4.7.1 Adaptations, interdependence and competition

4.7.1.1 Communities

Biodiversity

• Biodiversity is a measure of the variety of living organisms within a particular habitat, ecosystem, biome, or all over Earth.

Habitat

• A habitat is an area where one or more organisms live.
  • For example, a fish could have a pond as its habitat.

Population

• A population is all of the organisms of the same species in a certain area.

Community

• A community refers to all of the populations present inside a single habitat.
  • For example, a pond might have populations of birds, frogs, fish and insects.

Ecosystem

• An ecosystem is the interaction of the community with all of the abiotic and biotic features in the environment.

Abiotic and Biotic Factors

• Abiotic factors are non-living factors and biotic factors are living factors.

Food Chain

• There is a food chain in ecosystems.
• This consists of:
  • producers
  • primary consumers,
  • secondary consumers
  • tertiary consumers.
• These are known as trophic levels.

Producers

• Producers provide energy to the ecosystem by photosynthesising to produce food.
  • They are general algae and plants.

Primary Consumers

• Primary consumers are herbivores.
  • These are organisms that eat only plants.
  • Examples include deer and cows.

Secondary Consumers

• Secondary consumers get their energy from primary consumers.
  • Therefore, organisms at this level of organisation are called carnivores.
  • These types of organisms eat only animals.

1-1 GCSE Biology Tutoring

Boost your Biology exam scores with personalised lesson plans, tailored to your needs

Book a FREE Consultation

Tertiary Consumers

• Tertiary consumers eat the secondary consumers.
  • Organisms at this trophic level are also carnivores.

Interdependence

• Ecosystems are very intricately linked.
  • Each organism is inextricable linked to one another.
  • If one relationship fails, the whole food chain can fall.

Competition

• Competition occurs usually at the same trophic level.
  • Plants will compete with other plants for nutrients, space, light, water and minerals at the producer level.
  • Animals will compete for territory, mates and food.

Competition

• Organisms with better adaptations will outcompete the others, therefore will survive and have more offspring.
• Competition can come from within an a species or from different species.
  • It all depends on whether the resources required are from one species or another.

Stable Communities

• In stable ecosystems, the size of the community stays constant at all times.
  • This occurs in the ecosystem of the fruits, bats and eagles.
  • In such ecosystems, even the environmental factors, such as light and minerals are balanced.
• This explains why problems such as deforestation can cause so much harm to ecosystems.

4.7.1.2 Abiotic factors

Abiotic factors

• Abiotic factors are non-living factors that affect a community.

Light Intensity

• Light intensity is an incredibly important abiotic factor.
  • Plants require light for photosynthesis.
  • Therefore, if there is competition for light in an ecosystem, those organisms that are more adapted to catch more light are more likely to survive.
  • One example of this adaptation would be having larger leaves.

Light Intensity

• Some plants have developed an optimum light intensity.
  • This means that some plants require a lot of light, whereas others do not.
  • Dracaena plants and cacti grow well with little light, whereas plants such as aloe vera require a lot of light.

Temperature

• Plants and animals have an optimum temperature.
  • If the temperature is greater than the optimum temperature, its enzymes will denature.
  • If the temperature is too low, the enzymes will work too slowly.

Moisture

• Different plants have different optimum levels of moisture.
  • If you overwater a plant, the soil will become waterlogged.
  • This means that the roots will be drowned and unable to respire, killing the plant.

Soil and aquatic pH

• Some plants grow well in areas with a higher pH and others grow well in more acidic soils.
  • Some plants, like the hydrangea plants, can grow in both types of soil.
  • If the pH of an aquatic ecosystem changes, it could have a huge effect.
  • Organisms have adapted to survive at different pH levels in the water.

Mineral Content

• Plants have different optimal mineral content levels.
  • Some plants require a high mineral content to grow well.
  • For example, many plants require a lot of magnesium.
  • Magnesium is a key ingredient for the composition of chlorophyll.
  • Some plants even trap organisms in the soil in order to increase the level of minerals.

Wind Intensity and Direction

• Organisms often prefer sheltered environments.
  • Some locations are very affected by wind.
  • This will mean that plants suffer and the seeds of the plant will be easily dispersed around.
  • This will affect the organisms that feed upon these and the plant will struggle to grow.

Carbon Dioxide Levels for Plants

• Plants require an optimum carbon dioxide level.
  • Higher levels of carbon dioxide will lead to increased plant growth, as it will allow more photosynthesis.
  • Woodland areas have a high level of carbon dioxide, so promote crop growth.
  • Plants in other areas have evolved to survive in areas with lower carbon dioxide levels.

Oxygen Levels for Aquatic Organisms

• Oxygen dissolves into the water in order to provide supplies for aquatic organisms.
  • In polluted rivers, the oxygen level decreases.

Oxygen Levels for Aquatic Organisms

• You must take all of this info into account and analyse tables of data. For example:

GCSE Biology Online Course

Covering every topic in the GCSE syllabus

Buy Now£29

4.7.1.3 Biotic factors

Biotic factors

• A biotic factor is a living factor that can affect an ecosystem.

Availability of Food

• Organisms need food for survival.
  • This means that the areas where food is in abundance, such as rainforests, allow a great amount of growth.
  • Tundra areas, such as Siberia, however, have less food and so fewer organisms can survive here.

New Predators

• When a new predator enters a stable ecosystem, they provide more competition to the organisms in their trophic level.
  • This will mean that the number of prey will dramatically decline.
  • This could wipe out all of the other predators, as their food supply will be reduced dramatically.

New Pathogens

• Pathogens being introduced into an ecosystem can have a dramatic effect.
  • When Europeans colonised Australia, smallpox was introduced from the colonisers.
  • This devastated the Aboriginal population, as they had not developed the required immunity.

Uses of Pathogens

• Pathogens can be used for biological control.
  • Ash borers are controlled by introducing pathogens and parasites into their population.

Species Outcompeting

• New species can outcompete an existing species.
  • The cane toad was introduced from Europe to Australia.
  • This led to it outcompeting the existing species’ and led to an increase in the population of the cane toad.
  • Such a system also occurred with the introduction of grey squirrels in Europe.

4.7.1.4 Adaptations

Types of Adaptation

• Plants and animals are well adapted to different surroundings.
  • These adaptations have helped them to survive and reproduce.
• They can be:
  • behavioural
  • structural
  • Physiological.

Physiological Adaptations

• An organism’s physiology involves the processes it undergoes to stay alive.
  • Some plants are specifically adapted in order to stay alive. Some are toxic to  eat for predators, for example the Water Hemlock.
  • Some on the other hand are resistant to antibiotics and pesticides.
  • These advantages are internal or cellular features that help a plant to survive.

Behavioural Adaptations

• Some plants have modified their behaviour in order to survive.
  • The Venus Fly Trap for example can trap insects in its leaves for food.
  • Tropisms are also an example of a behavioural adaptation.

Structural Adaptations

• The structure of certain plants have been developed to survive.
  • For example, some plants, such as cacti, have thorns and spines to defend from predators.
  • They could also be a darker colour, to absorb solar heat.

Physiological Adaptations

• Animals can also be toxic or produce venom in order to add off predators.
  • The spitting cobra projects venom from its fangs as a form of defence.
  • This venom can blind predators.
  • More over, organisms secrete pheromones to attract or repel organisms.

Behavioural Adaptations

• Courtship behaviours attract the opposite sex.
  • They are ritualised actions to attract members of the opposite sex of the same species.
  • They enable the development of a bond to raise offspring together.
  • Wolves huntings in packs is another example of a behavioural adaptation.

Structural Adaptations

• Birds of prey have very sharp claws and are incredibly strong, in order to fly fast and hunt their prey.
• The most common structural adaptation is the difference between predators and prey.
  • Predators have eyes on the front of their face, whereas prey have eyes on the sides of their face.

Extremophiles

• Extremophiles are organisms are adapted to live in extreme environments.
  • This can include dangerous temperatures, pressures and salt levels.
  • The majority of these organisms are not animals and plants, but bacteria.

Animals

• Polar bears are well adapted to their Arctic conditions.
  • Polar bears have strong senses of smell and sight in order to sense well camouflaged prey.
  • They have a high surface area: volume ratio, which reduces heat loss as it reduces the speed of conduction.

Animals

• Penguins are adapted to the Antarctic conditions.
  • Emperor penguins must survive in winds of around -60 degrees celsius.
  • They are well adapted for this with blubber and a thick, waterproof set of feathers for insulation

Bacteria

• Ecosystems exist in the deep sea volcanic vents which have very high temperatures, pressures and are also pitch black.
  • Bacteria have adapted to live off the chemicals in these vents.
  • They act as producers and provide food for tubeworms.
  • These highly adapted organisms have a symbiotic relationship.
  • This means that they interact with one another and depend on each other to survive.