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Transcript
Year 7 Science Revision
The topics that you will tested on on Monday 2nd December are:
• Energy resources
• Acids and alkalis
• Cells, tissues and organ systems
Revision is very important if you want to achieve your best. Our memory works by constantly using
information. Revising means we are using the information.
Useful Websites:
1. The BBC bitesize website has lots of information, activities and quizzes for you to revise from. Remember to choose the
topics you have covered in year 7!
http://www.bbc.co.uk/bitesize/ks3/science/
2. Download short revision clips to your computer or mobile phone from the following website: Be sure you use the clips
relevant to your year!
http://www.collinseducation.com/Downloads/Pages/SeriesDownloads.aspx?Level1=Primary,Secondary&SeriesTitle=Collins%20
Revision&rt=Videos
3. Test yourself using Doc Brown’s quizzes. Be sure you test yourself on the test relevant to your year!
http://www.docbrown.info/ks3science.htm
Energy Resources
Energy Resources
Energy Resources and the environment
Non- renewable energy
Also know as fossil fuels.
Examples of fossil fuels:
• coal
• oil
• gas
They are non-renewable
because they have taken
millions of year to make and
we can’t make them in our
lifetime (they will run out).
Geothermal Energy
Uses the heat energy
in the Earth to
generate electricity
+ no pollution
- Found in very few
places in the world
Wave Energy
Uses kinetic energy in
waves to generate
electricity
+ no pollution
- Needs lots of
machines to get enough
energy, look ugly
Tidal Energy
Uses the gravitational
potential energy in tides to
generate electricity
+ reliable as always two
tides a day
- Costs a lot to build a local
dam, could cause flooding
Biomass
Uses the chemical energy in
living things to generate
electricity
+ no special equipment
needed so can used in
poorer countries
- Large areas of land are
needed to grow enough
trees
Renewable energy
resources
Examples of renewable
energy resources are:
• solar power
• wind power
• tidal power
• wave power
• hydroelectric power
• geothermal power
• biomass
They are renewable
because they will not run
out like fossil fuels will in
our lifetime.
Hydroelectric
Energy
Uses flowing water
(kinetic energy) to
generate electricity
+ no pollution
- Costs a lot of money
to build a dam
Wind Energy
Uses the wind
(kinetic energy) to
generate
electricity
+ no pollution, quite
cheap and easy to
build
- Some people think
they are ugly, only
works if windy!
Solar Energy
Uses the sun (heat energy)
to generate electricity or
heat up water
+ no pollution,
renewable (the sun
won’t run out any time
soon!)
- expensive, only
works if sunny!
Nuclear Energy
Uses the chemical energy in
metals to generate
electricity
+ no harmful gases
produced
- non-renewable (uranium
will run out), produces
dangerous radioactive
waste
Recycling, Reusing, Reducing
Recycling, reusing, reducing helps the environment because it means new objects don’t have to be
made using energy resources. This can reduce pollution. Examples of what you could do are: using
reusing plastic bags, turning lights off when you don’t need them, recycling aluminium cans.
Acids and Alkalis
Acids
Hazard Symbols
Alkalis
• Acids contain the element hydrogen
(H).
• Alkalis contain a hydroxide (OH oxygen and hydrogen).
• Examples of acids in the home are
vinegar, oranges and grapefruits.
• Examples of alkalis in the home are
soaps, oven cleaners and washing
powders.
• Examples of acids in the science
laboratory are hydrochloric acid and
sulphuric acid.
Indicators
Indictors are used to say whether
liquids or solutions are acidic, neutral
or alkaline
• Examples of alkalis in the science
laboratory are sodium hydroxide,
potassium hydroxide.
Litmus paper
Litmus paper is an indicator. If in a
neutral solution it’s colour is
unchanged, it turns red in an acidic
solution and blue in an alkaline
solution.
pH scale
Acids and alkalis are corrosive and have to be used
carefully. Scientists use hazard symbols to help know
about the dangers of chemicals.
i
Highly
flammable –
easily
catches fire
h
Harmful – e.g.
when swallowed,
breathed in
Radiation –
possibly causing
DNA damage
Universal indicator can be used to measure how strong or weak an acid or
alkali is (this means it gives more information than Litmus paper). Universal
indicator is a mixture of several dyes extracted from plants. The overall
colour the indicator solution is compared with the range of colours in the pH
scale (above).
A neutral solution has a pH of 7. An acidic solution has a pH of 1 to 6 (strong
acid = 1 to 3, weak acid = 4 to 6). An alkaline solution has a pH of 8 to 14
(weak alkali = 8 to 10, strong alkali = 11 to 14).
Corrosive – attacks
and destroys living
tissues
Toxic - Can
cause death
Environmental
hazard –
substance that
is dangerous
to the
environment
Irritant– can cause
reddening and
blistering of the skin
Oxidising –
provides oxygen to
make other
substances burn
Explosive – substance
that can explode
Neutralisation
Reactions between acids and alkalis are called
neutralisation reactions. We use neutralisation
reactions to help us:
• Indigestion tablets to reduce excess stomach acid
• Farmers add lime (alkali) to soil to neutralise excess
acidity from acid rain.
•Toothpaste (alkali) neutralises acid that builds up on
our teeth.
Cells
Animal and plant cells
Specialised Cells
Cell
Function
Adaptation
Absorbs and
carries oxygen
around the body
Large cell
membrane
surface area
Carries
messages around
the body
Long and thin
Develops into an
embryo
Large and
contains lots of
cytoplasm
Fertilise the egg
Has a long tail
allowing it to
move
Red blood cell
Nerve cell
Functions of animal and plant cell parts
Part
Function (job)
Found in
animal
cells
Found
in plant
cells

Cell membrane
Controls what passes into and
out of the cell

Nucleus
Contain the genetic material
and control the cell activities


Cytoplasm
Jelly-like liquid where
important chemical reaction
take place


Egg cell
Sperm cell
Absorb water
Cell wall
Made of cellulose and
supports the cell, helping it
keep its shape

Vacuole
Contains cell sap

Chloroplasts
Contain chlorophyll which
traps light for use in
photosynthesis (where plants
make their own food)

Large cell
membrane
surface area
Root hair cell
Site of
photosynthesis
Palisade cell
Contains lot of
chloroplasts
Tissues, Organs, Systems
Tissues
Animal cells and plant cells can form tissues, like
muscle tissue. A living tissue is made from a group
of cells with a similar structure and function,
which all work together to do a particular job.
Organ Systems
An organ system is made from a group of different organs, which all
work together to do a particular job.
Circulatory System
Digestive System
Here are some examples of tissues:
heart
• muscle
• the lining of the intestine
capillaries
• the lining of the lungs
• phloem (tubes that carry dissolved sugar around
a plant)
Job: To transport blood and
substances around the body.
• root hair tissue (for plants to take up water and
minerals from the soil)
Organs
Job: To break food we eat into
smaller pieces so that we can absorb
it into our blood.
Respiratory System
Nervous System
An organ is made from a group of different
tissues, which all work together to do a particular
job.
Here are some examples of organs:
• heart
• lung
• stomach
• brain
• leaf
• root
Contains: nerves, brain, spinal cord.
Job: To carry messages to
difference part of the body
Contains: nose, trachea, lungs, bronchus,
bronchioles and alveoli
Job: To bring oxygen into your body, and
remove the carbon dioxide from your
body.