Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology > 23 - Ecosystems > Flashcards

23 - Ecosystems Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Ecosystem

A

is made up of all the living organisms that interact with one another in a defined area, as well as the physical factors in that region

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

biotic factors

A

the living factors
- size of a population, competition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

abioic

A

the non-living factors
- rainfall and temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

light as an abiotic factor

A
  • plants are affected by light as it is needed for photosynthesis
  • plants do have adaptations eg wide leaves
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

temperature as an abiotic factor

A
  • effects enzyme controlled reactions
  • plants develop rapidly in warmer temps
  • activity of ectotherms also depends on temperature
  • can trigger migration and hibernations
  • trigger leaf-fall, dormancy, and flowering
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

water availability as an abiotic factor

A
  • lack of water means water stress, which can cause death
    -plants wilt
  • required for photosynthesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

oxygen availability as an abiotic factor

A
  • ## suffocation of aquatic organisms
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

three types of soil

A

clay- this has fine particles, is easily waterlogged and forms clumps when wet

loam- has different sized particles, it retain water but doesn’t become water logged

sandy- coarse, well-separated particles that allow free draining - does not retain water and can be eroded

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what are food chains/webs

A
  • diagrams that show the transfer of biomass and therefor energy through the organisms of an ecosystem.
  • each stage is called a trophic level
  • first stage is always a producer
  • subsequent trophic levels are consumers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is a producer

A

an organisms that converts light energy into chemical energy by the process of photosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is a consumer

A

organisms that obtain their energy by feeding on other organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Explain why food chains rarely have more than 3-4 trophic levels.

A

as there is not sufficient biomass and stored energy left to support any further organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what are decomposers

A

break down dead organisms releasing nutrients back into the ecosystem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is biomass

A

the living material present in a particular place of organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

how do you calculate biomass at each trophic level

A

multiply the biomass in each organism by the total number of organism in that trophic level

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

way to measure biomass

A
  • measure the mass of fresh material
  • water content must be removed
    • or calculate dry mass
      -> place organism in an oven at 80’c until water has evaporated (shown by two identical mass readings)
      -> to minimise destruction only a small sample is used
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

units for biomass

A

land; grams per square metre
water; grams per metre

18
Q

unit for energy available at each trophic level

A

kilojoules per metre squared per year

19
Q

why is energy at trophic levels different

A
  • only a small proportion of food ingested is converted into new tissue - this biomass is what is consumed for the next trophic level
20
Q

what is ecological efficiency

A

the efficiency with which a biomass or energy is transferred from one trophic level to the next

biomass transferred/biomass intake x 100

21
Q

why do producers only convert 1-3% of light energy into biomass

A
  • not all solar energy is available is used for phs. 90% is reflected, some is transmitted through the leaf and some is not a usable wavelength
  • other factors can affect PHS
  • energy is lost as it is used for PHS
22
Q

what is gross production

A

total solar energy a plant converts to organic matter

22
Q

what is net production

A

energy available for the next trophic level

gross production - repiratory loses

23
Q

why is gross and net prodcution different

A

plant use some of the energy in the organic matter fir respiration

24
Q

why is biomass of a consumer less than what they have consumed

A
  • not all biomass is eaten - eg roots may root be eaten
  • some energy is transferred to the environment as metabolic heat due to respiration and movement
  • some part of an organism are eaten but not digestible - instead they are egested
    -some energy is lost in excretory materials like urine
25
Q

what is decomposition- what is the point in it

A

when a compound is broken down into smaller molecules or constituent elements
- often essential elements cannot be directly used by organisms when is it in dead or waste matter
- so it has to be processed from organic to inorganic elements which are a more usable form
- and are returned to the environment

26
Q

what is a decomposer

A

organisms that feeds on and breaks down dead plant or animal matter, turning organic compounds into inorganic ones available to PHS producers un the ecosystems
- primarily fungi and bacteria (microscopic)

27
Q

why are decomposers saprotrophs

A

they obtain energy from dead or waste organic materials

28
Q

how do decomposers digest food

A
  • externally
  • they secrete enzymes onto dad matter
  • enzymes break down organic matter into simple soluble molecules
  • decomposer then absorbs these molecules
  • through this process they release stored inorganic compounds and elements back into the environment
29
Q

what are detritivores

A
  • they speed up the decay process by feeding on detritus - dead or decaying material
  • they break it down into smaller pieces of organic material, which increases the SA for decomposers
  • examples are woodlice and earthworms
30
Q

steps of the nitrogen cycle

A

Nitrogen fixation
Nitrification
Denitrification
Ammonification

31
Q

why does nitrogen have to be recycled

A

Nitrogen in the air N2 cannot be taken in by plants. so to be used by organism nitrogen has to be combined with other elements
- bacteria plat a role in this

32
Q

nitrogen fixation

A

the combination of atmospheric nitrogen with hydrogen to produce ammonia
N2 + H2 -> NH3

carried out by nitrogen fixing bacteria such as Azotobacter and Rhizobium. They contain the enzyme nitrogenase.

33
Q

where are the bacteria for nitrogen fixation found, why is it beneficial for organisms

A

Azotobacter - free soil bacteria

Rhizobium - inside root nodules, growths on leguminous plants like peas.
- bacteria have a symbiotic relationship. the plant gains amino acids from Rhizobium which is produced by nitrogen fixing
- bacteria gain carbohydrates from the plant from PHS, which is energy source

34
Q

nitrification

A

process where ammonium compounds in the soil are converted into nitrogen-containing molecules that can be used by plants
- oxidation R. so occurs in well-aerated soil

1) Nitrifying bacteria (Nitrosomonas) oxidise ammonium compounds into nitrates (NO2-)

2) Nitrobacter oxidise nitrites into nitrates (NO3-)

Nitrate ions are highly soluble so can enter plants

35
Q

Denitrification

A
  • in the absence of oxygen denitrifying bacteria convert nitrates in the soil back into nitrogen gas
  • only happens in anaerobic conditions
    -Pseudomonas denitrificans use nitrates as a source of energy and nitrogen gas is released
36
Q

Ammonification

A

decomposers convert nitrogen-containing molecules in dead organisms and faeces into ammonium compounds

37
Q

transects

A
  • a line or belt transect is used
  • a line transect involves laying out a line and taking samples at regular intervals
  • a belt transect is when two parallel lines are and samples are taken of the area between the specified points
  • examples of systematic non-random sampling
38
Q

why does abundance of organisms change

A
  • immigration and births increase number
  • emigration and deaths decrease number
39
Q

how to measure plant abundance

A
  • place quadrats in the area
    estimates N’= N’ of individuals in sample/ area of sample(m2)
40
Q

capture-mark-release

A
  • capture as many organisms in sample area
  • mark each individual
  • release the marked animal into the area and allow them to redistribute throughout the habitat
  • recapture as many marked and unmarked individuals in sample area
  • record number of marked and unmarked present
  • use Lincoln index

estimate pop = N’ in first sample x second sample/measures of recaptures marked individuals

41
Q

how to measure amount of diversity in a habitat

A

Simpsons diversity
D= diversity index
N= number of organisms in ecosystem
n= number of individuals of each species

1=infinite diversity
0= no diversity

Biology (24 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions