Scalar and vector quantities Scientists often make measurements. The physical quantities they measure fall into two categories: scalars and vectors. Scalar and vector quantities are treated differently in calculations. Scalar quantities A physical quantity is something that can be measured. Scalar quantities only have a magnitude or size. Examples of scalar quantities Read more…
Reproduction, the genome and gene expression The differences between sexual and asexual reproduction, the structure of DNA and its role in making proteins, mutations and their effects and how characteristics are inherited. Advantages and disadvantages of sexual and asexual reproduction Sexual reproduction involves the joining of two sex cells, or Read more…
Properties of waves Waves are one of the ways in which energy may be transferred between stores. Waves can be described as oscillations, or vibrations about a rest position. For example: sound waves cause air particles to vibrate back and forth ripples cause water particles to vibrate up and down Read more…
Terminology and definitions Convection currents Convection currents drive the movement of Earth’s rigid tectonic plates in the planet’s fluid molten mantle. In places where convection currents rise up towards the crust’s surface, tectonic plates move away from each other in a process known as seafloor spreading. Hot magma rises to the Read more…
Stars Our Sun The sun is the nearest star to earth. The sun is a bright yellow dwarf star The sun is about 4.6 billion years old. The sun belongs to the Milky Way Galaxy. Only 8.5 light-minutes away from Earth. The sun contains 98% of all the mass of Read more…
Reactants: Reactants are the starting substances in the chemical reaction. Products: Products are the substances produced in a chemical reaction. Conservation of Mass: Chemical equations show that atoms are conserved in the reaction; this is known as the conservation of mass. Total mass of products = Total mass of reactants Read more…