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Biology 💌 > Energy Transfers > Flashcards

Energy Transfers Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Explain how energy enters an ecosystem

A

-Photosynthetic organism absorb light energy and take up water to photosynthesize
-This enables the plant to synthesise organic compounds such as glucose
-The chemical energy stored in organic compounds is transferred through an ecosystem through consumers

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2
Q

Explain how energy is transferred between organisms within an ecosystem

A

-Energy is transferred between trophic levels
-When one organism eats another
-Producer -> primary consumer -> secondary consumer -> tertiary consumer

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3
Q

Define the term biomass

A

The total mass of living material (plant and/or animal) in a particular place at a particular time

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4
Q

Outline how biomass is measured

A

-Measured as dry mass of material in grams
-Measured in:
-Area: Grams per square meter (gm-2)
-Volume: Grams per cubic meter (gm-3)
-Measured using calorimetry

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5
Q

Outline the method used to measure biomass

A

Method: Calorimetry
1. Dry mass is weighed
2. Water tank at 400oC
3. Dry mass is burnt in a chamber with pure oxygen
4. Measure the temperature change
5. Energy released= energy stored (j or Kj)

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6
Q

State what a calorimeter is used for

A

Measures the chemical energy store of biomass

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7
Q

Explain two features of a calorimeter that would enable a valid measurement of the total heat energy released

A

-A stirrer distributes the heat energy
-Insulation of beaker means less heat is lost to the surroundings making the reading more accurate

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8
Q

A 2g sample of biomass was fully combusted in a calorimeter
The volume of water in the calorimeter was 100cm3
The increase in temperature recorded was 15.7oC
4.18 J of energy is needed to increase the temperature of 1cm3 of water by 1oC
Use this information to calculate the heat energy released in KJ per g of biomass

A

-2g= fully combusted in calorimeter
-100cm3 of water –> 1cm3 of water (divide by 100)
-4.18 J needed for 1cm3 –> (x100) 418 J needed for 100cm3
-418 J x 15.7 =6,502.6 J –> (divide by 1000) 6. 5026KJ
-6.5026KJ / 2 (for 1g)= 3.2813 KJg-1

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9
Q

Outline the problems with using biomass

A

-To gain dry mass the organism must be
-Results in a small sample size
-Data is not representative
-Also does not account for seasonal changes
-Improved using calorimetry

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10
Q

The diagram shows percentages of energy transferred from sunlight to zebra in a grassland ecosystem

Sunlight -(2.1%)-> Vegetation -(12.7%)-> Zebra -(36.1%)-> Respiration &-(58.2%)-> Faeces and urine & -(5.7%)-> New tissue

Use the diagram to calculate the percentage of sunlight energy that would be transferred into the faeces and urine of a zebra. Give your answer to 3 significant figures

A

12.7% x 2.1 = 0.2267
58.2% x 0.2267 = 0.155%

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11
Q

Explain how energy is lost along a food chain

A

-Not all the organism is eaten
-Not all material is digested (faeces)
-Lost in excretory materials (urine)
-Heat lost to the environment (movement)

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12
Q

How much of the suns light energy is absorbed by producers?

A

1-3%

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13
Q

Explain why very little energy is converted to organic matter (chemical energy) by photosynthesis

A

-Not all wavelengths of light can be absorbed and utilised
-Over 90% of the suns energy is reflected into space or absorbed by the atmosphere
-Limiting factors

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14
Q

State the equation to calculate energy efficiency

A

(Energy available after the transfer / Energy available before the transfer ) x100

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15
Q

Explain why in natural ecosystems the efficiency of energy transfers is low

A

-Only energy source is the sun -> but only 1-3% of this is absorbed by producers
-High species diversity -> results in competition
-There is a natural climax community -> max number of organisms an ecosystem can support without environmental damage
-Recycling of nutrients in the environment (decomposers) -> use some of the energy/ carbon compounds as well so there is less for consumers
-Loss of energy to the surroundings

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16
Q

What is intensive farming?

A

Farming methods that focus on:
-Minimal input
-Maximum output
-Converting the smallest amount of energy into the greatest yield
-Minimising energy losses

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17
Q

State six intensive farming methods

A

-Using chemical pesticides e.g. insecticides and herbicides
-Reducing species diversity through monoculture
-Maximising solar input
-Limiting movement
-Heating the environment
-Protein/ supplement rich diet

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18
Q

Explain how using chemical pesticides e.g. insecticides and herbicides would increase the efficiency of energy transfers

A

-Increased photosynthesis (because less eaten)
-Increased biomass
-Increased NPP

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19
Q

Explain two challenges of using chemical pesticides e.g insecticides and herbicides to increase the efficiency of energy transfers

A

-Eutrophication/ pollution
-Reduces species diversity

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20
Q

Explain how reducing species diversity through monoculture (grow one species) would increase the efficiency of energy transfers

A

-Reduces competition
-Higher yield of desired crop = more profit

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21
Q

Explain two challenges of reducing species diversity through monoculture to increase the efficiency of energy transfers

A

-Reduces diversity which decreases stability
-Drains nutrients from the soil

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22
Q

Explain how maximising solar input would increase the efficiency of energy transfers

A

-Increases initial energy input
-Increases NPP because of increase of GPP

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23
Q

Explain three challenges of maximising solar input to increase the efficiency of energy transfers

A

-Costly -> energy intensive
-Light pollution
-Affects temperature

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24
Q

Explain how limiting movement would increase the efficiency of energy transfers

A

-Reduces respiratory losses
-More energy to tissues

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25
Q

Explain three challenges of limiting movement to increase the efficiency of energy transfers

A

-Spread of diseases
-Unethical
-Antibiotic resistance occurs (antibiotics are given all of the time because if they get disease it would spread really fast amongst animals but this leads to antibiotic resistance)

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26
Q

Explain three challenges of limiting movement to increase the efficiency of energy transfers

A

-Spread of diseases
-Unethical
-Antibiotic resistance occurs (antibiotics are given all of the time because if they get disease it would spread really fast amongst animals but this leads to antibiotic resistance)

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27
Q

Explain how heating the environment would increase the efficiency of energy transfers in farming

A

-Reduces losses for temperature control
-Optimal conditions for growth

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28
Q

Explain two challenges of heating the environment to increase the efficiency of energy transfers in farming

A

-Costly
-Pollution

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29
Q

Explain how a protein/ supplement rich diet would increase the efficiency of energy transfers in farming

A

-Leads to increased biomass (more muscle + tissue)
-Increases profit

30
Q

Explain three challenges of a protein/ supplement rich diet to increase the energy efficiency of energy transfers in farming

A

-Costly
-Artificial (not natural)
-Ethics

31
Q

Farming cattle for humans to eat is less efficient than farming crops because of energy transfer. Explain why

A

-Simpler food chain ( crop= just producer , cattle= producer then cattle)
-Energy is lost between trophic levels
-Energy is lost via respiration

32
Q

What is GPP?

A

Gross primary productivity/ production

33
Q

Define the term Gross Primary Production (GPP)

A

-The chemical energy stored in plant biomass, in a given area or volume
-The total energy resulting from photosynthesis

34
Q

What is NPP?

A

Net Primary Production/ Productivity

35
Q

Define the term Net Primary Production (NPP)

A

The chemical energy stored in plant biomass taking into account the energy that will be lost due to respiration

36
Q

State the equation to calculate NPP

A

NPP = GPP - R

(R) = Respiration

37
Q

What are you calculating when using the equation NPP= GPP - R ?

A

The remaining energy available to the plant to create new biomass and therefore available to the next tropical level in a food web

38
Q

Calculate the NPP of algae if the GPP= 15 and the R= 5

A

NPP= 10

39
Q

State the equation to calculate the net production of consumers (N) , such as animals

A

N = I - ( F+R)

I= the chemical energy stored in ingested food
F= the chemical energy lost to the environment in faeces and urine
R= respiratory loses

40
Q

Why is nitrogen an essential mineral for plants?

A

Needed to create:
-Amino acids / proteins
-DNA
-RNA
-ATP

41
Q

What % of the atmosphere is composed of nitrogen?

A

78%

42
Q

Explain why atmospheric nitrogen is difficult for plants to take in

A

It is unreactive and doesn’t easily convert it into other compounds

43
Q

What four key processes is the nitrogen cycle split into?

A

-Nitrogen-fixation
-Nitrification
-Denitrification
-Ammonification

44
Q

What is the role of nitrogen-fixing bacteria?

A

They break the triple bond between the two nitrogen atoms in nitrogen gas

45
Q

Explain the role of nitrogen-fixation in the nitrogen cycle

A

-Nitrogen-fixing bacteria break the triple bond between the two nitrogen atoms in nitrogen gas
-They fix this nitrogen into ammonium ions (NH4+)
-The bacteria are either free-living (in the soil) or they are symbiotic (have a mutualistic relationship)

46
Q

What are the two types of nitrogen-fixing bacteria?

A

-Free-living —> found in the soil
-Symbiotic—> mutualistic relationship and co-exist in root nodules of plants

47
Q

What type of plants have symbiotic bacteria?

A

-Leguminous plants
-E.g. clover and beans

48
Q

What is the role of nitrification in the nitrogen cycle?

A

-Ammonium ions (NH4+) in the soil are converted to nitrite (NO2-) and then nitrate (NO3-) ions
-By nitrifying bacteria
-This is a two-stage oxidation reaction

49
Q

What is the role of nitrifying bacteria?

A

-Ammonium ions (NH4+) are converted to nitrite (NO2-) ions and then nitrate (NO3-) ions
-This is a two stage oxidation reaction (oxygen is needed)

50
Q

Explain the role of denitrification in the nitrogen cycle

A

-Converts the nitrogen in compounds back to nitrogen gas in the atmosphere
-This means it can’t be absorbed by plants
-Anaerobic denitrifying bacteria do this

51
Q

What is the role of anaerobic denitrifying bacteria?

A

-Converts nitrogen in compounds back to nitrogen gas in the atmosphere (convert nitrate (NO3-) -> nitrogen gas)
-Meaning it cannot be absorbed by plants

52
Q

Outline three farming practices used to prevent the build-up of anaerobic bacteria in the soil

A

-Ploughing –> aerates the soil which creates aerobic and not anaerobic conditions –> prevents build up of anaerobic bacteria
-Good drainage systems –> anaerobic denitrifying bacteria are present in greater numbers when the soil becomes waterlogged

53
Q

Denitrification requires anaerobic conditions. Ploughing aerates the soil. Explain how ploughing would affect the fertility of the soil.

A

-Ploughing increases O2 concentration in the soil
-This would reduce/ eliminate anaerobic conditions
-This means there would be fewer anaerobic denitrifying bacteria
-Less nitrates removed from the soil/ less converted into atmospheric nitrogen

54
Q

One farming practice used to maintain high crop yields is crop rotation. This involves growing a different crop each year in the same field. Suggest two ways in which crop rotation may lead to high crop yields

A

-They require different nutrients therefore when they decompose they would add different nutrients to the soil
-Using more crops that contain nitrogen-fixing bacteria

55
Q

Explain the role of ammonification in the nitrogen cycle

A

-Proteins, urea and DNA are decomposed to ammonium ions by saprobionts
-This returns ammonium ions to the soil
-Saprobiotic nutrition

56
Q

What are saprobionts?

A

-Digest waste extracellularly
-Decompose proteins, urea and DNA –> ammonium ions
-Bacteria and fungi
-Known as saprobiotic nutrition

57
Q

What is mycorrhizae?

A

Fungal associations between plant roots and beneficial fungi

58
Q

What is the role of mycorrhizae?

A

Found at plant roots to provide a larger surface area for water and mineral absorption

59
Q

Explain how mycorrhizae benefits plants in drought?

A

Mycorrhizae store water and minerals close to the roots making the plant more drought tolerant

60
Q

Describe the relationship between mycorrhizae and plant roots

A

-Mutualistic relationship
-Mycorrhizas take sugars and amino acids from plants
-Mycorrhizae store water and minerals close to the roots making the plant more drought tolerant

61
Q

Explain the importance of phosphorus

A

Needed to create DNA, RNA, ATP and phospholipid bilayers

62
Q

Where is phosphorus found?

A

In sedimentary rocks as a phosphate ion

63
Q

What are nitrates in plants used for?

A

Growth- as nitrates are used for creating amino acids/ proteins, DNA, RNA, ATP

64
Q

What is magnesium used for in plants?

A

Needed to make chlorophyll

65
Q

What are the two types of fertiliser?

A

-Organic/ Natural
-Inorganic/ Artificial

66
Q

What is an organic/ natural fertiliser?

A

-Dead and decaying plant and animal matter
-Animal excreta such as manure and slurry
-Bone meal

67
Q

What is an inorganic/ artificial fertiliser?

A

-Mined from rock
-Converted to a suitable form
-Blended to suit a particular crop

68
Q

What is the role of fertilisers?

A

Used to replace the nitrate and phosphate ions lost when harvested

69
Q

State one positive and one negative of natural fertilisers

A

+Cheaper and often free
-Exact minerals and proportions cannot be controlled

70
Q

State two positives and one negative of artificial fertilisers

A

+Exact minerals and proportions can be controlled
+Inorganic substances are more water soluble therefore more dissolve in the water surrounding the soil making it easier for plants to absorb nitrates and phosphates
-Inorganic substances are more water soluble therefore more dissolve in water surrounding the soil and large quantities are washed away with rainfall resulting in eutrophication

71
Q

What is leaching?

A

-The plant roots are unable to reach and absorb dissolved nutrients
-The leached water-soluble compounds are washed away into rivers or ponds
-Can lead to eutrophication

72
Q

What is eutrophication?

A

-Nitrates leeched from fertilised fields stimulate the growth of algae on water surface
-Excessive growth of algae over the water surface blocks out sunlight
-The aquatic plants beneath the surface cannot photosynthesise so they die
-Bacteria within the water feed and respire on the dead plant matter
-Results in an increase in respiring bacteria which use up the oxygen within the water
-Fish and aquatic animals die due to lack of dissolved oxygen in the water

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