4.1 Species And Ecosystems

Question 1

What is a species?

Answer 1

Group or organisms that can interbreed to produce fertile, viable offspring

Question 2

What is it called when 2 different species produce offspring by cross-breeding?

Answer 2

Hybrids (reproductively sterile)

Question 3

What is a population?

Answer 3

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

Question 4

What is a community?

Answer 4

A group of populations living together and interacting with each other within a given area

Question 5

What is a habitat?

Answer 5

Environment in which a species normally lives

Question 6

What is an ecosystem?

Answer 6

A community and its abiotic environment

Question 7

What is ecology?

Answer 7

Study of relationship between living organisms/ and their environment

Question 8

How do autotrophs (producers) obtain chemical energy? (2)

Answer 8

• Synthesis its own organic molecules from simple inorganic substances
• from sunlight (photosynthesis) or via oxidation of inorganic molecules (chemosynthesis)

Question 9

How do heterotrophs (consumers) obtain energy? (2)

Answer 9

• from other organisms
• can’t produce their own organic molecules

Question 10

How do mixotrophs obtain energy?

Answer 10

• using both forms
• eg. Photosynthesising but also feed on detritus

Question 11

What are the three types of ways that heterotrophs obtain organic molecules?

Answer 11

1. Consumers - ingest og from living/recently killed organisms
2. Detritivores - ingest og found in non-living remnants of organisms (detritus/humus)
3. Saprotrophs - release digestive enzymes and then absorb the external products of digestion (decomposers)

Question 12

What are some examples of the simple inorganic substances required for synthesis? (5)

Answer 12

Carbon, nitrogen, hydrogen, oxygen and phosphorus (from air, water and soil)

Question 13

What are the 3 types of consumers?

Answer 13

Herbivores - plant matter
Carnivores - animal matter
Omnivores - both plant and animal matter

Question 14

How do scavengers feed?

Answer 14

Dead and decaying matter instead of hunting live prey

Question 15

How do detritivores obtain nutrients? (2 ways)

Answer 15

Detritus - dead, particulate organic matter (decaying organic matter and fecal matter)
Humus - decaying leaf litter with topsoil

Question 16

How do saprotrophs obtain nutrients?

Answer 16

Enzymatic secretion to facilitate external digestion

Question 17

How does nutrient cycling work? (4 steps)

Answer 17

1. Autotrophs obtain inorganic nutrient from air, water and soil and convert them to organic compounds
2. Heterotrophs ingest organic compounds and use them for growth and respiration (releasing inorganic by products)
3. Organisms die and saprotrophs decompose the remains and free inorganic material into soil
4. Return of inorganic nutrient toi soil ensured continual supply of raw materials for the autotroph

Question 18

What are the three main components required for sustainability in ecosystem?

Answer 18

Energy availability - light from sun
Nutrient availability - decomposers ensure constant recycling of inorganic nutrients
Recycling of waste - cortina bacteria detoxify harmful waste byproducts

Question 19

What are mesocosms?

Answer 19

Enclosed environments that allow small part of natural environment to be observed under controlled conditions
(Eg. Terrarium)

Question 20

What is positive association? (And relationship)

Answer 20

If two species are typically found within the same habitat
- exhibit predator-prey / symbiotic relationship

Question 21

What is a negative association?

Answer 21

If two species tend to not occur within the same habitat

Question 22

why may species typically show a negative association if there is competition for the same resources? (2)

Answer 22

1. One species may utilise the resources more efficiently (competitive exclusion)
2. Both species may alter their use of the environment to avoid direct competition (resource partitioning)

Question 23

What occurs is the species do not interact? (2 points)

Answer 23

There will be no association between then
Their distribution will be independent of one another

Question 24

What is a quadrat?

Answer 24

A rectangular frame of known dimensions that can be used to establish population densities

Question 25

How do you use a quadrat? (3)

Answer 25

1. Quadrats are placed inside a defined area in either a random arrangement or according to a design
2. Number of individual of a given species is either counted or estimated via percentage coverage
3. Sampling process is repeated many times in order to gain representative data set

Question 26

How to do a chi-squared test?

Answer 26

1. Identify hypothesis (null v alternative)
2. Construct a table of frequencies
3. Apply the chi-squared formula
4. Determine the degree of freedom
5. N’identifiât the p value

Question 27

Do a chi-squared test