organisms and their environment

Question 1

principal source of energy input to biological systems

Answer 1

sun

Question 2

describe flow of energy through living organisms

Answer 2

light energy from the sun - chemical energy in organisms - eventual transfer to environment

Question 3

food chain

Answer 3

shows transfer of energy from one organism to the next, beginning with a producer

Question 4

food web

Answer 4

network of interconnected food chains

Question 5

producer

Answer 5

an organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesis

Question 6

consumer

Answer 6

an organism that gets its energy by feeding on other organisms

Question 7

herbivore

Answer 7

animal that gets its energy by eating plants

Question 8

carnivore

Answer 8

animal that gets its energy by eating other animals

Question 9

decomposer

Answer 9

an organism that gets its energy from dead or waste organic material

Question 10

advantages of using pyramid of
biomass instead of pyramid of numbers to represent a food chain

Answer 10

provide a better idea of quantity of plant/animal material at each level of a food chain, therefore a better way of representing interdependence within the food chain

Question 11

trophic level

Answer 11

position of an organism in a food chain, web, ecological pyramid

Question 12

advantages of using pyramid of energy instead of p.o.n + p.o.b to represent a food chain

Question 13

trophic levels

Answer 13

producer - primary consumer - secondary consumer - tertiary consumer - quaternary consumer

Question 14

why is energy transfer between trophic levels inefficient

Answer 14

only 10% of energy gets transferred to the next level as energy is lost or used by the organism

Question 15

why do food chains have 5 or less trophic levels

Answer 15

only 10% of energy is transferred to next level as energy is lost as some parts undigestible + respiration + movement so very less energy is transferred to 5th level which is not enough to sustain another level

Question 16

why is it more efficient for humans to eat crop plants than livestock that fed on crops

Answer 16

• if humans eat crops, there’s more energy available to them
• if humans eat livestock, there’s less energy as the cows lost energy

Question 17

ways energy is lost

Answer 17

• excretion
• movement
• heat
• undigested waste
• some parts are undigestible (cellulose parts)

Question 18

processes in carbon cycle that produce CO2

Answer 18

• respiration
• combustion

Question 19

processes in carbon cycle that remove CO2

Answer 19

• photosynthesis

Question 20

describe carbon cycle

Answer 20

photosynthesis - respiration - feeding - decomposition - fossil fuel formation - combustion

Question 21

describe nitrogen cycle

Answer 21

production of amino acids + proteins - feeding + digestion of proteins - deamination - decomposition of plants + animals into ammonium ions - nitrification - denitrification - nitrogen fixation- absorption

Question 22

nitrification

Answer 22

ammonium ions - nitrate ions
(nitrifying bacteria)

Question 23

denitrification

Answer 23

nitrate ions - nitrogen gas
(denitrifying bacteria)

Question 24

nitrogen fixation

Answer 24

nitrogen gas - nitrate ions
(lightning + bacteria)

Question 25

population

Answer 25

group of organisms of one species living in one area at the same time

Question 26

community

Answer 26

all the populations of different species in an ecosystem

Question 27

ecosystem

Answer 27

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

Question 28

factors affecting rate of population growth of an organism

Answer 28

• food supply
• competition
• predation
• disease

Question 29

phases of sigmoid growth curve

Answer 29

• lag phase
• exponential (log) phase
• stationary phase
• death phase

Question 30

lag phase

Answer 30

• organisms are adapting to the environment before being able to reproduce
• very few organisms so reproduction is not producing many offspring

Question 31

exponential phase

Answer 31

• food supply is abundant + birth rate is rapid + death rate is low
• growth rate is exponential + only limited by no. of new individuals produced

Question 32

stationary phase

Answer 32

• growth rate slows as resources become limited
• population reaches its carrying capacity
• death rate = birth rate

Question 33

death phase

Answer 33

• death rate > birth rate as food supply is short + metabolic waste builds up to toxic levels