energy flow in ecosystems

Question 1

what does the productivity of an ecosystem depend on

Answer 1

how much energy is captured by autotrophs during photosynthesis and how much is transferred to next trophic levels

Question 2

how do limiting factors affect the productivity of an ecosystem

Answer 2

limiting factors affect rate of photosynthesis
this affects the amount of energy captured by autotrophs
this effects amount if energy transferred to next trophic levels
which affects the productivity of the ecosystem

Question 3

main reasons why not all light energy from sunlight can be used productively in ecosystems

Answer 3

-90% of sunlight is reflected back into space by clouds and dust or is reflected back into the atmosphere
-some wavelengths cant be absorbed by chlorophyll & used in photosynthesis
-light may not fall on a chlorophyll molecule
-some light will be transmitted through the leaf

Question 4

what is GPP and what is it measured in

Answer 4

-rate at which energy is incorporated into organic molecules by plants
-kj m-2 y-1

kilojoules per square metre per year

Question 5

what is NPP and what is it measured in

Answer 5

-rate at which energy is incorporated into new biomass

-kilojoules per square metre per year

Question 6

what is respiration and what is it measured in

Answer 6

-sort of tax subtracted from GPP to give NPP
-the release of chemical energy for use in metabolic processes

-kj m-2 y-1

Question 7

what can NPP represent

Answer 7

the energy that can be passed onto primary consumers and decomposers

Question 8

what can galp be used to produce

Answer 8

-hexose sugars
like glucose, glucose can be converted to sucrose to be transported in phloem
-12 mols galp produced by 6 turns calvin cycle, 10 used to regen RUBP, used to form 1 mol glucose
-each galp mol contains 3 carbons
-hexose sugars can be joined together to form polysaccharides
like starch and cellulose-can form microfibrils in cell wall
-nucleic acids (contain sugar) basis of DNA in plant
-glycerol, can be used for building lipid molecules such as triglycerides and phospholipids

Question 9

3 most impotant hexose sugars/monosaccharides

Answer 9

glucose, fructose, galactose

Question 10

glycogen

Answer 10

animal equivalent of starch
-alpha glucose monomer
-1,4 and 1,6 glycosidic bonds
-highly branched, moreso than amylopectin, many terminal glucsoses allowing for rapid hydrolysis
-compact
-insoluble in water

Question 11

NPP used to compare different ecosystems: why might a tropical rainforest have a higher NPP than a desert

Answer 11

-higher temp
-little seasonal change
-higher plant density
-higher water availability/higher rainfall
-evergreen plants
-higher light intensity

Question 12

ecosystem

Answer 12

interaction of community with abiotic parts of the environment

Question 13

interspecific competition

Answer 13

competition between species for the same resources

Question 14

why does interspecific competition mean that population numbers of both species involved will have a decrease in numbers

Answer 14

resources have to be shared between both species meaning there will be less available for both

This means that both species will have less energy for growth and reproduction

SO population numbers of both species will decrease

Question 15

intraspecific competition

Answer 15

competition for resources between individuals within the same species

Question 16

carrying capacity

Answer 16

maximum stable population size that an ecosystem can support

Question 17

how does intraspecific competition cause population numbers within a species to fluctuate around carrying capacity?

Answer 17

when resources are abundant the population size increases,

the increase in population causes a greater level of intraspecific competition between individuals of a species, as resources will need to be shared between more organisms

this increased competition causes population size o decrease

this pattern causes population numbers to fluctuate around carrying capacity-eventually if population size increases there will be too many organisms for the available resources so competition between organisms in the species will cause the population number to decrease.

Question 18

predation

Answer 18

the more prey the more energy/resources for predators allowing them increased likelihood of survival,

numbers of predator populations increase as they have more resources

this causes prey population numbers to decrease as there are more predators reducing their numbers as theyre eaten for energy

as prey population numbers decrease, predators have less food resources available increasing competition between predators and causing their numbers to decrease

as predator population numbers decrease there will be fewer predators hunting prey so their population numbers will increase again

Question 19

kite diagram

Answer 19

show distribution and abundance of different species along a transect line

Question 20

x-axis

Answer 20

distance along the transect

Question 21

how is abundance shown on a kite diagram

Answer 21

the width of the kites for each species on the diagram around their own central horizontal line

called a kite diagram as the width of the kite extends an equal distance on each side of the horizontal line (distance obviously changes vertically though)

Question 22

efficiency of biomass transfer

Answer 22

(biomass transferred/biomass intake) x 100

biomass transferred=biomass that has passed to the higher trophic level

biomass intake=biomass of the lower trophic level that has been consumed

Question 23

how to measure biomass

Answer 23

dry biomass used as the amount of water stored in tissues can vary
dry a sample of the organism out in an oven at a low heat and weigh the sample at regular intervals until the mass becomes constant