B19. Population in Ecosystems (A2)

Question 1

What are species?

Answer 1

Group of organisms that share the same genes and are capable of breeding to produce fertile offspring

Question 2

What is a community?

Answer 2

Multiple populations of different species living and interacting in the same area

Question 3

What is an ecosystem?

Answer 3

Interaction between a community, biotic and abiotic parts of the environment

Question 4

What is a niche?

Answer 4

Traits that allow an organism to fit into an environment

Question 5

What is a habitat?

Answer 5

Place where a species lives

Question 6

What are the main process of an ecosystem?

Answer 6

Flow of energy through the system; Cycling of elements within a system

Question 7

What are the types of adaptations?

Answer 7

Anatomical, structural features; Behavioural, defensive; Physiological, Processes in the body eg digesting cellulose.

Question 8

What is the carrying capacity?

Answer 8

Maximum population size of a species that an ecosystem can support

Question 9

What are some exmaples abiotic factors affecting population size?

Answer 9

Light availability; Water supply; Temperature; Amount of space available; Soil pH

Question 10

What are some examples of abiotic factors affecting population size?

Answer 10

Light availability; Water supply; Temperature; Amount of space available; Soil pH

Question 11

What is a biotic factor and what are the subcategories?

Answer 11

Interactions between organisms, living factors of an ecosystem; Interspecific competition; Intraspecific competition; Predation

Question 12

Describe interspecific competitions.

Answer 12

Competition for same resources between individuals from different species;

Question 12

Describe interspecific competitions and it’s effects.

Answer 12

Competition for same resources between individuals from different species; Limiting population or decrease in one, increase (outcompeting) in another species

Question 13

Describe intraspecific competition and its effect.

Answer 13

Competition for the same resources between individuals from the same species; Resources become limiting and population cannot grow

Question 14

Describe the process of predation.

Answer 14

Producers eaten by primary consumer, in turn eaten by secondary consumers in turn eaten by tertiary consumers;

Question 15

What is a predator?

Answer 15

Consumers that kill and eat other animals

Question 16

What is a prey?

Answer 16

Animals that are eaten by predators

Question 17

How does predation affect an ecosystem?

Answer 17

Limits both population sizes of predators and prey; Predator increases as more prey; Prey decreases as more predators so predators decrease; Prey increases as fewer predators

Question 18

What is sampling and what are the types?

Answer 18

Method of investigating the abundance and distribution of species and populations; Random and Systematic

Question 19

Describe random sampling.

Answer 19

Positions of sampling points are completely random or due to chance; No bias; When area is uniform , no clear pattern

Question 20

Describe systematic sampling.

Answer 20

Position of sampling points are chosen; Bias possibility;

Question 21

What are the three main sampling methods for population sizes?

Answer 21

Quadrats, slow moving species; Transects, slow moving species; Mark-release-recapture, motile species

Question 22

How do you use quadrats?

Answer 22

Square frames laid randomly in area to avoid sampling bias

Question 23

How do you avoid sampling bias?

Answer 23

Convert the sampling area into grid format, labelling each square with a number; Random number generator to pick sample points

Question 24

What is species frequency?

Answer 24

Probability species will be found within any quadrat sample area; No. of quadrats species found in / Total quadrats

Question 25

When should you use belt transects?

Answer 25

Area where there are changes in physical conditions eg. abiotic factors, altitude, soil pH, light intensity

Question 26

How do you use belt transects?

Answer 26

Place quadrats at regular intervals along tape and record abundance of each species within quadrat; produces quantitative data

Question 27

How do you use quadrats?

Answer 27

Square frames used to mark areas being sampled; Can be different sized squares; Layed out randomly

Question 28

How do you use Mark-release-capture?

Answer 28

Large sample taken; Individuals are counted and marked; Marked individuals are returned to their habitat; When sufficient time has passed another large sample is capture; Number of marked and unmarked individuals within sampled are counted

Question 29

What is Mark-release-capture used to calculate and what is the forumla?

Answer 29

Estimate of population size; N = (n1 x n2) / m2
Population estimate = (No. of marked released x No. in second sample) / Number of marked in second sample

Question 30

What are the assumptions made with the mark-release-capture sample?

Answer 30

Individuals are given sufficient time to disperse and mix back full with main population; Marking doesn’t affect survival rates; Marking remains visible throughout sampling and doesn’t rub off; Population stays same size during study

Question 31

Describe succession of an ecosystem.

Answer 31

Change of an ecosystem from very simple to very complex; Biotic and abiotic conditions change over time; Ecosystems are dynamic

Question 32

Describe primary succession.

Answer 32

Newly formed/exposed land w/ no species is gradually colonised by an increasing number of species

Question 33

Detail the stages of primary succession.

Answer 33

Colonisation by pioneer species; Change in environment, caused by organism; Enables others species to colonise; Change in biodiversity; Stability increases, hostility decreases; Climax community formed

Question 34

Define humus.

Answer 34

Dead organic matter

Question 35

Define pioneer species.

Answer 35

First species to colonise an ecosystem

Question 36

Define climax community.

Answer 36

Stable, final community that exists in a balanced equilibrium and that makes up the final stages of succession

Question 37

Define conservation.

Answer 37

Protection and management of an ecosystem

Question 38

Why is preventing an area from reaching climax community a good thing sometimes?

Answer 38

Ecosystems at intermediate stage of succession hold distinct diversity of plant species

Question 39

What are the methods of preventing succession?

Answer 39

Grazing animals introduced temporarily, eat shrub, growing shoots, trees; Managed burning, controlled fires burn away shrubs and trees

Question 40

Explain what limits population size in a climax community.

Answer 40

Nutrient availability; No. of producers providing energy; Light intensity for photosynthesis; Pathogens and disease; Niches; Competition for resources; Intraspecific and interspecific competition; Predation