EFFICIENCY OF ECOSYSTEMS

Question 1

what is a biosphere? (1)

Answer 1

the total area of the earth and its atmosphere that is inhabited by living organisms.

Question 2

what is the population? (1)

Answer 2

a group of members of the same species that interact with each other.

Question 3

what is a habitat? (1)

Answer 3

a division of the biosphere with its own unique characteristics and conditions.

Question 4

what is a community? (1)

Answer 4

a group of populations of different species living together in one habitat.

Question 5

what is an ecosystem? (1)

Answer 5

a collection of communities and their non-living surroundings, which form a stable, self-perpetuating system in which there is an energy flow and nutrients are recycled.

Question 6

what is chemosynthesis? (1)

Answer 6

the use of chemical energy from the oxidation of inorganic compounds to synthesise organic compounds.

Question 7

what is a food chain? (1)

Answer 7

a feeding relationship in which a carnivore eats a herbivore, which itself has eaten plant matter.

Question 8

what is the initial source of energy in a food chain? (1)

Answer 8

light energy.

Question 9

what do the arrows point to in a food chain? (1)

Answer 9

the arrows point to the consumers and indicate the direction of energy transfer.

Question 10

what does a food chain tell us? (1)

Answer 10

a food chain tells us about the feeding relationship of organisms within an ecosystem but they also show quantitative relationships rather than providing quantitative data.

Question 11

what is a food web? (1)

Answer 11

in a whole ecosystem food chains are interconnected in many different ways to form a complex food web.

Question 12

what is meant by a trophic level? (1)

Answer 12

a level in aa food chain defined by the number of energy transfers an organism is from the primary energy source.

Question 13

what are the different trophic levels? (5)

Answer 13

-producer
-primary or first consumer
-secondary consumer
-tertiary consumer
-quaternary consumer

Question 14

why is the amount of the suns energy used by plants so low? (2)

Answer 14

the remainder of this energy is reflected into space as light or heat energy, some of the wavelengths transmitted aren’t the right wavelength and therefore cannot be absorbed by plants.

Question 15

what does GPP stand for? (1)

Answer 15

Gross primary productivity

Question 16

what is GPP? (1)

Answer 16

the total amount of light energy fixed by photosynthesis in a given area and fixed time.

Question 17

what are the units of GPP? (1)

Answer 17

KJ m-2 y-1

Question 18

what does NPP stand for? (1)

Answer 18

Net primary productivity

Question 19

what is NPP? (1)

Answer 19

the total amount of light energy fixed by photosynthesis in a given area and fixed time, which remains available to the next trophic level after losses and uses by a producer.

Question 20

what are the units of NPP? (1)

Answer 20

KJ m-2 y-1

Question 21

what equation can be used to work out NPP? (1)

Answer 21

NPP = GPP - R

Question 22

What is biomass? (1)

Answer 22

the total mass of a living organism in a given area.

Question 23

what do plants transfer light energy to? (3)

Answer 23

green plants light energy to the chemical energy of sugars in photosynthesis.
some is also transferred in the reactions of respiration that drive metabolism.
much is transferred to essential metabolites used in growth and devlopment of the plant.

Question 24

what happens to the energy stored in a plant when it dies? (1)

Answer 24

on death of a plant, the remaining energy passes to detritivores and saprotrophs when dead plant matter is broken down and decayed.

Question 25

how is energy transferred in a consumer? (4)

Answer 25

energy is transferred in the consumer when it eats, digests and then absorbs nutrients. It transfers energy in muscular movements for which it hunts and feeds and as it seeks to escape from predators (lost as heat energy). some of the food eaten remains undigested and is lost as faeces. heat energy is a waste product of the reactions of respiration and of the animals metabolism.

Question 26

what happens to the energy stored in a consumer once it dies? (1)

Answer 26

on the death of the consumer the remaining energy passes to the detritivores and saprotrophs when dead matter is broken down and decayed.

Question 27

what is the first consequence of limited energy transfer between trophic levels? (1)

Answer 27

the energy loss at transfer between trophic levels is the reason why food chains are so short, few transfers can be sustained when so little of what is eaten by one consumer is potentially available to the next step of the food chain.

Question 28

what is the second consequence of limited energy transfer between trophic levels? (1)

Answer 28

feeding relationships in a food chain may be structured by a pyramid, at the start of the chain is a very large amount of living matter (biomass) of green plants. This supports a smaller biomass of primary consumers , which in turn supports an even smaller biomass of secondary consumers.

Question 29

how can we illustrate feeding relationships quantitatively? (3)

Answer 29

-pyramids of numbers
-pyramids of biomass
-pyramids of energy

Question 30

what is a pyramid of numbers? (1)

Answer 30

counting the number of organisms at each trophic level and representing them by horizontal bars on top of each other

Question 31

what are the drawbacks of pyramids of numbers? (3)

Answer 31

accurately estimating the actual number for a whole ecosystem is difficult.
the bars simply compare counts of organisms but these organisms are of very different sizes and therefore distort the actual picture
the scale could be impossible to select on one axis as you would have cope with one producer and thousands of primary consumers.

Question 32

what are the drawbacks of pyramids of biomass? (2)

Answer 32

the biomass of all living organisms is made up of 80% water which is not helpful in illustrating relationships - we must find the dry biomass of organisms.
finding the dry biomass means that all organisms have to be killed.

Question 33

why is there a time unit in the conversion units? (1)

Answer 33

this is a vital part of the total energy calculation and overcomes the difficulties of different life-spans.

Question 34

what re saprotrophs? (1)

Answer 34

mainly fungi and bacteria; feed by secreting extracellular enzymes to break down dead organic matter and reabsorb the products

Question 35

what are scavengers? (1)

Answer 35

opportunist feeders on the remains of dead animals.

Question 36

what are detritivores? (1)

Answer 36

animals that feed off dead and decaying organic materials.

Question 37

what is saprotrophic nutrition? (1)

Answer 37

microorganisms can produce extracellular enzymes that break down dead tissues in decay processes, the products of this enzymic digestion are then reabsorbed into the cells of the microorganisms to be used as respiratory substrates or raw material for synthesis.

Question 38

what is hyphae? (1)

Answer 38

the large network of of fine threads that fungi produce in growth.

Question 39

what is a mycelium? (1)

Answer 39

a network of hyphae.

Question 40

what law does energy flow follow? (1)

Answer 40

obeys the law of conversation of energy, it cannot created or destroyed, only changed from one state to another.

Question 41

what are the limitations of dry biomass? (3)

Answer 41

• it is more accurate to calculate dry mass
  -drying out organisms is destructive to the ecosystem
  -wet mass is usually measured - different species may release different amounts of energy per unit mass

Question 42

why is less than 1% of the suns energy used in photosynthesis? (4)

Answer 42

-reflected by clouds and earths surface
-used to heat the earths atmosphere
-used to evaporate water
-is the wrong wavelength