B1.4 Interdependence and Adaptation
Organisms are well adapted to survive in their normal environment. Population size depends on a variety of factors including competition, predation, disease and human influences. Changes in the environment may affect the distribution and behaviour of organisms.
- To survive, organisms require a supply of materials from their surroundings and from the other living organisms there.
- Organisms live, grow and reproduce in places where, and at times when, conditions are suitable.
Animals often compete with each other for:
Plants often compete with each other for:
- Water from the soil
- Nutrients from the soil
- Organisms have features (adaptations) which enable them to survive in the conditions in which they normally live
- The organisms that are best adapted to make use of their resources in a habitat are more likely to survive and increase in numbers
- For example:
- To be able to obtain a certain food better.
- To make it more difficult for predators to catch them.
- To survive in extreme climates, eg arctic or deserts
- Plants lose water vapour from the surface of their leaves.
- It is essential that they have adaptations which minimise this.
- Extremophiles are organisms that live in extreme environments.
- Some may be tolerant to high levels of salt, high temperatures or high pressures.
- Animals and plants may be adapted to cope with specific features of their environment eg thorns, poisons and warning colours to deter predators.
- Animals may be adapted for survival in dry and arctic environments by means of:
- changes to surface area
- thickness of insulating coat
- amount of body fat
- The camel can go without food and water for 3 to 4 days.
- Fat stored in their humps provides long term food reserve, and a supply of metabolic water.
- The fat is not distributed around the body; this reduces insulation, allowing more heat loss.
They are tall and thin, increasing their surface area to volume ration, increasing heat loss by radiation.
- Polar Bear
- Polar bear has thick fur and fat beneath its skin to insulate it.
- Their large, furry feet help to distribute their weight as they walk on a thin ice.
- They are white which camouflages them against the snow. This helps them to hunt.
- They are compact in shape, reducing their surface area to volume ratio; this reduces heat loss by radiation.
- Plants may be adapted to survive in dry environments by means of:
- changes to surface area, particularly of the leaves
- water-storage tissues
- extensive root systems.
- Desert plants
- Eg the cactus, require very little water to survive
- Leaves are spines.
- Spines guard against most browsing herbivorous animals.
- Spines also reduce their surface area, reducing water loss by evaporation
- A thick waxy coating surrounds the plant to reduce evaporation.
- Fewer ‘stomata’, reducing water loss
Roots tend to spread sideways to catch rain water.
- Arctic plants
- Many of the plants are small, growing close to the ground and very close together to avoid the wind and conserve heat.
- Some possess a light, fuzzy covering to insulate the buds so they can grow.
- Many are dark colors of blue and purple to absorb the heat from the sunlight even during the winter months.
- Because of the cold and short growing seasons, arctic plants grow very slowly.
- Some grow for ten years before they produce any buds for reproduction.
- Microorganisms have adaptations that enable them to survive in different environments.
- Slime capsule around some bacterial cell wall sticks them to surfaces and prevents them drying out.
- Some have the ability to form spores to survive when conditions are harsh.
- Some microorganisms have flagella which enable them to move around quickly.
- Bacteria undergo rapid reproduction when conditions are favourable.
- Some bacteria can survive extreme conditions:
- Temperatures as little as -15°C to as high as 121°C
- pH values 0.0 to 12.8
- High levels of pressure deep in the oceans
- High salt concentrations
- Very dry conditions.
- Changes in the environment affect the distribution of living organisms.
- For example, the changing distribution of some bird species and the disappearance of pollinating insects including bees.
- Animals and plants are subjected to environmental changes.
- Such changes may be caused by living or non-living factors.
Non-living (abiotic) factors:
Living (biotic) factors:
- Competition – for: food, light, water, space.
Living organisms can be used as indicators of pollution:
- Lichens are symbiotic associations of algae and fungi species that attach to tree trunks and rock.
- They are sensitive to changes in air quality.
- They are very sensitive to sulphur dioxide (SO2) pollution in the air.
- This is released from industry and burning fossil fuels, especially coal.
- Lichens absorb sulphur dioxide dissolved in water.
- It destroys the chlorophyll in the algae preventing it from photosynthesising and killing the lichen.
- Some species only grow in non-polluted air.
- Some species grow in polluted air.
- These lichens can be used as air pollution indicators.
- Invertebrate animals are sensitive to changes in the concentration of dissolved oxygen in water.
- Oxygen concentrations decrease when pollutants are released into rivers and lakes.
- Some invertebrates survive in low-oxygen concentrations.
- Some invertebrates can only survive in higher oxygen concentrations.
- These invertebrate animals can be used as water pollution indicators.
- Environmental changes can be measured using non-living indicators.
- For example. oxygen levels, temperature and rainfall.
Scientists continually monitor these factors to show trends in environmental changes