Energy transfer

Question 1

what is the ultimate source of energy?

Answer 1

the sun

Question 2

why isnot all light energy that falls on plants used for photosynthesis?

Answer 2

• some light does not fall pon the photosynthetic part of the plant
• not all light is an apporopriate wavelinght
• some of the light is reflected or transmitted through the leaf

Question 3

why is only a small amount of energy used in photosynthesis converted unto chemical energy of glucose?

Answer 3

• some energy is lost in the efficient reaction of photosynthesis
• may be othere limiting factors of photosynthesis

Question 4

what is biomass?

Answer 4

the mass of organic material in an organism / ecosystem

Question 5

How would you estimate the biomass of a field of wheat?

Answer 5

Collect all the wheat plants in one square metre. Dry them at 80°C, weigh them and dry again, repeating until there is no further change in weight. This means that all
water has been removed. Multiply the answer by the number of square metres in the field.

Question 6

why is it important to use dry biomass?

Answer 6

water content varies over time

Question 7

in terms of what can biomass be measured…

Answer 7

mass of carbon or dry mass of tissue per given area

Question 8

what does a bomb calorimeter do?

Answer 8

estimates the chemical energy store in biomass

Question 9

how can we measure the chemical energy store in dry mass?

Answer 9

by using a bomb calorimeter

Question 10

describe how a bomb calorimeter works

Answer 10

-Dry material is burnt in oxygen.
-The energy given off heats up the water
in the calorimeter.
-The rise in temperature can be used to calculate the energy (in calories) that was contained in the material.

Question 11

what is gross primary production?

Answer 11

the chemical energy store in biomass, in a given area r volume

Question 12

what is net primary production?

Answer 12

the chemical energy store in plant biomass

after respiratory losses to the environment have been taken into account.

Question 13

give the equation for net primary production

Answer 13

Net primary production = Gross primary production – Respiration

Question 14

give the equation for energy transfer

Answer 14

energy transfer=energy available after the transfer/energy avaiable before the transfer

Question 15

explain how u would reduce the respiratory losses in cattle farming

Answer 15

1. Slaughtered when still growing/before maturity/while young so more energy transferred to biomass/tissue/production.
2. Feed on concentrate /controlled diet /controlled conditions/so higher proportion of (digested) food absorbed/lower proportion lost in faeces / valid
   reason for addition.
3. Movement restricted so less respiratory loss / less energy used.
4. Kept inside/heating/shelter / confined so less heat loss / no predators.
5. Genetically selected for high productivity.

Question 16

why is energy lost wehen transferred from priducers to consumers?

Answer 16

• some food is not digested so passes out as faeces
• some is lost due to excretionof metabolic waste products
• some of the enrgy remains in the previous organism as not all of it can be consumed
• enrgy is lost in consumer respiration
• to the evironment as heat

Question 17

why is more enegy lost by herbivores than carnivores?

Answer 17

herbivores consume high proportions of cellulose that cannot be digested so passes oput as faeces

Question 18

why is energy loss higher for species of fish, than mammals?

Answer 18

mammals have to regulate their body temperature