Unit 4.1 - Species, Ecosystems

Question 1

Ecological Organisation

Answer 1

• Species
• Population
• Community
• Habitat
• Ecosystem

Question 2

Species

Answer 2

A group of organisms that can interbreed and produce fertile, viable offspring

Question 3

Population

Answer 3

Group of organisms of the same species, living in the same area at the same time

Question 4

Community

Answer 4

A group of different populations living together and interacting in a given area

Question 5

Habitat

Answer 5

The environment in which a species lives or the normal location of an organism

Question 6

Ecosystem

Answer 6

A community and also its environment (all biotic and abiotic factors)

Question 7

Modes of Nutrition

Answer 7

Living organisms can obtain chemical energy by one of two methods of nutrition (a few species can use both methods)

Question 8

Autotrophs

Answer 8

Synthesise organic molecules from inorganic nutrients within the environment, using energy from either:
• Light (photoautotrophs)
• Oxidation reactions (chemoautotophs)
- Commonly referred to as producers, as they are responsible for the production of organic molecules

Question 9

Heterotrophs

Answer 9

Obtain their organic molecules from other organisms via a variety of feeding methods and food sources
• Consumers ingest other living organisms
• Detritivores ingest detritus (decomposing matter and faeces)
• Saprotrophs externally digest dead organisms (decomposers)
- Couldn’t survive without autotrophs

Question 10

Nutrients

Answer 10

Materials required by organisms for survival

Question 11

Supply of inorganic nutrients within the environment

Answer 11

Finite and therefore must be constantly recycled

Question 12

Autotrophs (nutrients)

Answer 12

Convert inorganic nutrients into organic molecules

i.e. they are producers

Question 13

Heterotrophs (nutrients)

Answer 13

Ingest organic molecules and may release inorganic byproducts
(e.g. carbon dioxide)

Question 14

Saprotrophs (nutrients)

Answer 14

Break down the nutrients in dead organisms and return them to the soil
(i.e. they are decomposers)

Question 15

Ecosystems

Answer 15

Have the potential to be sustainable over long periods of time, however this requires 3 conditions:
• Energy availability 
(e.g. light source)
• Nutrient availability 
(e.g. decomposers)
•  Waste recycling 
(e.g. detoxifying bacteria)

Question 16

Mesocosms

Answer 16

• Enclosed environments with controlled conditions
  (e. g. terrariums)
• They can be used to study sustainability

Question 17

Presence of species

Answer 17

May be dependent on the interactions between them (either positive or negative)

Question 18

If species are always found in the same habitat…

Answer 18

There is a positive association (such as):
• Predator / prey relationships
• Symbiotic interaction (mutualism, commensalism, parasitism)

Question 19

If species do not share the same habitat…

Answer 19

There is a negative association (such as):

• Competition (niche partitioning or competitive exclusion)

Question 20

Quadrat Sampling

Answer 20

• The presence of a species in a given area can be determined via quadrat sampling (to assess sessile/non-motile species)
• Rectangular frame placed in an area (+ repeat sampling)
• Species numbers within the frame are counted/estimated