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Topic 5) Energy Transfers In & Between Organisms > 5.3 - Energy & Ecosystems, 5.4 - Nutrient Cycles > Flashcards

5.3 - Energy & Ecosystems, 5.4 - Nutrient Cycles Flashcards

(67 cards)

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1
Q

What is a plants biomass?

A

The chemical energy stored in a plant
Measured in terms of the mass of carbon that an organism contains or the dry mass of its tissue per unit area per unit time

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2
Q

What do we use to measure biomass?

A

Calorimetry

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3
Q

How do we use a calorimeter in order to measure biomass?

A

A sample of biomass is burnt & the energy released is used to heat a known volume of water.
The change in temperature of the water is used to calculate the chemical energy of the dry biomass.

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4
Q

Apart from using a calorimeter, explain another method of measuring biomass?

A

Sample of organism is dried in an oven.
The sample is weighed at regular intervals.
Once the mass becomes constant, you know that all the water has been removed.
Typical units may be kg m^-2

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5
Q

What is gross primary production?

A

Total amount of chemical energy converted from light energy by plants, in a given area & time.

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6
Q

What is respiratory loss?

A

Amount of the gross primary production that is lost to the environment when plants respire. Approximately 50%.

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7
Q

What is net primary production?

A

Remaining chemical energy from gross primary production after respiratory losses.

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8
Q

What formula links gross primary production, net primary production & respiratory loss?

A

NPP = GPP - R

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9
Q

What does GPP stand for?

A

Gross primary production

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10
Q

What does R stand for?

A

Respiratory loss

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11
Q

What does NPP stand for?

A

Net primary production

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12
Q

What is the energy from NPP used for?

A

It’s available to plant for growth & reproduction, and is stored in the plant’s biomass. It’s also the energy available to organisms at the next trophic level.

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13
Q

Why does not all energy from an ingested organism transfer to the consumer?

A

Not all the organism can be eaten (e.g. bones, roots)
Some parts cannot be digested therefor are excreted in faeces, energy is lost to environment.
Some energy is lost to environment through respiration & urine excretion.

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14
Q

Approximately how much energy from an organism is transferred to consumer?

A

10%

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15
Q

What is a consumer’s net production?

A

Energy that’s gained from eating an organism, after loosing some through excretion & respiration.

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16
Q

What does N stand for?

A

Net production

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17
Q

What does I stand for?

A

Chemical energy in ingested food.

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18
Q

What does F stand for?

A

Chemical energy lost in faeces & urine.

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19
Q

What equation is used to calculate the net production of consumers?

A

N = I - ( F + R )

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20
Q

What equation is used to calculate efficiency of energy transfer?

A

Net production of trophic level / net production of previous trophic level,
X 100

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21
Q

As you move up the food chain, energy transfer becomes…

A

More efficient

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22
Q

Why does energy transfer become more efficient as you move up the food chain?

A

As plants contain more indigestible matter than animals.

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23
Q

What is a trophic level?

A

A stage in the food chain

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24
Q

What do decomposers do?

A

Break down dead or undigested material, allowing nutrients to be recycled.

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25
In order to **increase efficiency**, the farmer needs to increase…
Net primary production of **crops** Net production of **livestock**
26
Outline 2 ways of increasing efficiency.
- reducing energy lost to **other organisms** (e.g. pests) - reduce energy lost through **respiration** of livestock
27
Why does **simplifying food webs** increase efficiency?
As pests reduce the amount of energy available for crop growth, less energy is available to humans eating the crop. By getting rid of food chains that don’t involve humans, NPP of the crop will increase.
28
How can a farmer **simplify** a food chain?
By getting rid of pests, by using pesticides.
29
What is used to kill insects?
Insecticides
30
What is used to kill weeds?
Herbicides
31
How does killing **weeds** help to simplify the food chain?
Killing weed removes direct **competition** with the crop for for energy from the Sun. Also further reduces insect numbers, as could alter their preferred habitat or food source.
32
What **biological agents** can be used to lower pest numbers?
Parasites - lay egg on pest insect, killing them or reducing their ability to function Pathogenic bacteria & viruses - kill pest
33
Why does **reducing respiratory loss** increase efficiency?
More of the livestocks energy is used for growth & reproduction
34
How can farmers **reduce respiratory loss** of livestock?
Keeping them in **pens** where movement is restricted - movement increases rate of respiration. Keeping pens **warm** - less energy is wasted by generating body heat.
35
What are **saprobionts**?
Microorganisms that… -are a type of **decomposer**: feed on remains of dead plants & animals (and on their waste products), breaking them down, allowing important chemical elements in the remains to be recycled. -**perform extracellular digestion**: **secrete enzymes** & digest their food externally, then absorb the nutrients they need. During, organic molecules are broken down into inorganic ions.
36
What is **saprobiotic nutrition**?
Obtaining nutrients from dead organic matter & animal waste using **extracellular digestion**.
37
What are **mycorrhizae**?
**Symbiotic** relationships that fungi form with plant roots.
38
What are **hyphae**?
Long, thin strands that make up **fungi**, which connect to the plant’s root.
39
What is the **function** of the **hyphae**?
They increase the **surface area** of the plant’s **root system**, helping the plant to **absorb ions** from the soil that are usually scarce. Also increase uptake of water by the plant.
40
What do the **fungi** gain from their **mutualistic relationship** with plant **roots**?
Organic compounds, such as glucose, from the plant.
41
Why do plants & animals need **nitrogen**?
To make proteins, nucleic acid - DNA & RNA
42
What 4 processes, that involve **bacteria** make up the **nitrogen cycle**?
Nitrogen fixation Ammonification Nitrification Denitrification
43
Explain **nitrogen fixation**.
Nitrogen **gas** in the atmosphere is turned into nitrogen-containing **compounds**. Carried out by **bacteria**. Turns **nitrogen** into **ammonia**. Which goes on to from **ammonium ions**, in solution that can be used by plants. Bacteria are found inside **root nodules** on **leguminous** plant roots. From a **mutualistic relationship** with plant: they provide plant w/**nitrogen compounds**, plant provides them w/**carbohydrates**. Some bacteria also found in **soil**.
44
Explain **ammonification**.
Nitrogen compounds from dead organisms & animal waste are turned into **ammonia** by **saprobionts**, Which then go on to from **ammonium ions**.
45
Explain **nitrification**.
**Ammonium ions** in soil are changed into **nitrogen compounds**, That can then by used by plants (as nitrates). **Nitrifying bacteria** change **ammonium ions** into **nitrites**. Other nitrifying bacteria then change **nitrites** into **nitrates**.
46
Explain **denitrification**.
**Nitrates** in soil are converted into nitrogen **gas** by **denitrifying bacteria**, By using nitrates in soil to carry out **respiration** & **produce nitrogen gas**. Happens under **anaerobic** conditions.
47
Apart from the **nitrogen cycle**, list 2 other ways nitrogen gets into an ecosystem.
Lightning Artificial fertilizers
48
Why do plants and animals need **phosphorus**?
To make biological molecules such as phospholipids DNA, RNA, ATP
49
Where is phosphorus found?
In rocks Dissolved in water - phosphate ions dissolved in water in soil can be assimilated by plants & other producers
50
What is meant by **assimilated**?
Absorbed & then used to make more complex molecules
51
What is the **first** stage of the phosphorus cycle?
Phosphate ions in **rocks** are released into the **soil** by weathering
52
What is the **second stage** of the phosphorus cycle?
Phosphate ions are taken into plants through roots. **Mycorrhizae** greatly increase rate that phosphorus can be **assimilated**.
53
What is the **third** stage of the **phosphorus cycle**?
Phosphate ions are transferred through the food chain as plants are eaten by animals which are eaten by others etc
54
What is the **fourth** stage of the phosphorus cycle?
Phosphate ions are lost from animals in waste products.
55
Whats the **fifth** stage of the phosphorus cycle?
Plants & animals excrete urine & faeces, and die, **Saprobionts** break down organic compounds, releasing phosphate ions into soil For **assimilation** by plants
56
What is the **sixth** stage of the phosphorus cycle?
Weathering of rocks also releases phosphate ions into seas, lakes & rivers Absorbed by **aquatic producers** (e.g. algae) Passed along food chain, to birds
57
What is the **seventh** stage of the phosphorus cycle?
Waste produced by **sea birds** is known as **guano** Guano contains a high proportion of phosphate ions Returns to soil
58
What is **guano**?
Waste excreted by **sea birds**, containing lots of phosphate ions, often used as a natural fertiliser.
59
Why is it natural to find a lack of nutrients in farms?
After crops use up all nutrients, they are harvested. Therefore, don’t naturally decompose, so dont return nutrients & ions to soil. Animals also take up nutrients when they eat plants/grass When they are taken to a different field/slaughter house, they don’t give back nutrients through waste or decomposition.
60
Are **artificial fertilisers** organic or inorganic?
Inorganic They contain pure chemicals as powders or pellets
61
Are **natural fertilisers** organic or inorganic?
Organic They include manure, composted vegetables, crop residues, sewage sludge.
62
What is **leaching**?
When **water-soluble compounds** in the soil are washed away (e.g. by rain). Often washed into nearby ponds & rivers
63
Why might fertilisers cause environmental issues?
When too much is used, fertilisers may **leach** into waterways.
64
When/why is **leaching** more likely to occur?
When **artificial chemical fertilisers** are used, as they are relatively soluble. Also when heavy rainfall occurs
65
Why is **leaching** less likely to occur with the use of **natural** fertilisers than **artificial**?
Contains nitrogen & phosphorus in organic molecules, that still need to be decomposed by microorganisms before they can be absorbed by plants. So their release into the soil is slower & more controlled
66
The leaching of **phosphates** is … likely than the leaching of **nitrates**?
**Less** Phosphates are less **water-soluble**
67
What is **eutrophication**?
1) **Mineral ions leached** from fertilised fields stimulate the **rapid growth of algae** in ponds & rivers. 2) Large amounts of algae **block light** from reaching plants below. 3) Eventually, plants below die because they are **unable** to **photosynthesise** enough. 4) **Bacteria** feed on dead plant matter 5) This increases number of bacteria, **reducing** the **oxygen concentration** in water (respiration) 6) Fish & **aquatic organisms die**, due to lack of **dissolved oxygen**

Topic 5) Energy Transfers In & Between Organisms (4 decks)

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