Features Of Oceans

Question 1

How are mid ocean ridges formed

Answer 1

Convection currents caused by radioactive decay in the core heats the bottom of the mantle becoming less dense it rises and cools and creates a convection current the friction pulls the plates apart magma rises and cools and forms rocks

Question 2

What is the continental shelf

Answer 2

Flat plains located beneath the drowned edge of continents slope angle of 0.5 degrees

Question 3

Continental rise

Answer 3

Below shelf break average angle of 4 degrees

Question 4

sub marine canyon

Answer 4

found on the continental slope these features are steep sided with v shaped profiles and topographic releif up to 2 km

Question 5

abyssal plain

Answer 5

flattest areas on earth having regional slopes of 0.5 degrees lie at water depths of 3-5 km

Question 6

abyssal hill

Answer 6

domes or elongated hills that are no higher than 1000 metres high

Question 7

seamount

Answer 7

any type of abyssal mountain that rises above 1000 metres that does not extend out off the waters surface

Question 8

guyot

Answer 8

flat topped sea mounts their tops were once active volcanoes bit there tops were levelled by erosion edges colonised by coral reefs

Question 9

trench

Answer 9

steep sided long and narrow depressions some 3-5km deeper than the ocean floor

Question 10

continental slopes

Answer 10

nearly flat plains that are located between continents average 6 km in width slopes gently sea ward

Question 11

what 3 things affect salinity

Answer 11

freezing/evaporation of water
lots of rain
rivers and streams

Question 12

what overall factors affect ocean currents

Answer 12

coasts
Coriolis affect
planetary winds
variation in temperature

Question 13

how does wind affect ocean water

Answer 13

wind creates friction that creates waves
pulls water along

Question 14

what is the Coriolis effect

Answer 14

earth spins quicker at the centre so water is deflected towards the poles clockwise for the N. hemisphere and anticlockwise for the S. hemisphere

Question 15

what are gyres

Answer 15

large areas of circulating water in the sea caused by Coriolis effect

Question 16

why are some currents warm

Answer 16

found in warm areas possibly near the equator
i.e. gulf stream

Question 17

how does freezing/evaporation of water effect water salinity

Answer 17

evaporation - when water evaporates the water leaves but the salt doesn’t so all that is left is the salt increasing salinity freezing- when water freezes water is taken out of the ocean as ice floats

Question 18

what5 factors cause variation in surface salinity

Answer 18

precipitation = diluton of sea water = less salty
evaporation = water molecules removed = higher salt concentration e.g. red sea
freezing = addition of fresh water = lower salt concentration
ground water and river flow = addition of fresh water e.g Baltic sea 10 ppt because of the 200 rivers flowing into it

Question 19

why do ocean temperatures vary

Answer 19

angle of the sun means that the sun is directed onto the equator. Water has a high specifi heat capacity so it takes longer to warm up but takes longer to cool

Question 20

how and why do temperatures vary with depth

Answer 20

Temperature is much warmer at the surface where there is wind driven mixing when the surface water is heated and it is mixed with water lower down. Sunlight only penetrates 200m down(photic zone )Below 1000 metres the temperature is roughly 4 degrees centigrade

Question 21

where are warm ocean currents found

Answer 21

warm ocean currents are found near the equators and flow towards the poles. For example gulf streams from the gulf of mexico to the North pole towards Europe

Question 22

where are cool ocean currents found

Answer 22

The labrador current flows from the Artic Ocean into the North Atlantic . Cool ocean currents are found near the poles due to less input of solar radiation

Question 23

How does the global conveyor belt start?

Answer 23

Ocean water near the Poles has little input of heat from the sun and most of the heat inputted near the Equator has dissipated and so the ocean is cooler. Due to the formation of sea ice the salinity is increased as the salt in the seawater is left behind when the ice forms. The water therefore at the Poles is cooler and saltier both of which make it denser so the water sinks off the coasts of Greenland and Norway.
As it sinks it pulls down more water due to the cohesive nature of water. When it reaches the ocean floor then the water disperses horizontally across the abyssal plain towards the Equator.

Question 24

List 5 facts about ecosystems at hydrothermal vents and cold seeps (include named species)

Answer 24

Species are adapted to live up to 120 degrees centigrade. hydrothermal vents are found in the midnight zone so most live of chemosynthesis Species can include yeti crabs tubeworms and octopus.

Question 25

How and why do light levels affect ecosystems?

Answer 25

The photic zone is set at 200 metres Therefore inter tidal system are always within the photic zone so photosynthesis can occur throughout whereas in deep water systems the depth averages 4km so photosynthesis is not the option

Question 26

How and why does temperature affect ecosystems?

Answer 26

colder temperatures mean that metabolic rates are slower that can be found in both big and small animals

Question 27

Explain where nutrient levels are high in the oceans.

Answer 27

Along coasts there is inputs of nutrients from wind Areas of upwelling (caused by surface winds pushing water out of the way and water rising to fill the gap ) Eg trade winds off the coast of chile cause a lot of upwelling

Question 28

Compare the length of food chains in inter-tidal and deep-water ecosystems

Answer 28

Food chains in deep-water ecosystems are shorter due to the relative lack of nutrients available compared to inter-tidal ecosystems.

Question 29

Compare the biodiversity in inter-tidal and deep-water ecosystems

Answer 29

Higher level of biodiversity in inter-tidal ecosystems due to the higher available of nutrients (e.g: from land based sources).

Question 30

How big and wide is each of the 5 oceans

Answer 30

Pacific - area 155.6km2, average depth 4km, deepest point Mariana trench 11km
Atlantic - area 76.8km2, average depth 3.9km
Indian - area 68.6km2 average depth 3.9km
Southern - area 20.3km2, average depth 4km, deepest point 7km.
Arctic - area 14.1km2, average depth 1.2km