Year 8 Cycle 3 Science

Answer 1

A mutation is a change in the DNA sequence of a gene.

Answer 2

Mutations can lead to genetic conditions like cancer or they can lead to adaptations

Answer 3

Offspring inherit one version of each gene (allele) from each parent

Answer 4

The combination of inherited alleles leads to variation between individuals,

Answer 5

Static electricity is the build up of charge on an object due to the transfer of electrons

Answer 6

Opposite charges attract, the same charges repel

Answer 7

Circuit diagrams should be drawn with a pencil and ruler. Component symbols are used.

Answer 8

Current is the flow of electrons. Potential difference is the energy these electrons have.

Answer 9

In a series circuit, components are connected in a single loop, so the current can take only
one route around the circuit. Current is the same in all parts of the circuit.

Answer 10

In a parallel circuit, components are connected on separate branches, so the current can
take different routes around the circuit. Current is different in different pats of the circuit.

Answer 11

As resistance increases in a circuit, the current decreases.

Answer 12

Opposite poles of magnets attract. The same poles repel.

Answer 13

Electromagnets are made by wrapping wire around an iron bar and passing current through
the coil.

Answer 14

Uses of electromagnets include automatic door locks, scrap yard cranes and levitating trains.

Answer 15

Protons (+ve charge relative mass of 1) Neutrons (No charge, relative mass of 1) Electrons (–ve
charge, insignificant mass)

Answer 16

Number of protons = atomic number and Number of electrons = atomic number

Answer 17

Number of electrons = mass number - atomic number

Answer 18

Reactivity series: Magnesium → Aluminium → Zinc → Iron → lead → Copper → Silver → Gold

Answer 19

In a displacement reaction a more reactive element pushes out a less reactive element

Answer 20

Solid (s), liquid (l), gas (g), dissolved in water (aq)

Answer 21

Metal + acid → salt + hydrogen

Answer 22

Metal + water → metal hydroxide + hydrogen

Answer 23

Metal + oxygen → metal oxide

Answer 24

Combustion: fuel + oxygen → carbon dioxide + water

Answer 25

The law of conservation: matter is neither created or destroyed in a chemical reaction

Answer 26

A redox reaction occurs when both oxidation and reduction occurs

Answer 27

Thermal decomposition: chemical reaction in which a compound breaks down when heated

Answer 28

A salt can be made by reacting an acid with a metal, metal oxide or carbonate

Answer 29

A balanced diet contains the correct amount of all food groups

Answer 30

The food groups are: carbohydrates, lipids, proteins, vitamins, minerals, fibre and water

Answer 31

Malnutrition occurs when people do not eat the right amount of nutrients

Answer 32

Too little food can cause deficiency diseases or death. Too much food results in obesity which can lead to heart disease or type 2 diabetes.

Answer 33

The test for starch is iodine. A positive result is yellow/brown → black/blue

Answer 34

The test for sugar is Benedict’s solution. A positive result is blue → green/yellow/red

Answer 35

The test for protein is Biuret solution. A positive result is blue → purple

Answer 36

The test for vitamin C is DCPIP. A positive result is blue → colourless

Answer 37

The digestive system breaks down food into tiny particles which are absorbed into the blood

Answer 38

Digestive organs include the mouth, stomach, small intestine and large intestine

Answer 39

Enzymes are biological catalysts that speed up reactions including digestion

Answer 40

Enzymes (lock) only fit a specific substrate (key)