Ecosystems and biodiversity; quadrats; pyramids of Number, biomass and energy; Energy transfer and Food Webs

Question 1

What is a habitat?

Answer 1

The place where an organism lives, e.g. a rocky shore or a field.

Question 2

What is a population?

Answer 2

All the organisms of one species in a habitat.

Question 3

What is a community?

Answer 3

All the different species in a habitat.

Question 4

What is an ecosystem?

Answer 4

All the organisms living in a particular area and all the non-living (abiotic) conditions, e.g. temperature, climate, soil-type.

Question 5

What is biodiversity?

Answer 5

The variety of different species of organisms on Earth, or within an ecosystem.

Question 6

Why is high biodiversity important?

Answer 6

It ensures that ecosystems are stable because different species depend on each other for shelter and food.

Question 7

What human actions are reducing biodiversity?

Answer 7

Deforestation, pollution, and global warming.

Question 8

How do environmental changes affect communities?

Answer 8

They can cause population sizes to increase or decrease, or change the distribution of populations.

Question 9

What is an example of an abiotic factor affecting communities?

Answer 9

Environmental conditions: The distribution of bird species in Germany is changing due to a rise in average temperature.

Question 10

What are toxic chemicals and their effect on ecosystems?

Answer 10

Chemical pesticides can build up in food chains through bioaccumulation, leading to toxic doses in top predators.

Question 11

What is eutrophication?

Answer 11

A process caused by excess fertilizers released into lakes and ponds, leading to the death of organisms.

Question 12

How does food availability affect populations?

Answer 12

In a bumper year for berries, the population of blackbirds might increase due to sufficient food. So they are more likely to survive and reproduce.

Question 13

How does the number of predators affect prey populations?

Answer 13

If the number of predators decrease, the number of prey might increase due to fewer being eaten.

Question 14

What is competition in ecosystems?

Answer 14

Organisms compete with other species and members of their own species for resources like light, space, water, and food.

Question 15

What abiotic factors could affect the population size of a species?

Answer 15

Examples include temperature and light intensity.

Question 16

What is a quadrat?

Answer 16

A quadrat is a square frame enclosing a known area to compare the population size of an organism in two samples areas

Question 17

How do you use a quadrat to study population size?

Answer 17

1) Place a 1 m² quadrat randomly in the sample area. 2) Count the organisms of interest. 3) Repeat steps 1 and 2 multiple times. 4) Calculate the mean number of organisms per quadrat. 5) Repeat in a second sample area. 6) Compare the two means.

Question 18

How do you estimate population size from a quadrat sample?

Answer 18

Multiply the mean number of organisms per m² by the total area of the habitat.

Question 19

What is the formula to calculate mean number of organisms per m²?

Answer 19

Mean = total number of organisms ÷ number of quadrats.

Question 20

How do you use belt transects?

Answer 20

1) Mark out a line in the area of study. 2) Collect data using quadrats placed next to each other. 3) Count organisms or estimate percentage cover. 4) Record additional data (e.g. mean height, abiotic factors). 5) Repeat and find means, then plot graphs.

Question 21

What is the purpose of using quadrats in ecology?

Answer 21

To measure biodiversity and study the distribution of organisms across different habitats.

Question 22

What should you ensure when placing a quadrat?

Answer 22

Place the quadrat in a random location to ensure representative results.

Question 23

Estimate the total population of buttercups in a 1200 m² field with a quadrat area of 0.25 m² and a mean of 0.75 buttercups per quadrat.

Answer 23

Total population = (Mean per m²) × (Total area) = (0.75 ÷ 0.25) × 1200 = 3600 buttercups.

Question 24

What do food chains start with?

Answer 24

Food chains always start with a producer, e.g. a plant.

Question 25

What do producers do?

Answer 25

Producers make (produce) their own food using energy from the Sun.

Question 26

What are primary consumers?

Answer 26

Primary consumers are organisms that eat producers.

Question 27

What are secondary and tertiary consumers?

Answer 27

Secondary consumers are eaten by tertiary consumers.

Question 28

What do decomposers do?

Answer 28

Decomposers break down (decompose) dead material and waste.

Question 29

What is a trophic level?

Answer 29

Each stage (e.g. producers, primary consumers) is called a trophic level.

Question 30

What is an example of a food chain?

Answer 30

5000 dandelions → 100 rabbits → 1 fox.

Question 31

What does each bar on a pyramid of numbers represent?

Answer 31

Each bar shows the number of organisms at that stage of the food chain.

Question 32

How does the number of organisms change in a pyramid of numbers?

Answer 32

Every time you go up a trophic level, the number of organisms goes down.

Question 33

What does a pyramid of biomass show?

Answer 33

It shows the mass of living material at that stage of the food chain.

Question 34

What shape are biomass pyramids typically?

Answer 34

Biomass pyramids are practically always the right shape.

Question 35

What do pyramids of energy show?

Answer 35

They show the energy transferred to each trophic level in a food chain.

Question 36

What shape are pyramids of energy transfer?

Answer 36

Pyramids of energy transfer are always the right shape — a nice, regular pyramid.

Question 37

What should you know when interpreting a pyramid?

Answer 37

Make sure you know if it's a pyramid of number, biomass or energy transfer.

Question 38

What does the arrows represent?

Answer 38

The transfer of energy

Question 39

What is the primary source of energy for nearly all life on Earth?

Answer 39

Energy from the Sun is the source of energy for nearly all life on Earth.

Question 40

How do plants use energy from the Sun?

Answer 40

Plants use energy from the Sun to make food during photosynthesis.

Question 41

What happens to energy as it moves through the food chain?

Answer 41

Energy works its way through the food chain as animals eat the plants and each other.

Question 42

What percentage of energy is typically lost at each trophic level?

Answer 42

Around 90% of the energy is lost in various ways.

Question 43

What are some reasons energy is not passed on to the next trophic level?

Answer 43

Some parts of food aren't eaten, and some parts are indigestible, passing out as waste.

Question 44

What explains the pyramids of biomass and energy in food chains?

Answer 44

Material and energy are both lost at each stage of the food chain.

Question 45

How is energy used by organisms?

Answer 45

A lot of the energy taken in is used for staying alive, i.e., in respiration.

Question 46

What happens to most of the energy taken in by organisms?

Answer 46

Most of this energy is eventually transferred to the surroundings by heat.

Question 47

What percentage of total energy becomes biomass?

Answer 47

Only around 10% of the total energy available becomes biomass.

Question 48

What do food webs illustrate?

Answer 48

Food webs show how food chains are linked within an environment.

Question 49

What does interdependence in a food web mean?

Answer 49

All species in a food web are interdependent, meaning changes in one species affect all others.

Question 50

What happens if a species in a food web decreases significantly?

Answer 50

If a species decreases, it can lead to less food for its predators and an increase in the prey population.

Question 51

How are food webs typically structured in nature?

Answer 51

Food webs are normally tangled together and interlinked like a bowl of spaghetti.