Multi-species interactions

Question 1

What is an ecological community ?

Answer 1

A group of potentially interacting species living in the same place

Question 2

What is found at the basic trophic level of an ecosystem ?

Answer 2

Autotrophs or Heterotrophs

Question 3

What are autotrophs ?

Answer 3

Produce organic matter from inorganic material

Question 4

Give species specific examples of autotrophs.

Answer 4

Cyanobacteria

Giant Redwoods

Question 5

What are heterotrophs ?

Answer 5

Organisms which obtain organic matter from other organisms.

Question 6

Give species specific examples of heterotrophs.

Answer 6

Viruses and blue whales

Question 7

What are chemolithotrophs ?

Answer 7

The use of chemical oxidation to obtain energy from inorganic compounds.

Question 8

Give an example of Chemolithotrophs.

Answer 8

Hot sulphur springs

Question 9

Is all energy on a basic level, produced by light energy ?

Answer 9

NO

Question 10

What is the role of decomposers in an ecosystem ?

Answer 10

They process organic material, returning nutrients to the ecosystem in inorganic form.
These nutrients are taken up by primary producers

Question 11

What does the number of trophic levels in an ecosystem depend on ?

Answer 11

Amount of energy entering ecosystem
Energy loss between trophic levels
Form, structure and physiology of organisms at each level

Question 12

Only 10% of energy produced is transferred at each trophic level.
State why

Answer 12

The transfer is affected by;

Respiration 
Growth
Reproduction
Defecation
Non-predatory death

Question 13

Which is the best food source for conversion into new living tissue, High or low quality ?

Answer 13

High quality food sources are converted more effectively.

Question 14

Give the maximum number of trophic levels in a terrestrial system.

Answer 14

5

Question 15

Give the maximum number of trophic levels in a marine system.

Answer 15

7

Question 16

Why are marine systems able to have more trophic levels than terrestrial system ?

Answer 16

Terrestrial- plants are complex organisms, hard to break down.

Marine- Plankton is a simple structure, easier to digest.

Question 17

What is an ecosystems GPP ?

Answer 17

Gross primary productivity

= Total amount of organic matter produced by photosynthesis

Question 18

What is an ecosystems NPP ?

Answer 18

Net primary productivity

= Energy left for plant after subtracting what the plant uses in respiration

Question 19

What affects productivity in an terrestrial ecosystem ?

Answer 19

Temperature. will increase up to 30C and then decline

Question 20

What are the key factors affecting productivity in oceans ?

Answer 20

Light and nutrients

Question 21

Where does photosynthesis occur in the ocean ?

Answer 21

Light will only penetrate the top layer of the ocean, so photosynthesis only occurs in the surface waters

Question 22

Where do nutrients come from in the ocean ?

Answer 22

Upwelling’s

Runoff from the land

Question 23

What do nutrients promote in the ocean ?

Answer 23

Plankton blooms

Question 24

Where is the lowest productivity in an ocean ?

Answer 24

In the open ocean

Question 25

What do food webs demonstrate ?

Answer 25

The feeding connections in ecological communities

Question 26

How can the stability of a food web be increased ?

Answer 26

By increasing the complexity (number of species) in the web

Question 27

Who pioneered the food web ?

Answer 27

Charles Elton

Question 28

What is a keystone species ?

Answer 28

Species which have a DISPROPORTIONALLY LARGE IMPACT on their environment relative to their abundance

Question 29

How do keystone species impact their environments ?

Answer 29

Have a cascading effect on the ecosystem | Play a key role in maintaining structure.

Question 30

What are keystone mutualists ?

Answer 30

Species that have mutually beneficial interactions with other organisms

Question 31

Give 2 examples of keystone mutualists

Answer 31

Banksia Only nectar source for honeyeaters Cassowary Seed will only grow after passing through this species

Question 32

What would occur if mutualist species were lost ?

Answer 32

There would be a profound impact on the whole ecosystem.

Question 33

Give 2 examples of ecosystem engineers

Answer 33

Grizzly bears (leaving salmon on the riverbank for use as a fertiliser, nutrient rich faeces) ``` Prairie Dogs (Tunnels impact the ecosystem by channelling rainwater and giving shelter. Graze vegetation encouraging other species ) ```

Question 34

What are ecosystem engineers ?

Answer 34

An organism that modifies, creates or destroys habitats Affects the availability of resources to other species, Causes physical changes in biotic or abiotic materials

Question 35

What is ecosystem stability ?

Answer 35

The ability of an ecosystem to maintain its structure and function over long periods,

Question 36

Which ecosystems are at dynamic equilibrium ?

Answer 36

Mature ecosystems

Question 37

Define inertia in an ecosystem

Answer 37

The resistance of an ecosystem to change

Question 38

Define resilience in an ecosystem,

Answer 38

The ability of an ecosystem to return to normal after a disturbance

Question 39

What do theoretical models of ecosystems suggest ?

Answer 39

That there are multiple relationships between diversity and stability in an ecosystem

Question 40

Give an example of ecosystem stability at an ecosystem level in plants.

Answer 40

The abundance of a plant species will increase in response to the decreased abundance of another.

Question 41

Give an example of ecosystem stability at a species level

Answer 41

A plant species will be resilient to the habitat. | As more species arrive, this resilience will enable the community to the adapt to the changing environment

Question 42

What is the biological insurance hypothesis ?

Answer 42

Resilient species will buffer the habitat against the loss of other species by continuing to thrive Continue function of lost species

Question 43

When will succession of a population end ?

Answer 43

When the population becomes self-perpetuating and stable

Question 44

What does primary succession form ?

Answer 44

A new habitat

Question 45

Why does secondary succession occur ?

Answer 45

Due to a disturbance in a existing community.

Question 46

Describe the strategy of early succession communities

Answer 46

They are R strategists

Question 47

What happens to these R strategists as the community develops ?

Answer 47

They are outcompetes by K selected species to create a more stable ecosystem

Question 48

Can a climax community ever occur in a habitat ?

Answer 48

No, General environmental disturbance makes this unattainable.

Question 49

List the ways plants can effect an ecosystem.

Answer 49

Autogenic (changes in soil) Plant structure (shade, water filt) Encourage animals Alter climatic factors

Question 50

How are ecosystems maintained ?

Answer 50

By cycling energy and nutrients which are obtained from external sources

Question 51

What do food webs help organise ?

Answer 51

The complex network of interactions among species in a community.

Question 52

What are allogenic effects on a habitat ?

Answer 52

Changes due to external influences | Soil erosion, leaching, deposition of salt and clay

Question 53

What are autogenic effects on a habitat ?

Answer 53

Changes in soil, caused by organisms in a community | PH alteration by plants growing

Question 54

Describe an example where the collapse of a keystone species led to a positive impact for another species

Answer 54

Otter population crashed in 1990 Due to increase in killer whale Collapse in kelp forests, habitat for fish and regulate wave impact Decreased food source for eagles Switched diet to seabirds and other fish- Higher calorific content Increased in eagle population