populations in ecosystems

Question 1

Define habitat

Answer 1

The place where an organism lives

Question 2

Define population

Answer 2

All the organisms of one species in a habitat

Question 3

Define community

Answer 3

Populations of different species in a habitat

Question 4

Define ecosystem

Answer 4

A community, plus all the abiotic conditions in the area in which it lives

Question 5

Define abiotic conditions

Answer 5

The non-living features of the ecosystem

Question 6

Define biotic conditions

Answer 6

The living features of the ecosystem

Question 7

Define niche

Answer 7

The role of a species within its habitat

Question 8

Define adaptation

Answer 8

A feature that members of a species have that increases their chance of survival and reproduction

Question 9

What does a niche include?

Answer 9

• Biotic interactions e.g. the organism it eats or is eaten by
• Abiotic interactions e.g. the oxygen an organism breathes in, and the carbon dioxide it breaths out

Question 10

How many species are in a niche

Answer 10

One

Question 11

What are niches separated by

Answer 11

1. Time
2. Location
3. Behaviour

Question 12

Why are niches important?

Answer 12

To avoid inter-species competition

Question 13

Why are ecosystems described as being dynamic?

Answer 13

• Populations constantly rise and fall
• Any small change can have a large effect
• Biotic and abiotic factors may alter the conditions of the ecosystem

Question 14

What are the 3 different types of adaptations?

Answer 14

1. Physiological
2. Behavioural
3. Anatomical

Question 15

Describe how adaptations become more common in the population

Answer 15

• Organisms with better adaptations are more likely to survive, reproduce and pass on alleles for their adaptation
• So the adaptation becomes more common in a population

Question 16

Define population size

Answer 16

The total number of organisms of one species in a habitat

Question 17

Define the carrying capacity

Answer 17

The maximum stable population size of a species that an ecosystem can support

Question 18

List abiotic factors which may affect population size

Answer 18

1. Amount of light, water and space available
2. Temperature
3. Chemical composition of their surroundings

Question 19

What resources might organisms compete for?

Answer 19

1. Food
2. Water
3. Shelter
4. Minerals
5. Light
6. Mates

Question 20

Describe what happens to a population in their ideal abiotic conditions

Answer 20

• Individuals grow and reproduce

- Population size increases

Question 21

Describe what happens to a population in their non-ideal abiotic conditions

Answer 21

• Can’t grow fast and reproduce

- Population size decreases

Question 22

Define infraspecific competition

Answer 22

Infraspecific competition is when organisms of the same species compete with each other for the same resources

Question 23

Define interspecific competition

Answer 23

Interspecific competition is when organisms of different species compete with each other for the same resources

Question 24

What are the limiting factors for population size?

Answer 24

The amount of food available limits the population of any species

Question 25

Define predation

Answer 25

It is where an organism (the predator) kills and eats another organism (the prey)

Question 26

Describe and explain the relationship between the prey population and the predator population

Answer 26

- As the prey population increases, there’s more food for predators so the predator population grows - As the predator population increases, more pray are eaten so the prey population begins o fall - So there’s less food for the predators, so their population decreases

Question 27

How should you pick out a sample to investigate a population?

Answer 27

- Chose an area to sample, it should be random to avoid bias, e.g. random number generator for co-ordinates - Repeat the sampling method to take many samples to reduce the likelihood the results are due to chance

Question 28

How do you estimate the number of individuals in the whole area via a sample?

Answer 28

Mean of data collected in the sample x size of whole area

Question 29

Define non-motile

Answer 29

Organisms that don’t move

Question 30

What are the 2 ways of investigating non-motile organisms?

Answer 30

1. Quadrats | 2. Transects

Question 31

Define species frequency

Answer 31

How often a species is found or the number of individuals of each species is recorded in each quadrat

Question 32

How do you measure the percentage covered?

Answer 32

Measured by counting how much of the quadrat is covered by the species

Question 33

What do transects find out

Answer 33

Can find out how many species are distributed in an area

Question 34

Describe belt transects

Answer 34

Quadrats are placed next to each other along the transect to work out species frequency and percentage cover along the transect

Question 35

Describe interrupted belt transects

Answer 35

Quadrats are placed along lines at intervals to cover a long distance

Question 36

What does mark-release-recapture measure

Answer 36

Measures abundance of motile species

Question 37

Describe a method where you conduct a mark-release-recapture investigation

Answer 37

1. Capture a sample of a motile species 2. Mark them in a harmless way 3. Release back into the habitat 4. Wait a measured amount of time, and take 2nd sample from the same population 5. Count how many of the 2nd samples are marked

Question 38

What is the equation for mark-release-recapture

Answer 38

(total number of individuals in first sample x total number of individuals in the second sample) / number of marked individuals recaptured

Question 39

How can you mark a species harmlessly during a mark-release-recapture investigation?

Answer 39

1. Place a spot of paint on them | 2. Remove a tuft of fur

Question 40

How do you estimate the total population size from your data from a mark-release-recapture investigation?

Answer 40

(number caught in 1st sample x number caught in 2nd sample) / number marked in 2nd sample

Question 41

What assumptions do you make when estimating the total population size from your data from a mark-release-recapture investigation?

Answer 41

1. Marked sample has had enough time and opportunity to mix back into the population and be distributed evenly 2. Marking hasn’t affected the organism's chances of survival 3. There are no changes to the population size due to: births, death and migration during the study

Question 42

Define succession

Answer 42

Succession is the process by which an ecosystem changes over time, the biotic and abiotic conditions change

Question 43

What is meant by primary succession?

Answer 43

Where an area previously devoid of life is colonised by a community of organisms, there is no soil or organic material to start with

Question 44

Summarise the process of primary succession

Answer 44

- Abiotic conditions are hostile, pioneer species can survive harsh abiotic conditions because they are specially adapted to and colonise the area - They change abiotic factors of their environment, they die and microorganisms decompose the dead organic material to form soil - Conditions become less hostile, so new organisms with different adaptations can move in and grow - Over time this allows more complex organisms to survive

Question 45

What is climax community and how is it reached

Answer 45

- The final stage of succession where the ecosystem is balanced and stable - When the soil is rich enough to support large trees or shrubs and the environment is no longer changing

Question 46

Define conservation

Answer 46

The protection and management of species and habitats, in order to maintain biodiversity

Question 47

How might succession be managed in order to aid conservation?

Answer 47

Succession needs to be prevented in order to preserve an ecosystem at a certain point

Question 48

List various methods of conservation

Answer 48

1. Plants can be conserved using seedbanks which tore lots of seeds from different plant species, if the plant becomes extinct in the wild the stored seeds can be used to grow new ones 2. Fishing quotas are limited to the number of certain fish species fishermen are allowed to catch, reducing the numbers of fish that are caught and killed 3. Protected areas like national parks and nature reserves protect habitats by restricting urban development, industrial development and farming 4. Endangered species can be bred in captivity to increase their numbers and then returned to the wild