Chapter 19

Question 1

Ecology

Answer 1

the study of inter-relationships between organisms and their environment

Question 2

What are abiotic factors

Answer 2

non-living factors
e.g. temperature & rainfall

Question 3

What are biotic factors

Answer 3

living factors
e.g. competition & predation

Question 4

What are ecosystems

Answer 4

dynamic systems made up of a community and all non-living factors of its environment

Question 5

what are the major processes within an ecosystem

Answer 5

• the flow of energy through a system
• the cycling of elements within the system

Question 6

Population

Answer 6

a group of individuals of one species that occupy the same habitat at the same time and are potentially able to interbreed

Question 7

What is the carrying capacity

Answer 7

the size of population an ecosystem is able to support

Question 8

What can effect the size of a population

Answer 8

• the effect of abiotic factors
• interactions between organisms (inter or intraspecific)

Question 9

Community

Answer 9

all the populations of different species living and interacting in a particular place at the same time

Question 10

Habitat

Answer 10

the place where an organism normally lives and is characterized by the physical conditions and the other types of organisms present

Question 11

what are microhabitats

Answer 11

smaller units within a habitat that each have their own microclimates

Question 12

Niche

Answer 12

• describes how an organism fits into the environment
• refers to where an organism lives and what it does there
• includes all the biotic and abiotic conditions to which an organism is adapted in order to survive, reproduce and maintain a viable population

Question 13

what is the competitive exclusion principle

Answer 13

• some species may seem similar but their nesting habitats or aspects of their behaviour will be different
• no two species occupy exactly the same niche

Question 14

what are the abiotic factors that influence population size

Answer 14

• temperature
• light
• pH
• water & humidity

Question 15

how do temperature and pH influence population size

Answer 15

• each species has its optimum level and deviations from this reduce growth within the population

Question 15

how does light influence population size

Answer 15

low levels of light reduce the carrying capacity of producers (less photosynthesis) reducing the population size of consumers

Question 15

how does water influence population size

Answer 15

low water availability reduces the size of the population - as only the species adapted to dry conditions will be able to survive

Question 16

what are the biotic factors that influence population size

Answer 16

• interspecific competition
• intraspecific competition
• predation

Question 17

what is intraspecific competition

Answer 17

occurs when individuals of the different species compete for resources such as food, light, water

Question 17

what is interspecific competition

Answer 17

occurs when individuals of the same species compete with one another for resources such as food ,water etc.

Question 18

what is predation

Answer 18

when one organism is consumed by another

Question 19

how do predator-prey relationships effect population size

Answer 19

• reduced prey population
• fewer prey available, predators are in greater competition with each other
• predator population is reduced as some individuals are unable to obtain enough prey
• fewer predators = more prey survive as less are eaten
• prey population increases
• more prey available = predator population increases

Question 20

how can the size of a population be estimated

Answer 20

• randomly placing quadrats or quadrats along a transect for slow-moving or non-motile organisms
• count the number of individuals of each species in the quadrat or percentage of cover

Question 21

what is the mark-release-recapture method

Answer 21

• works well with motile organisms
• a known number of animals are caught, marked and released, later on a given number of individuals are collected randomly and then the number of individuals that are marked are is recorded the population size is then calculated using an equation

Question 22

what is succession

Answer 22

a series of changes in an ecosystem over time

Question 23

what is primary succession

Answer 23

the progressive colonisation of bare rock or other barren terrain by living organisms

Question 24

what is secondary succession

Answer 24

the recolonization of an area after an earlier community has been removed or destroyed. it starts with basic soil

Question 25

what is the process of succession

Answer 25

- the area is first colonised by the pioneer species changing the abiotic factors to be less hostile for other species to survive - different species may be present at each stage, who change the environment so that it becomes more suitable for the previous species - changing the biodiversity - the climax community is when a stable state is reached, where there is high biodiversity and a number of new species. the biodiversity can be reduced when the climax community is reached as one species may dominate

Question 26

Conservation

Answer 26

the maintenance of biodiversity, including diversity between species , genetic diversity within species and maintenance of a variety of habitats and ecosystems

Question 27

what does conservation involve

Answer 27

active human involvement and is often orientated around managing a community by halting succession to preserve species that would be extinct by the climax community being established

Question 28

What are the main reasons for conservation?

Answer 28

- personal - ethical - economic - cultural and aesthetic

Question 29

why is conservation important

Answer 29

- the rate of growth of the human population creates an increasing demand for raw material and food - a balance between conservation and human needs is necessary in order to maintain the sustainability of natural resources

Question 30

what is one way of conserving habitats

Answer 30

- by managing succession in a way that prevents change to the next stage - if the factor preventing succession is removed then the ecosystem develops naturally into its climatic climax (secondary succession)