4. ecology and the environment

Question 1

define population

Answer 1

group of organisms of the same species living in the same place at the same time

Question 2

define community

Answer 2

all of the populations living in the same area at the same time

Question 2

define habitat

Answer 2

the place where an organism lives

Question 2

define ecosystem

Answer 2

all the biotic factors and all the abiotic factors that interact within an area at one time (non and living components)

Question 3

define biodiversity

Answer 3

the range and variety of different species or organisms on earth, or within an ecosystem

Question 4

why is biodiversity important?

Answer 4

different species depend on each other for food, shelter and maintenance of the physical environment
high biodiversity ensures the stability of ecosystems by reducing the dependence of one species on another for the reasons above. populations with high diversity are also more likely to be resilient to sudden environmental impacts or disease

Question 5

what is an abiotic factor?

Answer 5

non living
e.g. temperature, light intensity and wind speed

Question 6

how does light intensity affect a community

Answer 6

light is needed by plants for photosynthesis, more light leads to an increase in the rate of photosynthesis and an increase in plant growth rate

Question 7

how does temperature affect a community

Answer 7

affects the rate of photosynthesis in plants

Question 8

how does moisture levels affect a community

Answer 8

plants and animals require water to survive

Question 9

how does soil pH and mineral content affect a community

Answer 9

different species of plants are adapted to different soil pH levels and nutrient concentration levels

Question 10

how does wind intensity and direction affect a community

Answer 10

wind speed affects transpiration rate in plants, transpiration affects the rate of photosynthesis as it ensures water and mineral ions are transported to the leaves

Question 11

how does carbon dioxide levels affect a community

Answer 11

co2 is required for photosynthesis in plants, so affects the rate of photosynthesis

Question 12

how does oxygen levels affect a community

Answer 12

some aquatic animals (like fish) can only survive in water with high oxygen concentrations

Question 13

what is a biotic factor

Answer 13

living factor
e.g. competition, predation and disease

Question 14

how does availability of food affect a community

Answer 14

more food means organisms have a higher chance of surviving and reproducing, this means their populations can increase

Question 15

how does new predators affect a community

Answer 15

in balanced ecosystems, predators catch enough prey to survive but not so many that they wipe out the prey population, if a new predator is introduced to the ecosystem, it may become unbalanced

Question 16

how does new pathogens affect a community

Answer 16

if a new pathogen enters an ecosystem, the populations living there will have no immunity of resistance to it and the population may decline or be wiped out

Question 17

how does competition affect a community

Answer 17

if 2 species compete for the same resource(s) and one is better adapted to take advantage, then the species will outcompete the other, this may continue until there are too few members of the lesser adapted species to breed successfully

Question 18

what are trophic levels

Answer 18

term used to describe the feeding relationships between organisms

Question 19

what are producers

Answer 19

they produce their own organic nutrients usually using energy from sunlight

Question 20

what are primary consumers

Answer 20

herbivores- they feed on producers (plants)

Question 21

what are secondary consumers

Answer 21

predators that feed on primary consumers

Question 22

what are tertiary consumers

Answer 22

predators that feed on secondary consumers

Question 23

true or false:
animals can be at different trophic levels within the same food web as they may both eat primary, secondary and/ or tertiary consumers

Answer 23

true!

Question 24

what are decomposers

Answer 24

bacteria and fungi that get their energy from feeding off dead and decaying organisms and undigested waste (such as faeces) by secreting enzymes to break them down

Question 25

why are food webs are more realistic way of showing connections between organisms within an ecosystem instead of a food chain?

Answer 25

as animals rarely exist on just one type of food source

Question 26

what does a food chain show

Answer 26

the transfer of energy from one organism to the next

Question 27

fill in the blank:
a food web shows the _______________ of organisms

Answer 27

interdependence

Question 28

what are most of the changes in populations or animals and plants a result of?

Answer 28

human impact- either by overharvesting of food species or by the introduction or foreign species to a habitat

Question 29

what are pyramids of numbers

Answer 29

-shows the number of organisms at each trophic level
-the width of the bars represents the relative number of organisms at that trophic level
-the bottom bar will always be a producer
-not always pyramid shaped

Question 30

what is a pyramid of energy

Answer 30

-shows the amount of energy at each trophic level
-always the shape of a pyramid- as energy is lost at each trophic level (about 10% transferred)

Question 30

what is a pyramid of biomass

Answer 30

-represents the dry mass of organisms at each trophic level
-the unit is usually mas per surface area
-will always have a pyramid shape as biomass decreases
-represents quantity of organisms and interdependence more accurately

Question 30

what is the equation for percentage efficiency transfer

Answer 30

percentage efficiency transfer = biomass in higher trophic level / biomass in lower trophic level x100

Question 31

fill in the blanks:
_________ convert light energy into _______ energy- this occurs during ___________, when producers convert co2 and h2o into _______ and oxygen
producers use this glucose (during __________) to produce their own _______ (a store of chemical energy)

Answer 31

producers
chemical
photosynthesis
glucose
respiration
biomass

Question 31

fill in the blanks:
when _______ consumers eat producers, they break down the biomass of the producer (________) and use the ______ energy to ______ or sustain their own biomass
(same thing occurs when ________ consumers eat primary consumers)
in this way chemical energy and _______ is _________ from one trophic level to the next

Answer 31

primary
digestion
chemical
increase
secondary
biomass
transferred

Question 32

approximately what % of energy is transferred at each trophic level

Answer 32

10%

Question 33

how is energy lost at each trophic level

Answer 33

-energy is used for movement
-used to generate heat
-for metabolic processes
-some is lost as waste (carbon dioxide, water, urea)
-not all the ingested material is digested and absorbed- some is egested as faeces
-some biological material is inedible (like bones and fur)

Question 34

what do nitrogen fixing bacteria do in the nitrogen cycle

Answer 34

convert nitrogen gas and convert it into nitrates in the soil
found in soil and in the root nodules of certain plants like peas and beans
lightning also does this
can be called nitrogen fixation

Question 35

what do nitrifying bacteria do

Answer 35

convert ammonium ions into nitrates, which can then be absorbed by plants
can be called nitrification

Question 36

what do denitrifying bacteria do

Answer 36

take nitrates out of the soil and convert them back into nitrogen gas
can be called denitrification

Question 37

what is the consequence of sulfur dioxide pollution

Answer 37

combines with water vapour to form acid rain, which damages plants, aquatic life and soil. can also cause respiratory problems in humans

Question 38

what is the consequence of carbon monoxide pollution

Answer 38

binds irreversibly to haemoglobin, which reduces oxygen transport in blood, can lead to suffocation and death in high concentrations

Question 39

name 5 greenhouse gases

Answer 39

water vapour, carbon dioxide, methane, nitrous oxides, CFCs

Question 40

fill in the gaps!
human activities have led to increasing levels of ______ _______ and ______ in the atmosphere
CO2 is produced during the __________ of fossil fuel
methane is produced by _____ as they digest grass, and released by rice paddy fields

Answer 40

carbon dioxide
methane
combustion
cattle

Question 41

describe the greenhouse effect process

Answer 41

• the sun emits rays that enter the earth’s atmosphere
• heat bounces back from the earth’s surface
• some heat is reflected back out into space
• some heat is absorbed by greenhouse gases and is trapped within the earth’s atmosphere- this is normal

the enhanced greenhouse effect happens when increasing levels of greenhouse gases from human activities cause the earths average temperature to rise above normal- leading to global warming

Question 42

what are the consequences of global warming?

Answer 42

• ocean temperatures increasing (causes polar ice caps to melt, rising sea levels- flooding, coral bleaching)
• increasing temperatures (causes extreme weather like super storms, flooding, droughts)
• changes in or loss of habitats
• decreases in biodiversity (as food chains are disrupted and extinction rates increase)
• increases in migration of species to new places, including increased spread of pests and disease