B18 - organisms and their environment, carbon cycle

Question 1

define the sun

Answer 1

Sun is the principal source of energy input into biological systems

Question 2

describe the energy transfer from the entering to leaving

Answer 2

-energy enters the ecosystem from the sun to the first trophic level in the form of light energy
- light energy is converted into chemical energy by producers through photosynthesis
-eventually all the energy leave the ecosystem as heat energy by respiration or lost and used in each trophic level

Question 3

what does it mean by energy flow being non-cynical

Answer 3

not recycled, you cant give energy back to the plants once it reaches the top of the food chain

Question 4

what do arrows show

Answer 4

direction of energy transfer

Question 5

define food chains

Answer 5

shows transfer of energy from 1 organism to the next beginning with a producer

Question 6

define food webs

Answer 6

a network of interconnected food chains

Question 7

why are food webs better than food chains

Answer 7

food webs show the relationships between multiple organisms

Question 8

define trophic level

Answer 8

the position of an organism in a food chain/ web

Question 9

define producer

Answer 9

an organism that make sit own organic nutrients usually using energy from the sunlight through photosynthesis (1 trophic level)

Question 10

define consumer

Answer 10

an organism that gets it energy by feeding on other organisms

Question 11

define predator

Answer 11

an organism at the top of the food chain/web and are not killed by other organisms

Question 12

define herbivore

Answer 12

an animal that gets its energy only from plants

Question 13

define carnivore

Answer 13

an animal that gets its energy by eating other organisms

Question 14

define primary consumer

Answer 14

organism that feeds on a producer

Question 15

define secondary consumer

Answer 15

organism that feeds on a primary consumer

Question 16

define tertiary consumer

Answer 16

organism that feeds on a secondary consumer

Question 17

define quaternary consumer

Answer 17

organism that feeds on a tertiary consumer

Question 18

define decomposers

Answer 18

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

Question 19

what makes up decomposers

Answer 19

fungi and bacteria

Question 20

state and explain the 3 things needed for decomposition

Answer 20

• heat - needed for optimum temperature for activity of enzymes and fast decomposition - gotten through respiration
• oxygen - needed for aerobic respiration to release energy to drive metabolism - without: slow and smelly decomposition
• water - many decompositions reactions are hydrolysis reactions so its needed to dissolve the broken down product before they can be absorbed

Question 21

2 importance of decomposers in the ecosystem

Answer 21

-remove dead organisms and waste from the environment
-release minerals from dead organisms that living organisms can use
eg, nitrate, magnesium ions

Question 22

name 2 human impacts on the food chain/webs

Answer 22

-overharvesting
-introduction of foreign species into a habitat

Question 23

define overharvesting and give an examples

Answer 23

humans removing more organisms than can be replaced by reproduction = unsustainable
eg, Atlantic cod

Question 24

what are the 3 impacts of overharvesting

Answer 24

• unbale to reproduce = population falls
• causes extinction
• impacts the whole food chain/ web

Question 25

define introduction of foreign species to a habitat and give an example

Answer 25

non-native species are introduced to the habitat
eg, cane toad

Question 26

what are the 3 impacts of introduction of foreign species to a habitat

Answer 26

• kill native species
• compete for food/ disrupts the food web
• destroys habitat

Question 27

how much energy is transferred to the next trophic level

Answer 27

10%

Question 28

how much energy is lost in each trophic level

Answer 28

90%

Question 29

how much energy is absorbed by producers

Answer 29

8%

Question 30

what are the 3 ways energy is lost

Answer 30

• as heat / respiration
• some parts of the organism are uneaten like bones and teeth or indigestible like fiber. (They contain energy because they can release heat when burned)
• lost as faeces (egestion), not all are digested, excretion, urine

Question 31

what is the usual number of trophic levels, why

Answer 31

5, because there is so much energy loss that there is usually not enough to support more than 5 trophic levels

Question 32

why does eating producers directly give more energy than eating animals

Answer 32

more energy is lost if there is an extra trophic level

Question 33

what implications does the energy efficiency have for the world food population

Answer 33

not eating animals = more land for crops = feed more people

Question 34

how much is 1 kilocalorie in kilojoules

Answer 34

4.2KJ

Question 35

what does a pyramid of biomass represent and how do you get the value

Answer 35

the biomass of each trophic level at any one time
no. of organisms x mass of each organism

Question 36

what is the unit used for pyramid of biomass

Answer 36

kilojoules per meter squared

Question 37

what 3 important food are carbon atoms part of

Answer 37

carbohydrates, fats and protein molecules

Question 38

where is carbon released from and by who

Answer 38

from dead organisms by decomposers

Question 39

name all the process that take place in the carbon cycle

Answer 39

photosynthesis, respiration, feeding, decomposition, fossilisation, combustion

Question 40

which is the only process where carbon is taken from the atmosphere

Answer 40

photosynthesis

Question 41

which processes give carbon back to the atmosphere

Answer 41

respiration, combustion