Population dynamics

Question 1

What are the 4 factors that control population

Answer 1

• Birth rate
• Death rate
• Immigration
• Emigration

Question 2

What is the equation to determine current population size

Answer 2

Past population + birth rate +immigration - emigration - death rate = current population

Question 3

How would a population increase

Answer 3

Population will increase if the reproduction (birth) rate is high and the death rate is low

Question 4

How would a population decline

Answer 4

Population will decline if the reproduction (birth) rate is low and the death rate is high

Question 5

What are 4 factors that control birth rates

Answer 5

• Age of population (reached sexual maturity)
  -Ratio of males : females
• Breeding cycles + timing (seasons)
• How many times/ how often an individual can produce offspring

Question 6

What are 4 factors that control death rates

Answer 6

• Food availability
• Drought (water availability)
• Predation
• Disease

Question 7

What is an expression that describes a population stable in size

Answer 7

B + I = D + E

Question 8

What is an expression that describes a population that is declining in size

Answer 8

B + I < D + E

Question 9

What is an expression that describes a population that is increasing in size

Answer 9

B + I > D + E

Question 10

What does “B” mean relating to population size

Answer 10

Birth rate

Question 11

What does “I” mean relating to population size

Answer 11

Immigration

Question 12

What does “D” mean relating to population size

Answer 12

Death rate

Question 13

What does “E” mean relating to population size

Answer 13

Emigration

Question 14

What is an expression that describes change in population size

Answer 14

B + I ≠ D + E

Question 15

How do you work out death rate

Answer 15

Number of deaths / number of organisms within the population

Question 16

How do you work out birth rate

Answer 16

Number of births / Number of organisms within the population

Question 17

Define carrying capacity

Answer 17

Number of individuals that an
ecosystem/area can support
sustainably without damaging or over-exploiting the environment

Question 18

Define density independent factors

Answer 18

factors where the density of the population has no effect on the chances of survival, eg flood, volcanic eruptions

Question 19

Define density dependent factors

Answer 19

factors where the chances of survival are dependent on the density of the populations, eg disease, food supply

Question 20

What is death rate

Answer 20

The number of deaths per 1000 population per year

Question 21

What is birth rate

Answer 21

The number of offspring per 1000 population per year

Question 22

What is emigration

Answer 22

Reduction in the population of the individuals leaving to another area

Question 22

What is immigration

Answer 22

Addition of new individuals to the population from another area

Question 23

What are 4 examples of density dependent factors

Answer 23

• Disease
• Competition (for..)
• Food supply
• Predation

Question 24

What are 4 examples of density independent factors

Answer 24

• Wild fires
• flooding
• Temperature change
• Earthquakes

Question 25

Density independent factors are..

Answer 25

..mostly abiotic

Question 26

Density dependent factors are..

Answer 26

..mostly biotic

Question 27

What is the definition of Sigmodial population growth

Answer 27

A growth pattern in which an organism’s population density rises slowly originally in a fresh setting, in an acceleration stage; then rises quickly approaching an exponential growth rate

Question 28

What does the Sigmodial population growth curve consist of

Answer 28

It consists of four phases: the lag phase, the log phase, the stable fluctuating phase

Question 29

What happens at the lag phase on a Sigmodial population growth graph

Answer 29

Population growth is slow as the population is adapting to its environment therefore rate of reproduction is low

Question 30

What happens at the log phase on a Sigmodial population growth graph

Answer 30

Rapid exponential growth and no limiting factors due to relatively low density

Question 31

What happens at the stable fluctuating phase on a Sigmodial population growth graph

Answer 31

Population is no longer increasing in size. Birth & death rates are balancing each other. The population has reached carrying capacity. The population will tend to fluctuate around this level

Question 32

What are three examples of artificial population control

Answer 32

• Culling
• Eradication of invasive species
• Pest control

Question 33

What is culling (example)

Answer 33

Purposely reducing a population
e.g. deer are culled as they cause damage to woodlands and graze on vegetation and because there are no wolves to naturally hunt them

Question 34

Explain what is meant by r-selected species

Answer 34

Smaller species that respond rapidly to low survival rates.
- Reach sexual maturity quickly
- Reproduces quickly,
- Produce many young
- Low parental involvement
- Low probability of survival

Question 35

Explain what is meant by k-selected species

Answer 35

Species that respond slowly from a decline in population.
- Reach sexual maturity at an older age
- Produce a small amount of young
- Longer gestation time
- High parental involvement
- High probability of survival

Question 36

What type of release would k-selected species need

Answer 36

Soft release

Question 37

What are three examples of k-selected species

Answer 37

• Rhino
• Elephant
• Whales

Question 38

What are three examples of r-selected species

Answer 38

• Spider
• Rabbits
• Frogs