2.4

Question 1

5 biomes

Answer 1

aquatic - freshwater and marine
forest - tropical, temperate, boreal
grassland - tropical or savanna and temperate
desert - hot and cold
tundra - arctic and alpine

Question 2

biome

Answer 2

a collection of of ecosystems sharing similar climatic conditions

Question 3

biosphere

Answer 3

part of the Earth inhabited by organisms

Question 4

biomes are where they are because

Answer 4

of climate

temperature, precipitation, geography/terrain - latitude. altitude

Question 5

factors that affect the global distribution of temperature

Answer 5

• hotter near the equator cooler towards the poles (increased latitude) This is because sun rays hit the earth at a more acute angle and so spread over a greater surface area
• colder with increasing latitude/altitude
• ocean currents and winds distribute surplus heat energy at the equator towards the poles - latent heat - El Nino

Question 6

temperate forests

Answer 6

rainfall sufficient to establish a forest
temperatures and light intensity vary between season
deciduous/coniferous trees
less complex structure than rainforest and often dominated by one species
some layering, although trees no taller than 30metres
lower and less dense canopy than rainforest means more light so rich shrub layer

Question 7

tropical rainforest

Answer 7

high rainfall, sunlight and temperature
no seasons, consistent light and temperature
complex structure trees up to 50m
dense canopy, only 1% sunlight reaches the floor, sparse shrub layer
soils are thin and nutrient poor

Question 8

desert

Answer 8

low rainfall (under 250mm a tear0
Hisgh sunlisht,; bery hot in the day cold at night
scarce vegetation
plants - cacti animals - adapted to desert conditons
soil has a low-water holding capacity, erodes easily in the wind

Question 9

tundra

Answer 9

high latitudes
low temperatures, low precipitation, seasonal sunlight; short-day length
simple structure, vegetation is low scrub and grasses it forms a single layer
permafrost and soil limit productivity

Question 10

temperate grasslands

Answer 10

flat areas dominated by grasses and herbaceous plants

temperature range high, low rainfall

Question 11

tricellular model of atmospheric circulation components

Answer 11

explains the distribution of biomes
polar cell
Ferrel cell
Hadley cell

Question 12

TRICELLULR MODEL CELLS

Answer 12

0 degrees the equator recieves the most insolation
hot air rises, as it cools the water vapour condenses as rain
air moves away from the equator north and south
30 degrees from the equator dry air sinks
some air returns to form the Hadley Cell
some is blown further north collecting water vapour from the sea
they meet cold polar air and rise (as they are less dense) at 60 degrees
this leads to low pressure areas associated with heavy rainfall
some air flows towards the poles and some back towards lower latitudes (Ferrel Cell)
the air at the poles then descends as it gets cooler forming a high pressure area at the poles (Polar Cell)

Question 13

deep ocean biome

Answer 13

the ocean and seafloor beyond continental shelves
pressure increases with depth
temperature variation decreases to a constant -2 degrees at depth
light limiting below 1000m there is none
nutrients - lower level and low primary productivity but some dead organic matter falls to deep ocean floors
3xample. arctic, Atlantic, pacific oceans

Question 14

succession

Answer 14

is how an ecosystem changes in time

Question 15

zonation

Answer 15

is how an ecosystem is changing along an environmental gradient,e g. altitude

Question 16

primary succession

Answer 16

the formation of an ecosystem from ,e..g, bare rock

Question 17

secondary succession

Answer 17

where soil formation starts the process or where soil already formed but the vegetation has been removed

Question 18

stages in primary succession

Answer 18

bare inorganic surface
S1; colonisation; pioneers ; r-selected species
S2; establishment; species diversity increases; invertebrate species visit and live in the soil increasing humus
S3: competition; new species colonise; larger plants provide shelter; k-selected species become established; r-species unable to compete with k-species for space, nutrients or light and are lost from the community
S4: stabilisation; fewer new species colonize as late colonizers become establish shading out early colonizers. Complex food webs develop
Climax community; stable & self-perpetuating, steady-state dynamic equilibrium; represents the max possible development that a community can reach under the prevailing environmental conditions of temperature, light and rainfall

Question 19

climax community

Answer 19

A climax community is stable and self-perpetuating and exists in steady state dynamic equilibrium. A climax community is the last stage of succession where the climax represents the maximum possible development that a community can reach under the prevailing environmental conditions of temperature, light and rainfall

Question 20

hydrosere

Answer 20

succession in water, eg.g in a lake

Question 21

example of succession

Answer 21

mosses and lichens-> grasses and herbs -> shrubs (e.g. birch) -> woodland

Question 22

sucession NPP GPP

Answer 22

in the first stages there is a low GPP but NP tends to be a large proportion of it
middle stage - high GPP increased biomass as plant forms become bigger
late stage - trees reach their max size, the ratio of NPP to R is roughly equal

Question 23

disturbances and pioneer species

Answer 23

communities are affected by periods of disturbances
this makes gaps available for pioneer species within the surrounding community, to colonise
this adds to the productivity and diversity of the community

Question 24

succesison on sand dunes

Answer 24

England, Dorset. Studland Bay
bare surface of sand, vegetation colonizes it
their fat fleshy wax-coated leaves means they are able to survive being submersed - temporarily
later, predominant plant species is marram grass leaves are adapted for strength and flexibility against winds
humus from precious stages has resulted in sandy soil developed which can support grasses and bushes
oldest dunes will have forest, pine and woodland on them, the climatic climax vegetation
as succession increases there are increases in vegetation cover, soil depth, humus content, soil acidity, moisture content and sand stability

Question 25

sub climax community

Answer 25

results from interrupted succession by;

- an abiotic factor, e.g. soil conditions such as waterlogging