Unit 13.4-5 : Energy Transfers And Nitrogen Cycles

Question 1

Autotrophic organisms

Answer 1

Producers- photosynthetic plants
Build up organic compound from (dna) simple molecules

Question 2

Heterotrophic organisms

Answer 2

Consumers- rely on external source of organic compound
E.g. animals

Question 3

Saprobionts

Answer 3

1)Bacteria/fung
2)break down polypeptides into amino acid and absorb the nitrates
3)decomposers

Question 4

What do the arrows represent in a food chain?

Answer 4

Energy transfer

Question 5

Food chains VS food webs

Answer 5

1)Food chains show feeding relationship
2)interrelationship between food chains
3)food chains do not occur in isolation

Question 6

Dry mass vs fresh mass

Answer 6

-Dead / Living
-Difficult to assess/ easier
-Small sample / water content varies
-Unreliable (unethical to collect sample) / unreliable due to VARYING water content

Question 7

What happens during each tropic level? Define tropic level

Answer 7

-stage of an organism in a food chain
-energy is lost

Question 8

Why the light is not all absorbed by sun. (4)

Answer 8

1. Some of light energy is reflected
2. Some light energy is absorbed by gases in atmosphere
   3 light energy in wrong wavelength
3. Some light energy does not strike chlorophyll

Question 9

GPP
R
NPP

Answer 9

Rate of photosynthesis
Respiratory losses
Energy stored or formed in new biomass

Question 10

Define biomass

Answer 10

Total organic material given at a specific time / area

Question 11

NPP = GPP — R
What are some large energy losses?

Answer 11

1. Large amount of animal/plant indigestible and lost from faeces
2. Not all plant may be eaten
3. Energy lost in excretion as urine
4. Energy lost in respiration as heat

Question 12

Explain why an increase in biomass can be taken as a product of net primary productivtiy.(2)

Answer 12

1.represents dry mass
2. NPP = GPP - R

Question 13

Determine the dry mass of a plant/ animal.(2)

Answer 13

1)Heat at 100 to evaporate h20
2)Weight until no further change in mass

Question 14

Dry mass over fresh mass

Answer 14

1.Water content is variable
2.will not affect dry mass

Question 15

Example of increasing energy transfer rate.(5)

Answer 15

1.restricting movement so less respiratory losses as less muscle contraction
2.Keeping animals indoors to reduce heat loss
3.selective breeding/ genetically breedigng
4.slaughtered before reaching adulthood so more energy transferred to biomass
5.feeding nutrients

Question 16

NC: describe process of nitrifyication
1)organisms 2)reaction

Answer 16

1)nitrifying bacteria
2) ammonia nitrites to nitrates
3) nh3 > No2 > no3

Question 17

NC: describe process of denitrification
1) microorganisms 2) reaction

Answer 17

1)denitrifying bacteria
2)No3- to N2

Question 18

NC: describe nitrogen fixation
1)microorganisms 2)reaction

Answer 18

1)nitrogen fixing bacteria
2) nitrogen to ammonia

Question 19

NC: decomposition
1)organisms 2)reaction

Answer 19

1)saprobionta
2)nitrog compounds to ammonia

Question 20

NC: nitrogen molecules and importance

Answer 20

1)aminoacids
2)proteins
3)nucleic acids- dna rna
4)adp
5)atp
6)nadp

Question 21

NC: Describe how the action of microorganisms in soil produces a source of nitrates.(5)

Answer 21

1) aminoacids /DNA/converted into ammonia
2)saprobionts
3)ammonia into nitrite to nitrate then
5)by nitrifying bacteria
6)n2to ammonia by nitrogen fixing bacteria

Question 22

NC: How could a farmer make farmland more fertile?(4)

Answer 22

1)add nh3 fertiliser
2) crop rotation with legumes
3)drain and derate soil

Question 23

NC: phosphate cycle (5) link with growth

Answer 23

1)saprobionts decompose
2) phospholipids rna, dna, atp, from dead organisms into po4- ions
3)po4- found in bones
4) phosphate ions transported by rivers and oceans
5)form sedimentary rocks

Question 24

Environment impact of using fertilizers(3) (GRowth)
-contain ?

Answer 24

Po4- NO4- K+
1)reduces species diversity
2)crops removed,less decomposition, less nitrates returned to soil
3)leaching

Question 25

NC: How do nitrates fertilizer may cause fish death?

Answer 25

1)nitrates and phosphates flushed into rivers
increased in algae bloom
2)reduced photosynthesis , less light intensity energy
3)saprobionts
4)uses o2 for aerobic respiration
5)less o2 available for fish

Question 26

Why has NPP decreased over years?

Answer 26

NPP =
Photosynthesis decreased

Question 27

Bacteria make the carbon in polymers in a dead work available to cells in a leaf. How.

Answer 27

1.saprobionts
2.secretes enzymes
3.absorb product of digestion /ammonium ions
4. They respire
5.co2 taken in leaves by stomata

Question 28

How enzyme destroy bacteria?

Answer 28

-hydrolyse
-murein cell wall

Question 29

Plants transmit signal from plant to plant.advantage

Answer 29

Faster response and direct transmission from plant to plant