Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

biology > 3.5 population size and ecosystems > Flashcards

3.5 population size and ecosystems Flashcards

1
Q

define population

A

an interbreeding group of organisms of the same species occupying a particular habitat

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

define:
abiotic
community
ecosystem

A

non living/physical

all the living species in a habitat

interaction between living and non living components

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

what is succession?
give an example

A

changes over time in the species that occupy a particular area
e.g. when bare rock or barren land is first colonised

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

what is the pioneer community?

A

first species to colonise a habitat

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

what is the climax community?

A

last species to colonise a habitat (stable community which has reached equilibrium - no further succession)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is sere?

A

a stage in succession

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is a dis climax/disruptive climax?

A

human interference that can affect the natural stages of succession

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what are some examples of human interference that can affect the natural stages of succession?

A
  • grazing by sheep
  • deforestation
  • using land to grow crops
  • deliberate burning of heather moors to prevent a climax community stage (woodland) being reached
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

factors affecting succession (5)

A
  • migration
  • competition
  • facilitation
  • mutualism
  • commensalism
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

the immigration of what affects succession? (4)

A
  • spores (moss, fern, fungus)
  • seeds
  • animals
  • non-native species
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what are the 2 types of competition? define them

A

intraspecific - same species
interspecific - different species (same niche)

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

what does niche mean?

A

the role and organism plays in a community

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

when can competition happen?
why does it happen?

A

at all seral stages. 2 species cannot occupy the same niche - the one with competitive advantages survive

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

what is facilitation?

A

allowing something to happen through positive interactions

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

how does facilitation benefit an ecological community?

A

provides better resource availability and refuge from physical stress, predation and competition

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

what does symbiosis broadly describe?

A

relationships between organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is mutualism?
give an example

A

interaction benefiting both species
e.g. clown fish and sea anemone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is commensalism?
give an example

A

one organism benefits and the other is unaffected. e.g cattle egret and cattle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is a detritivore?
give an example

A

an organism which feeds on dead/ decaying organic matter e.g. earthworms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what is a saprotroph/saprobiont?
give an example

A

organism which discrete enzymes and perform digestion externally e.g fungi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is nitrogen essential for?

A

protein synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what conditions are needed for nitrification?

A

aerobic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what are the 4 main biological processes in the nitrogen cycle?

A

ammonification
nitrification
denitrification
nitrogen fixation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what happens during ammonification?

A

decomposers secrete enzymes that decay the dead plant and animal products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
what happens during nitrification?
NH4+ (ammonium) from ammonification converted to nitrites then nitrates.
26
what are the 2 bacterias involved with nitrification?
- nitrosomonas - nitrobacter
27
what happens during denitrification?
nitrates are converted to atmospheric nitrogen
28
what is the bacteria involved with denitrification?
pseudomonas
29
what happens during nitrogen fixation?
reduction of nitrogen to ammonium ions
30
what are the 2 bacterias involved with nitrogen fixation?
- azotobacter (free-living in soil) - rhizobium (in root nodules of plants (legumes))
31
how is nitrogen taken up by plant roots? (what form?)
as ammonium and nitrate ions by active transport and facilitated diffusion
32
once taken in by the roots, how does the plant use the nitrogen from the nitrate ions?
to synthesise: - amino acids (to make proteins) - nitrogenous bases (to make the nucleic acids RNA and DNA) - chlorophyll
33
what are some examples of human impact on the nitrogen cycle? (6)
- soil aeration from ploughing - drainage - harder process - manure - slurry (manure + water) - fertilisers
34
how do fertilisers reduce species diversity on grasslands? (2)
- grasses and nettles grow well - shade out smaller plants
35
how do fertilisers reduce species diversity in lakes? (2)
- may result in eutrophication - leaching nitrates and phosphates adding to the natural process of salt build up
36
explain eutrophication (5)
- when it rains fertiliser runs into the lake - this leads to an increase in growth of algae and block the light from the plants - plants die and decomposers carry out decomposition - decomposers multiply - respiration of decomposers uses up oxygen so aquatic animals die due to lack of oxygen
37
farmers need to abide by legislation to reduce nitrate leaching, give examples on how they do this? (3)
- restrict amount of fertiliser on crops - only apply when crops readily growing - dig drainage ditches – eutrophication occurs here instead of natural water courses
38
what is ecology?
the study of living things and their interactions with each other and their environment
39
define habitat
a place in an ecosystem where an organism lives
40
define niche
the role of an organism in an ecosystem, generally a feeding role
41
what is the benefit to living in a population? (3)
- more successful breeding and rearing of young - gaining protection from predators by living in groups - the group size effect - working as a group to locate new food sources
42
what are the problems to living in a population? (2)
- competition for resources like food and space - some individuals are better adapted than others and more likely to survive
43
what are the factors causing a population size to increase? (2)
- birth - immigration
44
what are the factors causing a population to decrease? (2)
- death - emigration
45
how do plants emigrate?
via seed dispersal
46
what is exponential growth?
when species colonising a new area have favourable conditions and the birth rate exceeds the death rate
47
what is an equilibrium species?
the control of a species' population is by competition in a stable habitat
48
what graph is used to show an equilibrium species?
exponential J shaped curve
49
what is an overshoot and what does it cause? (on a exponential J shaped curve)
the population growth exceeds carrying capacity causes a die off in population
50
what is an unstable equilibrium? (on an exponential J shaped curve)
the fluctuation of population above and below carrying capacity
51
what is the cause of decreasing carrying capacity? (on an exponential J shaped curve)
resource destruction during an overshoot
52
what is the carrying capacity?
the amount of organisms within a region that the environment can support sustainably
53
what graph is used to show a fugitive species?
J-shaped curve
54
what is a fugitive species' strategy and why? give an example of a fugitive species
to have high reproduction rates and disperse to increase their numbers as fugitive species are poor at competition e.g. algae
55
what are the 4 phases in the one step growth curve?
lag phase log (exponential) phase stationary phase death phase
56
explain the lag phase (3)
- organisms adapt and prepare for growth - metabolic activity - enzyme synthesis - need to reach sexual maturity, find a mate and gestate
57
explain the log phase (3)
- happens as long as no factor limits growth - bacteria divide at a constant rate and population doubles - cannot grow indefinitely due to environmental resistance (food, space)
58
explain the stationary phase (4)
- birth rate = death rate - max size, reached carrying capacity for that environment - fluctuates in response to environmental changes - biotic factors in 'normal environment' e.g. predators will affect growth
59
explain the death phase (2)
- same factor as end of log phase - death rate greater than birth rate
60
are biotic factors density - dependant or independent? abiotic?
dependent independent
61
explain density dependent
affect a higher proportion of the population when more dense
62
give an example of a density dependent biotic factor
food - depletion of food supply
63
explain density independent
the effects of abiotic factors are the same regardless of the size of population
64
what is negative feedback?
regulates population size. it's a change in response to a first change to bring the numbers back to their original levels
65
define abundance
the number of individuals in a species inna given area/volume
66
how could you sample animals? (2)
- capture - recapture (Lincolns index) - kick sampling in a stream
67
how could you sample plants? (2)
- quadrat - mean tubers of individuals, density - % cover - % frequency
68
what does a belt transect provide?
abundance data
69
what does a kite diagram show? (2)
- the % cover of the species across a belt transect/across a set distance - show abundance and distribution of a species along a transect
70
fill in the blank and define: plants are ______ organisms
autotrophic - can produce its own food using light, water an carbon dioxide
71
why does 60% of light that falls on a plant not get absorbed by photosynthetic pigments? what happens as a result?
could be the wrong wavelength - can't absorb green therefore it is reflected or transmitted straight through the leaf
72
what is photosynthetic efficiency (PE)?
the ability of a plant to absorb light energy (so it becomes part of the organic products of photosynthesis)
73
what is the equation for photosynthetic efficiency?
PE = quantity of light energy incorporated into product ÷ quantity of light energy falling on the plant x100
74
what range is PE usually between?
1-8%
75
what is primary production? what is primary productivity?
the production of new organic matter in plants (e.g. glucose) the rate of production of new organic matter in plants.
76
define GPP
the total amount of energy fixed inside new organic products in plants
77
define NPP
the total amount of energy left in plants after respiratory losses are subtracted from the GPP - this is the energy in plants which is available to primary/first stage consumers in the ecosystem
78
what is the equation for NPP?
GPP - respiration
79
what is secondary productivity?
the rate of production of new organic matter/biomass in consumers

biology (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions