Energy And Food Webs

Question 1

What are the two laws of thermodynamics?

Answer 1

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.

Question 2

Define ecosystem

Answer 2

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

Question 3

Define standing crop

Answer 3

The bodies of living organisms within the unit area

Question 4

Define biomass

Answer 4

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)

Question 5

What does entropy mean?

Answer 5

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

Question 6

How does the flow of energy start?

Answer 6

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

Question 7

What are autotroph’s?

Answer 7

Organisms that produce their own food

Question 8

What is the equation for photosynthesis?

Answer 8

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

Question 9

What are lithotrophs?

Answer 9

Organisms that are use inorganic substrates as energy

Question 10

What type of environments do lithotrophs like to live in?

Answer 10

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

Question 11

Why are lithotrophs Important?

Answer 11

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

Question 12

What two things can lithotrophs be?

Answer 12

Bacteria or archea

Question 13

Define primary productivity

Answer 13

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

Question 14

What are the two types of productivity?

Answer 14

Gross primary productivity GPP

Net primary productivity NPP

Question 15

Define gross primary productivity

Answer 15

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

Question 16

Define net primary productivity

Answer 16

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

Question 17

How do you find net primary productivity, give an equation

Answer 17

NPP=GPP - Cellular respiration (R)

Question 18

What is cellular respiration?

Answer 18

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

Question 19

What can be used to measure the net production?

Answer 19

Harvesting of carbohydrates from the plant

Question 20

How can the carbon dioxide uptake be measured?

Answer 20

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

Question 21

What three things influence primary productivity?

Answer 21

Water
Temperature
Nutrient availability

These are make up the climate around the plant

Question 22

How does primary productivity vary among ecosystems?

Answer 22

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.

Question 23

How does net primary production vary amongst oceans?

Answer 23

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

Question 24

How much carbon is made in terrestrial ecosystems?

Answer 24

56.4 pg of C12 per year

Question 25

How much carbon is made in marine ecosystems?

Answer 25

48.3 pg of C12 per year

Question 26

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

Answer 26

32%

Question 27

How much do humans make up of land based biomass?

Answer 27

0.5%

Question 28

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

Answer 28

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

Question 29

Describe the energy flow from producers onwards

Answer 29

Produces Primary consumers Secondary consumers et cetera Decomposes

Question 30

Why are secondary composers usually carnivores?

Answer 30

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

Question 31

What is the link in a food chain called?

Answer 31

A trophic level

Question 32

Define ecological efficiency

Answer 32

The percentage of energy transferred from one trophic level to another

Question 33

Who created the universal model of energy flow through ecosystems?

Answer 33

E.P. Odum

Question 34

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

Answer 34

Respiration and excretion and heat loss

Question 35

What are the three types of ecological pyramids?

Answer 35

Pyramid of energy Pyramid of numbers Pyramid of biomass

Question 36

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

Answer 36

They all have a loss of energy as heat

Question 37

What does a pyramid of energy show?

Answer 37

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

Question 38

What does the pyramid of numbers show?

Answer 38

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

Question 39

What does the pyramid of biomass show?

Answer 39

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

Question 40

What do the links in food web show?

Answer 40

Feeding connections

Question 41

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

Answer 41

Temporal or seasonal change

Question 42

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

Answer 42

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

Question 43

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

Answer 43

If an apex predator is removed. This causes trophic cascades

Question 44

How do you find the connectance of a food web?

Answer 44

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

Question 45

What is the general trend for connectance?

Answer 45

As the number of species increases connectance decreases

Question 46

Give an example of trophic cascades

Answer 46

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.