1 The diagram below represents a food chain in a garden.
Rose
Greenfly
Ladybird
Blackbird
A food chain in a garden
1.1
Name the organism above that represents the following:
(a) Herbivore
(b) Producer
(1)
(1)
1.2
A rose bush contains 1 000 kJ/m2 /year of energy and only 10% of this
energy is passed on at each trophic level of the food chain. How much
energy will be passed on to the blackbird? Show ALL your calculations.
(4)
1.3
If all the greenflies in this garden were removed, explain what would
happen to the populations of the following:
(a) Rose plants
(b) Ladybirds
(C) Blackbirds
(2)
(2)
(2)
(12)​

The correct answer is -

1.1 A. herbivore - greenfly

b. producer - rose

1.2. 1 kJ/m2/year

1.3 rose plants will increase, ladybirds will decrease, blackbirds will decrease.

Explanation:

In this food chain,

Rose >>Greenfly >>Ladybird >>Blackbird

Rose plants are the producers as they generate their food and energy and does not depend on other organisms where as greenfly are the primary consumer or herbivore as they depend on the rose plant for their food and energy only, however, ladybird as secondary consumer and blackbird as tertiary consumer depend on greenfly and ladybird respectively.

If rose plants have 1000 kJ/m2 /year of energy and as it is known that only 10% moves to the next tropic level then blackbird would have:

rose = 1000

greenfly = 1000*10/100= 100 kJ

ladybird = 100*10/100 = 10kJ

blackbird = 10*10/100 = 1 kJ

If greenfly removes from here the rose plant will increase as these depends and eat rose plants and lady bird will decrease as these are the primary source of food for lady bird and if ladybird decrease blackbird also decrease.