Conservation, human impact

Question 1

Competitive exclusion principle

Answer 1

no two species can occupy the same niche in the same environment for an extended period of time

Question 2

defined Population:

Answer 2

A group of individuals of the same species living in the same place at the same time and interbreeding

Question 3

Why individuals live in populations

Answer 3

• more successful in breeding and rearing their young
• gain protection from predators in a group
• locate new food resources in a group
Located where resources are, where danger is not and can migrate due to season changes

Question 4

Patterns of dispersion:

Answer 4

• Uniform: e.g. planted forests, penguins
• Clumped: fish, plants (where water is)
• Random: rainforest

Question 5

What determines population growth:

Answer 5

Birth rate (natality):
Death rate (mortality): 
Immigration: 
Emigration:
Net migration rate: 

Rate = (births + immigration) – (deaths + emigration)

Question 6

Define: Birth rate (natality):

Answer 6

the reproductive capacity of the population

Question 7

Define: Death rate (mortality):

Answer 7

the death rate of organisms in the population

Question 8

Define: Immigration:

Answer 8

is the movement of individuals into a population

Question 9

define: Emigration

Answer 9

is the movement of individuals out of a population

Question 10

Define: Net migration rate

Answer 10

the difference between immigration and emigration

Question 11

2 types of Population growth

Answer 11

J shaped curve

S shaped curve

Question 12

what is J shaped curve

Answer 12

If conditions are favourable, the birth rate will exceed the death rate and lead to exponential growth

Question 13

what is S shaped curve

Answer 13

logistic growth curve. As the population increases it encounters resistance from the environment as it begins to fill the environment up.
This environmental resistance increases as the population overshoot the carrying capacity.
The population tends to fluctuate around an equilibrium level.

Question 14

Define: Carrying capacity (k)

Answer 14

the maximum stable population size a particular environment can support

Question 15

what is Environmental resistance

Answer 15

all the factors that may limit the growth of the population, such as accumulation of waste products, scarcity of resources such as food and space, or adverse climate conditions

Question 16

2 Factors affecting population growth:

Answer 16

Abiotic

and biotic

Question 17

what Abiotic factors affect population growth

Answer 17

Lack of shelter exposes individuals to harsh climates
Plants need light at the correct intensity, duration and wavelength if they are able to achieve optimum growth
Shortage of oxygen can limit the number of aquatic species
Water quality is affected by pollution and intolerant species may die

Question 18

what Biotic factors affect population growth??

Answer 18

Plants and animals may have to compete for scarce resources such as food, water, light and space
Predators can reduce the number of prey species
The higher the density of the population, the more rapidly disease could spread through
Parasites reduce the ability of the host species to survive and reproduce

Question 19

2 type of affecting population growth

Answer 19

Density-dependent factors

Density-independent factors

Question 20

Density-dependent factors

Answer 20

vary on the effect they have on a population depending on the size (always biotic)
• Space, competition, predation, parasites

Question 21

Density-independent factors

Answer 21

affect all plants and animals in a population irrespective of population size
• Severe storms, flooding, severe cold spells, earthquakes, volcanoes, meteors

Question 22

what are Keystone species

Answer 22

A species that is not necessarily abundant in an area but has a strong control on the structure of the community due to its role or ecological niche (e.g. cassowary: dispersal of seeds)

Question 23

Ecological Role of Fire in forest ecosystem

Answer 23

Fire reduces the probability of catastrophic fires: controlled fires can get rid of leaf litter
Nutrient input into soils: soil nutrients are usually tied up in organic matter released in pulse after fire
Control of insect pests: high temperatures and smoke can kill adults, larvae and eggs
Control of tree pathogens: spore germination and spread is inhibited by smoke
Maintains species diversity: some species are fire-adapted

Question 24

what are Plants adoption to fire:?

Answer 24

vegetative reproducers: regrow through means of buds located under the bark or in underground stems
obligate seeders: the plants do not survive the bushfire but the seeds do and germinate after in the mineral-rich soil

Question 25

What are Animals adaptions to fire?

Answer 25

Mobile organisms, such as birds and fast moving mammals may escape flames and avoid the lethal radiant heat by flying or running away
Slower moving animals escape by retreating into burrows or sheltering under thick bark where they are insulated from the fire
Some animals exploit opportunities provided by fire for feeding

Question 26

define: Succession

Answer 26

The change in structure and species composition of a community over time

Question 27

Primary succession

Answer 27

Succession that happens when an area is first colonised

Question 28

Examples of primary succession

Answer 28

• A retreating glacier depositing rock
• Wind or sea piling sand into dunes
• Volcanoes erupting and depositing lava
• Land subsiding and creating lakes or ponds
• Silt and mud being deposited at river estuaries

Question 29

Define: Secondary succession

Answer 29

Secondary succession is the series of community changes which take place on a previously colonised, but disturbed or damaged habitat

Question 30

Define: Pioneer species

Answer 30

The first stage of succession involves pioneer species colonising an inhospitable environment
Pioneer species have features that suit them to colonisation (they have no roots)

Question 31

Features of pioneer species

Answer 31

Production of a lot of wind-dispersed seeds to easily reach isolated areas
Rapid germination of seeds
The ability to photosynthesise
The ability to fix nitrogen from the atmosphere
Tolerance to extreme conditions

Question 32

Stages of plant succession

Answer 32

Colonisers (lichens): when they die, they release nutrients. This changes the abiotic environment by creating soil.
Mosses, then Ferns: rock is continually eroded, as these die organic matter increases, building up soil
Small flowering plants: shrubs then trees establish

Question 33

Climax community

Answer 33

The organisms that make up the final stage of ecological succession. A balanced equilibrium. The rainforests of SE Queensland are an example of a climax community

Question 34

Common features in any succession

Answer 34

The non-living environment becomes less hostile
A greater number and variety of habitats
Increased biodiversity
More complex food webs
Increased biomass

Question 35

Animal Succession

Answer 35

Animal species present depend on the plant species found in the area. For example, mosses and grasses provide food and habitats for insects and worms. These can then support secondary consumers