Methods of food Preservation
ZIMSEC O Level Combined Science Notes: Methods of food Preservation
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February 2025
Rhythm/Natural Family Planning
Image credit atlantablackstar.com ZIMSEC O Level Combined Science Notes:Contraception:Rhythm/Natural Family Planning
How it works
- Various techniques are used:
- Learn to recognise the fertile periods in the menstrual cycle and avoid sex during that period
- Several techniques are used to identify this fertile period:
- The temperature method is when […]
- The temperature method is when […]
Water closet/Flush toilet
Water Closet. Image credit rakbathware.com ZIMSEC O Level Combined Science Notes: Water closet/Flush toilet
- Is part of the water borne sewage
- This means that wastes from the toilet are carried by water to a place where it is processed
- This is very common in urban homes […]
Factors,Inputs and outputs of photosynthesis
ZIMSEC O Level Combined Science: The test for starch
- The diagram below shows the requirements and outputs of photosynthesis.
- We have already looked at what photosynthesis is here
The requirements of photosynthesis
- As already mentioned the food making process in plants is called photosynthesis.
- In order for a plant to […]
The digestion process
The digestive system of a human being. Image credit MediaWiki ZIMSEC O Level Combined Science Notes: The digestion process
- Food is broken down in the alimentary system from large pieces/molecules into smaller molecules.
- The food most mammals ingest is in large pieces e.g. leaves, grass, cake, meat etc.
- All […]
Examining the structure of stems and roots
Tree roots. Image credit lawnsite.com ZIMSEC O Level Combined Science Notes: Examining the structure of stems and roots
Aim: To examine the structure of roots and stems under a microscope/bio-viewer.
Materials: Bio-set and bio-viewers, microscopes, prepared slides of root and stem sections.
Method ![Structure of roots. [...]
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Blood and its properties
The composition of blood. ZIMSEC O Level Combined Science Notes: Blood and its properties
- Blood circulating in a mammal constitutes about 7.5% of its body mass.
- An average human weighing between 68-80 kgs has about 4.7 to 5 litres of blood in their body
- Blood can be considered as tissue […]
Experiment: Comparing the water holding capacity of the soil
Testing the water holding capacity of soil ZIMSEC O Level Combined Science Notes: Comparing the water holding capacity of the soil
Materials: Measuring cylinders, funnels, cotton wool, water, dry soil samples, stop watch/clock
Method
- Set up your apparatus as shown in the diagram
- Add known volume of water
- Measure […]
Structure of atoms: protons,electrons and neutrons
The atomic structure of carbon. Image credit ucsb.edu ZIMSEC O Level Combined Science Notes: Structure of atoms: protons,electrons and neutrons
Protons and neutrons
- The protons are the positive charge in the nucleus of an atom
- The neutrons are also in the nucleus but they have […]
Loading a beam
Loading a beam ZIMSEC O Level Combined Science Notes: Loading a beam
- When a beam is loaded it will bend
- Bending movement creates stress
- The top of the beam is compressed and the underside is stretched
- This is because there are compressive forces at the top and stretching/tensile forces at the underside
- If […]