energy and ecosystems

Question 1

why would suns energy not be made into organic matter by plants in photosyn

Answer 1

light reflected away
wrong wavelength
light misses chlorophyll molecule
respiration of producer

Question 2

describe pyramids of energy

Answer 2

always pyramid shape
energy flow measured in kJm2 per year
hard to collect data for them

Question 3

what happens between levels of the pyramids of energy

Answer 3

energy is lost between trophic levels in respiration as heat and movement and excretory products
most food chains don’t have more than 5 trophic levels

Question 4

formula for net productivity

Answer 4

net productivity = gross productivity - respiratory losses

Question 5

what is net productivity affected by

Answer 5

area of ground covering leaves of crop

and efficiency of crop at carrying out photosyn

Question 6

what is biomass

Answer 6

total mass of living material in a specific area at a given time g/m3

Question 7

how to overcome the issue of varying water content in plants

Answer 7

using dry biomass can overcome the problem
organism must be dead
ecologists can ensure all water is removed
by heating to 100 degrees to evap water
record mass and keep heating til no change in mass

Question 8

whats the link between organisms and trophic levels

Answer 8

combined biomass of organisms in each higher trophic levels is tends to be lower

Question 9

whats the equation for energy transfer

Answer 9

energy available after transfer x 100 divided by energy available before transfer

Question 10

what dont pyramids of numbers do

Answer 10

can be any shape. doesn’t account for size of organism and often so many individuals make it hard to show on a scale
doesn’t show seasonal differences

Question 11

what are agricultural ecosystems

Answer 11

aiming to improve productivity

Question 12

what does less species diversity lead to

Answer 12

population prevented from reaching natural climax community

Question 13

heat affect on food to biomass conversion

Answer 13

conversion from food to biomass generally lower at colder temps
lose more heat
more resp
more heat used in resp

Question 14

methods to improve productivity

Answer 14

add fertilisers
use pesticides
use greenhouse gases/ irrigation systems remove limiting factors of photosyn
ploughing improve drainage and increase o2 levels in soil for saprophytes
covering crops with nets protect from birds
intensive farming selective breeding

Question 15

aim of intensive farming

Answer 15

aims to convert smallest amount of food energy into most animal mass.

Question 16

how does intensive farming achieve its goal

Answer 16

restrict movement- less energy wasted for movement
warm temps- less energy wasted on thermoregulation
no predators - no loss to natural food chain
feeding controlled- optimum amount of food and type for growth

Question 17

define biomass

Answer 17

formed from biological molecules of plants. can be measured in terms of mass of carbon or dry mass of tissue per given area per time.

Question 18

how can the chemical energy store of biomass be estimated

Answer 18

using bomb calorimetry
sample of dry material is weighed and then burnt in pure oxygen within a sealed chamber. bomb surrounded by water the heat of combustion causes a small temp rise in the water use specific heat capacity of water to calculate the energy released from the mass of burnt biomass.