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Grade 7 Term 2 exams > science > Flashcards

science Flashcards

1
Q

What is the definition of the word ‘sphere’

A

a round, solid figure

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2
Q

What does the prefix “bio” mean?

A

life

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3
Q

What is the biosphere?

A

The place where life exists on planet earth

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4
Q

What are the three components that form part of the biosphere?

A

the atmosphere,
the lithosphere
the hydrosphere

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5
Q

what are the elements of the lithosphere?

A

soil
rocks
sand

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6
Q

what are the elements of the hydrosphere?

A

all the water on earth, in all its forms (liquid, solid and gas)

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7
Q

What does the atmosphere consist of?

A

All the gases

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8
Q

What are the three most important gases in the atmosphere?

A

Oxygen
Nitrogen
Carbon Dioxide

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9
Q

What word is used to describe something to do with water?

A

Aquatic

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10
Q

What word would be used to describe organisms that live in the ocean or salt water?

A

Marine

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11
Q

What would a marine biologist study

A

the life of organisms in the ocean

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12
Q

What are the 7 life processes of all living organisms?

A

Movement
Respiration
Sensitivity
Growth
Reproduction
Excretion
Nutrition

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13
Q

What is cellular respiration?

A

The process where organisms release energy from their food

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14
Q

What is the meaning of the word “sustain”?

A

To keep something alive or in existance

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15
Q

What is the meaning of the word “sustainable”?

A

Something that is able to continue to exist for a long period of time

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16
Q

What are the requirements of living organisms in order to sustain life?

A

energy
gases
water
soil
favourable temperatures

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17
Q

Where do plants get there energy from?

A

The sun

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18
Q

Where most organisms (other than plants) get their energy from?

A

the food they eat (such as plants and other animals)

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19
Q

What do all living things require for cellular respiration?

A

oxygen

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20
Q

___?_____ is used to release energy from nutrients, and ___?______ and _______?_____ is produced as a waste product of respiration?

A

Oxygen is used to release energy from nutrients, and
Water and carbon dioxide is produced as a waste product from respiration.

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21
Q

What gas do plants require to photosynthesise?

A

Carbon dioxide

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22
Q

What gas do plants excrete?

A

Oxygen

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23
Q

What gas do humans excrete as a waste product when they breathe out?

A

Carbon dioxide

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24
Q

What do most plants depend on for support, water and minerals?

A

soil

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25
Q

Plants that do not grow in soil, such as mosses and orchids are called….

A

epiphytes

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26
Q

Where do epiphytes get their minerals and water from?

A

The air and rain

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27
Q

Explain why Earth is said to be in the solar systems “Goldilocks zone”.

A

It is neither too close nor too far from the sun, therefore, not too hot nor too cold and has favourable temperatures to sustain life

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28
Q

What is a hypothesis?

A

An OBSERVATION and EDUCATED GUESS on what the OUTCOME will be on an INVESTIGATION

The hypothesis is stated BEFORE starting the investigation and must be written in the FUTURE TENSE.

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29
Q

If you are wanting to investigate if eating a lot of sugar will make you gain weight? What kind of variable would the amount of sugar you eat be? Explain why?

A

The amount of sugar you eat will be an INDEPENDANT VARIABLE
because
you are IN CONTROL of HOW MUCH sugar you would eat.

An INDEPENDENT VARIABLE is a variable that you are IN CONTROL of.

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30
Q

In an investigation to see if eating a lot of sugar would make one gain weight, what would be the DEPENDENT VARIABLE, and why?

A

The dependent variable would be the thing that I am OBSERVING in the investigation - HOW MUCH weight I am gaining or losing.
It will change DEPENDING on the independent variable.

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31
Q

Explain what a controlled variable is.

A

The variable that stays the same in each test in order to follow out a fair test.

EG. Each participant must do the same exercise but consume different amounts of sugar.

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32
Q

Each organism is able to survive in their environment because they have acquired the characteristics for them to thrive in that particular environment, we say they have

A

ADAPTED to their environment.

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33
Q

What term describes the great variety of living organisms on Earth and their varied habitats?

A

biodiversity

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34
Q

Describe the grouping system that the Greek philosopher, Aristotle came up with 2400 years ago.

A

He divided all organisms into either plant or animal.
He then divided all animals into - with blood and without blood.
Lastly he divided the animals into 3 groups: walkers, flyers and swimmers.

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35
Q

Did Aristotle’s grouping system work?

A

No

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36
Q

Describe the classifying system that Carl Linnaeus developed in the 1700’s.

A

He classified organisms according to:
similarities
functions
and relationship with other organisms

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37
Q

What five kingdoms are all living organisms divided into?

A

Animals
Plants
Fungi
Protists
Bacteria

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38
Q

What kingdom do humans belong to?

A

Animal kingdom

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39
Q

The kingdom “bacteria” is also often referred to as….

A

Monera

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40
Q

Each kingdom is divided into smaller and smaller groups called….
divide this group into the smaller groups that follow

A

Kingdom - Phylum - Classes - Order - Family - Genus - Species

(Remember: King Phil Cuts Open Five Green Snakes)

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41
Q

What does “Binomial nomenclature” mean?

A

Calling things by two names.
The common name and the scientific name.
The scientific name would refer to the genus that the organism belongs to plus the species within the genus.

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42
Q

The scientific name for which animal is Loxodonta africana?

A

An elephant

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43
Q

Why are human beings also called Homo sapiens?

A

They belong to the Genus - Homo and the species “sapiens.

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44
Q

In what ways would we compare plants?

A

The way that they move
What and how they get their food or nourishment
How they reproduce

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45
Q

Mushrooms, truffles, yeast and morels are all examples of…

A

fungi

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46
Q

Why does fungi play an important role in our biosphere?

A

They are decomposers and break down dead ORGANIC matter and
return nutrients to the soil for plants to use.

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47
Q

Organisms that cannot be seen with the naked eye are called…

A

microscopic

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48
Q

What are the 2 distinct groups of the animal kingdom,
name and describe these two groups.

A

Vertebrates - Animals with back bones.
Invertebrates - Animals without back bones.

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49
Q

What type of skeleton do vertebrates have?

A

An endoskeleton (a skeleton INSIDE the body)

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50
Q

Invertebrates are divided into 5 phyla. Name them:

A

Sea Sponges
Jelly Fish
Round Worms
Molluscs
Arthropods

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51
Q

What phylum do vertebrates belong to?

A

Chordata

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52
Q

What percentage of animals are vertebrates?

A

2%

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53
Q

What are the 5 classes of vertebrates?

A

Fish
Amphibians
Reptiles
Birds
Mammals

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54
Q

Fish are divided into two groups. Namely…

A

Cartilaginous Fish - (skeletons made of cartilage)
Bony Fish - (skeletons made of bone)

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55
Q

Is a whale shark a whale or a fish?
Give 2 intersting facts on it.

A

It is a whale.
It is the largest fish in the world and
it only eats plankton

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56
Q

Give an interesting fact about seahorse.

A

The male seahorse becomes pregnant.
The female squirts her eggs into the male’s puch, which he ferilizes and incubates until they hatch.

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57
Q

Explain what is meant when saying, “reptiles are ectothermic”

A

Reptile cannot regulate their own body temperature and depend on the environment for heat.

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58
Q

What is the difference between turtles, terrapins and tortoises?

A

Turtles live in salt water (the ocean)
Terrapins live in fresh water
Tortoises live on land and do not swim

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59
Q

Explain the meaning of the term “endothermic”

A

Animals that are able to maintain their body temperature at a constant level.

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60
Q

describe the characteristics of mammals

A

All mammals are vertebrates
Almost all mammals are endothermic
Mammals give birth to live young and feed them milk
Mammals have hair on their bodies
Mammals have teeth
Mammals breath using their lungs

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61
Q

Why do Cheetahs hunt during the day?

A

There is less chance of them losing their catch to larger cats who hunt at night.

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62
Q

Name 2 characteristics of arthropods.

A

All arthropods are invertebrates.
They also have jointed (segmented) legs

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63
Q

Which animal is responsible for the most human deaths each year

A

the mosquito

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64
Q

Which animal is the largest land-living arthropod on earth?
Why is it called that?

A

The coconut crab
It can crack coconuts with its pincers

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65
Q

Which animals belong to the group of Molluscs?

A

Slugs
snails
squid
Octopuses
mussels
oysters
other soft bodied animals

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66
Q

How can we easily classify plants?

A

The shape and size of their leaves
If they have flowers and the shape of their petals
The length and depth of their roots
Their type of root system

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67
Q

Their are two distinct groups of plants referring to how they reproduce, name these two groups.

A

Plants with seeds
Seedless plants

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68
Q

How do ferns, mosses and algae reproduce?

A

They produce spores.

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69
Q

Explain what Linchen is.

A

Linchen is actually two different organisms growing together.
fungus and green algae.
The fungus absorbs water from the environment and provides an environment for the algae to grow.
The green algae photosynthesis and provides food for itself and for the fungus.

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70
Q

Plants that produce seeds in flowers are called….

A

angiosperms

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71
Q

Plants that produce seeds in cones are called….

A

gymnosperms

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72
Q

Flowering plants are divided into 2 groups: called:

A

monocotyledons - bears a single seed leaf
dicotyledons - bears 2 seed leaves

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73
Q

What do all angiosperm plants have in common?

A

roots
stems
leaves
flowers
fruits
seeds

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74
Q

There are two basic ways in which reproduction can take place.. name them:

A

Asexual reproduction - the parent organism does not need to mate
sexual reproduction - 2 parent organisms mate and their DNA combine.

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75
Q

The male part of the flower is called the…

A

stamen (includes the anthers and filament)

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76
Q

What does the stamen produce?

A

Pollen

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77
Q

What is the role of the filaments?

A

They are stalk like structures that support the anthers

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78
Q

What is the female organ of the plant called?

A

The pistil (which includes the style and ovary)

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79
Q

Which part of the plant become seeds after fertilisation?

A

The ovules

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80
Q

Which part of the plant receives pollen during fertilisation

A

The stigma

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81
Q

A long tube that connects the stigma with the ovary and the ovules is called…

A

The style

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82
Q

What is pollination?

A

The process where pollen from the stamen is transferred to the stigma of the flower.
Fertilisation occurs and the plant is able to produce seeds or fruit.

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83
Q

How are flowers able to be pollinated?

A

Either by wind or animals such as bees and butterflies drink the nectar from flowers, moving pollen from one flower to another.

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84
Q

What is the difference between fruits and vegetables?

A

Fruits are ripened ovaries of flowering plants and contain seeds.
Vegetables are other parts of the plants, such as their leaves, roots and stems.

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85
Q

is a pumpkin a fruit or vegetable?

A

a fruit. (It is the ripened ovary and contains seeds)

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86
Q

Name different ways plants disperse theirs seeds.

A

Gravity
Animals
Explosive force
Wind
Water

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87
Q

How do humans reproduce?

A

When the sexual organs reach maturity, the sperm from the male combines with the egg cell from the female. The DNA from the parents is combined.

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88
Q

Explain the physical changes in human beings during puberty.

A

The sexual organs start to mature
Pubic hair starts to grow on the genitals
Females will start secreting hormones, menstrual bleeding will occur and become fertile. (able to reproduce)
Males will start producing sperm in their testicles which is able to fertilise the egg in females.
Body shape changes such as widened hips, increased body fat and enlarged breasts in females,
Males bones and muscles increase in size.
Body odour and acne as there is changes in hormones and skin produces more oils

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89
Q

The green colour in plants is from something called….

A

chlorophyll

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90
Q

What are three classes of arthropods?

A

Insects
Arachnids
Crustaceans

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91
Q

What three parts are all insects bodies made up of?

A

The head
The thorax
The abdomen

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92
Q

Describe the legs of insects

A

All insects have 6 jointed legs
(3 pairs of jointed legs)

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93
Q

How do insects sense their environment?

A

They have a pair of antennae to sense their environment

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94
Q

Give three examples of arachnids

A

Spiders
Ticks
Scorpions

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95
Q

Are spiders vertebrates or invertebrates?

A

invertebrates

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96
Q

What two parts are arachnids bodies divided into?

A

cephalothorax
abdomen

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97
Q

Describe the legs of arachnids

A

They have 4 pairs of jointed legs
(8 legs altogether)

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98
Q

How many eyes do arachnids have?

A

8

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99
Q

What do arachnids eat?

A

Arachnids are mostly carnivores

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100
Q

What is a scavenger?

A

An animal that does not hunt but eats animals that are already dead

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101
Q

A plants root system that has many short roots is called….

A

fibrous root system

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102
Q

Describe a tap root system

A

One long main root with shorter roots coming out of the sides of the main root

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103
Q

Give three differences between monocotyledon and dicotyledon plants

A

Mono - 1 cotyledon / Di - 2 cotyledon
Mono - flower parts are in 3’s or multiples of 3
Mono - long strap like leaves, parallel veins /
Di - leaves of many shapes - branch like veins
Mono - stems stay / Di - stems harden as plant ages
Mono - fibrous roots / Di - Tap root

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104
Q

What do you call any method that is used to prevent pregnancy

A

contraception

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105
Q

What needs to take place in a flower before fertilization is possible?

A

pollination

106
Q

What is it called when a male sex cell fuses with a female sex cell?

A

fertilization

107
Q

The female sex cells that are found inside the ovary of the flower are called the ….?

A

ovules

108
Q

What is pollination?

A

The transfer of pollen from the anther in a flower to the stigma in a flower

109
Q

Give 2 examples of wind pollinated plants

A

mielies
grasses

110
Q

What is the hormone called that causes puberty in males

A

testosterone

111
Q

What is the hormone that causes puberty in females?

A

Oestrogen

112
Q

What are the three main parts of the female reproductive system?

A

The ovaries
The uterus
The vagina

113
Q

Where are the egg cells stored in the female reproductive system?

A

The ovaries

114
Q

What are the egg cells in the female reproductive system called?

A

The ova

115
Q

When does the female produce egg cells?

A

She is born with them

116
Q

How often do females release an unfertilized ovum?

A

About every 28 days

117
Q

What is the space inside a woman’s body where a baby grows called?

A

The uterus

118
Q

Where is sperm made?

A

In the male’s testes

119
Q

What is the scrotum?

A

The bag outside the males body where the testes are held

120
Q

How are the testes connected to the penis?

A

By a long thin tube

121
Q

How does sperm leave the body?

A

Through the penis

122
Q

How long does pregnancy usually last in the female human?

A

40 weeks / 9 months

123
Q

For the first 2 months a developing baby is called….

A

an embryo

124
Q

What is a developing baby called after the first 2 months?

A

A foetus

125
Q

Where does a developing foetus get its food and oxygen from?

A

Its mother

126
Q

What happens during labour?

A

The baby turns itself so that the head is pushing down on the cervix.
The strong muscles in the uterus push the baby out through the vagina

127
Q

What happens if a mother is unable to birth her baby naturally?

A

An operation called a caesarian, where doctors will cut open the mothers stomach and uterus to take the baby out

128
Q

How does one avoid pregnancy after puberty?

A

Choosing not to have sex
Using contraceptives such as condoms or the contraceptive pill.

129
Q

What is menstruation and why do females have it?

A

If pregnancy does not happen , blood flows from the lining of the uterus out through the vagina.
The thick lining is needed for a fertilized egg to attach to, to become pregnant.

130
Q

Is contraceptive 100% effective?

A

No

131
Q

What is the ONLY way a female will not become pregnant?

A

By not having sexual intercourse

132
Q

What can be other consequences of having unprotected sex?

A

The danger of getting a STD - sexually transmitted disease, such as
HIV,

133
Q

What is AIDS?

A

Acquired Immune Deficiency Syndrome caused by the HIV virus.
The disease attacks the immune system which helps the body fight illness and infection.
When the immune system cells drop below a certain level the person will be diagnosed with AIDS.
There is no cure for HIV or AIDS.

134
Q

How is HIV and AIDS transmitted from one person to another?

A

Through unprotected sexually intercourse. (not using a condom)
Infected blood entering another persons body.
From an infected mother to child during child birth or breastfeeding

135
Q

How is HIV or AIDS NOT transmitted?

A

Sweat, tears and vomit
Touching, Kissing and hugging
Mosquitos
Sharing knives, forks and cups

136
Q

Can you tell if someone has an STD (sexually transmitted disease) by looking at them?

A

No

137
Q

An illness where the body cannot break down sugar.

A

Diabetes

138
Q

A condition where there is a shortage of red blood cells in your body, which causes tiredness and weakness

A

Anaemia

139
Q

What are genes?

A

Genes are found inside the chromosomes inside cells of the body. They carry information about your ancestors and determine which traits you will inherit, such as eye colour, height, allergies and illnesses, etc

140
Q

Can a history of disease in your family put you at greater risk of getting the same diseases? (such as diabetes, heart conditions, cancers etc)

A

Yes

141
Q

What is matter?

A

Matter is the term for anything that has mass and takes up space

142
Q

Able to bend easily without breaking

A

flexible

143
Q

What is boiling point?

A

The point where a material changes from a liquid to a gas

144
Q

What is melting point?

A

The point where a material changes from a solid to a liquid

145
Q

Unable to be bent or forced out of shape

A

rigid

146
Q

The strength of an object that stops it from being crushed or change shape when being pushed or squeezed

A

comprehensive strength

147
Q

What is tensile strength?

A

The strength of an object that prevents it from breaking apart when being pulled apart

148
Q

What is conductivity?

A

How easily an object or material allows heat or electricity to flow through it

149
Q

A substance that does not allow heat or electricity to flow through it?

A

Insulator

150
Q

What is greenhouse gas?

A

A gas like carbon dioxide that traps heat in the atmostphere

151
Q

What does it mean if something is biodegradable?

A

It can be broken down / decomposed by bacteria

152
Q

What does thermal mean?

A

relates to producing or using heat

153
Q

Everything around us is made up of….

A

matter

154
Q

In what forms can matter be?

A

liquid, solid or gas

155
Q

We chose materials for certain things depending on their physical properties, such as their:

A

Strength
Flexibility
Melting point
Boiling point
Electrical conductivity
Heat conductivity

156
Q

Why does water have a different boiling point in Johannesburg and Durban?

A

Because Johannesburg has a lower air pressure

157
Q

Do all substances have the same boiling point or melting point?

A

No

158
Q

How does electricity move?

A

By electrical current

159
Q

Which metal is a good conductor?

A

copper

160
Q

What material is a good insulator?

A

plastic

161
Q

What material would be a good material to make a cooking pot out of and why?

A

Stainless steel, because it is a good thermal conductor and has a high melting point.

162
Q

What would be a good material to make a cooking pots handles out of and why?

A

Plastic, does not conduct heat so will not be too hot to pick the pot up

163
Q

What do we call the physical property that describes how something feels when you touch it?

A

texture

164
Q

What are 5 words that would describe the properties of a material?

A

Smooth / Rough / Soft / Hard
Expensive / Cheap / Colourful
Durable / Rigid / White / etc

165
Q

Name 5 natural resources

A

Grass
Stone
Gold Ore
Cotton Plant
Trees
Coal

166
Q

Name 5 processed materials or products

A

Tyres
Table
Glass
Oil
Paper
ETC

167
Q

What do we call something that should NOT change in a fair test.

A

A constant

168
Q

What do we call something that we change in a fair test?

A

A variable

169
Q

What is a fair test?

A

It is a controlled test, experiment or investigation to answer a question

170
Q

What does a scientist always start a fair test with?

A

A question that needs an answer

171
Q

Why do we only change one variable at a time when doing a fair test

A

Changing one variable at a time will give an accurate answer

172
Q

How many variables and how often should they be changed in a fair test?

A

One at a time

173
Q

What is mining?

A

The process of taking precious minerals or resources from the Earth

174
Q

Why is mining harmful to the environment?

A

Often, chemicals are used in the process of mining, which end up in water supplies.
The chemicals are harmful to plants, animals and humans.
Dust that blows off the mines is harmful to the people who live nearby.
Mining requires a lot of energy, therefore a lot of coal and oil needs to be burnt, releasing poisonous gases into the environment
The poisonous gases get trapped inside the atmosphere, causing the planet to become hotter. We call these gases Greenhouse gases.

175
Q

What are plastics made of?

A

Chemicals called polymers

176
Q

Why are plastics a problem?

A

Plastics are NOT biodegradable and litter our environment.
When plastics are burnt; it releases harmful chemicals into the environment
Many plastics end up in the ocean and kill fish and birds

177
Q

What is the name of the main electricity supplier in South Africa?

A

Eskom

178
Q

What are the pros (positives) of mining?

A

Mining provides many jobs for people and
raw materials to export overseas.
We are able to manufacture goods from the raw materials that are useful to us and to sell and export.

179
Q

Why is plastic useful to us?

A

It is cheap
strong
easy to shape
light weight

180
Q

What processed material is responsible for most litter

A

plastic

181
Q

What processed material is responsible for most litter

A

plastic

182
Q

Why is their a government tax on plastic shopping bags?

A

The government is trying to encourage people to use reusable shopping bags to prevent more waste and litter.

183
Q

Name one fossil fuel that plastic is made from

A

oil

184
Q

How long does it take plastic to break down?

A

thousands of years

185
Q

What is a mixture

A

When two or more substances with DIFFERENT physical properties are mixed together

186
Q

Small parts that make up matter are called…

A

particles

187
Q

Explain the definition of the word ‘dissolve’

A

When the particles of a SOLID substance spread BETWEEN the particles of a LIQUID so that you can no longer tell the two substances apart.
The solid has dissolved into the liquid.

188
Q

A solid that does NOT dissolve into a liquid is…

A

insoluble

189
Q

What is a pure substance?

A

A substance that is made up of only ONE kind of particle

190
Q

The method used to seperate a solid from a liquid using a filter is called…

A

filtration

191
Q

What is a solution?

A

A mixture made up of a solid dissolved into a liquid.
EG. Sugar dissolved into water is a sugary water solution

192
Q

What is the substance that is dissolved into the liquid called.
(eg. the sugar that is dissolved into water)

A

A solute

193
Q

What is a solvent

A

The LIQUID that a solid is dissolved into

194
Q

What is evaporation?

A

The process where a liquid changes into a gas.
The liquid is heated and evaporates.

195
Q

How can a solute be separated from a solvent.

A

Through evaporation

196
Q

A method of separating two liquids through different boiling points is called…

A

distillation

197
Q

What method is used to purify a liquid?

A

distillation

198
Q

What is condensation?

A

The change of state of a gas to a liquid.
This normally happens when a gas is cooled.

199
Q

A scientific method of separating a mixture into two different parts using dyes and machines to process the mixture at different speeds to separate them is called….

A

chromatography

200
Q

Taking waste and turning it into something useable is called…

A

recycling

201
Q

Waste that comes from plants or animals and can be broken down naturally by decomposers is called…

A

organic waste

202
Q

A place where our waste is taken and buried is called …

A

A landfill

203
Q

What is methane?

A

A greenhouse gas that is made by rubbish which is breaking down landfills

204
Q

What gases are found in the air that we breathe

A

Oxygen
Nitrogen
Carbon dioxide

205
Q

Is the air that we breathe a pure substance or a mixture?

A

A mixture

206
Q

In a sugar, water and salt solution, what are the the solutes?

A

sugar and salt

207
Q

In a sugar, water and salt solution, what are the the solutes?

A

sugar and salt

208
Q

What would be a suitable method of separating maize seeds and stones

A

hand-sorting

209
Q

What would be a suitable method of separating sand and stones?

A

sieving

210
Q

Is using a magnet a suitable method for separating paper and plastic? Why?

A

No, neither paper nor plastic is magnetic

211
Q

What is a good method to separate a liquid and a insoluble solid?

A

filtration

212
Q

What would be a good method to separate a solution?

A

Evaporation

213
Q

Where does water go in the process of salt harvesting?

A

It evaporates

214
Q

What speeds up the process of salt harvesting.

A

The sun and wind

215
Q

Distillation involves ____________________ of the solvent, followed by _________________________ and then ___________________________________________________________….

A

Distillation involves EVAPORATION of the solvent, followed by CONDENSATION, and then COLLECTION OF THE CONDENSED LIQUID

216
Q

What does liquid turn into when heated?

A

Water vapour

217
Q

How can we reuse organic waste?

A

We can use it to create compost, which is then used to feed plants nutrients.

218
Q

What are 5 consequences of poor waste management?

A

Pollution of our soil, which is harmful to plants and animals.
Diseases can be spread through house flies and rats that are attracted to waste.
Blocked sewages can be a health hazard and spread disease
More land is needed for landfills which could be used for farming instead
Drains become blocked causing flooding
Valuable materials are wasted instead of being recycled

219
Q

a substance that eats through certain materials like clothing and metals,
and burns the skin. We would describe this substance as…

A

corrosive

220
Q

What is meant by the term ‘Caustic’

A

able to burn or corrode organic tissue by chemical reaction

221
Q

dyes that change colour in acids and bases

A

indicators

222
Q

paper stained with a substance called litmus, used to indicate acids,
bases and neutrals

A

Litmus paper

223
Q

The four different tastes are…

A

Sweet
Salty
Bitter
Sour

224
Q

What are the little bumps on the tongue called?

A

taste buds

225
Q

Why is the sense of taste important

A

It is important for our survival as it stops us from eating food that can be harmful such as unripe or rotten food.

226
Q

What do acids / acidic foods taste like?

A

Sour

227
Q

How do acids feel on the skin?

A

Rough

228
Q

Are acids safe and why?

A

Many acids are not safe as they are corrosive

229
Q

Where would you find citric acids?

A

in citrus foods like oranges, limes and lemons

230
Q

Where would you find lactic acid?

A

In sour milk

231
Q

Where would you find carbonic acid

A

In fizzy soda drinks

232
Q

Where would you find hydrochloric acids?

A

In stomach juices

233
Q

Where would you find ethanoic acids?

A

In vinegar

234
Q

Can you name an example of a strong acid

A

hydrochloric acid or sulphuric acid

235
Q

What is the opposite of acids?

A

Bases

236
Q

Can you name the properties of bases?

A

Bases taste bitter
Bases feel slippery on the skin
Bases can be caustic and can be dangerous to taste or feel

237
Q

What are neutral substances?

A

Neither base nor acid

238
Q

Are neutrals dangerous?

A

No

239
Q

Name some things that are neutral.

A

Cooking oil
Pure water
A salt or sugar water solution

240
Q

How can you make a neutral substance?

A

By reacting an acid with a base.

241
Q

What is a pH scale?

A

It is used to measure the strength of an acid or a base.

242
Q

What is the pH of a neutral?

A

pH7

243
Q

What is the pH of an acid?

A

From pH 0 to pH 6

244
Q

What is the pH of a base?

A

From pH 8 to pH 14

245
Q

The higher the pH the stronger the….

A

Base

246
Q

Red Litmus paper turns ______________ in a base

A

Blue

247
Q

Blue Litmus Paper turns ____________ in an acid

A

Red

248
Q

What colour will the litmus paper turn if the substance is neutral?

A

The colour will stay the same

249
Q

What is the periodic table

A

A list of all the elements arranged in a table

250
Q

A pure substance that cannot be broken down is called…

A

An element

251
Q

What is an atomic number?

A

the number of protons in one atom of an element

252
Q

The total number of protons and neutrons in a nucleus is called…

A

atomic mass

253
Q

A chemical element that conducts heat and electricity…

A

a metal

254
Q

What is a semi-metal?

A

An element that shares some properties of metals and some properties of non-metals

255
Q

What is a semi-conductor

A

An element or substance that only conducts electricity when it is heated up

256
Q

Define ‘brittle’

A

breaks easily

257
Q

Define ‘ductile’

A

Can be stretched

258
Q

Define malleable

A

Can be bent and flattened or shaped

259
Q

A stable gas that does not combine with other elements is called …

A

a noble gas

260
Q

What are the rows on a periodic table called?

A

periods

Grade 7 Term 2 exams (13 decks)

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