system. Image credit anatrik.org ZIMSEC O Level Combined Science Notes: The respiratory system and gaseous exchange

  • The respiratory system is responsible for gaseous exchange and breathing so that oxygen is taken into the body and carbon dioxide is released from the body.
  • Mammals including […]
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Reproduction in plants: Comparing different plant seeds and fruits

By |2025-02-12T09:31:29+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Different fruits showing their seeds. Image credit blogspot.com Different fruits showing their seeds. Image credit blogspot.com ZIMSEC O Level Combined Science Notes: Reproduction in plants: Reproduction in Plants:Comparing different fruits and seeds  

Materials: a variety of fruits

Method

  1. Collect and gather different types of fruits that are found in your area
  2. Group the fruits […]
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Experiment: Testing for the presence of micro-organisms in soil

By |2025-02-12T08:57:22+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Testing for organisms in the soil. Testing for organisms in the soil. ZIMSEC O Level Combined Science Notes: Experiment: Testing for the presence of micro-organisms in soil

Material:2 test tubes, lime water/bicarbonate indicator, cotton thead, corks, muslin cloth or cotton material, burner

Method

  1. Put a sample of fresh soil (about 50g mass) in a muslin […]
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Experiment:Hydrogen as a reducing agent

By |2025-02-12T09:45:03+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Experiment:Hydrogen as a reducing agent

Aim: To show that hydrogen can act as a reducing agent

Materials: hard glass test-tube with a small hole near the end, copper oxide, burner, cork with a short glass tube, rubber tube

Reducing copper using hydrogen Reducing copper using hydrogen

Method

  1. Place a spatula load […]
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Experiment: Demonstrate the effect of surface area on the rate of a reaction

By |2025-02-12T09:14:05+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

 ZIMSEC O Level Combined Science Notes: Experiment: Demonstrate the effect of surface area on the rate of a reaction

Materials: magnesium ribbon, magnesium powder, marble chips (another form of calcium carbonate), powdered calcium carbonate, 250cm3 beakers, dilute hydrochloric acid, spatula, splint

Method a

  1. Into two beakers pour an equal volume of dilute hydrochloric acid about 20cm3
  2. Add a small spatula load […]
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Extraction of copper from oxides

By |2025-02-12T09:29:40+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Extraction of copper from oxides

  • In addition to sulphides
  • Copper ore can also be in the form of oxides
  • For example Cuprite
  • Unlike withe sulphides the oxygen in copper oxides cannot be driven off by roasting
  • Copper can be yielded by using the reduction process
  • Sodium carbonate is used in the process
  • It […]
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