Populations and sampling

Question 1

What is population size

Answer 1

The total number of organisms of one species in a habitat

Question 2

Why does the population size of any species varies

Answer 2

Due to abiotic factors

Question 3

What is interspecific competition

Answer 3

When organisms of different species compete with each other for the the same resources

Question 4

What causes inter and intraspecific competition

Answer 4

Biotic factors

Question 5

What are the repercussions of interspecific competition

Answer 5

The resources avaliable to both populations are reduced. So both populations will be limited by a lower amount of food and have less energy for growth and reproduction.

It can also affect the distribution of species as if two species are competing and one is out-competed it likely won’t survive alongside the more adapted species.

Question 6

What is intraspecific competition

Answer 6

When organisms of the same species compete with each other for the same resources

Question 7

How does the number of species fluctuate during intraspecific competition

Answer 7

1) The population of a species increases when resources are plentiful

2) Eventually resources such as food and space become limiting and the population declines

3) A smaller population means there is less competition for space and food so is better for growth and reproduction. And the population grows again

Question 8

What is the carrying capacity

Answer 8

The maximum stable population size of a species that an ecosystem can support

Question 9

What is predation

Answer 9

Where an organism kills and eats another organism

Question 10

What is negative feedback

Answer 10

It restores systems to their original level and is a mechanism in which the output of a process leads to a decrease in the output.

Question 11

How does negative feedback control population size

Answer 11

1) As prey population increases there is more food for predators, so predator population grows

2) As the predator population increases, more prey is eaten so the prey population begins to fall

3) There is then less food for the predators so their population decreases

Question 12

How do limiting factors affect population size

Answer 12

They determine the carrying capacity of an ecosystem, therefore stopping the population size increasing

Question 13

Define conservation

Answer 13

The protection and management of ecosystems so that natural resources in them can be used without running out

Question 14

What economic benefit does conservation have

Answer 14

Ecosystems provide resources for humans such as drugs, clothes and food. They are then traded globally and locally so if not conserved trade will reduce

Question 15

What social benefit does conservation have

Answer 15

Ecosystems bring joy to people as they are attractive to look at and are used for activities.

Question 16

What ethical benefits does conservation have

Answer 16

1) Some people think it is the right thing to do as the organisms should have a right to exist

2) We have a moral responsibility to conserve ecosystems for future generations

Question 17

What is coppicing

Answer 17

It involves felling trees at their base to create a ‘stool’ where new shoots will grow

Question 18

What is planted in preference when sustaining a woodland

Answer 18

Native tree species as they are better for biodiversity

Question 19

What is clear felling

Answer 19

All the trees in an area are cut down

Question 20

What is pollarding

Answer 20

A type of coppicing where the trees are cut higher up

Question 21

What is selective logging

Answer 21

The removal of selected trees within a forest based on criteria such as diameter, height, or species.

Question 22

Why are fish stocks declining

Answer 22

Overfishing

Question 23

How can fishing happen in a sustainable way

Answer 23

Using fishing quotas - limits the amount fisherman are able to catch

Controlling mesh size of net - bigger mesh size stops the unwanted fish such as shrimps being caught as well. It also means younger fish can slip through and then reach breeding age.

Question 24

Disadvantage of fishing quotas

Answer 24

Fish of the wrong species or size accidently get caught and then put back dead or dying

Question 25

Disadvantage of controlling mesh size of nets

Answer 25

It can be difficult to determine how big the mesh size should be.
Also some people use two approved nets one inside the other reducing the reported net size