7.1 Adaptations, Interdependence & Competition

Define an individual.

Single organism of specific species

Define a population.

All organisms of same species living together in habitat

Define a community.

All populations of different species living together in habitat

Define competition.

• Different organisms compete for same resources in ecosystem

• Limits population sizes + stimulates evolutionary change

• The image shows what the extinct Siberian rhinoceros (Elasmotherium sibiricum) might have looked like.

• The horn of the Siberian rhinoceros is estimated to have been 150 cm long.

Suggest one advantage of this adaptation to the Siberian rhinoceros. [1 mark]

Competing for food

What are the levels of organisation in an ecosystem?

individual → population → community → ecosystem

What is the definition of an ecosystem?

Interaction of a community of living organisms (biotic) w/ the non-living (abiotic) parts of their environment

To _________ and ___________, organisms require a supply of materials from their _______________ and from the other ___________ _____________ there.

• survive

• reproduce

• surroundings

• living organisms

What do plants in a community or habitat compete for?

• Light

• Space

• Water

• Mineral ions

What so animals compete for?

• Food

• Mates

• Territory

• Within a ____________ each species depends on other species for ______, shelter, ___________, seed dispersal etc.

• If one species is ___________ it can affect the whole _____________.

• This is called __________________.

• community

• food

• pollination

• removed

• community

• interdependence

What is the definition of interdependence?

The dependence of different organisms on each other for survival.

What is meant by a stable community?

One where all the species and environmental factors are in balance — population sizes remain fairly constant.

What are examples of stable communities? (3)

• Tropical rainforests

• Oak woodlands

• Coral reefs

What is the definition of an abiotic factor?

The non-living aspects of an ecosystem.

What are some abiotic (non-living) factors which can affect a community? (7)

• light intensity

• temperature

• moisture levels

• soil pH and mineral content

• wind intensity and direction

• carbon dioxide levels — plants

• oxygen levels — aquatic animals

Explain the effect of a change in light intensity on a community.

• Light — needed for photosynthesis

• Rate of photosynthesis — affects plant growth rate

• Plants = food sources/shelter for other organisms

Explain the effect of a change in temperature on a community.

• Temperature — affects rate of photosynthesis

• Rate of photosynthesis — affects plant growth rate

• Plants = food sources/shelter for other organisms

Explain the effect of a change in moisture levels on a community.

Animals and plants need water to survive.

Explain the effect of a change in soil pH and mineral content on a community.

• Soil pH — affects rate of decay → speed that mineral ions return to soil (taken up by other plants)

• Different species of plants thrive in different nutrient concentration levels

Explain the effect of a change in wind intensity and direction on a community.

• Wind — affects rate of transpiration (movement of water from roots → leaves) in plants

• Transpiration — affects temperature of plant and rate of photosynthesis (transports water and mineral ions → leaves)

  • Rate of photosynthesis — affects plant growth rate

  • Plants = food sources/shelter for other organisms

Explain the effect of a change in carbon dioxide levels on a community.

• CO₂ — affects rate of photosynthesis

  • Rate of photosynthesis — affects plant growth rate

  • Plants = food sources/shelter for other organisms

• Affects distribution of organisms — some thrive in high CO₂ environments

Explain the effect of a change in oxygen levels (aquatic animals) on a community.

• O₂ levels vary greatly in water

• Most fish need high concentration of O₂ to survive

What is the definition of a biotic factor?

The living aspects of an ecosystem.

What are the biotic factors which can affect a community? (4)

• availability of food

• new predators

• new pathogens

• one species outcompeting another — numbers are no longer sufficient to breed

Explain the effect of food availability on a community.

More food = organism breed more successfully → population increase

Explain the effect of new predators on a community.

• New predator = decrease in prey population

• Existing predators — less food → have to compete → decrease in predator population

Explain the effect of new pathogens on a community.

New pathogen — population has no resistance to it → decrease in population

Explain the effect of competition on a community.

• If one species is better adapted to the environment — it will outcompete

  • Until numbers of lesser adapted species are insufficient for breeding

• The growth of daisy plants on a lawn is affected by biotic factors and by abiotic factors.

• The table below shows six factors.

Factor	Biotic	Abiotic
A — Nitrates in the soil
B — Rabbits eating the plants
C — Shading by a building
D — Soil pH
E — Temperature
F — Trampling by people

Choose one box in each row to show whether the factor is biotic or abiotic. [3 marks]

• A — abiotic

• B — biotic

• C — abiotic

• D — abiotic

• E — abiotic

• F — biotic

What is the definition of an adaptation?

A feature of an organism — increases its chance of survival in its environment.

Organisms have features (___________) that enable them to ___________ in the conditions in which they normally live.

• adaptations

• survive

What can adaptations be? (3)

• Behavioural

• Structural

• Functional

What is meant by a structural adaptation?

Shape or colour of a part of an organism

What are examples of structural adaptations? (3)

• Sharp teeth (carnivore) — tear meat apart

• Camouflage — avoid predators/prey spotting them

• Thick layer of fat (insulation) — keep warm in cold environments

What is meant by a behavioural adaptation?

The way an organism behaves.

What are examples of behavioural adaptations? (3)

• Playing dead — avoiding predators

• Basking in sun — absorb heat

• Courting behaviour — attract a mate

What is meant by a functional adaptation?

Involved in processes — e.g. reproduction and metabolism

What are examples of functional adaptations? (2)

• Late implantation of embryos

• Producing little sweat — conserves water

What are extremophiles?

Organisms that live in environments that are very extreme.

• Some organisms live in environments that are very ________ — such as:

  • high _____________

  • high _________

  • high ______ ____________

• These organisms are called _____________.

• Bacteria living in _____ ____ _______ are ______________.

• extreme

• temperature

• pressure

• salt concentration

• extremophiles

• deep sea vents

• extremophiles

What are some examples of adaptations for cold climates? (2)

• Smaller SA:V — reduces heat loss

• Lots of insulation — e.g. blubber, fur coat

What are some examples of adaptations for dry climates? (4)

• Adaptations to kidneys — retain lots of water → produces very concentrated urine

• Being active in early mornings and evenings — it is cooler

• Larger SA:V — increases heat loss

• Resting in shady areas

What are some examples of plant adaptations? (4)

• Curled leaves — reduces water loss

• Extensive root systems — takes in lots of water

• Waxy cuticle — stops water evaporating

• Water storing tissue in stem

• The stone plant, Lithops bromfieldi, is adapted to live in very dry deserts.

• Figure 1 shows several stone plants.

• The stone plant has many adaptations that help it to survive in the desert.

Draw one line from each adaptation to how the adaptation helps the stone plant to survive. [4 marks]

• A — 4

• B — 5

• C — 2

• D — 6

• The jerboa is a small desert animal.

• Figure 2 shows a jerboa.

• The jerboa is adapted for survival in the desert.

• The jerboa spends the daytime in its underground burrow.

• The jerboa only leaves its burrow to look for food during the night.

Describe how these adaptations help the jerboa to survive in the desert. [2 marks]

• The jeroba can keep cool

• It loses less water as it sweats less

• The jerboa is a small desert animal.

• Figure 2 shows a jerboa.

• The jerboa is adapted for survival in the desert.

• The jerboa spends the daytime in its underground burrow.

• The jerboa only leaves its burrow to look for food during the night.

What type of adaptations are described? [1 mark]

Choose one box.

Behavioural

• Figure 1 shows a type of camel called a dromedary (Camelus dromedarius).

• The dromedary lives in hot, dry deserts.

• One adaptation of the dromedary is ‘temperature tolerance’.

• This means that the animal’s body temperature can rise by up to 6 °C before it starts to sweat.

Explain how temperature tolerance can help the dromedary to survive in the desert. [2 marks]

• Less sweating so less water loss

• As there is little water available in the desert

• Figure 1 shows a type of camel called a dromedary (Camelus dromedarius).

• The dromedary lives in hot, dry deserts.

• One adaptation of the dromedary is ‘temperature tolerance’.

• This means that the animal’s body temperature can rise by up to 6 °C before it starts to sweat.

• Three more adaptations of the dromedary are given in Figure 1.

  • Fat store

  • Hard mouth

  • Produces little urine and dry faeces

Give a reason why each adaptation helps the animal survive in the desert. [3 marks]

• Fat store — can be metabolised to water

• Hard mouth — not damaged by spines on plants

• Produces little urine and dry faeces — conserves water