UNIT 1: Ecology

Question 1

ecology

Answer 1

the study of the interactions between organisms and between organisms and their environment

Question 2

ecosystem

Answer 2

a group of clearly distinguished organisms that interact with their environment as a unit

Question 3

biosphere

Answer 3

that part of the planet in which living organisms can be found

Question 4

habitat

Answer 4

the place where a plant or animal lives

Question 5

population

Answer 5

all the members of the same species living in the habitat

Question 6

community

Answer 6

all the different populations of species living in the habitat

Question 7

environmental factors (terrestrial): abiotic factors

Answer 7

non-living factors e.g. aspect, north facing slopes are cooler and darker than south facing (northern hemisphere only)

Question 8

environmental factors (terrestrial): biotic factors

Answer 8

living factors e.g. available food, more food will enable more organisms to survive.

Question 9

environmental factors (terrestrial): climatic factors

Answer 9

effects of weather over a long period of time e.g. rainfall

Question 10

environmental factors (terrestrial): edaphic factors

Answer 10

effects of soil e.g. soil pH. ph affects growth of particular plants as pH effects enzyme action

Question 11

energy flow

Answer 11

sun: ultimate source of energy

feeding allows energy flow from organism to organism

Question 12

producers

Answer 12

photosynthetic organisms that make their own food

Question 13

consumer

Answer 13

organisms that obtain their food from other organisms

Question 14

primary consumers

Answer 14

feed on producers (herbivores, decomposers, detritus feeders, omnivores)

Question 15

secondary consumers

Answer 15

feed on primary consumers (carnivores, scavengers, omnivores)

Question 16

tertiary consumers

Answer 16

feed on secondary consumers (carnivores, scavengers, omnivores)

Question 17

grazing food chain

Answer 17

a sequence of organisms in which each one is eaten by the next member in the chain

Question 18

examples of food chains

Answer 18

leaf -> caterpillar -> thrush -> falcon.
grass -> rabbit -> fox.
algae -> limpet -> starfish -> gull.
plankton -> barnacle -> whelk -> crab.

Question 19

food web

Answer 19

consists of two or more interlinked food chains

Question 20

pyramid of numbers

Answer 20

represents the number or organisms at each stage in a food chain.
a way of comparing different communities of an ecosystem in order of different trophic levels

Question 21

upright pyramids of numbers

Answer 21

the number of organisms at each trophic level decreases.

Question 22

partially upright pyramid of numbers

Answer 22

the number of organisms at the beginning of the chain is very small when compared to the trophic levels that follow

Question 23

inverted pyramid of numbers

Answer 23

the numbers of organisms at each trophic level increases

Question 24

niche

Answer 24

the functional role an organism plays in a particular habitat e.g. fox’s role is to keep number of rabbits and hares down

Question 25

nutrient recycling

Answer 25

the way in which elements ( such as carbon and nitrogen) are exchanged between living and non-living components of an ecosystem

Question 26

pollution

Answer 26

any harmful addition to the environment

1. domestic: household waste
2. agricultural: pesticides, insecticides, fertilizers, slurry
3. industrial: chimney smoke, chemicals

Question 27

conservation

Answer 27

the wise management of our existing natural resources

Question 28

agricultural conservation

Answer 28

• storing slurry in leak-proof pits
• only spread slurry on land in summer
• do not spread fertilisers or spray insecticides in wet conditions
• growing of organic crops and livestock

Question 29

problems associated with waste disposal

Answer 29

• disease causing micro-organisms (pathogens)
• toxic / harmful chemicals
• nutrient elements: phosphorus and nitrogen can cause eutrophication of rivers and lakes.
• landfill sites are unsightly and attract vermin / scavengers.
• dumping waste at sea leads to pollution
• incineration can release toxic chemicals such as dioxins (which are known carcinogens)

Question 30

agricultural waste minimisation

Answer 30

slurry is stored in leak-proof pits and only spread on land when it is dry.

Question 31

Reduce, reuse, recycle

Answer 31

1. do not buy foods that use excess packaging
2. household objects can be reused
3. many materials used can be recycled, such as glass bottles, paper, plastics, metals, and organic waste

Question 32

role of microorganisms in waste management and pollution control

Answer 32

landfill sites: bacteria break down the organic waste.
sewage; small amounts of sewage are treated naturally by bacteria in water, large amounts of sewage have to be treated by sewage treatment plans (also involves bacteria)

Question 33

inferences of a pyramid of numbers

Answer 33

• number of organisms declines as you go up the pyramid

- organisms body usually (but not always) increases as you go up the pyramid

Question 34

limitations of a pyramid of numbers

Answer 34

• pyramid of numbers does not take into account the actual number of organisms involves.
• pyramid of numbers cannot be drawn to scale
• some are not technically pyramids - they are inverted

Question 35

competition

Answer 35

occurs when organisms actively struggle for a resource that is in short supply - limits population growth

Question 36

contest competition

Answer 36

active physical confrontation between two organisms with one organism obtaining all of the resource

Question 37

scramble competition

Answer 37

struggle between a number of organisms with all the organisms obtaining a small amount of the resource

Question 38

adaptation

Answer 38

occurs to reduce competition e.g. caterpillar eats cabbage, butterfly eats nectar

Question 39

predation

Answer 39

the catching, killing and eating of another organism e.g. snake is a predator and a mouse is its prey

Question 40

parasitism

Answer 40

occurs when two organisms of different species live in close association and one organism (parasite) obtains its food from, and to the disadvantage of, the second organism (host) e.g. athletes food, ringworm

Question 41

symbiosis

Answer 41

occurs when two organisms of different species live in close association and atleast one of them benefits e.g. bacteria in human digestive system produce vitamin K and get food and a safe environment in return

Question 42

factors in predator-prey relationships

Answer 42

• availability of food
• concealment
• movement

Question 43

contemporary issues in population dynamics

Answer 43

disease
famine
war
contraception

Question 46

Decomposers

Answer 46

Organisms that feed on dead organic matter

Question 47

Detritus feeders

Answer 47

Organisms that feed on small pieces of dead organic matter

Question 48

Nitrogen fixation

Answer 48

The conversion of nitrogen gas into ammonia, ammonium or nitrate

Question 49

Nitrification

Answer 49

The conversion of ammonia and ammonium compounds to nitrite and then to nitrate

Question 50

Denitfrication

Answer 50

The conversion of nitrates to nitrogen gas

Question 51

Intra-specific competition

Answer 51

Takes place between members of the same species

Question 52

Inter-specific competition

Answer 52

Occurs between members of different species

Question 53

Predator

Answer 53

An organism that catches, kills and eats another organism

Question 54

Prey

Answer 54

The organism that is eaten by the predator