Populations

Question 1

Factors which control population size:

Answer 1

intensity of energy flowing through them 
biological cycles (nitrogen and carbon)
habitat changes as succession occurs 
new species arriving and species which are no longer present

Question 2

the size of a population is determined by:

Answer 2

birth rate
death rate/ mortality
immigration
emigration

Question 3

Fugitive species

Answer 3

species that are poor at competition: instead they rely on a large capacity for reproduction and dispersal to increase their numbers
they invade a new environment rapidly eg Alge

Question 4

1 step growth curve stages:

Answer 4

Lag phase
exponential/ log phase
stationary phase
death phase

Question 5

population

Answer 5

an interbreeding group of organisms of the same species occupying a particular habitat

Question 6

Birth rate

Answer 6

The reproductive capacity of a population; the number of new individuals derived from reproduction per unit time

Question 7

Immigration

Answer 7

the movement of individuals into a population of the same species

Question 8

Equilibrium species

Answer 8

species that control their population by competition rather that by reproduction of dispersal

Question 9

Lag phase

Answer 9

initially it doesn’t increase then there is a period of slow growth - can be a few mins or several days
period of adaptation for growth, intense metabolic activity (especially enzyme synthesis)
can also represent the time it takes a species to reach sexual maturity

Question 10

Exponential phase (1)

Answer 10

As number increase & as long as there is no limiting factor more individuals become available for reproduction
Bacterial cells divide at a constant rate and the population doubles per unit time, the cell number increases logarithmically and so this phase can be called the log phase

Question 11

Exponential phase (2)

Answer 11

The rate of increase can’t be maintained due to environmental resistance:
less food
concentration of waste products becomes increasingly toxic
not enough space for nesting sites
the population continues to increase but more slowly so the gradient decreases

Question 12

Abiotic

Answer 12

A part of an environment of an organism that is non living eg air, temp, oxygen availability

Question 13

Biotic

Answer 13

A part of an organism’s environment that is living eg pathogens, predators

Question 14

Carrying capacity

Answer 14

The maximum number around which a population fluctuates in a given environment

Question 15

Environmental resistance for bacteria:

Answer 15

Overcrowding
accumulation of toxic waste
lack of food
competition

Question 16

Environmental resistance for rabbits:

Answer 16

Lack of food
Predation
Parasitism/disease (can spread rapidly in large populations)
Competition

Question 17

Stationary Phase

Answer 17

Birth rate is equal to the death rate
graph levels off
population has reached its carrying capacity
population fluctuates around the carrying capacity in response to environmental changes

Question 18

Death Phase

Answer 18

The factors that slow the population growth at the end of the lag phase become more significant and population size decreases until the death rate is greater than the birth rate.
the graph has a negative gradient

Question 19

Predator - Prey relationship

Answer 19

The amount of prey limits the number of predators and the number of predators controls the number of prey
this relationship causes the predator and prey numbers to oscillate and these are regulated by negative feedback
number of prey increase, number of predators increase due to more food available, therefore the number of prey decreases so does the predators as there as decrease in food available.
this means with less predators the prey population increases and thus does the predator.

Question 20

Density dependent factors

Answer 20

Biotic factors that have more of effect is the population is larger eg parasitism, depletion of food supply and disease

Question 21

9 planetary boundaries:

Answer 21

Climate change - crossed
Biosphere integrity - crossed
Ocean acidification - avoidable
Ozone layer - avoided 
Nitrate and phosphate flows crossed
Land use change - crossed 
Freshwater -avoidable
Aerosol - unknown 
Inorganic pollution unknown

Question 22

What are the causes and consequences for climate change?

Answer 22

Burning fossil fuels
Positive feedback

Increase in atmospheric CO2 —> temp affects wind patterns and sea levels
Increase is greenhouse Gases —> global warming

Question 23

What are the remedial measures for Climate change?

Answer 23

Renewable energies eg wind wave, geothermal, solar, hydroelectric & biofuel

Reduction in energy use eg fuel economic cars, insulate homes, cycle/ public transport, locally sourced food

Question 24

What are the causes and consequences of biosphere integrity?

Answer 24

Habitat destruction
Over exploitation for food
Intro of alien species
Ocean acidification

Species becoming endangered or extinct
Species interact and put whole communities at risk

Question 25

What are the remedial measures for biosphere integrity?

Answer 25

``` Increase public awareness Monitor and conserve biodiversity Prohibit international trade Limit fishing when fish are spawning Limit logging and use of agricultural chemicals ```

Question 26

What are the causes and consequences for land use change?

Answer 26

Deforestation for urban development and livestock farming Pollutants from agricultural & human activities Production of biofuel (crops) Degrade remaining land Not enough food for locals Reduction in biodiversity Affects water, N & C cycle