4.1 species, communities and ecosystem

Question 1

species

Answer 1

a group of organisms that can interbreed and produce fertile (and viable) offspring.

Question 2

habitat

Answer 2

the environment within which a species normally lives

Question 3

population

Answer 3

a group of organisms of the same species who live in the same area at the same time.

Question 4

community

Answer 4

populations of different species(plants&animals) living and interacting in the same area

Question 5

ecosystem

Answer 5

a community and its abiotic environment

Question 6

ecology

Answer 6

the scientific study of the relationship between living organisms and between those organisms and their environments

Question 7

abiotic factor

Answer 7

non-living components within an ecosystem such as water, soil, and atmosphere

Question 8

biotic factors

Answer 8

living things within an ecosystem; such as plants, animals, and bacteria.

Question 9

autotrophs

Answer 9

synthesises its own organic material from simple inorganic substances (CO2, nitrates).
Energy for this process is derived from sunlight (photosynthesis) or via the oxidation of inorganic molecules (chemosynthesis).
as autotrophs synthesise their own organic molecules they are commonly referred to as producers

Question 10

heterotrophs

Answer 10

1. Obtains organic molecules from other organisms (either living / recently killed or their non-living remains and detritus)
2. heterotrophs cannot produce their own organic molecules and obtain it from other sources, they are called consumers

Question 11

mixotrophs

Answer 11

Certain unicellular organisms may on occasion use both forms of nutrition, depending on resource availability.
Euglena gracilis possess chlorophyll for photosynthesis (autotrophic) but may also feed on detritus (heterotrophic).

Question 12

types of heterotrophs and their differentiation

Answer 12

Detritivores ingest organic molecules found in the non-living remnants of organisms (e.g. detritus, humus)
Saprotrophs release digestive enzymes and then absorb the external products of digestion (decomposers)
Consumers ingest organic material from living or recently killed organisms.

Question 13

types of autotrophs (not v imps)

Answer 13

photoautotrophs - makes organic compounds using energy derived from the sun
chemoautotrophs - makes organic compounds using energy derived from the oxidation of chemicals

Question 14

detritivore

Answer 14

Detritivores ingest organic molecules found in the non-living remnants of organisms (e.g. detritus, humus)

Question 15

saprotrophs

Answer 15

Saprotrophs release digestive enzymes and then absorb the external products of digestion (decomposers)

Question 16

types of decomposers

Answer 16

detritivores, saprotrophs
(ingest - release digestive enzymes)

Question 17

nutrients

Answer 17

refer to the material required by an organism, and include elements such as carbon, nitrogen and phosphorus

Question 18

why is nutrient cycling necessary?

Answer 18

The supply of inorganic nutrients on Earth is finite – new elements cannot simply be created and so are in limited supply. this necessitates nutrient cycling.

Question 19

how are chemical elements constantly recycled after being used?(organic, inorganic material)

Answer 19

1. Autotrophs obtain inorganic nutrients from the air, water and soil and convert them into organic compounds
2. Heterotrophs ingest these organic compounds and use them for growth and respiration, releasing inorganic byproducts
3. When organisms die, saprotrophs decompose the remains and free inorganic materials into the soil
4. The return of inorganic nutrients to the soil ensures the continual supply of raw materials for the autotrophs

Question 20

mesocosm

Answer 20

Mesocosms are enclosed environments that allow a small part of a natural environment to be observed under controlled conditions

Question 21

if two species are typically found within the same habitat, they show a…… they have a ______relationship

Answer 21

positive association

Species that show a positive association include those that exhibit predator-prey or symbiotic relationships

Question 22

if two species are tend not to occur within the same habitat, they show a…… they have a ______relationship

Answer 22

negative association.

competitive relationship where they compete for the same resources.

One species may utilise the resources more efficiently, precluding survival of the other species (competitive exclusion)
Both species may alter their use of the environment to avoid direct competition (resource partitioning)

Question 23

If two species do not interact,

Answer 23

there will be no association between them and their distribution will be independent of one another

Question 24

quadrant sampling

Answer 24

is used to determine the presence of two species within a given environment.

Question 25

what is a quadrat and how is it used?

Answer 25

1. A quadrat is a rectangular frame of known dimensions that can be used to establish population densities
2. Quadrats are placed inside a defined area in either a random arrangement or according to a design (e.g. belted transect)
3. The number of individuals of a given species is either counted or estimated via percentage coverage
4. The sampling process is repeated many times in order to gain a representative data set

Question 26

limitation of quadrat sampling

Answer 26

Quadrat sampling is not an effective method for counting motile(capable of movement) organisms – it is used for counting plants and sessile(immobile) animals

Question 27

chi-squared test purpose

Answer 27

A chi-squared test can be applied to data generated from quadrat sampling to determine if there is a statistically significant association between the distribution of two species

Question 28

how to conduct chi-squared test

Answer 28

1. Identify hypotheses (null versus alternative)
2. Construct a table of frequencies (observed versus expected)
3. Apply the chi-squared formula
4. Determine the degree of freedom (df)
5. Identify the p value (should be <0.05)