AQA Geography GCSE 3.1.2.1-2: Ecosystems and Tropical Rainforests

Flashcards covering the definitions of ecosystems, their components, interactions, nutrient cycling, impacts of change, global biomes (Tundra, Taiga, Temperate Deciduous/Grassland, Desert, Tropical Rainforest, Savanna, Mediterranean), and detailed information on tropical rainforest characteristics, human impacts (deforestation causes and impacts), and sustainable management strategies.

What is an ecosystem?

A natural system in which a community of plants and animals interact with each other and their physical environment.

What are biotic components in an ecosystem?

Living organisms, such as plants and animals.

What are abiotic components in an ecosystem?

Non-living environmental factors which have influence over the ecosystem.

Give examples of abiotic components.

Climate (temperature, humidity, precipitation), light exposure, and soil type.

What is a small-scale ecosystem?

Local ecosystems, such as in a freshwater pond or on the seashore.

What is a global-scale ecosystem?

Large regions of the world with similar environmental conditions (especially climate, vegetation, and soil type).

What is another term for global-scale ecosystems?

Biomes.

What are producers?

Organisms that convert energy from the environment (mainly sunlight) into sugars (glucose).

Give an example of a producer.

Plants.

How do plants produce energy?

They convert energy from the sun into glucose via photosynthesis.

What are consumers?

Organisms that receive energy from consuming (i.e. eating) living organisms.

How do consumers get energy from producers?

They eat producers and receive energy from the sugars made by them (e.g., rabbits eating grass).

How do some consumers get energy from other consumers?

They eat other consumers (e.g., a fox eating a rabbit).

What are primary consumers?

Organisms that eat producers.

What are secondary consumers?

Organisms that eat primary consumers.

What are decomposers?

Organisms that break down organic material (e.g., dead plants and animals or faeces) and release nutrients into the soil.

How do decomposers help plants?

They release nutrients from organic material into the soil, which are then absorbed by plants when they grow.

Give examples of decomposers.

Fungi and bacteria.

How are interactions in ecosystems demonstrated?

With food chains or food webs.

What does a food chain show?

How producers and consumers interact within the ecosystem.

How are food chains usually depicted?

In a straight line, starting with the producer and ending with the last consumer.

What role do decomposers play in food chains?

They recycle energy back into the producers.

Give an example of a simple food chain.

Grass (producer) -> Rabbit (consumer) -> Fox (consumer).

What is a food web?

An illustration of how multiple producers and consumers interact within ecosystems through several different food chains.

How do food webs differ from food chains?

Food webs demonstrate complex relationships involving multiple interconnected food chains, whereas food chains are usually linear.

What are nutrients?

Substances that fuel plant and animal growth, such as nitrates and phosphates.

Give examples of nutrients.

Nitrates and phosphates.

Where do nutrients come from (geological source)?

Rocks and minerals breaking down by weathering.

Where do nutrients come from (atmospheric source)?

Chemicals in the atmosphere washed out within precipitation.

Where do nutrients come from (biological source)?

Special bacteria absorbing chemicals from the air and storing them in soil.

How are nutrients transferred throughout the ecosystem (living to non-living)?

Animals and plants die, and decomposers break up their organic matter into nutrients, which are returned to the soil.

Describe the general nutrient cycle process.

Producers take up nutrients, consumers eat producers, both die, and decomposers break down organic matter into nutrients, returning them to the soil.

How are abiotic and biotic components related in an ecosystem?

They are delicately balanced and interrelated, meaning changing one factor can have knock-on effects on others.

What happens if changes in an ecosystem are slow?

The ecosystem can adapt over time.

What happens if changes in an ecosystem are abrupt?

They can throw off the ecosystem's balance and potentially completely alter it.

What are two categories of changes within ecosystems?

Natural or human-induced.

Give an example of a global-scale change.

Climate change.

Give an example of a local-scale change.

A change to a habitat.

How can the introduction of disease affect an ecosystem?

It can devastate both plant and animal populations.

How can changes in population size affect an ecosystem?

They can affect food chains and have knock-on effects on other species numbers.

How can extreme weather, climate change, and natural disasters affect an ecosystem?

They can radically change an ecosystem, for example, by drying up ponds and lakes.

Provide an example of drought impacting an ecosystem.

A drought in Australia caused many duck ponds to dry up, destroying ducks' habitats.

How can the introduction of a new species alter food chains?

A new predator could dramatically decrease populations lower down the food chain.

How can a new species act as a new food source?

It can increase the population size of animals higher up the food chain.

Provide an example of an invasive species affecting bird populations.

Mice introduced to sub-Antarctic islands have caused reductions in seabird numbers by eating eggs and small birds.

How can human activities disrupt ecosystems?

Activities like construction, agriculture, and deforestation can make conditions unsuitable for plants and animals.

Give an example of a simple human change altering an ecosystem.

Removing a hedge or building a road can alter the nutrient cycle and disrupt animal behaviour.

What is a trophic cascade?

The concept where removing a top predator has knock-on effects lower down the food chain.

Give an example of removing a top predator leading to a trophic cascade.

Removing wolves in a woodland ecosystem would cause higher levels of deer, reducing vegetation levels.

What is eutrophication?

Changes to nutrient levels in freshwater ecosystems.

What causes eutrophication in freshwater ecosystems?

Agricultural fertilisers washing into ponds when it rains.

What happens to algae growth during eutrophication?

Algae grows rapidly due to the nutrients in the fertilisers.

How does rapid algae growth impact light penetration?

It stops light from penetrating lower down into the water.

What happens to plants in oxygen-depleted waters?

They cannot photosynthesise and don't produce oxygen, leading to their death.

What is the final impact of eutrophication on aquatic life?

Oxygen-depleted waters cannot support aquatic life, causing animals to die.

What is the origin of zebra mussels?

They are native to Russia and Ukraine.

How were zebra mussels introduced to North American waters?

They were accidentally introduced in the 1980s.

What impact have zebra mussels had on native mussel populations?

Native mussel populations have declined due to competition for food and space.

What food source do zebra mussels compete for with native fish?

Small organisms like plankton.

What is the effect of zebra mussels on fish populations?

Fish populations have declined due to the reduced food source.

What are global ecosystems also known as?

Biomes.

How are global ecosystems categorised?

By similar environmental characteristics such as climate, vegetation type, and soil.

How do biomes usually occur geographically?

In latitudinal belts, present across the world at similar latitudes.

Why do latitudinal patterns of biomes occur?

Because the climate in these regions is similar due to atmospheric circulation.

What other influences can cause variations in biome distribution?

Ocean currents, winds, and land-sea temperature differences.

Where is the Tundra biome located?

In the far north, from the Arctic circle to 60-70°N (e.g., Canada, Northern Russia).

Describe the winter and summer conditions in the Tundra.

Harsh, cold winters and extremely short summers.

Is the Tundra a treeless ecosystem, and why?

Yes, it is too cold and not wet enough for trees.

What is the precipitation level in the Tundra?

Extremely low (10-25cm/yr).

What are the soil conditions in the Tundra?

Soils are permanently frozen (permafrost).

Where is the Taiga biome located?

At latitudes below the tundra biome, anywhere from 50-70°N (e.g., North America, Russia, Scandinavia).

What type of forest characterizes the Taiga?

Coniferous forest (conifers), which are drought resistant, cone-bearing trees.

How do coniferous trees adapt to maximize photosynthesis?

They retain their leaves all year round, especially during short summers.

What is the annual rainfall in the Taiga?

Around 50cm/yr.

What animals are found in the Taiga?

Small animals, migrating birds, wolves, bears, and moose.

Where is the Temperate Deciduous Forest located?

Around 40-50°N and S of the equator, including Eastern USA, Europe (UK), and Eastern Australia.

What type of vegetation characterizes this biome?

Deciduous vegetation, such as broad-leaf trees.

How do deciduous trees adapt to winter?

They shed their leaves in winter to retain moisture.

Describe the seasonal temperatures in a Temperate Deciduous Forest.

Highly seasonal temperatures: hot summers and cold winters.

What is the moderate precipitation level in this biome?

75-150cm/yr.

Where is the Temperate Grassland located?

Roughly 30-40°N and S of the equator, away from coastal areas (e.g., Central Europe and Asia, Central USA).

What is the dominant vegetation in Temperate Grasslands and why?

Grasses, due to periodic fires and precipitation being too low to support trees.

What animals are found in Temperate Grasslands?

Prairie dogs and originally bison.

Where are Deserts primarily located?

Around 30°N and S of the equator (e.g., Northern Africa, Australia, Middle East).

What is the precipitation level in Deserts?

Extremely low, under 25cm/yr.

Describe the temperature fluctuation in Deserts.

It fluctuates from well above 20°C in the day to below 0°C at night.

What limits plant growth in Deserts?

Precipitation, leading to very low nutrient soils and high salts.

What percentage of the world's land surface do Deserts cover?

One fifth.

Where are Tropical Rainforests located?

Close to the equator (e.g., equatorial South America, South-East Asia).

What is a key characteristic of Tropical Rainforests regarding species?

They are species-rich ecosystems, with over half of the world's species of plants and animals.

Describe the climate in Tropical Rainforests throughout the year.

Warm, moist climate with little variation; temperatures stay around 26°C.

What is the extremely high precipitation level in Tropical Rainforests?

200-450cm/yr.

What is unique about the nutrient cycle in Tropical Rainforests?

It is very quick, leading to nutrient-poor soils but a thin layer of organic matter making plants productive.

Where is the Savanna (tropical grassland) located?

Between 15-30° N and S of the equator (e.g., India, Central Africa, Central South America).

Describe the temperature variation in the Savanna.

Temperature varies little throughout the year, staying in the high 20°Cs.

Describe the precipitation pattern in the Savanna.

Precipitation is very seasonal, with distinct wet and dry seasons (around 76-150cm/yr, mostly in winter).

What characterizes dry seasons in tropical grasslands and how is vegetation adapted?

Wildfires, and the vegetation is adapted to this.

What animals are common in the Savanna ecosystem?

Hoofed animals, herds, and large predators like lions and leopards.

Where is the Mediterranean (chaparral) biome located?

Around 40-45°N of the equator and in some areas of South Africa and Western Australia south of the equator.

Describe the winter and summer conditions in the Mediterranean biome.

Mild, moist winters and hot, dry summers (precipitation around 50cm/yr).