Community

Question 1

Define ‘community’.

Answer 1

Refers to a group of plant and animal populations that live in a particular area at a particular time and interact with each other.

Question 2

How does a population differ from a community?

Answer 2

A population consists of only one type of species.

Question 3

What are possible types of interactions in a community?

Answer 3

Competition
Predation
Herbivory
Symbiosis

Question 4

What are the 4 types of symbiotic relationship?

Answer 4

Amensalism
Commensalism
Parasitism
Mutualism

Question 5

Explain the interaction competition and provide an example.

Answer 5

The interaction that occurs when individuals of different species compete for same resources which is limited in supply. Both are negatively affected as this limits the growth and survival of organisms involved.
Example, Red ants and black ants both opting for the same food, and ending up competing with each other to obtain it. This will negatively impact both ants.

Question 6

Define ‘niche’.

Answer 6

Is the ecological role a species play in its ecosystem. It refers to everything about its life, particularly its relationship with other organisms with its physical surroundings (both biotic and abiotic)

Question 7

What are the ecological niche’s of an earthworm?

Answer 7

Burrowing through the soil eating organic matter. They prefer moist, dark habitat, birds are their main predators. They produce sexually, with internal fertilisation, each individual having both male and female sexual organs.

Question 8

How is niche overlap between species reduced?

Answer 8

Division of resources, which is favoured by natural selection.

Question 9

What does resource division do?

Answer 9

It reduces competition, allowing greater population size and diversity in communities.

Question 10

Explain the interaction ‘predation’ and provide an example.

Answer 10

Is the interaction between species in which the predator kills and eats the prey In this interaction, the predator benefits and the prey is negatively affected.
Example, mongoose killing and eating a chicken.

Question 10

Explain the interaction ‘predation’ and provide an example.

Answer 10

Is the interaction between species in which the predator kills and eats the prey In this interaction, the predator benefits and the prey is negatively affected.
Example, mongoose killing and eating a chicken.

Question 11

Explain the interaction ‘herbivory’ and provide an example.

Answer 11

Is the interaction where an organism eats a part of the plant or algae In this, the herbivore benefits and the plant is negatively affected.
Example, a cow eating grass, the cow benefits by getting food and the plant is negatively affected as it loses its greens and photosynthesis will be affected.

Question 12

Explain the term ‘symbiosis’ .

Answer 12

Symbiosis is the relationship when individuals of two or more species live together in direct contact with one another.

Question 13

Explain the symbiotic relationship, Amensalism and give an example.

Answer 13

Is a relationship where one organism is harmed, the other one remains unaffected.
Example, an algal bloom in the river causes death to many aquatic animals but the algae remains unaffected.

Question 13

Explain the symbiotic relationship, Amensalism and give an example.

Answer 13

Is a relationship where one organism is harmed, the other one remains unaffected.
Example, an algal bloom in the river causes death to many aquatic animals but the algae remains unaffected.

Question 14

Explain the symbiotic relationship, Parasitism and give an example.

Answer 14

Is the relationship where the parasite benefits and the host is harmed.
Example, mosquitos, they benefit by obtaining food (sucking blood) while the host is harmed because it causes redness and itchiness.

Question 15

Define ‘zonation’.

Answer 15

Is the division of organisms into areas or zones, of varying environmental factors.

Question 16

Differentiate between zonation and stratification.

Answer 16

Zonation is the horizontal environmental division (side by side) whereas stratification is the vertical environmental division.

Question 17

Explain an example of zonation.

Answer 17

The stream ecosystem has roughly 3 zones; wet zone, damp zone and dry zone. Different organisms are adapted to different zone conditions. Algae will be found in the wet zone, mosses and ferns in the damp zone, and herbaceous plants in the dry zone.

Question 18

Explain ‘stratification’.

Answer 18

Is the vertical layers of organism in communities. Each layer is known as a stratum and different organisms live in the various strata depending on their living requirements.

Question 19

Explain an example of stratification.

Answer 19

The rainforest. The top layer is known as the canopy with the most amount of sunlight and wind but with the least amount of humidity. The middle layer is known as the understory, receiving less sunlight and wind compared to the compared to the canopy, but have higher humidity. The bottom layer is known as the forest floor, with the highest humidity but with lowest amount of sunlight and wind.

Question 20

How does stratification reduce competition?

Answer 20

1. it divides the organisms into separate areas, like zonation.
2. The many strata create a large number of varied habitats, greatly increasing the diversity and number of organisms the ecosystem can support.

Question 21

Define ‘succession’.

Answer 21

Is the orderly progression of species composition in an empty area of land, from colonizing pioneer species to a stable community.

Question 22

Briefly describe the several stages that occur in succession.

Answer 22

• A new habitat is formed with no form of life, example, an island created by a volcanic eruption.
  -Pioneer species colonize the newly available habitat.
• Once the pioneers sheltered the soil, the seeds of perennial plants take root. Overtime perennials crowd out the original pioneer species.
• Finally, after several stages of successive groups of organisms, the environmental conditions stabilize and the community reaches a stable composition of species called the climax community.

Question 23

What are the 2 competitive advantages of perennials over annuals.

Answer 23

• early growth each year, since they live for more than one growing season.
  -larger energy store.

Question 24

How does succession divide resources between its different species?

Answer 24

They divide the resources with respect to time.

Question 25

How do zonation and stratification divide their resources?

Answer 25

divide resources by space.

Question 26

What does periodicity mean?

Answer 26

An organisms activity cycle according to time periods.

Question 27

What are some common types of periodic cycles observed in organisms?

Answer 27

-daily cycles
-seasonal cycles
-photoperiodism

Question 28

Explain the daily cycle.

Answer 28

Is the cycle which is based on 24 hours. Species of flowers and insects available at night differ from the ones available during the day. The ones available during the day are diurnal (birds) and the ones active during night are nocturnal (bats).

Question 29

What are crepuscular animals?

Answer 29

Are animals which show daily cycle. These are animals that are active during near sunset such as mosquitoes, frogs and crabs.

Question 30

State another example of daily cycle.

Answer 30

Another example is the tides (lunar), there are high and low tides daily.

Question 31

Explain an example of seasonal cycles.

Answer 31

An example of seasonal cycle is annual plants and perennial plants. Annual plants germinate, grow, reproduce and die all within a year. They are adapted for survival in harsh, infertile environments and wide dispersal by wind to new, unexploited places. On the other hand perennial plants live for more than a year. They invest in support and energy storage. And they normally flourish in areas already colonized and moderated by annual pioneer species.

Question 32

What are some plants that show seasonal cycles?

Answer 32

Sugarcane, duruka, ivi.

Question 33

Explain the winter seasonal behaviours observed during seasonal cycles.

Answer 33

During winter, tree’s drop their leaves, animals go through hibernation-hiding and sleeping throughout the season. Also some mammals change from brown to white fur to camouflage in the snow.

Question 34

Explain the summer seasonal behaviours observed during seasonal cycles.

Answer 34

During high temperature and arid conditions, animals go through aestivation- hiding and sleeping throughout the season. Also many crabs spend dry seasons in an inactive state at the bottom of their burrows.

Question 35

What is photoperiodism?

Answer 35

Is the response of an organism to the duration of light.

Question 36

How do organisms tell the time of the year?

Answer 36

By the length of the day.

Question 37

How do plants and animals time their reproduction?

Answer 37

They time their reproduction with the season that provides the offspring with the best environmental conditions possible.

Question 38

Identify the hotter and colder months in Fiji and whether the days are short or long..

Answer 38

In Fiji, the colder months are June and July whereas the hotter months are November and December.
Colder seasons have shorter days whereas hotter seasons have longer days.

Question 39

Provide an example of photoperiodism.

Answer 39

For example, some plants only flower when days are long and some when days are short.
Some long day plants are oats, peas, wheat and some short day plants are rice and cotton.

Question 40

Explain the gauze’s principle of competitive exclusion

Answer 40

States that 2 species of the same ecological niche cannot co-exist in the same area for long. The one adapted better to the local conditions will out -number the other one. The ‘loser’ species must shift niche, migrate or die.

Question 41

Explain an example for Gauze’s principle of competitive exclusion.

Answer 41

Example, 2 flour beetles cannot co-exist in the same jar of flour if forced to be in direct competition. However if the environment within the flour varies a bit, for example, one part of the jar being warmer of damper than the others, then the 2 species can specialize in their separate zones. The zonation reduces the competition so both of them can survive.

Question 42

What does Liebig’s law of the minimum state?

Answer 42

States that out of all the resource requirements of an organism, one resource will always be scarce than the others. That would be the limiting factor of the organisms growth.

Question 43

Explain an example of Liebig’s law of minimum.

Answer 43

Example. desert plants have enough co2 and sunlight for photosynthesis. But the scarce resource in deserts is water, if they had more water, photosynthesis could be carried out with ease, without having to invest in special adaptative structures to conserve water.

Question 44

Explain the biological principle of tolerance.

Answer 44

States the organisms can survive only within certain ranges of physical factors, such as light intensity, temperature and humidity.

Question 45

What is the range of tolerance?

Answer 45

Is the area between minimum and maximum conditions in which the organisms can survive.

Question 46

What happens to an organism if it tries to function outside its ideal range?

Answer 46

It’s activity level would drop and the organism will become physically stressed.