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A2 Biology > Ecosystems- Topic 10 > Flashcards

Ecosystems- Topic 10 Flashcards

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1
Q

Interspecific competition

A

Competition between different species in a community for the same resources.

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2
Q

Effect of interspecific competition

A

Reduce abundance of the competing species. If there is a greater density of one species or it has a faster reproduction rate then the other species may become locally extinct.

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3
Q

Intraspecific competition

A

Competition between the same species for limited resources

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4
Q

Effects of intraspecific competition

A

Some individuals may not survive or reproduce causing population growth to slow. This strengthens the population through natural selection.

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5
Q

What is an autotroph?

A

An organism that can make its own organic molecules from inorganic molecules

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6
Q

What is a heterotroph?

A

An organism that derived its nutritional requirements from organic substances

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7
Q

What is succession?

A

Directional change in an ecosystem over time to form a climax community

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8
Q

Primary succession

A

When organisms colonise a lifeless habitat

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9
Q

Secondary succession

A

When organisms re-colonise a devastated ecosystem (there is still some life)

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10
Q

What is the role of pioneer species?

A

Stabilise, add nutrients which riches the ground and add humus (organic matter)

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11
Q

What are 5 seres of primary succession

A

Sere 1: empty habitat- harsh environment
Sere 2: habitat colonised by pioneer species
Sere 3: pioneer species will modify the environment creating conditions that support new species
Sere 4: new plant species increases diversity- various animals enter habitat. The early species are replaced by new species.
Sere 5: a climax community.

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12
Q

Structure of lichens

A

Composed of fungus and algal cells.

the algal cells photosynthesise and the fungus secretes enzymes to break down food which it then reabsorbs.

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13
Q

Primary succession of bare rock

A

Bare rock has minerals but lack of soil and water
Lichens are pioneer species that are the primary colonisers of bare rock.
When these die humus is added forming soil which begins the growth of a new community that outcompetes lichens.

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14
Q

Quantifying populations: size

A

Number of individuals in a population

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15
Q

Quantifying populations: density

A

Number of individuals per unit area

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16
Q

Quantifying populations: growth rate

A

The changes in the number of individuals per unit time

17
Q

Growth of populations: 1

A

LAG PHASE

initial population growth rate is slow due to individuals being widely dispersed

18
Q

Growth of populations: 2

A

LOG GROWTH
population grows at its maximum possible rate- birth rate is higher than death rate
(Biotic potential)

19
Q

What is biotic potential and what is it determined by?

A

The ability of a population to increase under ideal conditions. It is determined by rate of reproduction and size or litter

20
Q

Growth of populations: 3

A

TRANSITION PHASE

Environmental resistance increases- increased competition increases death rate- growth rate slows

21
Q

Growth of populations: 4

A

PLATEAU PHASE
Population reaches the maximum size that it’s ecosystem can sustain. This is the carrying capacity (k). Population now remains roughly stable

22
Q

What does destruction go part of the ecosystem do to population size

A

Drops below carrying capacity

23
Q

What is a density dependent factor?

A

As the population increases the limiting factor becomes a problem and impacts the community eg. Competition for food, disease

24
Q

What is a density independent factor?

A

Remains constant regardless of population size eg: rainfall, temp

25
Q

How do you calculate population growth rate?

A

Population at end of period - population at start of period
—————times 100
Population at start of period

26
Q

Describe a predator prey interaction diagram

A
  1. Peaks of prey should be higher than peaks of predator
  2. troughs of predator lower than troughs of prey
  3. Predator to the right prey to the left
27
Q

Why are the predator prey interaction diagrams rare

A

Most predators have multiple prey species

28
Q

How will density independent factors affect the distribution of organisms?

A
  1. May need to move/migrate

2. Could limit distribution because only one area is suitable

29
Q

As succession progresses what 4 things increase?

A
  1. Habitats and niches
  2. Biodiversity
  3. Complex food webs
  4. Biomass
30
Q

What is deflected succession?

A

A pause in succession eg. Agriculture, grazing, pesticide

31
Q

What is ACFOR?

A 
Abundant 
Common
Frequent
Often
Rare
32
Q

What does the null hypothesis state?

A

Any differences between data sets are due to chance alone- no link

A2 Biology (19 decks)

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