Community Interactions

Question 1

Trophic levels

Answer 1

Feeding levels

Question 2

The main trophic levels in an ecosystem

Answer 2

• Producers
• Consumers
• Decomposers

Question 3

Predation

Answer 3

A feeding interaction where a predator eats the prey

Question 4

Predator adaptation examples

Answer 4

• Agile
• Speedy
• Good sense of sight and smell
• Predator dentition and claws
• Camouflage

Question 5

Example prey adaptations

Answer 5

• Herding
• Camoflage
• Warning colouration
• Poisonous secretions

Question 6

Predator prey relationships

Answer 6

• Similar fluctuations in numbers since predators depend on prey for food
• Predators control numbers of prey
• Prey determine numbers of predators
• A density dependent factor

Question 7

Predator-prey graph

Answer 7

• A graph showing the interaction
• General pattern is that there is a delay in response of predator numbers to increase or decrease
• Generally fewer number of predators than prey

Question 8

Features making lions succesful predators

Answer 8

• Powerful and agile
• Sharp teeth and claws
• Camouflage

Question 9

Typical prey of lions

Answer 9

• Wildebeest
• Zebra
• Gemsbok
• Kudu
• Warthog

Question 10

Lion biomes

Answer 10

• Savannah
• Grassland
• Bushveld

Question 11

Hunting strategy of lions

Answer 11

• Females predominant hunters
• Males help with bigger prey
• Hunt usually at night
• Ambush as a group (stalk till 30m away)

Question 12

Hunting strategy of crocodiles

Answer 12

• Drift quietly and unseen with submerged body
• Ambush using high speed over short distances
• Prey grasped with jaws and drowned
• Chunks of carcass eaten as these rot underwater

Question 13

Top predators

Answer 13

Animals at the top of the food chain with few or no natural predators

Question 14

Competition

Answer 14

Occurs when individuals compete for the same limited resource

Question 15

Ecological niche

Answer 15

• Each species has its own particular role in an environment
• This has a limiting effect on competition between different species

Question 16

Competition between individuals of the same species

Answer 16

Intraspecific competition

Question 17

Examples of intraspecific competition

Answer 17

• Yellowood trees in the same grove of forest compete for light
• Piglets feeding from a sow compete for milk

Question 18

Competition between individual of different species

Answer 18

Interspecific competition

Question 19

Competition a density dependent or density independent factor?

Answer 19

• Density dependent
• The more individuals in a particular area, the more limited the available resources, the more competition there is

Question 20

Examples of interspecific competition

Answer 20

• Different species of tree competing for light in a forest
• Hyena and lions competing for food as they feed on a dead zebra

Question 21

Competitive exclusion

Answer 21

• In a stable ecosystem
• Two species will not be able to occupy the same niche for an extended time
• One will outcompete the other
• (Known as Gause’s Law)

Question 22

Organism originally used to illustrate Competitive Exclusion

Answer 22

Paramecium sp.

(Kingdom Protista)

Question 23

Resource partitioning

Answer 23

• Two or more species can co-exist in the same habitat
• because they occupy different specialised niches
• E.g. different feeding times
• E.g. Different parts of the habitat

Question 24

Symbiosis

Answer 24

A close and often long term interaction between two different species

Question 25

Mutualism

Answer 25

Symbiotic relationship between two species where both benefit

Question 26

Example mutualisms

Answer 26

* Bees and flowers (pollination) * Honeyguide bird and humans (honey hunting)

Question 27

Commensalism

Answer 27

A symbiotic relationship between two species where one benefits and the other is unaffected

Question 28

Examples of commensalism

Answer 28

* Birds nesting in trees * Plant epiphytes on tree branches * Remora suckerfish and sharks

Question 29

Parasitism

Answer 29

A symbiotic relationship between two species where one benefits and the other is harmed

Question 30

Parasites living outside the host organism

Answer 30

Ectoparasites

Question 31

Parasites living inside the host organism

Answer 31

Endoparasites

Question 32

Example ectoparasites

Answer 32

* Ticks on a dog * Aphids on a rosebush * Dodder on various plants

Question 33

Example endoparasites

Answer 33

* Malaria * Bilharzia