Energy and ecosystems A2

Question 1

what happens to the majority of the sun’s energy when not used in making organic matter

Answer 1

it is reflected, the wrong wavelength, light misses the chlorophyll molecule used in respiration of producer

Question 2

equation of net productivity

Answer 2

net productivity = gross productivity - respiratory losses

Question 3

how is energy lost between trophic levels

Answer 3

in respiration
as heat
in excretory products
movement

Question 4

what’s the maximum number of trophic levels most food chains have

Answer 4

5

Question 5

units for energy flow

Answer 5

kJm^-2 year

Question 6

what is the unit for biomass

Answer 6

gm^-3

Question 7

define biomass

Answer 7

the total mass of living material in a specific area at a given time

Question 8

pros and cons of dry biomass

Answer 8

overcomes the problem of varying volumes of water in an organism but you must kill organism to find this

Question 9

how do you remove water from a sample of biomass

Answer 9

recording mass and heating until a constant mass is recorded

Question 10

what shape are pyramids of numbers and why

Answer 10

any shape because it doesn’t account for size of organism

Question 11

cons of pyramids of numbers

Answer 11

there’s often so many individuals it’s hard to show on a scale
doesn’t show seasonal differences

Question 12

why is conversion of food to biomass lower in colder temperatures

Answer 12

lose more heat
more respiration
more energy used in respiration

Question 13

equation for energy transfer (% efficiency)

Answer 13

energy available after transfer/energy available before transfer

Question 14

what is the purpose of an agricultural ecosystem

Answer 14

to improve productivity

Question 15

how is an ecosystem prevented form reaching natural climax community

Answer 15

decrease species diversity

Question 16

methods to improve productivity

Answer 16

adding fertilisers
using pesticides
using greenhouses/irrigation systems
ploughing
covering crops with nets
intensive farming
selective breeding

Question 17

why use greenhouses/irrigation system

Answer 17

to remove limiting factors of photosynthesis

Question 18

why use nets to cover crops

Answer 18

to protect from birds

Question 19

why plough

Answer 19

improve drainage and increase O2 for saprobionts in nitrogen cycle

Question 20

how do factory farms intensively farm animals

Answer 20

restrict movement
keep warm
no predators
feeding controlled

Question 21

why do factory farms restrict movement of their animals

Answer 21

less energy being used for muscle contraction and more on growth

Question 22

why do factory farms keep warm

Answer 22

less energy spent keeping warm and more for growing

Question 23

how to estimate energy store in biomass

Answer 23

calorimetry

Question 24

define biomass

Answer 24

formed from the biological molecules of plants

can be measured in terms of carbon or dry mass of tissue, per given area, per time