Ecosystems

Question 1

Habitat

Answer 1

The place where an organism lives

Question 2

Population

Answer 2

All the organisms of one species in a habitat

Question 3

Community

Answer 3

All the different species in a habitat

Question 4

Ecosystem

Answer 4

All the organisms living in a particular area and all the non-living conditions

Question 5

how much energy is lost from each trophic level?

Answer 5

90%

Question 6

how is energy lost from each trophic level?

Answer 6

• some parts of the food aren’t eaten
• some parts are excreted
• some is used for respiration
• some is lost as heat

Question 7

nitrogen fixation

Answer 7

the process of turning nitrogen gas in air into nitrogen compounds in the soil which plants can use

Question 8

two main ways that nitrogen fixing happens:

Answer 8

• lightning

- nitrogen-fixing bacteria in roots and soil

Question 9

the four bacteria involved in the nitrogen cycle:

Answer 9

• decomposers
• nitrifying bacteria
• nitrogen-fixing bacteria
• denitrifying bacteria

Question 10

what is the role of the decomposers?

Answer 10

to break down proteins and urea and turn them into ammonia

Question 11

what is the role of the nitrifying bacteria?

Answer 11

turn ammonia in decaying matter into nitrates

Question 12

what is the role of nitrogen-fixing bacteria?

Answer 12

turn atmospheric N2 into nitrogen compounds that plants can use

Question 13

what is the role of denitrifying bacteria?

Answer 13

turn nitrates back into N2 gas

Question 14

how is carbon monoxide produced?

Answer 14

when fossil fuels are burnt without enough air supply

Question 15

how is sulfur dioxide produced?

Answer 15

by burning fossil fuels

Question 16

what is eutrophication?

Answer 16

• nitrates are leached into rivers and lakes
• algae grow really fast
• plants can’t photosynthesise
• microorganims feed on dead plants
• less oxygen in water
• organisms that need oxygen die

Question 17

leaching

Answer 17

• trees take up nutrients from the soil
• the leaves return the nutrients when they die
• when trees are removed, nutrients get leached away but don’t get replaced

Question 18

water cycle

Answer 18

• trees prevent floods
• transpiration from trees also releases some rainwater back into the atmosphere
• deforestation makes local climates drier

Question 19

soil erosion

Answer 19

• tree roots hold soil together

- when trees are removed, the soil can be easily washed away

Question 20

the balance of C02 and O2

Answer 20

• forests take up CO2 and store it. They release it when they die
• when they are cut down and burnt, the CO2 is released
• there is also less oxygen as less photosynthesis takes place