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Ecology And Conservation > Energy And Food Webs > Flashcards

Energy And Food Webs Flashcards

1
Q

What are the two laws of thermodynamics?

A
  1. Energy cannot be created or destroyed; it can change from one form to another.
  2. When energy is converted from one form to another, some of it is lost in the form of heat and the entropy increases.
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2
Q

Define ecosystem

A

Biological community Together with the abiotic environment in which it is set

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3
Q

Define standing crop

A

The bodies of living organisms within the unit area

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4
Q

Define biomass

A

Mass of organisms per unit area of ground (of water). Usually expressed as joules per metre squared or dry matter. Dead organisms are not regarded as biomass (dead organic matter)

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5
Q

What does entropy mean?

A

Thermal energy cannot be converted to mechanical energy as the degree of disorder increases

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6
Q

How does the flow of energy start?

A

The flow of energy starts by harnessing the Sun by autotroph’s which are mainly plants.

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7
Q

What are autotroph’s?

A

Organisms that produce their own food

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8
Q

What is the equation for photosynthesis?

A

6CO2 + 12H2O + radiant energy —> C6H12O6 + 6H2O + 6O2

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9
Q

What are lithotrophs?

A

Organisms that are use inorganic substrates as energy

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10
Q

What type of environments do lithotrophs like to live in?

A

Extreme areas as they’re extremophiles (e.g deep trenches)

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11
Q

Why are lithotrophs Important?

A

They are important in the formation of soil and in biogeochemical cycling

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12
Q

What two things can lithotrophs be?

A

Bacteria or archea

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13
Q

Define primary productivity

A

The rate at which light energy is converted by photosynthesis to biomass or area

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14
Q

What are the two types of productivity?

A

Gross primary productivity GPP

Net primary productivity NPP

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15
Q

Define gross primary productivity

A

The total amount of energy that plants capture and assimilate in a given period of time (total rate of photosynthesis)

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16
Q

Define net primary productivity

A

Plant growth per unit area per time. It represents the rate of production of new biomass

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17
Q

How do you find net primary productivity, give an equation

A

NPP=GPP - Cellular respiration (R)

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18
Q

What is cellular respiration?

A

Chemical energy captured in photosynthesis it’s released within cells of plants and animals.

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19
Q

What can be used to measure the net production?

A

Harvesting of carbohydrates from the plant

20
Q

How can the carbon dioxide uptake be measured?

A

It can be measured by a decrease in carbon dioxide concentration in a close chamber or by the uptake of carbon-14 labelled CO2.

21
Q

What three things influence primary productivity?

A

Water
Temperature
Nutrient availability

These are make up the climate around the plant

22
Q

How does primary productivity vary among ecosystems?

A

There is a high net primary production in the equator and the coast but there is a low net primary productivity on the poles and the deserts, this is because there is no water in the desert so plants cannot grow and the temperature is too low in the poles.

23
Q

How does net primary production vary amongst oceans?

A

Shallow coast means high productivity as there is a higher temperature and high in nutrients in shallow water. There is a greater transport of nutrients from the bottom sediments to the top waters which is aided by waves.

Inputs from nutrients are also from terrestrial ecosystems

24
Q

How much carbon is made in terrestrial ecosystems?

A

56.4 pg of C12 per year

25
Q

How much carbon is made in marine ecosystems?

A

48.3 pg of C12 per year

26
Q

How much land-based net primary productivity do humans use?

A

32%

27
Q

How much do humans make up of land based biomass?

A

0.5%

28
Q

What happens as a result of this over use of land-based net primary production?

A

It causes extinction to occur and threatens planets availability to support everyone

29
Q

Describe the energy flow from producers onwards

A

Produces
Primary consumers
Secondary consumers et cetera
Decomposes

30
Q

Why are secondary composers usually carnivores?

A

As carnivores don’t eat each other as there is little energy to gain from this so they must eat primary consumers which eat plants

31
Q

What is the link in a food chain called?

A

A trophic level

32
Q

Define ecological efficiency

A

The percentage of energy transferred from one trophic level to another

33
Q

Who created the universal model of energy flow through ecosystems?

A

E.P. Odum

34
Q

Three reasons why there is less energy at the next trophic level

A

Respiration and excretion and heat loss

35
Q

What are the three types of ecological pyramids?

A

Pyramid of energy
Pyramid of numbers
Pyramid of biomass

36
Q

What important feature do all three types of ecological pyramid share?

A

They all have a loss of energy as heat

37
Q

What does a pyramid of energy show?

A

How much energy is present at each level and how much is transferred onto the next trophic level

38
Q

What does the pyramid of numbers show?

A

The number of organisms at each level. Usually there are more organisms at the bottom

39
Q

What does the pyramid of biomass show?

A

Total biomass at each successive tropic level. Biomass indicates the amount of fixed energy at a given time

40
Q

What do the links in food web show?

A

Feeding connections

41
Q

What type of change can affect the diet available to a predator in a food chain?

A

Temporal or seasonal change

42
Q

Give an example of an animal that’s diet changes with temporal change

A

Great tits

In winter eats beech seeds and moss capsules and in summer it eats animals and small organisms.

43
Q

What type of change can affect a food chain the most?

A

If an apex predator is removed. This causes trophic cascades

44
Q

How do you find the connectance of a food web?

A

Connectance = (Actual number of interspecific interactions) Divided by (Potential number of interspecific interactions)

45
Q

What is the general trend for connectance?

A

As the number of species increases connectance decreases

46
Q

Give an example of trophic cascades

A

Wolves in Yellowstone National Park

The Wolves used to eat the elk which is a herbivore it used to eat the aspen and willow trees in the park. When the wolves were removed the elks ate too many plants and ruined the ecosystem so wolves were reintroduced to hunt the elk.

Ecology And Conservation (2 decks)

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