Ecology - Populations In Ecosystems

Question 1

What is an ecosystem

Answer 1

All the interacting abiotic and biotic factors in a specific area

Question 2

What is a succession

Answer 2

The changes overtime, we can recognise stages in succession
Stages are characterised by the presence of certain species.
Change is slow or rapid

Question 3

What is a pioneer species and its features

Answer 3

Organisms that are able to colonise an inhospitable environment
Asexual reproduction
Rapid germination
Ability to photosynthesise - no animal reliance
Ability to fix atmospheric nitrogen

Question 4

What do pioneer species do

Answer 4

Change the environment
Die and decompose - release minerals into the soil
Create small amounts of soil
Allow other organisms to then colonise the area

Question 5

What is a climax community

Answer 5

A stable balanced state is reached
Population stable, abiotic factors are constant, same species present
It has dominant plant and animal species that characterise it

Question 6

What is a secondary succession

Answer 6

When land that has already sustained life is suddenly altered
It is quicker than primary succession

Question 7

What is conservation?

Answer 7

Management of the earth’s natural resources, species and habitats in a sustainable way

Question 8

Reasons why we conserve

Answer 8

Cultural and aesthetic reasons - looks nice and is important
Preserve species - some of which are essential to human life e.g bees
Ethical reasons - learning to coexist with other species
Economic - production of essential genes/products. Healthier ecosystems also are more productive

Question 9

How do we conserve

Answer 9

Seed banks - seeds kept in a bank as a back up to reintroduce back into the wild
Captive breeding - breeding in captivity to increase numbers
Fishing quotas - prevents extinction of certain fish species
Protected areas - national parks, restricted urbanisation and farming

Question 10

Why is it important to stop succession

Answer 10

Stopping succession can enable conservation to be conserved
Allowing grazing/mowing shrubs cannot fully grow too large
Setting fires causes secondary succession - first (pioneer species) to regrow are the species to be conserved

Question 11

Define population

Answer 11

Group of organisms of the same species living in the same habitat

Question 12

Define habitat

Answer 12

Part of an ecosystem in which particular organisms leave

Question 13

Define community

Answer 13

All the populations of different species in the same area at the same time

Question 14

Define ecosystem

Answer 14

All the interacting biotic and abiotic factors in a specific area

Question 15

Define carrying capacity

Answer 15

Maximum stable population size of a species that an ecosystem can support

Question 16

What will a predator-prey graph show?

Answer 16

Prey and predator both fluctuate
Prey peak is higher
Change in prey before the predator

Question 17

Quadrat (uniform distribution) mark scheme answer

Answer 17

Create a gridded area by placing two tape measures at a 90° angle
Use a random number generator to create 2 coordinates
Place the quadrat and calculate the percentage cover/density
Repeat 30 times, find a mean AND use a large sample

Question 18

How to answer a succession long answer question

Answer 18

Increase in species richness/biodiversity
State what the pioneer species is
Pioneer species leads to a change in environmental factor - less hostile
It gets outcompeted by the next species
State the climax community

Question 19

Two features of a climax community

Answer 19

Stable population
Abiotic factors are constant

Question 20

How do pioneer species allow for the next species to form in succession?

Answer 20

Makes it less hostile

Question 21

Why do the pioneer species eventually die out?

Answer 21

They are outcompeted by the next species forming (they are better competitors)