4.1 & 4.2

Question 1

what is the difference between an autotroph and a heterotroph?

Answer 1

autotroph = obtains food by producing organic compounds from inorganic compounds
heterotrophs = obtains food by consuming other organisms

Question 2

what are the 3 types of heterotroph?

Answer 2

1. consumers
2. detritivore
3. saprotroph

Question 3

what is the difference between a consumer, a saprotroph and a detritivore?

Answer 3

consumer; obtains nutrients by digesting other organisms
saprotroph; obtains nutrients from dead organisms via external digestion
detritivore; obtains nutrients from detritus via internal digestion

Question 4

what is a chi-squared test?

Answer 4

a test that calculates the association between species viewed in quadrant sampling

Question 5

what is the formula for chi-squared?

Answer 5

x^2 = Σ (observed value - expected value)^2/ expected value

Question 6

what is the formula for degree of freedom in a child-squared test?

Answer 6

dof = number of groups tested - 1

Question 7

what is the formula for expected frequency in a chi-squared test?

Answer 7

expected frequency = (row total x column total)/ grand total

Question 8

what is the difference between the abiotic and biotic components of an environment?

Answer 8

abiotic factors = non-living things
biotic factors = living things

Question 9

define species

Answer 9

can interbreed to produce fertile offsprings

Question 10

define population

Answer 10

same species living in the same area at the same time

Question 11

define community

Answer 11

multiple populations living in the same area at the same time

Question 12

define ecosystem

Answer 12

the interaction of a community with its abiotic environment

Question 13

what are the 3 types of species present in a community

Answer 13

1. autotrophic
2. heterotrophic
3. mixotrophic

Question 14

what is a common method used for autotrophs to obtain energy (make food)

Answer 14

photosynthesis

Question 15

what are the 3 types of autotrophs?

Answer 15

1. plants
2. algae
3. cyanobacteria

Question 16

define mixotrophs

Answer 16

species that can carry out both heterotrophic and autotrophic nutritions
e.g. venus fly trap

Question 17

what is speciation?

Answer 17

if members of species are isolated, either geographically or behaviourally, they diverge to become 2 different species

Question 18

what is nutrient cycling?

Answer 18

recycling of nutrients and minerals
this includes
- carbon
- hydrogen
- oxygen
- nitrogen
- phosphorus
for an ecosystem to be fully sustainable, ^ these nutrients must be continually available

Question 19

what are mesocosms and what does it require?

Answer 19

an artificial mini ecosystem to investigate the effects of factors on ecosystem sustainability
- light source
- water
- air
- autotroph, to produce organic compounds and uptake nutrients and minerals
- a saprotroph or a detritivore, to decompose waste material and dead organisms, returning nutrients and minerals to the ground

Question 20

what are the 2 representations of feeding networks?

Answer 20

1. food webs
2. food chains

Question 21

what is always at the bottom of the food chain?

Answer 21

the producer, an autotroph
e.g. grass

Question 22

where does the arrow in a food chain point to the direction of?

Answer 22

the direction of energy transfer
e.g.
grass —> beetle —> salmon —> bear

Question 23

what is each stage of the food chain known as?

Answer 23

a tropic level

Question 24

why is it so common that most communities only have a maximum of 3 - 4 trophies levels?

Answer 24

due to the inefficient nature of energy transfer
loss of energy in the ecosystem
- sunlight (light energy) is brought into the ecosystem whilst the process of heat loss occurs

Question 25

list the 4 main ways of energy loss

Answer 25

1. respiration; therefore losing heat energy to the environment 2. uneaten parts e.g. roots of plants 3. undigested parts e.g. hair or cellulose 4. death of organisms; dead before consumption can occur, their energy pass on

Question 26

only x% of energy within one trophic level moves to the next trophic level due to energy loss

Answer 26

10% - this percentage is very low since - its organisms convert chemical energy into useful kinetic and heat energy - the KE and heat energy cannot convert back to chemical energy therefore its lost

Question 27

what is the units measured in for the pyramid of energy?

Answer 27

kJ m^-2 yr^-1 width proportional to energy present within the trophic level

Question 28

define biomass

Answer 28

the total mass of group of organisms

Question 29

what is the use of a quadrat?

Answer 29

used to view the relationship between 2 different organisms within a given area

Question 30

describe the step by step process of using the quadrat

Answer 30

1. select an area and divide it into a numbered grid 0f 1m x 1m squares 2. use a random number generator to randomly select study areas 3. select 2 study organisms 4. create a null hypothesis and an alternative hypothesis 5. place a quadrat and note which organisms are present in the selected study areas 6. create a table to show the presents and or absents of the 2 chosen study species (noting the observed frequencies) 7. calculate the row and column total 8. calculate the grand total 9. calculate the expected frequencies; f(e) = (row total x column total)/ grand total 10 determine the value of chi-squared 11. find the degrees of freedom 12. compare chi-squared value to the critical chi-squared table - if the chi-squared number is greater than 3.841, then the results are significant and there is a statistical difference between the 2 chosen study organisms, vice versa

Question 31

how does energy flow in a food chain?

Answer 31

from organisms to organisms

Question 32

outline the role of an autotroph within an ecosystem (3)

Answer 32

- autotrophs make their own carbon compounds from CO2 - autotrophs are often producers - start the food chain so they are vital to the ecosystem - they constitute most plants within an ecosystem

Question 33

using 4 named organisms, outline the meaning of the term food chain (3)

Answer 33

- grass —> beetle —> salmon —> bear - a food chain is a diagram that links organisms together that consume on one another - starts with a producer, autotroph

Question 34

outline the meaning of the term food chain (2)

Answer 34

- a food chain is a diagram that links organisms together that consumes on one another - starts with a producer/ autotroph

Question 35

describe how mesocosms can be used to investigate the sustainability of ecosystems (6)

Answer 35

- mesocosms are small experimental ecosystems - they can be terrestrial or aquatic - factors can be removed or added to investigate their effects - can be sealed to investigate which are sustainable over the long term - possible harm to organisms should be considered - careful selection of organisms is required for balance - oxygen supply must be balanced

Question 36

what are the 3 requirements for a sustainable ecosystem? (3)

Answer 36

- energy; sunlight as this where producers source their energy from and producers are the foundation of every food web in every ecosystem - nutrients; decomposers guarantee the availability of inorganic nutrients through recycling - waster removal; bacteria serve to breakdown and sometimes detoxify harmful waste material

Question 37

how do saprotrophs feed? (4)

Answer 37

- saprotrophs are heterotrophs that - obtain organic nutrients from dead organisms and waste material via - external digestion that occurs when they secrete - enzymes

Question 38

outline the use, transfer and efficiency of energy within an ecosystem (8)

Answer 38

energy is used for - growth and repair - respiration - feeding and reproduction - energy is transferred form one trophic level to the next - lots of energy is lost from producers to primary consumers - only 10% of energy is transferred from one organism to the next energy is lost in - incomplete digestion - uneaten food - energy transfer through an ecosystem is inefficient

Question 39

why is heat generated by living organisms lost from the ecosystem? (2)

Answer 39

- heat is transferred from warmer to cooler bodies - at each transfer heat is lost to the abiotic environment

Question 40

what is the function of ATP? (4)

Answer 40

- ATP is used to fuel various cellular functions - it is a universal energy currency of the cell - it is used for endocytosis and exocytosis - nerve transmission - growth and repair - movement - light emission