Chapter 19: Populations In Ecosystems

Question 1

Community

Answer 1

All populations of all different species living and interacting in a particular place at the same time.

Question 2

Habitat

Answer 2

Place where an organism normally lives and is characteristic by physical conditions and other types of organisms present.

Question 3

Niche

Answer 3

Describes how an organism fits into the environment.

Refers to where an organism lives and what it does there.

Question 4

Population

Answer 4

Group of individuals of one species that occupy the same habitat at the same time and are potentially able to interbreed.

Question 5

Carrying capacity

Answer 5

The size of a population of a species that an ecosystem can support.

Question 6

What can affect the size of the population?

Answer 6

Effect of abiotic factors.

Interactions between organisms.

Question 7

Abiotic

Answer 7

Non living factors.

Question 8

Biotic

Answer 8

Living factors.

Question 9

Abiotic factors that influence the size of a population…

Answer 9

Temperature
Light
pH
Water and Humidity

Question 10

Infraspecific competiton

Answer 10

Competition between members of the same species.

Question 11

Interspecific competiton.

Answer 11

Competition between different species.

Question 12

Predator-prey relationship.

Answer 12

Predator feeds on prey.

Question 13

Effect of the predator-prey relationship…

Answer 13

1) Predators feed on prey, thereby decreasing the population of prey.
2) Fewer prey available so predators in greater competition.
3) Some predators cannot survive, so population decreases.
4) Fewer predators means more prey survive and reproduce.
5) Prey population increases.
6) More prey available as food, so predator population increases.

Question 14

Two types of quadrat.

Answer 14

Point quadrat.

Frame quadrat.

Question 15

What is a point quadrat?

Answer 15

Horizontal bar supported by two legs. There are ten intervals at set intervals along the bar. Through each bar, a pin may be dropped. Each species which touches the pin is recorded.

Question 16

What is a frame quadrat?

Answer 16

Square frame divided by string or wire into equally sized sub divisions. Quadrat is placed in different locations within studied area. Abundance of each species with quadrat is recorded.

Question 17

Factors to consider when using quadrats…

Answer 17

Size of quadrat to use
Position of each quadrat within the study area
Number of sample quadrats to record within the area

Question 18

Estimated population size calculation

Answer 18

Total number of individuals in first sample X Total number of individuals in second sample/
Number of marked individuals recaptured.

Question 19

Assumptions the mark-release-recapture relies on…

Answer 19

1) Population has a boundary
2) Few births or deaths
3) Marking is not toxic or does not make animal more likely to be eaten
4) Mark remains on throughout investigation
5) Marked individuals released from first sample distribute themselves evenly amongst populations and have sufficient time to do so
6) Proportion of marked to unmarked individuals in the second sample is the same as the whole population

Question 20

Abundance

Answer 20

Number of individuals of a species within a given area.

Question 21

Frequency

Answer 21

Likelihood of a particular species occurring in a quadrat.

Question 22

Percentage cover

Answer 22

Estimate of the area within a quadrat that a particular plant species covers.
Good- If species hard to count or very abundant.

Question 23

What are the main reasons for conservation?

Answer 23

Personal.
Ethical.
Economic.
Cultural and aesthetic.

Question 24

Succession

Answer 24

Describes the changes, over time, to species that occupy an area.

Question 25

In what ways can succession alter the environment for species?

Answer 25

It can make it LESS SUITABLE for EXISTING SPECIES.

MORE SUITABLE for OTHER SPECIES.

Question 26

Pioneer species

Answer 26

Make up a pioneer community.

Often have features that suit them to colonisation.

Question 27

Common features that emerge during succession,

Answer 27

• Increased biomass
• More complex food webs
• Increased biodiversity
• Greater number and variety of habitats and niches
• Abiotic environment becomes less hostile

Question 28

What land does primary succession happen on?

Answer 28

Newly formed or exposed rocks.

Question 29

What type of land does secondary succession occur on?

Answer 29

Land that’s been cleared of all plants, but where soil remains.

Question 30

How is primary and secondary succession different?

Answer 30

Secondary succession occurs at a later stage as there’s already a soil layer.
Also, the pioneer species are larger plants.

Question 31

Pioneer stage of succession

Answer 31

Starts when a species colonise a new land.
Seeds and spores are blown by wind and begin to grow.
First species to colonise an area is the pioneer species.
Abiotic conditions are hostile and only pioneer species can grow because they are specifically adapted to cope with the harsh conditions.

Question 32

How do pioneer species change the abiotic conditions?

Answer 32

Species die and microorganisms decompose the dead material. These form a basic soil.
This makes conditions less hostile so new organisms with different adaptations can move in and grow.
New organisms die and get decomposed, adding more organic material to the soil, making it more rich in minerals.
These minerals can then be used by plants.

Question 33

Which species make most change to the abiotic environment, making it more suitable for other species?

Answer 33

Dominant species.

Question 34

What is meant by uniformly distributed?

Answer 34

Same number of organisms in each region/ equally spread organisms.

Question 35

Units for gross productivity

Answer 35

J/g

Question 36

Why does gross productivity decrease as woodland matures?

Answer 36

More shading, so less light, so greater competition for light, so less photosynthesis.

Question 37

What is Mark-release-recapture?

Answer 37

Known number of animals are caught and marked.
They then released.
After time, given number collected and number of marked recorded.