Give two reasons for the loss in mass between green plants and carnivore?

Question

I would begrateful if I have the answers today.The ques is worth two marks

Answer 1

I agree with "Tiger tracks".

However, at "A" level, you would also get credit for :

Not all of the food was eaten - so plant roots are not grazed, feathers don't get eaten etc.

Not all of the food is digested/absorbed.

Answer 2

1. Plants (Primary Producers) produce say 100 parts of energy.

2. Herbivores (Primary Consumers) consume 100 parts of energy, but only 10 parts of the energy stored, other 90 parts are spent in respiration, metabolism, foraging, sleeping, procreation and other activities.

3. Carnivores (Secondary Consumers) consume 10 parts of stored energy through herbivores, but only 1 part of the energy stored, other 9 parts (90% of energy) is spent in respiration, metabolism, foraging, sleeping, moving, procreation and other activities.

At each trophic level (Primary Producers, Primary Consumers, Secondary Consumers, Tertiary Consumers),

1. Net production is only a fraction of gross production because the organisms must expend energy to stay alive. Note that the difference between gross and net production is greater for animals than for the producers - reflecting their greater activity.

2. Much of the energy stored in net production was lost to the system by (a) decay and (b) being carried downstream

3. Note the substantial losses in net production as energy passes from one trophic level to the next.

4. The ratio of net production at one level to net production at the next higher level is called the conversion efficiency. Here it varied from

(a) 17% from producers to primary consumers (1478/8833) to

(b) 4.5% from primary to secondary consumers (67/1478).

5. From similar studies in other ecosystems, we can take 10% as the average conversion efficiency from producers to primary consumers.

Check this informational webpage (has a good diagram which you can use): http://users.rcn.com/jkimball.ma.ultrane...