6.3.1 Ecosystems COMPLETE

Question 1

Population

Answer 1

All the organisms belonging to one species that live together in the same area, at the same time, and can interbreed.

Question 2

Community

Answer 2

All the populations of different species that live in the same place at the same time.

Question 3

Habitat

Answer 3

The place an organism lives

Question 4

Niche

Answer 4

The role of an organism in the ecosystem including how it feeds, reproduces, finds shelter and how it interacts with its biotic and abiotic environment.

Question 5

Producer

Answer 5

An organism that transfers energy from light or an inorganic compound to an organic compound.

Question 6

Consumer

Answer 6

An organism that obtains energy from organic compounds i.e. carbs. Feed on other organisms.

Question 7

Decomposer

Answer 7

Organisms that feed saprophytically on dead organic matter, releasing mineral ions and other material into the soil and air.

Question 8

Trophic Level

Answer 8

The stage at which an organism feeds in the food chain

Question 9

Ecosystem

Answer 9

A relatively self contained unit of living organisms interacting with each other and their abiotic environment

Question 10

Biotic Factors

Answer 10

LIVING

i.e. grazing, predation, mutualism, pollination, parasitism

Question 11

Abiotic Factors

Answer 11

NON LIVING

i.e. Temp, water availability, light intensity, wind speed, pH

Question 12

Ecological efficiency

Answer 12

efficiency of biomass as its transferred through trophic levels

Question 13

GPP

Answer 13

Gross primary productivity- amount of light converted into chemical energy for photosynthesis

Question 14

NPP

Answer 14

Net primary productivity- Remaining biomass after respiration to go to the next trophic level

Question 15

Energy loss in primary productivity

Answer 15

• light not hitting plant
• lands on non photosynthetic part
• other limiting factors i.e.
• lost as heat during evaporation

Question 16

Energy loss between producer and consumer

Answer 16

• Not all parts of plant are eaten
• can’t digest entire plant (Cellulose)
• lost as heat in digestion

Question 17

Energy loss between two consumers

Answer 17

• some animals aren’t eaten
• some parts of animal aren’t eaten (bone)
• heat loss during respiration

Question 18

Pyramid of Numbers

Answer 18

Created by counting numbers of a species, no mention of biomass and effected by seasonal variation

Question 19

Pyramid of Biomass

Answer 19

Weigh dried out specimen, inconvenient as need to kill specimen

Question 20

Pyramid of Energy

Answer 20

Once dried you need to burn the specimen, this is time consuming and disrupts the ecosystem

Question 21

Methods to increase agriculture production

Answer 21

• High crop density, plant in small areas
• Increasing temp and CO2 for photosynthesis
• Crop rotation/ fertiliser so plants have all minerals they need
• good irrigation so stomata remain open

Question 22

Increasing Secondary Productivity

Answer 22

• Use herbivores
• Restrict their movement
• Antibiotics and steroids
• Kill just before adulthood
• high energy food

Question 23

Feeding Saprophytically

Answer 23

Secrete enzymes which the digest and hydrolyse large organic molecules into smaller inorganic ones, these are absorbed into the bacteria or fungus’ body.

Question 24

Free living Nitrogen Fixing Bacteria

Answer 24

e.g. Azotobacter, live in soil taking N gas from air spaces and manufacture amino acids for growth. Once dead they decompose and nitrates are released.

Question 25

Nitrogen fixing bacteria in Root Nodules

Answer 25

e.g. Rhizobium, live in leguminous plants such as peas, clovers and beans. Have a mutualistic relationship with plant exchanging fixed nitrates for glucose.
Leghaemoglobin in nodes keeps it anaerobic allowing nitrogen reductase to produce nitrates.

Question 26

Ammonification

Answer 26

Ammonia produced from dead organisms, faeces and urine. Then become ammonium ions by saprophytic fungi and bacteria. Decomposition of amino acids.

Question 27

Nitrification

Answer 27

1) Ammonium ions oxidised into nitrites by nitrosomonas bacteria.
2) Nitrites oxidised into nitrates by nitrobacter bacteria
Happens in aerated soils, the bacteria are Chemoautotrophic as gain energy from reaction.

Question 28

Denitrification

Answer 28

Convert nitrates back to nitrogen gas, present tin waterlogged anaerobic soil. Use nitrates as a source of oxygen

Question 29

Fluctuations in CO2

Answer 29

• Changes during day and seasonally based on rates of photosynthesis
• combustion of fossil fuels has increased levels

Question 30

Problems with increased CO2

Answer 30

increase in greenhouse effect, leading to global warming,
CO2 dissolving in rain, carbonic acid damages rocks,
as temp rises less CO2 dissolving in oceans

Question 31

Measuring Distribution

Answer 31

Use transect across a gradient, i.e. distance from path for trampling

Question 32

Measuring Abundance

Answer 32

Use the SACFOR scale for %Frequency

Question 33

Capture-Mark-Release-Recapture

Answer 33

Animals may become trap happy or trap shy effecting frequency of catching animals. i.e. marking snails

Question 34

Measuring Abiotic Factors

Answer 34

Temp= Thermometer
Humidity= Hydrometer
Light= Luxmeter

Question 35

Succesion

Answer 35

A directional change in an ecosystem overtime,
Primary=from bare ground to climax
Secondary= from altered state to climax
Deflected= factors preventing climax being reached

Question 36

Pioneer Community

Answer 36

Organisms that change abiotic features to enable others to settle in the area

Question 37

Climatic Climax

Answer 37

The final stage when an equilibrium is reached

Question 38

Lag Phase

Answer 38

a small number of individuals acclimatising to habitat, reproduction is low so slow increase in population

Question 39

Log Phase

Answer 39

Resources are plentiful so increased numbers of breeding individuals. Birth rate greatly exceeds death rate so population increasing rapidly.

Question 40

Stationary Phase

Answer 40

Population reached carrying capacity, no longer enough resources, death and birth rates are equal. Numbers fluctuate due to environmental conditions

Question 41

Density dependant limiting factors

Answer 41

A bigger population means greater % likely to die, i.e. disease or starvation.

Question 42

Density independant limiting factors

Answer 42

Population size has no effect on % death, i.e. natural disasters or climatic features like it being freezing cold

Question 43

Competition

Answer 43

Either good competitors and win idea niche, or good at tolerating realised niche. (Interspecific)