A photosynthetic organism (usually a green plant or alga) that makes glucose by photosynthesis. Producers are the source of biomass for life on Earth and begin every food chain.

Name the levels of a food chain in order, starting with the organism that begins it.

Producer → Primary consumer → Secondary consumer → Tertiary consumer

What do the arrows in a food chain represent, and where does the energy originally come from?

The arrows show the transfer of energy (and biomass) from one organism to the next. The original source of energy is light energy from the Sun .

A square frame placed on the ground to sample the abundance of plants or slow-moving animals (e.g. by counting individuals, species richness or percentage cover).

A line through a habitat along which quadrats are placed at regular intervals , used to measure how the abundance of a species changes across a changing habitat (e.g. with an abiotic factor such as altitude).

What do the terms mean , median and mode describe in a set of data?

Mean → the sum of all values divided by the number of values Median → the middle value when the data are put in order Mode → the most common (most frequent) value

A predator is a consumer that kills and eats other animals; the prey are the animals that are eaten.

Describe how the numbers of predators and prey change in a stable community.

As prey numbers rise, there is more food, so predator numbers rise More predators eat more prey, so prey numbers fall With less food, predator numbers then fall, allowing the prey to recover, and the cycle repeats

organisms are the producers of biomass for life on Earth.

Photosynthetic organisms are the producers of biomass for life on Earth.

What is the aim of the required practical on investigating ecosystems?

To measure the population size of a common species in a habitat, and to use sampling to investigate the effect of a factor on the distribution of that species.

When using quadrats to estimate population size, how are they placed and why?

They are placed randomly (e.g. using a grid and a random number generator ) so the sample is unbiased and represents the whole habitat.

How do you estimate the total population size of a species in a field using a quadrat?

Find the mean number of the species per quadrat. Divide the total survey area by the area of one quadrat. Multiply the mean per quadrat by this number to estimate the total population.

Why do ecologists take samples rather than count every organism in a habitat?

Counting every organism would take too long. A sample represents the population, so it must be large enough and unbiased to be reliable.

Which piece of equipment is used to investigate how an abiotic factor affects the distribution of a species?

A transect (a line along which quadrats are placed at regular intervals).

To place quadrats without bias, their positions are chosen using a grid and a number generator.

To place quadrats without bias, their positions are chosen using a grid and a random number generator.

All materials in the living world are to provide the building blocks for future organisms.

All materials in the living world are recycled to provide the building blocks for future organisms.

How is carbon removed from the atmosphere in the carbon cycle?

Plants and algae take in carbon dioxide from the air and use it during photosynthesis to make glucose (biomass).

What processes return carbon dioxide to the atmosphere?

Respiration by plants, animals and microorganisms Combustion (burning) of wood and fossil fuels

The burning of wood or fossil fuels, which combines the carbon in them with oxygen and releases carbon dioxide into the atmosphere.

Describe the main processes of the water cycle .

Water evaporates from oceans, rivers and lakes (and plants release water by transpiration ). Water vapour rises, cools and condenses into clouds. Water returns to Earth as precipitation (rain, snow, sleet) before draining into the seas.

In the water cycle, water is continuously from the surface and later returned to Earth as precipitation.

In the water cycle, water is continuously evaporated from the surface and later returned to Earth as precipitation.

A microorganism ( bacteria or fungi ) that breaks down dead organisms and waste , returning carbon to the atmosphere and mineral ions to the soil.

Explain the role of microorganisms in cycling materials through an ecosystem.

Decomposers break down dead organisms and waste. As they respire , they return carbon dioxide to the atmosphere, and they release mineral ions back into the soil.

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Organisation of an Ecosystem (AQA GCSE Combined Science: Trilogy: Biology): Flashcards

Exam code: 8464

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Producer

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Cards in this collection (23)

Producer
A photosynthetic organism (usually a green plant or alga) that makes glucose by photosynthesis. Producers are the source of biomass for life on Earth and begin every food chain.
Name the levels of a food chain in order, starting with the organism that begins it.
Producer → Primary consumer → Secondary consumer → Tertiary consumer
What do the arrows in a food chain represent, and where does the energy originally come from?
The arrows show the transfer of energy (and biomass) from one organism to the next. The original source of energy is light energy from the Sun.
Quadrat
A square frame placed on the ground to sample the abundance of plants or slow-moving animals (e.g. by counting individuals, species richness or percentage cover).
Transect
A line through a habitat along which quadrats are placed at regular intervals, used to measure how the abundance of a species changes across a changing habitat (e.g. with an abiotic factor such as altitude).
What do the terms mean, median and mode describe in a set of data?
Mean → the sum of all values divided by the number of values
Median → the middle value when the data are put in order
Mode → the most common (most frequent) value
Predator and prey
A predator is a consumer that kills and eats other animals; the prey are the animals that are eaten.
Describe how the numbers of predators and prey change in a stable community.
- As prey numbers rise, there is more food, so predator numbers rise
- More predators eat more prey, so prey numbers fall
- With less food, predator numbers then fall, allowing the prey to recover, and the cycle repeats
organisms are the producers of biomass for life on Earth.
Photosynthetic organisms are the producers of biomass for life on Earth.
What is the aim of the required practical on investigating ecosystems?
To measure the population size of a common species in a habitat, and to use sampling to investigate the effect of a factor on the distribution of that species.
When using quadrats to estimate population size, how are they placed and why?
They are placed randomly (e.g. using a grid and a random number generator) so the sample is unbiased and represents the whole habitat.
How do you estimate the total population size of a species in a field using a quadrat?
1. Find the mean number of the species per quadrat.
1. Divide the total survey area by the area of one quadrat.
1. Multiply the mean per quadrat by this number to estimate the total population.
Why do ecologists take samples rather than count every organism in a habitat?
Counting every organism would take too long. A sample represents the population, so it must be large enough and unbiased to be reliable.
Which piece of equipment is used to investigate how an abiotic factor affects the distribution of a species?
A transect (a line along which quadrats are placed at regular intervals).
To place quadrats without bias, their positions are chosen using a grid and a number generator.
To place quadrats without bias, their positions are chosen using a grid and a random number generator.
All materials in the living world are to provide the building blocks for future organisms.
All materials in the living world are recycled to provide the building blocks for future organisms.
How is carbon removed from the atmosphere in the carbon cycle?
Plants and algae take in carbon dioxide from the air and use it during photosynthesis to make glucose (biomass).
What processes return carbon dioxide to the atmosphere?
- Respiration by plants, animals and microorganisms
- Combustion (burning) of wood and fossil fuels
Combustion
The burning of wood or fossil fuels, which combines the carbon in them with oxygen and releases carbon dioxide into the atmosphere.
Describe the main processes of the water cycle.
1. Water evaporates from oceans, rivers and lakes (and plants release water by transpiration).
1. Water vapour rises, cools and condenses into clouds.
1. Water returns to Earth as precipitation (rain, snow, sleet) before draining into the seas.
In the water cycle, water is continuously from the surface and later returned to Earth as precipitation.
In the water cycle, water is continuously evaporated from the surface and later returned to Earth as precipitation.
Decomposer
A microorganism (bacteria or fungi) that breaks down dead organisms and waste, returning carbon to the atmosphere and mineral ions to the soil.
Explain the role of microorganisms in cycling materials through an ecosystem.
Decomposers break down dead organisms and waste. As they respire, they return carbon dioxide to the atmosphere, and they release mineral ions back into the soil.

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