Energy Transfer And Nutrient Cycle Flashcards
(113 cards)
1
Q
What does an ecosystem include?
A
- all the organisms living in a particular area.
- all the non-living (abiotic) conditions.
- producers.
2
Q
What are producers?
A
organisms that make their own food, i.e plants and algae produce their own food in photosynthesis.
3
Q
What do plants use during photosynthesis to make glucose and other sugars?
A
- Energy from the sunlight.
- Carbon dioxide (from the atm in land based ecosystems, or dissolved in water in aquatic ecosystems).
4
Q
What are the sugars produced from photosynthesis used for?
A
- In respiration, to release energy for growth.
5
Q
Other than in respiration, what is the rest of the glucose used to make?
A
- Biological molecules, such as cellulose. They make up the plant’s biomass.
6
Q
What is biomass?
A
- The total mass of a living material in a specific area at a given time.
- The chemical energy stored in the plant.
7
Q
How is energy transferred through the living organisms of an ecosystem?
A
When organisms eat other organisms, i.e. producers eaten by primary consumers,
primary consumers eaten by secondary consumers,
secondary consumers eaten by tertiary consumers.
8
Q
What are the three groups organisms are divided into?
A
- Producers = photosynthetic organisms that manufacture organic substances using water, light energy CO2 and other mineral ions.
- Consumers = obtain energy by feeding on other organims rather than using energy of sunlight directly.
- Saprobionts = group of organisms that break down complex materials in dead organisms into simple ones. They release valuable minerals and elements in a form that can be absorbed by plants and contribute to recycling.
9
Q
Food chain
A
Describes feeding relationship in which producers eaten by primary, eaten by secondary, eaten by tertiary.
10
Q
What is fresh mass?
A
Easy assess but presence of amount of water makes it unreliable.
11
Q
How can you overcome the problem of fresh mass?
A
With it having water its unreliable but measuring the mass of carbon or dry mass overcomes this problem.
However it must be killed so its only a small smaple which may not be representative.
12
Q
What are the typical units for dry mass?
A
kg m-2
13
Q
What are the typical units for biomass?
A
kg m-2 yr-1
14
Q
What is dry mass?
A
Mass of the organism with the water removed.
15
Q
Biomass can be measured in terms of…
A
mass of carbon that an organism contains or the dry mass of its tissue per unit area per unit time.
16
Q
Why is dry mass used as a measure of biomass rather than wet mass?
A
The water content in living tissue varies.
17
Q
How can you measure the dry mass?
How can you find out the dry mass of the total population or the area being investigated?
A
- A sample of an organism is dried, in an oven set as a low temperature.
- Sample is weighted at regular intervals.
- Once mass becomes constant you know the waters all been removed.
- The sample can be scaled up to give the dry mass of the total population or the area being investigated.
18
Q
What is used to measure the chemical energy stored in dry biomass?
A
- Estimated using calorimetry.
- The amount of heat given off tells you how mych energy is in it.
19
Q
Does biomass change over time?
A
Yes, i.e. trees lose their leaves in winter so biomass changes over the year.
20
Q
What is energy measured in?
A
Joules (J)
or
kilojoules (kj)
21
Q
Explain steps of colorimetry
A
- Sample of dry biomass burnt.
- Energy released used to heat a known volume of water.
- Change in the temperature of water is used to calculate chemical energy of dry biomass.
22
Q
What is GPP?
A
Gross primary production is the total amount of chemical energy converted from light energy by plants, in a given area, in a given time.
23
Q
When plants respire what happens to the GPP?
A
Around 50% of the GPP is lost to the environment as heat when plants respire.
24
Q
What is respiratory loss (R)?
A
- GPP lost to the environment as heat when plants respire.
25
What is NPP?
* Net primary production.
* It's the energy available for plant **growth** and **reproduction**.
* The energy is stored in the plants biomass.
* Also the energy available to the **organisms** at the **next stage** in the **food chain**.
26
What's the calculation for NPP?
NPP = GPP - R
27
What are the units for NPP?
kJ m-2 yr-1
28
Where do consumers store chemical energy?
In their biomass
29
How do consumers get their energy?
By ingesting plant material, or animals that have eaten plant material.
30
Not all the chemical energy stored in the consumers food in trasnferred to the trophic level. 90% of total available energy is lost.
How is energy lost/ not all transferred?
1. Some isn't the correct wavelength.
2. Some passes straight through.
3. Made into biomass when trapped for photosynthesis.
4. Not all food eaten so energy it contains is not taken up.
5. Some are indigestible - so are egested as faeces so the chemical energy stroed in them parts is lost to the environment.
6. Some lost to environment through respiration.
7. Some lost through excretion of urine.
31
Suggest appropriate units for gross productivity. (1)
Unit of energy / mass, per area, per year.
32
Explain the decrease in gross productivity as the woodland matures. (2)
1. Less light / more shading / more competition for light;
2. Reduced photosynthesis.
33
Use your knowledge of succession to explain the increase in biomass during the first 20 years. (3)
1. Pioneer species;
2. Change in abiotic conditions / less hostile / more habitats / niches;
Accept: named abiotic change or example of change e.g. formation of soil / humus / organic matter / increase in nutrients
Neutral: reference to change in environment unqualified Neutral: more hospitable / habitable / homes / shelters
3. Increase in number / amount / diversity of species / plants / animals.
Accept: other / new species (colonise)
34
Suggest one reason for conserving woodlands. (1)
1. Conserving / protecting habitats / niches;
2. Conserving / protecting (endangered) species / maintains / increases (bio) diversity;
3. Reduces global warming / greenhouse effect / climate change / remove /take up carbon dioxide;
4. Source of medicines / chemicals / wood; 5. Reduces erosion / eutrophication.
35
What is the consumers net production?
Where the energy that's left over is stroed in the consumer's biomass and is available to the next trophic level.
36
What's the calculation for net production of consumers?
N = I - (F + R)
N= net production
F= Chemical energy lost in faeces and urine.
I= Chemical energy in ingested food.
R= Energy lost through respiration.
37
How would you calculate the efficiency of energy transfer?
Net production of trophic level/ Net production of previous trophic level (or what they receive?) x 100
38
As you move up the food chain does the efficiency become more or less?
More, because plants contain more indigestible matter than animals.
39
Suggest how you could determine the dry mass of a sample of plant material.
1. Weigh the dry mass.
2. Leave to dry in a oven at 100oC.
3. Weigh at regular intervals, once mass constant you know the waters removed.
40
What is the advantage of using dry mass and not fresh mass to compare the yield of plants?
1. Amount of water present.
2. Varies affecting fresh mass.
41
Explain how quadrats could be used to determine the percentage of mussels that had been eaten by starfish on a rocky shore
1. Random sampling using quadrats.
2. Count amount in it of dead and alive.
3. Large number of quadrats.
42
What do food webs and food chains show?
How energy is transferred through an ecosystem.
43
What are food chains?
show simple lines of energy transfer.
44
What is a trophic level?
What each of the stages in a food chain is called.
45
What are food webs?
show lots of food chains in an ecosystem and how they overlap.
46
what is the role of decomposers in a food web?
They are part of the food web that break down dead or undigested material, allowing nutrients to be recyled.
47
What do farming practises increase?
* The efficiency of energy transfer.
* Means increase NPP and N of live-stock.
48
How do farming practises aim to increase amount of energy available?
1. The energy lost to other organisms i.e. pests, can be reduced. - simplifying food webs reducing energy loss to other organisms.
2. The energy lost through respiration can be reduced - reducing respiratory losses means energy is transferred more efficiently.
49
Simplifying the food webs means...
getting rid of pests.
50
How would farmers get rid of pests?
// simplifying food webs to reduce energy losses to non-human food chains
Need pest control.
1. Reduce by using chemical pesticides.
2. Biological agents
51
How can farmers reduce the number of pests by using chemical pesticides?
// how does simplifying a food web involving a crop increase the productivity of the crop?
1. Insecticides kill insects pests - so less biomass lost from crops, giving a greater productivity due to them growing larger.
2. Herbicides kill weeds = removes direct competition with the crop for energy from the sun (less competition). It can also remove preferred habitat or food source of the insect pests, helping to further reduce their numbers and simplify the food web.
52
What are the benefits of simplifying a food web?
i.e. getting rid of food chains that dont involve humans, energy losses will be reduced and the productivity of the crop will increase.
53
How can farmers reduce the number of pests by using biological agents?
Crops lose less energy and biomass, increasing the efficiency of energy transfer to humans.
1. Parasites kill insect or reduce ability to function.
2. Pathogen bacteria and viruses used to kill pests, and produces toxins.
54
What is a intergrated system?
Combine both chemical and biological methods. The combined effect of using both can reduce pest numbers even more than either method alone, meaning productivity increases more.
55
How do farmers reduce respiratory losses making energy transfer more efficient?
How is the productivity increased?
By **controlling** the **conditions** that they live in, so that **more** of their **energy** is used **for** **growth** and **less** is **lost** through **respiration** and activites,
1. **Restricted movement**/ kept in pens so restricted as movement increases rate of respiration.
2. The pens are often indoors and kept warm, so **less energy is wasted** by generating body heat.
That means **more biomass** is produced and **more chemical energy** can be store, **increasing productivity** and efficiency of energy transfer to humans.
56
What are the benefits of increasing productivity and efficiency?
* More food can be produced in a shorter space of time, often at lower cost.
57
What are the ethical issues of enhancing productivity?
Keeping animals in pens in these conditions cause pain, distress or restricts their natural behaviour, so it shouldn't be done.
58
What is a natural ecosystems?
One that **hasn't been changed** by **human activity**. **Nutrients** get **recycled** through the **food webs** but **human activity** often **disrupts** the cycling of nutrients.
59
What are important in the food webs?
Micro-organisms such as bacteria and fungi.
Many are saprobionts.
60
What are saprobionts?
decomposers.
1. Feed on remains of dead plants and animals and waste, breaking them down.
2. allows important chemicals to be recycled.
3. secrete enzymes and digest food externally, then absorb nutrients needed. This is known as extracellular digestion.
organic molecules are broken down into inorganic ions.
61
What is saprobiotic nutrients?
Obtaining nutrients from dead organic matter using extracellular digestion.
62
What is a symbiotic relationship?
when two species live closely together and one or both depends on the other for survival.
known as mycorrhizae.
63
What do fungi form with roots of plants?
Symbiotic relationships
64
What are mycorrhizae? // What are fungi made up from?
//The role of mycorrhizae in facilitating the uptake of water and inorganic ions by plants.
* Symbitoic relationships within the roots of the plants.
* Fungi made up of long, thin strands called hyphae.
* Hyphae increases the surface area of the plant's root system, helping the plant to absorb ions from the soil that are usually scarce.
* Increases water uptake.
65
What do hyphae increase?
* Hyphae increases the surface area of the plant's root system, helping the plant to absorb ions from the soil that are usually scarce.
* Increases water uptake.
66
Explain why determination of dry mass was an appropriate method to use in this investigation. (2)
1. Dry mass measures / determines increase in biological / organic material;
2. Water content varies.
67
Describe the role of microorganisms in producing nitrates from the remains of dead organisms. (3)
1. Saprobiotic (microorganisms / bacteria) break down remains / dead material / protein / DNA into ammonia / ammonium;
2. Ammonia / ammonium ions into nitrite and then into nitrate;
3. (By) Nitrifying bacteria / nitrification;
68
Upwelling often results in high primary productivity in coastal waters.
Explain why some of the most productive fishing areas are found in coastal waters. (2)
1. Nitrate / phosphate / named ion / nutrients for growth of / absorbed / used by plants / algae / producers;
2. More producers / consumers / food so more fish / fish reproduce more / fish grow more / fish move to area;
69
Nitrate from fertiliser applied to crops may enter ponds and lakes. Explain how nitrate may
cause the death of fish in fresh water. (5)
1. Growth of algae / surface plants / algal bloom blocks light;
2. Reduced / no photosynthesis so (submerged) plants die;
3. Saprobiotic (microorganisms / bacteria);
4. Aerobically respire / use oxygen in respiration;
5. Less oxygen for fish to respire / aerobic organisms die;
70
What does the nitrogen cycle show?
How nitrogen is recycled in ecosystems.
71
Why do plants and animals need nitrogen?
To make proteins and nucleic acids (DNA and RNA).
72
How much of the atmosphere is made up of nitrogen gas?
78%
73
Why do plants and animals have to convert nitrogen from the atm into a usable form?
because they cant use nitrogen in the air in the atm and need to pass it on between living and non living organisms.
74
What does the nitrogen cycle include?
* Food chains
* Four different processes;
1. Nitrogen Fixation
2. Ammonification
3. Nitrification
4. Denitrification
75
Why is it important to recycle nitrogen, carbon and phosphorus?
nutrients dont have an extra terrestrial source and theres a limited availability of nutrients ions in a usable form which is why its important to recycle nitrogen, carbon and phosphorus.
76
Explain nitrogen fixation
1. Nitrogen gas in the atmosphere is turned into nitrogen - containing compounds.
2. Nitrogen turned into NH3 which forms ammonium ions by nitrogen fixation.
3. Rhizobium inside root nodules of leguminous plants. They form a mutalistic relationship with the plants - they provide the plant with nitrogen compounds and the plant provides them with carbohydrates.
77
What's the most important form of nitrogen fixation?
1. Free living nitrogen-fixing bacteria.
2. Mutalistic nitrogen-fixing bacteria.
78
Explain ammonification
1. Nitrogen compounds from dead organisms are turned into ammonia by saprobionts which form ammounium ions.
2. Faceal waste/ urine release NH4+ when broken down.
3. Dead organisms - removal of NH2 group.
4. N2 go from living components of an ecosystem to non living.
5. Ammounium ions released when saprobionts break down waste.
79
Explain nitrification
1. When amounium ions in the soil are changed into nitrogen compounds (nitrates) that can be used by plants.
2. Nitrifying bacteria (nitrosomonas) change ammonium ions into nitrites.
3. Then other nitrifying bacteria (nitrobacter) change nitrites into nitrates.
4. use light energy to produce the organic compounds.
80
State the two stages of reactions for free living-soil microorganisms (nitrifying bacteria)
1. Oxidation of NH4+ to NO2- (nitrite ions)
2. Oxidation of NO2- to NO3- (nitrate ions)
81
How to raise productivity?
1. ploughing
2. good drainage prevents air spaces being filled with water - prevents air being forced out.
82
What are other ways nitrogen gets into an ecosystem?
lightning or artifical fertilisers
83
Explain denitrification
When the soils become water logged and has lower o2 conc, the type of microorganism present changes.
1. nitrates in the soil are converted into nitrogen gas by denitrifying bactera. They use nitrates in the soil to carry out respiration and produce nitrogen gas.
2. This happens under anaerobic conditions (where there's no oxygen) i.e. in waterlogged soils.
84
How do animals obtain phosphate ions?
Phosphate ions are transferred through the food chain as animals eat the plants and are in turn eaten by other animals.
85
what do plants and animals need to make biological molecules such as phospholipids, DNA and ATP?
phosphorus
86
Where is phosphorus found?
In rocks and dissolved in the oceans in the form of phosphate ions (PO4 3-).
87
Phosphate ions dissolved in water in the soil can be _______ (absorbed and then used to make more complex molecules) by plants and other producers.
assimilated.
88
How are phosphate ions transferred from the sea to the land// Explain how phosphorus is passed through an ecosystem
1. Phosphate ions in rocks released into soil by weathering.
2. Phosphate ions are taken into the plants through the roots. Mycorrhizae greatly increases the rate at which phosphorus is assimilated.
3. Phosphate ions transferred through the food chain as animals eat the plants and are in turn eaten by other animals.
4. Phosphate ions are lost from the animals in waste products.
5. When plants and animals die, saprobionts are involved in breaking down the organic compounds, releasing the ions into soil for assimilation by plants. The microorganims also release the phosphate ions from urine and faeces.
6. Weathering of rocks also releases phosphate ions into seas, lakes, and rivers. Thats then taken up by aquatic producers such as algae and passed along the food chain to birds.
7. The waste products by sea birds are known as guano and contains a high proportion of phosphate ions. Guano returns a significant amount of phosphate ions to soils. Its often used as a natural fertiliser.
89
During the light-independent reaction of photosynthesis, carbon dioxide is converted into organic substances. Describe how. (6)
1. Carbon dioxide combines with ribulose bisphosphate / RuBP;
2. Produces two glycerate (3-)phosphate / GP;
3. GP reduced to triose phosphate / TP;
4. Using reduced NADP;
5. Using energy from ATP;
6. Triose phosphate converted to glucose / hexose / RuBP / ribulose bisphosphate / named organic substance;
90
Nitrate from fertiliser applied to crops may enter ponds and lakes. Explain how nitrate may cause the death of fish in fresh water. (5)
1. Growth of algae / surface plants / algal bloom blocks light;
2. Reduced / no photosynthesis so (submerged) plants die;
3. Saprobiotic (microorganisms / bacteria); Neutral: decomposer
4. Aerobically respire / use oxygen in respiration;
5. Less oxygen for fish to respire / aerobic organisms die;
91
What do crops take in from the soil? and what do they use them for?
nutrients and to build their own tissues
92
what happens when plants are harvested?
they are removed from the field when theyre grown rather than being allowed to die and decompose there
93
What aren't returned by the plants into the soil when they're harvested due to them not decomposing?
mineral ions that they contain (i.e. phosphate and nitrates)
94
What happens when animals or animal products are removed from the land?
Phosphate and nitrates are lost from the system.
95
why is it a bad thing when plants or animals are taken elsewhere to be slaughted or transferred to a different field?
The nutrients aren't replaced through their remains or waste products.
96
Why are fertilisers added to soils?
To replace the lost nutrients, increasing the efficiency of energy transfer as more energy from the ecosystem can be used for growth.
97
What are artifical fertilisers?
They are inorganic and contain pure chemicals as powders or pellets.
98
What are natural fertilisers?
They are organic matter that include manure, composted vegetables, crop residue and sewage sludge.
99
How do fertilisers increase productivity?
1. Nitrogen essential component of amino acids, ATP, and nucleotides in DNA = Both N2 and minerals needed for plant growth.
2. Plants develop earlier where nitrate ions are readily available and grow taller and have a greater leaf area.
3. Rate of photosynthesis increases, improving crop productivity.
4. Nitrogen containing fertilisers beneift cheap food.
100
What are environmental issues of in fertilisers?
1. **Leach** into waterways when **excess** of **fertiliser**. They're washed into nearby ponds and rivers which can lead to **EUTROPHICATION**.
2. There are **inorganic ions** in chemical fertilisers which are **relatively soluble**. This means that excess minerals that are not used immediately are more likely to leach into waterways. (natural fertilisers still contain organic ions as nitrogen and phosphorus need to be decomposed so leaching less likely as realsed into soil for uptake).
3. Changes the balance of nutrients in the soil - too much of a nutrient can cause crops and other plants to die.
101
What is the definition of Leaching
When **water soluble compounds** in soil are **washed away** i.e. by rain or irrigation systems.
102
why do natural fertilisers cause less leaching?
natural fertilisers still contain organic ions as nitrogen and phosphorus need to be decomposed before absorbed so leaching less likely as realsed into soil for uptake.
103
Why is the leaching of phosphate less likely than the leaching of nitrates?
Phosphates are less soluble in water.
104
What causes eutrophication?
excess nutrients
105
Explain the process of eutrophication
1. Mineral ions leached from fertilised fields stimulate the rapid growth of algae in ponds and rivers.
2. Large amount of algae blocks the light from reaching the plants below. (algae bloom).
3. Plants die because unable to photosynthesise enough.
4. Bacteria feed on dead matter.
5. The increased number of bacteria reduce the oxygen concentration levels in the water as they carry out aerobic respiration using oxygen.
6. Fish and other aquatic organisms die because there isn't enough dissolved oxygen.
106
Compare benefits of inorganic and organic compounds/ fertilisers
**Inorganic**
* Manufactured.
* Easily leached from soil.
* Applied in smaller amounts as it's concentrated.
* Easier to handle and spread onto a field.
**Organic**
* Natural i.e. animal waste adds organic matter.
* Manure is a good way of recycling manure produced.
107
Describe the role of microorganisms in producing nitrates from the remains of dead organisms (3)
* Saprobiotic (microorganisms/bacteria) break down remains/dead material/protein/DNA into ammonia/ammonium;
* Ammonia/ammonium ions into nitrite and then into nitrate;
* (By) Nitrifying bacteria / nitrification;
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