unit 4

Question 1

define specie

Answer 1

A group of organisms that can potentially interbreed to produce fertile, viable offspring.

Organisms that live in different populations still count as species if interbreeding is possible.

Question 2

define population

Answer 2

A group of organisms of the same species that are living in the same area at the same time.

Question 3

define community, habitat, abiotic, biotic and ecosystem?

Answer 3

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

habitat: Environment in which a species lives

abiotic: Non-living

bioitc: Living

ecosystem: A community and its abiotic environment

Question 4

explain Reproductive isolation

Question 5

Autotroph

3 groups of autotrophs

Answer 5

Obtains inorganic molecules from abiotic environment
Synthesizes own organic molecules from simple inorganic substances like CO2

Commonly called producers

Plants, algae, cyanobacteria

Question 6

Heterotroph

Answer 6

Obtains organic molecules from other organisms
Commonly called consumers

Herbivores feed principally on plant matter (e.g. cows, sheep, rabbits)

Carnivores feed principally on animal matter (e.g. crocodiles, wolves, tigers)

Omnivores eat both plant and animal matter (e.g. pandas, humans)

Question 7

Scavengers

Answer 7

Scavengers feed on dead and decaying carcasses rather than hunting live prey (hyenas, vultures, crows)

Question 8

Detritivores

Answer 8

Detritivores obtains nutrients from non-living organic sources
- digest internally

Question 9

Saprotrophs

Answer 9

Live on/in non organic matter, secrete digestive enzymes into it and absorb products of digestion
Feed by external digestion unlike everyone else
Decomposers - mostly bacteria and fungi

Question 10

Outline the generalized flow of nutrients between the abiotic and biotic components of an ecosystem.

Answer 10

Elements like carbon, nitrogen, oxygen, and hydrogen are moved through biotic components of an ecosystem through food chains and recycled through abiotic environments including the atmosphere, water, and soil

Question 11

Define sustainability

3 requirements of a sustainable ecosystem

Answer 11

Capacity of ecosystems to maintain their essential functions and processes over time

Nutrient availability, energy, and ability to detoxify waste products

Question 12

Define food chain and food web

Meaning of arrow in food web/chain

Answer 12

Food chain: sequence of organisms through which energy and nutrients pass as one organism eats the other
Food web: interconnected feeding relationships within an ecological community

Represent flow of energy + nutrients between trophic levels

Question 13

Outline the flow of energy through a food chain

Answer 13

Light energy is converted to chemical energy by autotrophs, stored in carbon compounds

Energy is transferred from organism to organism through feeding

Aprox. 90% of energy is lost between every trophic level (either because it’s unconsumed or lost as heat/fecal matter)

Energy is not recycled

Question 14

Biomass

Answer 14

Mass of living organisms in a given area at a given time

Question 15

Trophic level

Answer 15

Group of organisms in ecosystem occupying the same position on a food chain (producer, primary consumer, secondary consumer, tertiary consumer… decomposer)

Question 16

Average amount of energy passed through each level of a food chain

Answer 16

10%

Question 17

Describe shape of a pyramid of energy

Answer 17

Top trophic level is the smallest, only part of the energy of one trophic level will become part of the next trophic level

Question 18

Outline the process that converts CO2 to hydrogen carbonate ion in water

Answer 18

CO2 is diffused in water. Some will remain as dissolved gas, the remainder will combine with water to form carbonic acid (H2CO3) which dissociates to form hydrogen ions and hydrogen carbonate ions (H+ and HCO3-)
The increased H+ concentration in water will reduce its pH, making it more acidic

Question 19

Role of diffusion in carbon cycle

Answer 19

CO2 diffuses into autotrophs from atmosphere/water = carbon source for photosynthesis
CO2 diffuses out of living things back to atmosphere/water because it’s a waste product from cell respiration

Question 20

Outline the role of methanogenic archaea in the transformation of organic material into methane

Answer 20

Methanogenic archaea are microorganisms that produce methane as metabolic byproduct in anaerobic respiration, which will either be diffused in the atmosphere as greenhouse gas or accumulate underground

Question 21

Oxidation of methane

Answer 21

Methane is oxidised (loses hydrogen) to form CO2 in the atmosphere
CH4 + 2O2 → CO2 + 2H2O

Question 22

Formation of peat

Answer 22

Brown deposit resembling soil
Formed when organic material doesn’t fully decompose
Formed in acidic/anaerobic conditions where decomposers are inhibited

Question 23

Formation of coal

Answer 23

Forms from peat over long time periods
Heat + pressure produce physical + chemical changes in peat levels, forcing out oxygen and leaving rich carbon deposits (coal)

Question 24

Formation of oil + natural gas

Answer 24

Dead microscopic plants + animals sink to bottom of sea floor. Over time, layers of sediments formed on top = heat + pressure began to rise, forms gas/oil which deposits in surrounding rock

Question 25

Coral + molluscs shells

Answer 25

Hard shells like molluscs and coral are made of calcium carbonate (CaCO3)
When organisms die these components may be fossilized in limestone

Question 26

Lithification

Answer 26

Compaction of sediments into rocks

Question 27

Formation of limestone

Answer 27

Composed of calcium carbonate, is an organic sedimentary rock from the accumulation of shell, coral, etc. in water

Question 28

Carbon flux + processes

Unit of measure for carbon flux values

Answer 28

Exchange of carbon between Earth’s carbon pools (locations that take in + release carbon, like biosphere, hydrosphere, geosphere, atmosphere)

Photosynthesis, respiration, decomposition, diffusion, lithication, combustion, fossilization, feeding

Gigatonnes

Question 29

Greenhouse gases in atmosphere

Answer 29

Water vapour, carbon dioxide, methane, nitrogen oxides
Water + CO2 are most abundant

Question 30

Sources of nitrous oxide + methane in atmosphere

Answer 30

Nitrous oxide - agriculture, fuel combustion, industrial processes, cars, nitrogen cycle

Methane - methanogens in ruminants (cattle) and wetlands

Question 31

Greenhouse effect

Answer 31

Natural process by which radiation (heat) is trapped in atmosphere, warming its surface to temperatures needed for life + prevents rapid temperature fluctuations (like at night with no sunlight)

Question 32

Mechanism by which gases trap heat in atmosphere

Answer 32

Surface of Earth absorbs short wave radiation from sun + re-emits it into atmosphere at longer wavelength, greenhouse gases absorb that radiation and radiate it back to surface

Question 33

Ice core data

Answer 33

Earth’s climate can be studies up to 800 000 years back by drilling in ice sheets in Antarctica and Greenland, info about CO2 concentrations is trapped in there