Year 8 Science

Christmas Exam

Safety in Science

Make sure you follow all safety rules when in the lab for your own safety and the safety of others.

Hazard Symbols

Hazard Symbols are used to quickly identify dangerous Chemicals in the lab. They are easily identifiable and have universally understood pictures, especially if they are used for a concentrated Acid or Alkali:

Weak Acids or Alkalis with have a Caution (Health Hazard) symbol !

Stronger more concentrated Acid or Alkalis will have a Corrosive symbol.

Science Apparatus

Measuring Apparatus - Uses and Units

Investigating Science

Variables are things that can change during an experiment. There are 3 main types of variables in any experiment. This experiment is investigating how changing the volume of water affects growth.

· Independent Variable – This is the one thing that is changed each time during an investigation. Eg the volume of water is the only thing changed in this investigation.

· Control Variables – These are things that must be kept the same during the investigation. This provides a ‘fair test’. Eg, type of plant, pot size, soil type, amount of light.

· Dependent Variable – This is what is measured during the investigation. Eg. The height the plant grows.

To make any investigation more Reliable, the investigation should be Repeated as many times as possible.

Revision Notes - Cells

Cells

All living things (organisms) are made up of cells. Cells are very small. Cells can be magnified by observing them under a microscope.

A stain (Iodine) can be added to the specimen on slide to help make the cell visible.

The slide is placed on the stage and viewed through the eyepiece lens.

The stage is moved up and down using the Focus wheel to sharpen the image.

Animal v Plant Cells

Animal and Plant cells all have at least

a Nucleus, Cell Membrane and Cytoplasm.

Plant cells can have 3 extra organelles that Animal cells do not have; Vacuole, Cell Wall and Chloroplasts.

Cell Specialisation

Cells have particular shapes and parts to help them do their job in the Animal or Plant.

This makes them specialised:

· Cells in the windpipe might have Cilia to help move mucus and dust out of the lungs. (bottom left)

· Cells in leaves have Chloroplasts to make food in Photosynthesis. (bottom right)

Revision Notes - Levels of Organisation

Animals and Plants are multicellular organisms – they are built from many cells. There is a level or organisation from Cell up to Organism:

Cells build Tissues, Tissues build Organs, Organs build Organ Systems and Organ Systems all work together to build a living Organism.

Organ Systems

As cells have specialised shapes and jobs, they build organs and organ systems with their own specific shapes and jobs. Here are the main organ systems in the Human Body and their Function:

Skeletal System – Built from Bone tissue for Structure and Support.

Muscular System – Built from Muscle tissue for Movement.

Digestive System – Built from many different organs for the breakdown and absorption of food into the blood.

Respiratory System – Built from Lung tissue for Breathing.

Nervous System – Built from Nerve tissue for Co-ordination and Control.

Circulatory System – Built from Heart and Blood Vessels for transport of blood around body.

Other systems include:

Reproductive System – built from Male Testes and Female Ovaries.

Excretory System – built from the Kidneys and Bladder. (right diagram)

Revision Notes - Solids, Liquids & Gases

All matter is made from very small particles (atoms). The particles are arranged in such as way that they can form Solid, Liquid or Gas materials. These are the 3 States of Matter:

Depending on their arrangement of particles; Solids, Liquids & Gases can have particular properties, as seen in the table.

By adding or removing energy (heat) the particles in can gain or lose energy and change state from one state to another.

Some substances can exist in all 3 states. Water can be in the form of Solid Ice, Liquid Water or Gas Steam.

These 3 states can change back and forward by adding heat or cooling.

· Water Freezes below 0oC

· Ice Melts above 0oC

· Water Boils (evaporates) at 100oC

· Steam Condenses below 100oC

On a warm day water evaporates and forms water vapour which condenses to form clouds.

Revision Notes - Printable Copy

Year 8 Science Assessment 1 - Xmas Revision Notes New.pdf

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