February 2025

Suspension bridge

By |2025-02-12T09:32:16+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

The Hong Kong Bridge. Image credit plus.maths.org The Hong Kong Bridge. Image credit plus.maths.org ZIMSEC O Level Combined Science Notes: Suspension bridge

  • Old suspension bridges were usually built using rope/vegetable fibre
  • The ropes could withstand tension forces while they were new but they would quickly deteriorate
  • Suspension bridges are usually constructed […]
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Pumps: Blair pump

By |2025-02-12T09:05:51+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

The blair pump The blair pump ZIMSEC O Level Combined Science Notes: Pumps: Blair pump

  • The pumped was first developed in 1976
  • The design was further refined at the Blair Research Laboratory in Harare
  • Various models have been subsequently designed and made
  • Cumulating in the famous Type B bush pump
  • It is popularly known […]
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The purification of Water

By |2025-02-12T09:08:32+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Water Purification Plant. Image credit cdrmaguire.com Water Purification Plant. Image credit cdrmaguire.com ZIMSEC O Level Combined Science Notes: The purification of Water

  • Large residential areas such as Harare, Chitungwiza and other urban establishments are supplied with piped running water
  • This water is treated so that it is safe to drink and […]
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Chlorophyll and Photosynthesis

By |2025-02-12T09:41:18+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

A green leaf. Image credit wallconvert.com A green leaf. Image credit wallconvert.com ZIMSEC O Level Combined Science: Chlorophyll and Photosynthesis

Aim: To test whether chlorophyll is necessary for photosynthesis.

Materials

Two plants with variegated leaves i.e. leaves that are partly green, permanent marker  and equipment for the start test. A [...] </p srcset=

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The enzyme amylase

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

Starch food. Image credit eurofins.com 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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Experiment: Testing for osmosis in living plants

By |2025-02-12T09:37:52+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Peeled potatoes. Image credit alsalamgroup.com Peeled potatoes. Image credit alsalamgroup.com ZIMSEC O Level Science Notes: Experiment: Testing osmosis in living plant tissue

Materials: potatoes, knife or blade, distilled water, sugar or salt, three containers,weighing balance.

Method

osmosis_plants

Prepare three pieces of peeled potato. Each block must be […]

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The differences between wind and insect pollinated flowers

By |2025-02-12T09:26:15+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Maize flower close up. image credit freeimagescollection.com Maize flower close up. image credit freeimagescollection.com ZIMSEC O Level Combined Science Notes: Reproduction in plants: The differences between wind and insect pollinated flowers

  • Not all flowers are  exactly the same
  • Some flowers have adapted to be pollinated by wind
  • Others have adapted in a way […]
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Experiment: Testing the alkalinity/acidity of the soil

By |2025-02-12T09:45:43+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Testing the PH of soil. Image credit blogspot.com Testing the PH of soil. Image credit blogspot.com ZIMSEC O Level Combined Science Notes: Testing the alkalinity/acidity of the soil

Materials: Universal indicator/PH paper/PH Test meter, distilled water, test tubes, soil samples

Method

  1. Place the soil samples into test tubes to a height of about […]
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