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Biology > Chapter 19 - Population in Ecosystems > Flashcards

Chapter 19 - Population in Ecosystems Flashcards

1
Q

Define abiotic

A

An ecological factor that makes up part of the non-biological environment of an organism

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2
Q

Define biotic

A

An ecological factor that makes up part of the living environment of an organism

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3
Q

Give 3 examples of an abiotic factor

A

pH of soil
temperature
light intensity

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4
Q

Give 3 examples of a biotic factor

A

food availability
predators
competition

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5
Q

Define biosphere

A

the part of the earth that is capable of supporting life / the sum of all ecosystems

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6
Q

Define environment

A

the surroundings or conditions in which an organism lives. (non-living components)

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7
Q

Define ecosystem

A

All the living and non- living components of a particular area

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8
Q

Define population

A

A group of individuals of 1 species that occupy the same habitat at the same time and are able to interbreed

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9
Q

Define community

A

All the living organisms present in an ecosystem at a given time

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10
Q

How does an ecosystem sustain its community?

A

It will have its own plants that collect the necessary sunlight energy to support all the populations and will also contain its own nutrients which will be recycled within the ecosystem

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11
Q

What is carrying capacity?

A

The population size of a species that an ecosystem is capable of supporting

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12
Q

What causes the size of a population within an ecosystem to vary?

A

The effect of abiotic factors and the interactions between organisms that affect the biotic factors

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13
Q

What is a habitat?

A

a place where an organism normally lives.

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14
Q

What is a microhabitat?

A

Smaller units that make up a habitat, each with their own microclimates and factors

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15
Q

What is an ecological niche?

A

how an organism fits into an environment by refering to where an organism lives and how it behaves

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16
Q

what does the competitive exclusion principal state?

A

No two species can occupy exactly the same niche

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17
Q

What factors can inhibit an organisms capacity to grow indefinitely?

A

Availability of resources including: food, light, water, oxygen, space, CO2, shelter
Accumulation of toxic waste
Disease
Predators

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18
Q

List 4 abiotic factors that can influence population size

A

Light
pH
Temperature
Water and humidity

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19
Q

What is the general trend when abiotic factors are not optimal for an organism?

A

When an abiotic factor is above or below optimum for a population, fewer individuals will be able to survive because their adaptations are not suited to the conditions

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20
Q

What happens to population size if temperature is too low for warm blooded animals?

A

They expend more energy to keep a constant temperature and therefore less energy is available for growth and reproduction

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21
Q

What happens to population size if temperature is too low for cold blooded animals?

A

The enzyme function of the organisms are reduced and the metabolic rate of the organism slows which reduces carrying capacity

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22
Q

What happens to population size if temperature is too high for plants and animals?

A

The enzymes are denatured meaning they cannot grow and repair as well, and carrying capacity is reduced

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23
Q

How is population size related to pH for organisms?

A

In an area with sub optimal pH the population size is smaller or non existent
In an area with optimal pH the population size is larger

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24
Q

How is population size related to light intensity for organisms?

A

The higher the light intensity the higher the population size for producers and consumers which rely on light energy.
The lower the light intensity the smaller the population size for both producers and consumers

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25
Q

How is population size related to water availability and humidity for organisms?

A

In dry conditions the population size of organisms that are not adapted is exceedingly low
In dry conditions population size of organisms which are adapted to the environment will be higher than organisms without those adaptations

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26
Q

Explain the benefits of using a logarithmic scale for data with a wide range

A

You can include the whole spectrum of data and be able to see the relationships between the data points to be able to establish an overall trend

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27
Q

Define intrAspecific competition

A

Competition between individuals from the same species for resources

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28
Q

Define intERspecific competition

A

Competition between individuals of different species for resources

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29
Q

Give 2 examples of resources specific to intraspecific competition

A

mates

breeding sites

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30
Q

Give an example of resources specific to interspecific competition

31
Q

What does the competitive exclusion principle show will happen to 2 species who are competing for the same niche?

A

1 with an advantage over the other will survive and grow and 1 will die out

32
Q

How can you see how a factor affects the size of a population?

A

you have to compare it to the birthrate and deathrate of that population to be able to distinguish the effect is had on population size.

33
Q

What is predation?

A

The process of one organism being consumed by another

34
Q

What happens when prey and predators are left in a lab?

A

The prey is exterminated

35
Q

Why will prey become exterminated in a lab but not in the wild when exposed to predators?

A

Because prey has a limited space and range of hiding spaces and therefore the prey will be caught, whereas in the wild there is much more space and a wider variety of hiding spaces.

36
Q

Explain what happens when predators each their prey (next stage in cycle)

A

The population size of prey falls

37
Q

What happens if the population size of prey falls? (next stage in cycle)

A

The number of predators is reduced because they have less food available and so are in greater competition with each other

38
Q

Explain what happens when the number of predators is reduced (next stage in cycle)

A

Fewer prey are eaten and so the population of prey rises

39
Q

What happens when the population of prey rises? (next stage in cycle)

A

more prey is available so the number of predators increases in turn

40
Q

Explain the difference in a graph showing laboratory observed predation and natural ecosystem observed predation

A

In a natural ecosystem the fluctuations of the graph will be less severe because organisms consume a large range of food.

41
Q

What factors other than predation can cause fluctuations in a predatory prey graph?

A

Disease
Adverse weather
Shortage of food for prey
Shortage of water

42
Q

How do the fluctuations in population size lead to evolution of organisms?

A

In the troughs of the fluctuations, the organisms experience selection pressures which leads to natural selection where only organisms with advantageous alleles survive and breed. This leads to a greater proportion of organisms having desirable alleles, meaning more of the population is adapted to the environment

43
Q

How can you assess which factors have a greater influence in population size?

A

Create an experiment with 4 groups : 1 control, 2 with different conditions and 1 with both conditions. By comparing the growth of the population you can assess which has a greater impact in population size, by comparing growth with the control

44
Q

What are the 2 types of quadrats?

A

Framed or point

45
Q

What 3 things do you have to consider when using quadrats ?

A

Size
Sample number
Where to sample

46
Q

What does avoiding bias do?

A

Ensure results are reliable

47
Q

When might you need to use systematic sampling?

A

When wanting to measure gradual changes in a community

48
Q

What is one method of carrying out systematic sampling?

A

Using a belt transect

49
Q

Explain the method for using a belt transect

A 
Lay out the belt. 
Place a frame quadrat along the line
Record the desired data.
Move the quadrat the distance of itself along the belt
Repeat
50
Q

What type of data does a belt transect give you?

A

Continuous data

51
Q

Explain 2 ways to get random coordinates for sampling

A

Number chart

Random number generator

52
Q

What is abundance?

A

The number of individuals of a species within a given area

53
Q

Describe 3 ways for calculating abundance regardless of the organism

A

Frequency
Percentage cover
Mark, release, recapture

54
Q

What are 3 things you can do to make your data more reliable?

A

Use a large sample size
Use random sampling
Use many quadrats

55
Q

What are methods of measuring abundance in sessile organisms?

A

Percentage coverage

Frequency

56
Q

What is a sessile organism?

A

Organisms that are not able to move freely

57
Q

What is a motil organism?

A

Organisms with the ability to move around

58
Q

How can you calculate abundance in motile organisms?

A

Mark, release recapture

59
Q

Explain the method of mark, release, recapture

A

Capture a known quantity of organisms and mark them.
Release them back to their community and wait a period of time to allow them to redisperse
Capture a given number of the organism in the same area.
Record the number of organisms from the second sample that are marked

60
Q

What is the equation for estimating population size?

A

(Total number of individuals in sample 1 x total number of individuals in sample 2) / number of marked individuals recaptured

61
Q

List 4 requirements of the marker they use to mark organisms

A

Non toxic
Cannot be removed
Does not fade
Does not make the organism more conspicuous

62
Q

List 6 assumptions made when using mark, release, recapture method to estimate population size.

A
  1. The marked individuals redistribute evenly among the rest of the population
  2. The marker is not toxic
  3. The death and birthrate do no alter significantly during the investigation
  4. The marker does not make the organism more liable to predation
  5. The marker cannot be removed or faded
  6. The proportions of marked individuals to unmarked individuals in the sample is equal to in the community`
63
Q

Define succession

A

a term used to describe changes in the species that occupy a particular area overtime

64
Q

Define pioneer species

A

Species that colonise inhospitable land

65
Q

Define climax community

A

The final stage in succession where the maximum number of species that can be supported in the ecosystem are supported

66
Q

List 2 ways new species change the prevalence of existing species

A

They make the environment less suitable for an existing species causing the new species to outcompete the old
They make the environment more suitable for species with adaptations which outcompete them

67
Q

A series of successional changes ……

A

Alter the abiotic environment

68
Q

How does altering the abiotic environment lead to an increase in biodiversity ? (1 mark - general)

A

The environment becomes less hostile and so it is easier for species to survive and grow

69
Q

What is primary succession?

A

The first stage of succession in which pioneer species colonise inhospitable land

70
Q

List 5 adaptations of pioneer species to make them more adapted to colonising land

A
  1. Photosynthetic - produce their own energy
  2. Asexual reproducers - reproduce rapidly without having to mate
  3. Nitrogen fixing - allows them to grow in the absence of nitrogen
  4. Tolerant to extreme conditions with adaptations such as low lying
  5. Ability to widely disperse seeds and spores to multiply rapidly
71
Q

List 4 ways pioneer organisms make land less hostile -

A

Nitrogen fixing and release nitrogen when they die
Create habitats by weathering rock into soil
Create higher water retention in land
Increase food sources available

72
Q

List 5 common features that emerge from primary succession

A 
Less hostile conditions
Greater number of habitats
Increased biodiversity
More complex food webs
Increased biomass
73
Q

What is secondary succession?

A

Succession that occurs when land that has already sustained life is suddenly altered

74
Q

What is the main difference between the processes of primary and secondary succession?

A

Secondary succession is much faster because of the pre -existing presence of spores, seeds, nutrients and soil which makes it much quicker to take over

Biology (21 decks)

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