B4: Community-level Systems

Question 1

1 MARK

What is an Ecosystem?

Answer 1

An ecosystem is made up of all the living organisms and physical conditions in an area.

Question 2

2 MARKS

what is a community?

And what is where they live called?

Answer 2

A community is the organisms within the ecosystem.The area they live in is the habitat.

Question 3

1 MARK

Meaning of population

Answer 3

The total number of organisms of each species in a habitat.

Question 4

3 MARKS

What 3 groups can u divide organsims in a community by?

P.C.D

Answer 4

producers- make their own food by photosynthesis(algae and plants)

consumers- Cannot make their own food and have to eat other organisms to gain energy.All animals are consumers

Decomposers- Gain energy by feeding in dead or decaying material

Question 5

How is energy transferred between organsims?

Answer 5

-energy from sun by light to the chlorophyll in the cell of a producer

-co2 and water react to produce glucose which stores energy in its chemical bonds

-glucose can be used to be converted into carbs,fats and proteins.-used for growth and repair

-as an organism grows it increases biomass(mass of living material present).

Consumers then eat producers and when organism respires,energy stored in its food is transferred in the production of ATP.Organism grows and biomass increases.

Question 6

What is a food chain

Answer 6

displays what organisms eat

Arrow in food chains represent transfer of biomass/energy

Each step in the food chain is a trophic level

Question 7

Order of food chain

Answer 7

Producer-primary consumer-secondary consumer-tertiary consumer

Question 8

What is a food web

Answer 8

only shows organisms eating one food source. For example a sparrow eats slugs,snails and worms

Question 9

What factors affect an ecosystem

Answer 9

Biotic- living factors: animals/plants/trees

Abiotic-non-living/physical factors: rainfall/temperature/soil ph

Question 10

How does light intensity affect communities

Answer 10

Needed for photosynthesis

Greater light, greater success of a plant

Question 11

temp affect on communities

Answer 11

Effects the enzymes that control metabolic reactions

Plants will develop more rapidly as metabolism will be quicker with higher temp.

Also true for warm blooded animals(ectotherms) which rely on sun to keep them warm.

Question 12

moisture level affect on communties

Answer 12

-lack of water leads to death as water is the main component for blood plasma
-plants will wilt as they need water to keep cells turgid and for photosyntheis

Question 13

soil ph affect on communities

Answer 13

affects biological activity in soil and availability of certain minerals.

some plants grow better in acidic soils.-ferns
others grow better in alkaline soils-cauliflower

Question 14

what is competition

Answer 14

when plants and animals compete for limited resources.Leads to weaker and animals dying or leaving the area,and weaker plants dying.

Question 15

what do plants need to survive

Answer 15

light
water
minerals
space
co2

Question 16

what do animals need to survive

Answer 16

food
water
mates
shelter
territory

Question 17

what is population?

Answer 17

the number of organisms of each speices living in an area.

Question 18

what is the interactions between orgainsms called

Answer 18

ecological relationships

Question 19

what is interdependence

Answer 19

the word to describe how different organisms rely on eachother within a community

Question 20

predation

Answer 20

name given to relationship between predator and pray.

when pred pop high=prey pop low

pred pop low=pred prop low-prey increase

cyclic relationship.

Question 21

mutualism

Answer 21

both organisms beneffiting from the relationship.

birds and buffalo

Question 22

paratism

Answer 22

when only one organism benefits (parasite) and other (host) is harmed.

tapeworms and humans

Question 23

what is a flaw of food chains

Answer 23

do not show organisms involved

does not show size of biomass transferred

Question 24

what do pyramids of numbers show?

Answer 24

population at each trophic level

the width=number of organisms present in each trophic level

Question 25

what is biomass

Answer 25

amount of living material in an organism

Question 26

what happens in the pyramid of numbers

Answer 26

as you go along,size of organisms generally increases.However there are fewer and fewer organisms at each level

Question 27

what can u take into account by plotting the amount of biomass in each tropic level

Answer 27

number and size of organisms present

Question 28

why does biomass decrease at each tropic level

Answer 28

energy is trnasferred to prodcuers by sunlight.

only 1% is transferred into chemical stores where most of the light is reflected from the leaf.

most of remaining energy is limited by factors like temp or water availability.

up to half the remaining energy is transferred in order to increase the plants biomass

Question 29

why do scientists ususlaly calculate the dry mass of an organism

Answer 29

as water contents can vary between individuals.

Animals must be dead and dried in a kiln

Question 30

what is the general percentage of biomass transferred between tophic levels

Answer 30

10%

Question 31

how is biomass lost

Answer 31

not all of an organism is eaten-plant roots or animal bones cant be consumed

respiration- produces ATP and this is used by muscles for movement.Also causes thermal energy to transfer to the environment

egestion-some parts of an organism cant be digested and are removed from the body by faeces

excretion-waste products released through excretion and water lost through urine

Question 32

what happens at each stage of the food chain

Answer 32

energy transferred decreases.

Question 33

formula for efficecny of biomass transfer

Answer 33

efficency=

biomass after transfer/biomass before transfer X100

Question 34

nutrient cycling

Answer 34

-plants obtain nutrients needed from the soil
-passed onto animals when plant is eaten
-when plants die,decomposers release the trapped nutrients back to the soil and absorbed by other plants
-some into the atmosphere
-in this process materials are passed between the abiotic and biotic compnents of an ecosystem

Question 35

materials that are cycled-carbon

Answer 35

one of the most elements in organisms

used to make carbs,fats,proteins and DNA

cycles between atmosphere,living organisms and fossil fuels

can also become trapped in oceans and rocks

Question 36

materials cycled-nitrogen

Answer 36

-Plants absorb nitrates (a form of nitrogen) from the soil through their roots to grow. They do this with the help of bacteria living in their roots (called root nodule bacteria).
-Plants can also absorb nitrogen from the air.
-Farmers may add fertilisers (containing extra nitrates) to the soil, which plants can absorb.
-The nitrogen is passed-on to animals that eat the plants.
-When plants and animals die, bacteria recycle nitrogen back into the soil through decomposition.
-When lightning strikes soil, nitrogen is released back into the air.

Question 37

nutrient cycling-water

Answer 37

-Water evaporates from the Earth’s surface, before rising up into the atmosphere.
-Once in the atmosphere, the water vapour cools and condenses into either rain or snow. This eventually returns to the Earth’s surface.
-The rain or snow will either become surface runoff (water flowing off land) or will travel through the earth as ground water.
-Plants take up water through their roots.

Question 38

what is the carbon cyce

Answer 38

process by which carbon is cycled through the atmosphere,earth,plant and animals,

Question 39

process of carbon cycle

Answer 39

-Carbon is removed from the atmosphere by producers (e.g. algae) who use it in photosynthesis.
-By consuming plant matter, animals obtain carbon compounds.
-Carbon is returned into the atmosphere (as carbon dioxide) because of the respiration that happens in plant and animal cells.
-When animals and plants die, decomposers return the carbon locked in their bodies back to the atmosphere via decay.
-Combustion of fossil fuels is another source of carbon entry into the atmosphere.

Question 40

how is carbon removed from the atmosphere?

Answer 40

during photosynthesis- converts carbon dioxide and water into glucose and oxygen.