20- organisms and their enviroments

Question 1

food chain

Answer 1

a diagram showing the flow of energy from one

organism to the next, beginning with a producer.

Question 2

food web

Answer 2

a network of interconnected food chains.

Question 3

main energy input and how is it transferred between organisms

Answer 3

sun, in a food chain by ingestion

Question 4

trophic level

Answer 4

the position of an organism in a food chain, food

web, pyramid of numbers or biomass.

Question 5

how is the energy lost in the enviroment

Answer 5

• respiration, movement
• animals dont eat the whole organism
• not all food molecules are digested or absorbed

Question 6

producers

Answer 6

organisms that produce their own organic nutrients using energy from sunlight

Question 7

herbivores

Answer 7

an animal that gets its energy from eating plants

Question 8

carnivore

Answer 8

an animal that gets it energy by eating other animals

Question 9

primary consumers

Answer 9

herbivores- feed on producers

Question 10

decomposers

Answer 10

organisms that get their energy from dead waste or organism material; fungi, bacteria

Question 11

interdependence

Answer 11

how the change in one population can affect others within the food web

Question 12

why are food chains limited

Answer 12

because of inefficient loss of energy at each trophic level

Question 13

pyramid of number

Answer 13

Diagram that represents the relationship between the number of organisms in each trophic level in food chain.

Question 14

pyramid of biomass

Answer 14

it represents the dry mass of organisms at each trophic in the food chain

Question 15

biomass

Answer 15

the total dry mass of a population.

Question 16

the three processes that release CO2

Answer 16

respiration, combustion, decomposition

Question 17

three places CO2 in stored

Answer 17

in living things, oceans, fossil fuels

Question 18

the carbon cycle

Answer 18

1- Carbon is taken out of the atmosphere by photosynthesis
2-I t is passed on to animals and decomposers by feeding
3- it is returned by respiration; in plants, in animals and in decomposing microorganisms
**In addition, it is returned (in increasing amounts) by combustion of fossil fuels

Question 19

nitrogen fixation

Answer 19

changing nitrogen into a reactive form

Question 20

6 ways of nitrogen fixation

Answer 20

1- lightning 4- nitrifying bacteria
2- fertilizers 5- animal excretion
3- nitrogen fixing bacteria 6-denitrifying bacteria

Question 21

lightning in nitrogen fixation

Answer 21

Allow nitrogen gas to combine with oxygen to form
nitrogen oxide, then dissolved in rain & washed into soil
to form nitrates.

Question 22

fertilizers in nitrogen fixation

Answer 22

Ammonia is used to make ammonium compounds and

nitrates to be part of the fertilizers.

Question 23

nitrogen fixing bacteria

Answer 23

They use nitrogen gas from air & combine it with other

substances to make ammonium ions, to fix nitrogen to make proteins.

Question 24

nitrifying bacteria

Answer 24

Found in soil or in root nodules on plants as peas.
They use nitrogen gas from air & combine it with other
substances to make ammonium ions, to fix nitrogen to make proteins.

Question 25

nitrogen

Answer 25

an element required to make protein

Question 26

why cant plants and animals absorb nitrogen from the air

Answer 26

its a very stable gas, unreactive

Question 27

animal excretion

Answer 27

By deamination, nitrogenous wastes [ammonia or urea] will be excreted from animals, then nitrifying bacteria turn it to nitrates.

Question 28

deamination

Answer 28

removal of an amino group from a molecule

Question 29

denitrifying bacteria

Answer 29

They turn nitrates & ammonia in soil to nitrogen gas into

atmosphere.

Question 30

population

Answer 30

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

Question 31

community

Answer 31

all the populations of different species in the ecosystem.

Question 32

ecosystem

Answer 32

a unit containing the community of organisms & their environment, interacting together.

Question 33

Factors affecting the rate of population:

Answer 33

1- food supply
2- predation
3- disease

Question 34

lag phase

Answer 34

growth of population is slow, it needs time to adjust to new conditions

Question 35

log phase

Answer 35

rapid increase in population size, as they grow and divide

Question 36

stationary phase

Answer 36

population number is stabilized, as the rate of birth = rate of death.

Question 37

death phase

Answer 37

the death rate is more than birth rate, so the number of organisms starts to fall.

Question 38

reasons for the death phase

Answer 38

• no food supply
• competition
• build up of excretory products

Question 39

factors effecting human population

Answer 39

1- disease

2- food supply

Question 40

when did human population start to increase

Answer 40

300 years ago

Question 41

why did the human population start to increase

Answer 41

1- reduction of disease ( due to improvment of water supply, sewage treatment.. etc)
2- increase in food supply (as more cultivation lands
are used to make agriculture more efficient.)

Question 42

two ways water enters the atmosphere

Answer 42

evaporation and transpiration

Question 43

precipitation

Answer 43

the water droplets in the cloud get bigger and heavier, they begin to fall as rain, snow and sleet