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Science > Year 8 Cycle 2: Mixtures & Materials, Waves and DNA & Genetics > Flashcards

Year 8 Cycle 2: Mixtures & Materials, Waves and DNA & Genetics Flashcards

(51 cards)

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1
Q

What is an element and what is a compound?

A

An element is a substance that is made of only one type of atom.
A compound is a substance made of two or more different atoms chemically bonded together

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2
Q

What is a mixture and what is a solution?

A

A Mixture is a substance with 2 or more elements/compounds present not chemically bonded.
A solution is formed when a solute dissolves into and solvent.

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3
Q

What four methods can be used to separate mixtures?

A

filtration
evaporation
distillation
chromatography

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4
Q

What is filtration?

A

Separating substances using a filter to produce a filtrate (solution) and residue

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5
Q
A
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5
Q

What is evaporation?

A

Evaporation is a way to separate a solid dissolved in a liquid by the liquid turning into a gas

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6
Q

Get ready to memorise this diagram of evaporation:

A

https://ichef.bbci.co.uk/images/ic/480x270/p0b29922.png

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7
Q

What is distillation?

A

Distillation is separating substances by boiling and condensing liquids

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8
Q

Get ready to memorise this diagram of distillation:

A

https://ichef.bbci.co.uk/images/ic/480x270/p0b51gqv.png

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9
Q

Define:
Solute
Solution
Solvent

A

Solute: the dissolved substance in a solution

Solution: mixture formed when a solute is dissolved in a solvent

Solvent: the liquid in which the solute dissolves to form a solution

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10
Q

What is chromatography used for?

A

It is used to separate different coloured substances

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11
Q

Get ready to memorise this diagram of chromatography:

A

https://bam.files.bbci.co.uk/bam/live/content/z2hcjxs/large

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12
Q

Materials: how are ceramics made and what are their properties?

A

Ceramics are made by baking a starting material in a very hot oven called a kiln. They are hard and durable.

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13
Q

Materials: what are polymers and what are their properties?

A

Polymers are very long chain molecules. They are unreactive, moldable, insulators, strong and
hard-wearing

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14
Q

What are composite materials?

A

Composite materials are made from two or more different types of material. They are synthetic and are made by a chemical process.
Composite materials are designed for specific uses and their properties complement each other.

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15
Q

What is combustion?

A

Combustion is burning a fuel in oxygen, which gives out heat energy and is called an exothermic reaction. It happens in a car engine.

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16
Q

What is a catalyst?

A

A catalyst is a substance that speeds up a chemical reaction and is not used up in the reaction.

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17
Q

Which two toxic gases are produced by car exhausts?

A

Car exhausts produce toxic gases: carbon monoxide and nitrogen oxides.

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18
Q

What are some advantages and disadvantages of new fuels?

A

Some new fuels are better for the environment. But they can be more expensive

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19
Q

What are nanoparticles?

A

Nanoparticles are extremely small structures, 1-100 nanometres (nm) in size. They have lots of
potential uses in medicine, cosmetic and electronics.

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20
Q

How are sounds made?

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A

Sounds are made by something that is shaking or vibrating

21
Q

What is a vacuum?

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A

A volume of space with no particles in.

22
Q

Explain how sound travels.

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A

A sound wave (longitudinal) is a vibration that travels through a solid, liquid or gas. The vibrations are passed on between particles. (This is the particle model of explaining sound waves)

23
Q

What is a longitudinal wave?

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A

In a longitudinal wave, the direction the wave moves and the direction of vibrations making the wave are in the same direction.

24
What is volume and how do you show it on a sound wave diagram?
Volume is the amplitude of a sound wave: how loud it is. The volume of a sound is shown by the height of the wave above the middle of the wave: a loud sound has a large amplitude.
25
What is amplitude?
The height of the wave above the middle of the wave
26
How do you show pitch on a sound wave diagram?
The pitch of a sound is shown by the frequency of the wave (how many waves there are). A high pitched sound has a high frequency.
27
What is frequency?
The number of waves travelling past a point per second.
28
Get ready to memorise the parts of the ear on this diagram:
https://bam.files.bbci.co.uk/bam/live/content/zpsrcdm/large
29
What does an eardrum do?
When a sound reached the eardrum, it vibrates and passes these vibrations to the ear bones.
30
What is up with dogs' and bats' hearing?
Dogs and Bats are examples of animals that can hear higher frequencies than humans
31
What is ultrasound?
Frequencies higher than humans can hear is called ultrasound.
32
Give some examples of uses of ultrasound.
Ultrasound is used for lots of things including in medicine (e.g. scanning to check a baby in the womb), shipping (e.g. to check the structure) and engineering (e.g. to check for defects and to monitor liquid flow).
33
What is light and how does it travel?
Light (transverse wave) is a type of electromagnetic radiation that can be detected by the eye. Light travels in straight lines and can travel through a vacuum Can you draw a light-ray diagram?
34
What is a transverse wave?
The direction the wave moves and the direction of vibrations causing the wave are at right angles
35
What is reflection?
When light (or sound) bounces off a surface.
36
What is the law of reflection?
the angle of incidence = the angle of reflection
37
Define refraction
Refraction is the bending of light as it passes through one substance to another
38
What are the seven colours of light contained in white light?
Seven colours of light in order of frequency are: red, orange, yellow, green, blue, indigo, violet
39
Why do objects appear a certain colour?
Objects appear different colours because they absorb some colours and transmit others.
40
Objects are luminous and non-luminous. What does that mean?
Luminous means they emit their own light - like the Sun, or a torch. Non-luminous objects can't emit their own light, like a mug or a hamster.
41
Get ready to memorise the labels on this diagram of the human eye:
https://bam.files.bbci.co.uk/bam/live/content/zst2v9q/large
42
What are the jobs of each part of the eye? *The ones in bold are the key ones to remember*
Cornea: Refracts light - bends it as it enters the eye **Iris: Controls how much light enters the pupil Lens: Further refracts light to focus the image onto the retina Retina: Contains the light receptors** Optic nerve: Carries impulses between the eye and the brain Sclera: Tough white outer layer of the eye. It helps protect the eye from injury
43
What is asexual reproduction?
Asexual reproduction = no fusion of gametes, one parent, identical offspring (clones)
44
What is sexual reproduction?
Sexual reproduction = fusion of gametes, two parents, variety of offspring
45
What causes variation between individuals?
Variation can be caused by genetics, environment or a combination.
46
. What are continuous and discontinuous variations in a population?
Continuous variation is a range of variation and changes gradually (e.g. height) - displayed in line graphs and bar charts with a line of best fit. Discontinuous variation is values which come in groups (e.g. eye colour) and can be shown in a chart.
47
What is DNA?
A long, twisted molecule that carries a persons genetic information
48
What is the basic structure of DNA?
DNA has a double-helix structure with 4 base pairs (A-T, G-C)
49
How was the structure of DNA discovered?
The structure of DNA was discovered by numerous scientists working together including: Wilkins, Franklin, Watson and Crick.
50
What is DNA profiling?
In DNA profiling, a person's unique DNA code can be sequenced and compared to a sample

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