Module 7 - Populations in ecosystems

Question 1

What is a community?

Answer 1

Populations of different species

Question 2

What is an ecosystem?

Answer 2

A community plus all the abiotic conditions in that area

Question 3

What is the difference between abiotic and biotic factors?

Answer 3

Abiotic means non living conditions and biotic means living conditions

Question 4

What is a niche?

Answer 4

The role of species in a habitat. Every species has its own unique niche

Question 5

What happens if two species occupy the same niche?

Answer 5

They will both compete and the specie that is more successful is more likely to survive and reproduce.

Question 6

What does a species have to be adapted too in order to survive, reproduce and pass on its alleles?

Answer 6

Be best adapted to abiotic factors and biotic factors

Question 7

What is a carrying capacity in a ecosystem?

Answer 7

This is the maximum stable population that an ecosystem can carry

Question 8

What are some examples of abiotic factors?

Answer 8

Water, temperature, space available, light

Question 9

How does abiotic factors cause population sizes to vary?

Answer 9

If the abiotic conditions are ideal for a species, this means that metabolic reactions are able to take place at a normal pace and therefore the organism is more likely going to survive, reproduce and pass on advantageous alleles

Question 10

What are the two ways biotic factors can vary population sizes?

Answer 10

Intraspecific competition and interspecific competition

Question 11

What is interspecific competition and how does it affect variation in a population size?

Answer 11

This is competition between different species. If there are two species who are competing for the same resources, this will lead both populations being reduced because not all organisms in the same species will be able to get those resources. However this does depend if one species is better adapted because that one will more likely survive

Question 12

What is intraspecific competition and how does it affect competition within a species?

Answer 12

This is competition between the same species. When there is a rise in population, there will be more competition for food and resources so eventually some will die and population will decrease but then, there will more available resources so population will increase again

Question 13

What is predation and how does it vary population sizes?

Answer 13

This is where an organism kills and eats another organism.

Question 14

Explain how predation works?

Answer 14

When the population of prey increases, there is more food for predators so their population increases. More predators eat prey and so prey population decreases. A fall in the population of prey means predators compete more food so some will die and predator population will also decrease. Eventually less prey is hunted and the population for prey increases again. The cycle will continue.

Question 15

Simply how to investigate populations?

Answer 15

1. Choose a small area that you want to sample
2. Choose samples at random to avoid bias
3. Use an appropriate technique to take a sample of a population
4. repeat the experiment as many times as possible
5. Take the mean of the data and multiply by the size of the whole area

Question 16

How is a quadrat used to investigate organisms?

Answer 16

A quadrat is place on the ground and the number of species covering the quadrat is determined

Question 17

What is the difference between motile and non-motile organisms?

Answer 17

Non-motile organisms are slow-moving organism and motile organisms are more mobile organisms

Question 18

What is the difference between a belt transect and an interrupted belt transect

Answer 18

A belt transect is when quadrats are placed across a line and a disrupted belt transect is when they are placed along a line in intervals

Question 19

What is the mark-release re-capture method?

Answer 19

1. A sample of a species is taken
2. They are marked in a harmless way
3. They are released back into their habitat
4. Count how many in the new sample are marked

Question 20

What 3 assumptions have to be made when using the mark-release-recapture method?

Answer 20

1. The marked sample has enough time to mix back in with the population
2. The marking hasn’t affected the individual’s chance of survival
3. There are no changes in population size due to births, deaths or migration

Question 21

What is succession?

Answer 21

Succession is the process by which an ecosystem changes overtime through biotic and abiotic factors

Question 22

What is the difference between primary and secondary succession?

Answer 22

Primary - takes place on land that’s newly exposed, no soil or organic matter, with just bare rock
Secondary - happens on land that has been cleared of all plants but, where the soil remains

Question 23

Explain how primary and secondary succession begins

Answer 23

When spores and seeds are blown in by the wind, this causes pioneer species to grow. These pioneer species can sustain hostile environments. They die and decompose eventually forming layers of soil. Conditions become less hostile and more species can begin to grow. The process continues

Question 24

What happens to succession as time goes on?

Answer 24

Different plants at each stage become better adapted and out-compete the previous species and therefore they become the dominant species. The ecosystem eventually becomes more complex and biodiversity increases.

Question 25

What is the final stage of succession known as?

Answer 25

The climax community - the ecosystem is now at a steady state

Question 26

What is it called when there is a climax community for a specific climax?

Answer 26

A climatic climax. For each climate, different ecosystems develop

Question 27

What is conservation?

Answer 27

Conservation is the prevention of succession from taking place.

Question 28

What is it called when succession is stopped artificially?

Answer 28

Plagioclimax

Question 29

Why does conservation happen?

Answer 29

Conservation happens to prevent succession from taking place so that it can protect ecosystems with animals and organisms in it

Question 30

How do evaluate evidence about conservation issues?

Answer 30

• Describe the data
• Drawing conclusions
• Evaluating the method

Question 31

How does an increase in diversity of a specie develop?

Answer 31

• Increased diversity of species means more niches available such as more foods and different habitats for different species