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Biology🧬 > Population size and ecosystems (C1) > Flashcards

Population size and ecosystems (C1) Flashcards

1
Q

Ecology definition

A

the study of living organisms within a habitat and their interactions with both biotic and abiotic factors

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2
Q

Ecosystem definition

A

a characteristic community of interdependent species interacting with the abiotic components of their habitat

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3
Q

Habitat definition

A

the place in which an organism lives

  • often contains a community of organisms
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4
Q

Population definition

A

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

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5
Q

Community definition

A

interacting populations of two or more species within a particular habitat

i.e populations of different species living within the same habitat

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6
Q

Biotic factors

A

living factors within the environment including…

  • competition for recourses
  • predators
  • disease/ pathogens
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7
Q

Abiotic factors

A

non living factors including…

  • light intensity
  • water/nutrients/o2 availability
  • temperature
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8
Q

Niche definition

A

the specific role and position a species plays within a particular ecosystem

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9
Q

Random sampling

A

method of sampling when abiotic factors are uniform

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10
Q

Systematic sampling

A

method of sampling when there is a change is abiotic factors

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11
Q

What are population numbers dependent on?

A

population numbers will fluctuate, this is dependent on various factors, including…

  • birth rates/cell division
  • death rates
  • immigration
  • emigration
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12
Q

Name the shape of the graph of a usual pattern of growth of an equilibrium species

A

S-shaped

sigmoidal

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13
Q

What are the phases of the population growth curve for an equilibrium species and what happens?
*draw the graph

A
  1. LAG - slow rate of reproduction, cellular activity but not growth, a period of intense metabolic activity like enzyme synthesis i.e reaching sexual maturity in animals, time taken for yeast to hydrate in nutrient broth
  2. LOG/EXPONENTIAL - rapid increase in population, no factors limiting growth
  3. STATIONARY - birth rate/cell division is equal to death rate, factors are limiting further growth, pop has reached carrying capacity
  4. DEATH/DECLINE - environmental factors result in death rate greater than birth rate/cell division i.e glucose depleted in nutrient broth or yeast producing toxic waste ethanol
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14
Q

Carrying capacity definition

A

the maximum number of individuals a population can sustain within a particular environment
(the actual number fluctuates around the carrying capacity in response to environmental changes)

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15
Q

Where is environment resistance and where does it start to occur?

A
  • any factors that may limit the growth of a population

- end of log phase

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16
Q

How do you calculate population changes when populations are plotted on a log scale?

A 
number of bacteria at one specified day
number of bacteria at the other day
antilog10 those numbers
take away from each other
divide over the difference of days

i.e antilog10 ? - antilog10 ??
————————————–
day/time difference

17
Q

What are density dependent factors affecting the size of a population?

A
  • the larger the population size the greater the effect (more likely to slow down pop growth rate)
    e.g…..
    • disease and parasites
    • food availability
    • toxic waste build up
    (often biotic)
18
Q

What are density independent factors affecting the size of a population?

A
  • factors have an effect regardless of population size, the effect is ‘independent’ to the population
    (more likely to cause a population crash)
    e.g…..
    • natural disaster i.e volcanic eruption, eq, floods etc..
    • sudden changes in temp
    • hunting
    (often abiotic)
19
Q

How can competition affect population size, and the types of competition?

A
  • by impacting potential breeding success (comp for mates) and survival of organism (comp for land, food, fight)
  1. INTRA - specific competition
  2. INTER - specific competition
20
Q

Factors affecting population size (3)

A
  • density dependent factors
  • desntisy independent factors
  • competition
21
Q

What is INTRA specific competition?

A

(comp between the same species)

  • between members of the SAME species, occupy same niche/specific habitat, compete for same recourses
  • driving force behind natural selection ( as n.s is survival of fittest between that single species - pass on beneficial alleles, variation, adaption can occur)
  • as pop of that species a greater proportion of individuals fail to survive because comp excels
22
Q

What is INTER specific competition?

A

(comp between different species)

  • competition for resources between members of different species
  • in general one species will out compete the other
23
Q

What is the definition of niche and its concept?

A

NICHE - the specific role and position a species plays within a particular ecosystem

• only one species can occupy a particular niche within an ecosystem - one species will always outcompete the other
e.g two different species of protozoan grown in lab flasks - grow well in flasks separately but when grown together one outcompetes the other for nutrients, the population of one grows and the other falls

24
Q

What is the concept of an ecosystem?

A

ECOSYSTEM is a characteristic community of interdependent species and their habitat

*ecosystems range in size from very large to very
small

25
Q

What is the source of energy for an ecosystem?

A
  • the SUN is the source of energy for an ecosystem
  • light energy, trapped by photosynthesis is the source of energy for most ecosystems (other than those based on chemosynthesis, e.g. hydrothermal vents)
26
Q

What are trophic levels? energy between? biomass?

A

feeding levels within an ecosystem, the level at which an organism falls within the food web

  • producers are the first trophic level i.e photosynthesising plants
  • then a series of consumers (4/5 levels - only enough energy to support)
  • flow is energy is shown between the levels from the initial energy source, the sun to producers and consumers
  • energy is lost between trophic levels
  • biomass decreases up the levels
27
Q

What is gross primary productivity (GPP)?

A

Gross primary productivity (GPP) is the rate of
production of chemical energy in organic chemicals by
photosynthesis (in kJ m-2 year-1).

28
Q

What is net primary productive (NPP) and its equation?

A

Net Primary Production is gross primary production minus the chemical energy generated in respiration and used up by the producers metabolism in the year (respiration = R)

(NPP = GPP - R)

*NPP represents the potential food/chemical energy available to heterotrophs in ecosystems.

29
Q

Why is energy lost from the food chain at each level?

A
  • energy is egested - mostly cellulose as indigestible
  • energy lost as heat during respiration (farmers keep animals inside during winter - less energy lost regulating body temp)
  • energy remains in inedible parts of the animal - fur, bones, horns

*INEFFICIENCY OF ENERGY TRANSFER BETWEEN TROPHIC LEVELS

30
Q

Primary productivity vs secondary productivity

A
  • primary productivity involves the producers
  • secondary productivity involves the rate at which consumers accumulate energy from assimilated food in biomass in their cells/tissues
31
Q

Why do carnivores have a more efficient energy conversion than herbivores?

A

protein is more rapidly and easily digested than cellulose which is lost in much of herbivores faeces

32
Q

What is gross ecological efficiency? equation?

A

measure of how much energy is transferred from one trophic level to the next (often around 10% but oceanic food chains higher approx. 40%)

GEE = energy in that trophic level
——————————————– x 100
energy in previous trophic level

Biology🧬 (18 decks)

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