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grade 8 science > Unit 5 final exam > Flashcards

Unit 5 final exam Flashcards

1
Q

what is the water cycle?

A

control the distribution of earth water as it evaporates from bodies of water, condenses, precipitates, and returns to those bodies of water.

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2
Q

the ability for water to disappear is a result of two common changes of state what are those?

A

Condensation and evaporation

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3
Q

what is evaporation ?

A

converts liquid water from earth’s surface into gaseous water vapour

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4
Q

what is condensation ?

A

is the change of state from a gas to a liquid,

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5
Q

what happens when gaseous vapour remains in the atmosphere?

A

its starts ti cool as it cools, water vapour condenses to form clouds.

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6
Q

what is precipitation ?

A

liquid and solid water fall from the clouds, they form snow or rain

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7
Q

what energy drives the water cycle ?

A

the suns energy

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8
Q

what eventually happen to water vapour after in the air for quite a bit?

A

The water condenses and eventually falls to the earth.

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9
Q

where does a percent of earths water go after precipitation ?

A

78 % of the earths precipitation falls into the ocean.

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10
Q

what is aquifer ?

A

the system of water flowing through porous rock is called aquifer

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11
Q

how does the water is aquifers move?

A

like rivers on the surface the water in aquifers moves, although its flow is very slow.

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12
Q

how long might it take for water in a aquifers to travel with sand?

A

80 years or more to travel through 1m of sand.

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13
Q

explain what water table is ?

A

the layer of porous rock in which all pores are full of water forms

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14
Q

how might the level of water table change?

A

rising closer to the surface in wet seasons and sinking in dry seasons.

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15
Q

explain the definition of lakes and ponds ?

A

they are basically large holes in the ground.

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16
Q

what are the characteristics of a lake ?

A

a lake differs from a pond not in size but in depth. Sunlight does not reach the bottom.

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17
Q

what are the characteristics of a pond ?

A

a pond is where sunlight reaches all the way to the bottom.

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18
Q

what is one thing that a pond is able to be from a lake ?

A

larger than a lake

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19
Q

what is clarity?

A

is determined by the amount of matter suspended in the water.

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20
Q

what is the comparison and the differences between both streams and river?

A

are both fast-waterways.
differences is that they differ greatly is speed, tempeture, and clarity. They also differ on the nature of their banks and bottoms.

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21
Q

what are fast- flowing water ways most common in?

A

are usually rich in oxygen, which fish and other animals need to survive.

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22
Q

river and lakes are the most visible form of what?

A

fresh water

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23
Q

how does the water reach underground?

A

it goes downwards from connected pores and crack s

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24
Q

explain how water filled layers make wells?

A

when groundwater cannot move any deeper, it begins to back up. It fills the pores of the bedrock, that how they make wells.

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25
Q

what are the ice ages

A

Any of the major periods when glaciers covered much of the earth.

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26
Q

when did the most recent ice age began?

A

120 000 years ago

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27
Q

Describe how it was like during the ages and the climate?

A

Glaciers covered as much as 28 percent of the land. It was very cold

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28
Q

how much space did the glaciers cover of the land int he arctic?

A

it covered from the land of the Arctic to as far south as the Great Lakes.

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29
Q

what are some examples of the features glaciers create In the land?

A

Striations, Moraines, U-shaped valleys, and erratics.

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30
Q

what happens if more of the land is covered in snow and ice?

A

a greater amount of sunlight is reflected back into the atmosphere, adding to the cooling.

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31
Q

what are some reasons scientists think the ice ages were cold?

A
  1. Mountains that had extra snow remained on the cold peaks through the summer and reflects sunlight and may reduce temperature
  2. The movements of the Earths tectonic plates alter the shape of the oceans. Creating less flow and not enough mixing between cold and hot waters making some regions cold.
  3. Changes in the tilt of the earths axis, or orbit around the sun may reduce colder climates.
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32
Q

what is a crevasse

A

Is a fissure, or crack, in the ice

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33
Q

How is a crevasse formed

A

when the glacier stretches, cracks and crevasses form

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34
Q

what is pack Ice

A

is a sheet of ice rarely more than 5 m thick that breaks easily.

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35
Q

how does packed Ice form?

A

it is formed from freezing sea water.

36
Q

what are Icebergs

A

are large chinks of ice the break loose or cable from continental glaciers as the glaciers flow downslope in the ocean

37
Q

what are calves

A

when large chunks of ice break off from the edge of a glacier and become icebergs

38
Q

what is the green house effect

A

is natural warming caused by gases in our atmosphere trapping heat.

39
Q

what is the main source of greenhouse gas?

A

Carbon Dioxide

40
Q

what is the meaning of global warming

A

means that the global temperatures are rising.

41
Q

An increase go greenhouse gases also increases what?

A

the great house effect

42
Q

what are some events that occur because of Global warming

A

ice caps beginning to break apart and sea level is rising

- low- lying areas might experience increased flooding.

43
Q

how does a glacier form?

A

it begins as snow. snowflakes aciculate and gradually become grains, then ice crystals, and finally ice

44
Q

what do snow crystals have the tendency to do ?

A

to rearrange themselves into a circular form.

45
Q

what is watershed

A

area of land that drains into a body of water

46
Q

what are explains of watershed

A

river, pond, wetland, lake or ocean

47
Q

what is run-off

A

water that doesn’t soak into the ground or evaporate but instead flows across Earth’s surface

48
Q

what is continental divide?

A

The continues ridge of mountain summits dividing the continent into two main drainage areas.

49
Q

what is one way to prevent run-off in watersheds?

A

paving over the land

50
Q

what does soil, conditions, vegetation, and human settlement patterns influence?

A

it influences the amount of water discharged by a watershed.

51
Q

slowing down run-off plants and roots prevent what?

A

loss or erosion of soil

52
Q

what areas have more run-off?

A

urban areas that lack of vegetation have more runoff than areas covered with vegetation

53
Q

what are currents

A

floating objects carried over thousands of kilometres of ocean by broad, continuous moments of ocean water is called currents.

54
Q

currents of water at the ocean surface are driven by what?

A

by winds

55
Q

what effects the flow of ocean currents?

A

the movement of earths tectonic plates alters the shape of the oceans. This change affects the flow of ocean currents

56
Q

how can you describe a ocean current?

A

Is like a massive river within the ocean.

57
Q

what do trade winds do to ocean currents?

A

they push ocean currents towards the west.

58
Q

what do westerly winds do to ocean currents?

A

drive currents the opposite way, form west to east.

59
Q

what are the three factors that influence the direction of winds and surface currents?

A

uneven heating of the atmosphere

rotation of earth and the continents.

60
Q

how does wind produce an area of low pressure?

A

warm air expands upward and outward as its particles move farther apart.

61
Q

How do moving masses of wind create winds?

A

cool air, with a high pressure moves into the area of low pressure.

62
Q

explain the motion that effects the earths surface in the northern hemisphere and the Southern Hemisphere?

A

as winds and water currents flow over the earths surface the planet tuns beneath them from west to east. This motion causes currents in the northern hemisphere to turn to their right, and the Southern Hemisphere to turn to their left.

63
Q

where does the overall wind along the equator blow?

A

from the east

64
Q

what combined influence keeps ocean currents circulating clockwise in the northern hemisphere and counterclockwise in the Southern Hemisphere?

A

the influence of winds keep the ocean currents moving evenly.

65
Q

where do warm currents begin?

A

near The equator where the Suns heat is most intense. As the warm currents circulate they affect the climate and sea life of the regions to which they move.

66
Q

water has a very high Heat capacity what does that mean?

A

which means that it takes a long time to heat up or cool down

67
Q

what are tides

A

they are covered and uncovered in regular daily cycles by the slow rise and fall of the ocean surface caused by the gravitational pull of the sun and the moon

68
Q

what is tidal movement is linked to what?

A

to the motion of the moon

69
Q

the largest tidal movement is called what

A

spring tides

70
Q

what is tidal range

A

level between a high tide and a low tide is called tidal range

71
Q

what do tidal movements mainly result from

A

fro the pull of the moos gravity on the ocean

72
Q

the link between earth, the moon, and the sun and tides is what?

A

gravity

73
Q

during the spring tides what does the sun add to it?

A

gravitational pull to the moons producing a large tidal range.

74
Q

on the earths shorelines how many times a day does the tides rise and fall?

A

twice a day

75
Q

the moons pull causes the ocean to do what on the side of the earth facing the moon?

A

to bulge on the side of Earth facing the moon

76
Q

why does the second budge occur?

A

because the moon pulls more strongly on earth itself than on the ocean on the far side.

77
Q

when do neap tides occur?

A

twice per month during the first-quarter phase and third quarter phase of the moon

78
Q

what are some features of aquatic habitats

A

may be warm or cold, shallow or deep light or dark.

79
Q

what are some animals that live in ponds and lakes

A

fish, insects, and amphibians such as frogs. as well as larger animals such as a beaver, musket, ducks, and turtles

80
Q

streams and rivers usually alternate between areas where what?

A

the water is calm (pools) and areas where water is moving quickly

81
Q

what are some things that live in river habitats?

A

insect larva, trout, frogs

82
Q

what is the difference between a ocean and a lake

A

they are only different because oceans are salty and they are deeper

83
Q

what is the average depth to which light can penetrate in the ocean?

A

180 m

84
Q

Most marine organisms live where in the ocean?

A

continental shelf where the greatest source of food is located

85
Q

what is water quality

A

the characteristics of a water resources that make it suitable for various uses.

86
Q

what does water management involve?

A

balancing the water needs of people, industries and wildlife. and the environment with the ability of fresh water systems to remain clean

87
Q

why to we need to manage water properly

A

to ensure it will be plentiful and safe forever.

grade 8 science (22 decks)

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