Component 1.5 - Population growth And Its Factors Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What is the size of population determined by? (4)

A

1) Birth rate (Mammals are born, bacteria undergo binary fission, reptiles hatch from eggs and plants develop from seeds)
2) Death rate
3) Immigration
4) Emmigration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is an equilibrium species and how is their pattern of growth shown on a graph?

A

Species that control their population by competition rather than by reproduction and dispersal. The graph is a sigmoid shape.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the lag phase?

A
  • A period of slow growth
  • A period of adaptation or preparation for growth (metabolic activity)

E.g in a population of rabbits it would represent the time for individuals to reach sexual maturity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the exponential phase?

A
  • As long as there is no factor limiting growth, more individuals become available for reproduction
  • The cell numbers increase logarithmically
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

State what is meant by environmental resistance and give 3 examples

A
  • The environmental factors that slow down population growth

1) Less food available
2) Concentration of waste products is toxic
3) Not enough space or nesting sites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the result of environmental resistance?

A

The population still increases but more slowly so the gradient of the line decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

State some biotic and abiotic factors that could affect population size?

A

Biotic:

1) Predation
2) Parasitism - increased population density allows infection to spread more rapidly
3) Competition from other species for nesting sites and food

Abiotic:

1) Temperature
2) Light intensity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe what is meant by the stationary phase and what happens during this period

A
  • It is what occurs when the birth rate is equal to the death rate and therefore the population has reached its maximum size (carrying capacity)
  • Population is not absolutely constant and fluctuates around the carrying capacity in response to environmental changes e.g number of predators
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How could the carrying capacity be increased ?

A

It could be increased by there being a larger amount of food available or more nesting sites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the death phase?

A
  • The factors that affected population growth at the end of the lag phase become more significant and population size decreases
  • When the death rate becomes larger than the birth rate the graph has a negative gradient
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a predator-prey relationship?

A
  • Where the abundance of prey limits the number of predators and the number of predators controls the number of prey.
  • populations oscillate due to negative feedback
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are density-dependent factors and give an example of how it works?

A
  • Factors that affect a higher proportion of the population if the population is denser
  • These are biotic factors e.g parasitism, disease, depletion of food supply, predation
  • For bacteria: oxygen concentration, waste
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are density independent factors and give an example

A
  • Abiotic factors which have the same effect on the population regardless of the population density
  • Usually due to a sudden change in an abiotic factor e.g flood or fire (can cause population crash)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the method of population regulation using negative feedback ?

A
  • Population rises above carrying capacity, a density-dependent factors increase and raised environmental resistance, mortality/reduced breeding meaning population declines
  • Population falls below carrying capacity, environmental resistance is temporarily relieved and less effect of density-dependent factors so population increases again
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Why are ecosystems described as dynamic?

A

1) Energy flow varies
2) Biological cycles vary mineral availability
3) Succession changes habitat
4) Species arrive and some species are no longer present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is meant by biotic and abiotic

A

Biotic - A part of the environment that is living

Abiotic - A part of the environment that is non-living

17
Q

Define ecology

A

the branch of biology that deals with the relations of organisms to one another and to their physical surroundings.

18
Q

Define population

A

Population - The number of an interbreeding group of organisms of the same species occupying a particular habitat

19
Q

What is meant by carrying capacity?

A

Maximum size of a population that an environment can support/maintain