Chapter 18 Organisms and Their Environment, Chapter 19 Human Influences On Ecosystems

Question 1

Define ecology:

Answer 1

the study of organisms and their environment

Question 2

Define habitat:

Answer 2

the place where an organism lives

Question 3

Define community:

Answer 3

All of the populations of all the different species in an ecosystem

Question 4

Define ecosystem:

Answer 4

a unit containing all of the organisms in a community and their environment, interacting together

Question 5

Define niche:

Answer 5

the role of an organism
in its natural environment;
the way in which it interacts with other organisms
and with the non-living parts of the environment

Question 6

Define food chain:

Answer 6

A diagram showing
the flow of energy
from one organism
to the next,
beginning w a producer

Question 7

Define food web:

Answer 7

a network
of interconnected
food chains

Question 8

Define producer:

Answer 8

An organism
that makes its own organic nutrients,
generally using energy from sunlight,
through photosynthesis

Question 9

Define herbivore:

Answer 9

An animal that
gets its energy by
eating plants

Question 10

Define consumer:

Answer 10

An organism that
gets its energy by
feeding on other organisms

Question 11

Define carnivore:

Answer 11

An animal that
gets its energy from
eating other animals

Question 12

Define decomposer:

Answer 12

An organism that
gets its energy from
dead/waste organic material

Question 13

Define pyramid of numbers:

Answer 13

A diagram
in which the area of the bar
at each trophic level
shows the relative nr of organisms
at that level in the food chain

Question 14

Define trophic level:

Answer 14

The position of
an organism
in a food chain, food web/pyramid of biomass/numbers

Question 15

Define pyramid of biomass:

Answer 15

A graph showing
the relative quantity of biomass
at each trophic level

Question 16

Define Pyramid of Energy:

Answer 16

A graph showing
the relative quantity of energy
at each trophic level

Question 17

Define nitrogen fixation:

Answer 17

Converting inert nitrogen gas
into a more reactive form,
such as nitrate ions/ammonia

Question 18

Define nitrification:

Answer 18

Converting ammonium ions to nitrate ions

Question 19

Define denitrification:

Answer 19

Converting nitrate ions to nitrogen gas

*nitrate is 1 part nitrogen, 3 parts oxygen

Question 20

Define lag phase:

Answer 20

The stage at the start
of a population growth curve
where the population remains small
and grows only very slowly

Question 21

Define log/exponential phase:

Answer 21

The stage in
a population growth curve
where the population grows
at its maximum rate;
birth rate exceeds death rate

Question 22

Define stationary phase:

Answer 22

The stage in
a population growth curve
where the population remains ** roughly constant**;
birth rate equals death rate

Question 23

Define death phase:

Answer 23

The final stage in
a population growth curve
where the population falls;
death rate exceeds birth rate

Question 24

Define sigmoid growth curve:

Answer 24

an S-shaped curve showing the
change in the size of a population
through all the phases in population growth

Question 25

Define limiting factor:

Answer 25

A factor that is in short supply, which stops an activity (such as photosynthesis) happening at a faster rate

Question 26

Define age period:

Answer 26

A diagram showing the relative numbers of individuals of different ages in a population

Question 27

Define monoculture:

Answer 27

An area of ground covered by a single crop, with almost no other species present

Question 28

Define biodiversity:

Answer 28

The number of different species that live in an area

Question 29

Define extinction:

Answer 29

The complete loss of a species from earth

Question 30

Define greenhouse gasses:

Answer 30

Gases such as **carbon dioxide** and **methane** that *trap heat within the atmosphere*

Question 31

Define greenhouse effect:

Answer 31

The heating effect on the Earth of the trapping of heat by greenhouse gas’s was; Note that this is a natural and useful effect as without it the Earth would be much too cold to support life

Question 32

Define **enhanced** greenhouse effect:

Answer 32

The increased heating effect caused by an increase of greenhouse gases in the atmosphere

Question 33

Define eutrophication:

Answer 33

A chain of events caused by **addition of extra plant nutrients to water**, resulting in a **decrease** in the concentration of dissolved oxygen available for organisms that require it for aerobic respiration

Question 34

Define non-biodigradible:

Answer 34

Not able to be broken down by decomposers

Question 35

Fine sustainable resource:

Answer 35

One that is produced as rapidly as it is removed from the environment; so that it does not run out.

Question 36

Define endangered:

Answer 36

At serious risk of becoming extinct

Question 37

Define captive breeding:

Answer 37

Keeping animals in captivity (eg. in a zoo) and allowing them to breed, in order to increase the numbers in the population

Question 38

Define seed banks:

Answer 38

Facilities in which seeds of different plant species/crop varieties, are stored for long periods of time, in order to conserve as many different species and varieties as possible

Question 39

Define insemination (AI):

Answer 39

Introducing semen, containing sperm, to the reproductive organs of a female, fertilization occurs in her body in the normal way

Question 40

Define in vitro fertilization (IVF):

Answer 40

Adding semen, containing sperm, to eggs in a container in a laboratory, fertilization occurs in the container, and the embryos can later be inserted into the body of a female

Question 41

Define population:

Answer 41

A group of organisms, of the same species, living in the same area, at the same time