Feeding Relationships (Edexcel GCSE Biology)

Figure 1 shows a food chain for different organisms living in the sea. This biomass at each trophic level is also shown.

Figure 1

Describe the third trophic level of this food chain.

Draw a pyramid of biomass for the food chain shown in Figure 1 on the graph axis provided below.

You should use a suitable scale and ensure that all labels are included.

Calculate the percentage of the biomass transferred from the phytoplankton to the snapper fish.

Give the answer to 2 significant figures.

Give three ways in which energy can be lost between trophic levels.

Figure 1 shows a food chain in an ecosystem that has five different organisms occupying five trophic levels, A, B, C, D and E.

Figure 1

Decomposers are not shown in the food chain in Figure 1.

Identify which trophic level decomposers would occupy and explain the role these microorganisms play in an ecosystem.

Figure 2 below shows the energy transferred by each organism in one year.

Explain why organism D would transfer much less energy than organism A.

Explain why food chains rarely have more than five trophic levels.

Figure 1 shows the flow of energy through a food chain in a habitat over the course of one year. The figures are in kJ m^–2.

Figure 1

Calculate the percentage of the energy in sunlight that was transferred into energy in the mayfly larvae

Show your working.

Give your answer in standard form.

Explain how energy from sunlight is converted into biomass in the algae.

Suggest explanations for the difference in the amount of energy transferred from the trout to the humans.

Two food chains are shown below:

Food chain 1: Soya bean plants → Salmon  → Human

Food chain 2: Soya bean plants → Human

Figure 1 shows some data about the energy transferred between organisms in the food chains.

Figure 1

Using the information provided, compare the efficiency of these two food chains.

Figure 2 below shows a pyramid of numbers and a pyramid of biomass for an area of woodland.

Figure 3 shows a food chain in a woodland area.

Figure 3

Energy from the sun is captured by the plants in the wood.

Describe and explain the route of this energy through the food chain after it has been captured by the plants in the wood.

Figure 1 contains information about two farms. Both farms are of similar size and have similar conditions.

Figure 1

The data in Figure 1 show that farms like Haverstock Farm can be more than 12 times as efficient at meeting the food energy requirements for our growing human population than farms which grow feed for livestock.

Explain why Haverstock Farm is much more efficient at meeting human food energy requirements

Figure 2 shows a food web found in a woodland ecosystem.

Figure 2

A student investigated fish food.

The student added some fish food to a blue liquid in a test tube.

The solution turned from blue to purple.

(i)

Use words from the box to complete the sentences.

(2)

The blue liquid was .................................... solution.

The purple colour showed that the fish food contained .....................................

(ii)

The blue solution may be harmful if swallowed.

Which procedure is a health and safety precaution needed for this investigation?

(1)

Fish eat fish food.

The fish food contains energy.

Some of this energy is used by the fish for growth.

Figure 1 shows this energy transfer.

Each square in Figure 1 represents 1kJ of energy.

Figure 1

Calculate the percentage of energy from the fish food that has been used in the growth of fish.

(2)

(ii)

Describe what happened to the fish food that was eaten but was not used in the growth of the fish.

(2)

Since 2003, in France, people have been buying Siberian chipmunks as pets but then releasing them into the wild when they are no longer wanted.

They are now classified as an invasive species.

Figure 1 shows a Siberian chipmunk (Tamias sibiricus).

Alpsdake, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons

Figure 1

Siberian chipmunks eat acorns, which are the seeds of oak trees.

In Siberia, the natural predators of Siberian chipmunks are wild dogs.

(2)

In France, Siberian chipmunks have very few natural predators.

Describe how this affected the Siberian chipmunk population in France.

(2)

(iii)

The percentage of energy transferred from the acorns to the chipmunks is 9.5%.

The energy contained in the acorns is 97 500 kJ.

Calculate the amount of energy transferred to the chipmunks.

Give your answer to the nearest whole number.

The black-legged tick (Ixodes scapularis) is a parasite that feeds on the blood of animals including Siberian chipmunks and humans.

The tick transmits the Lyme disease pathogen.

Figure 2 shows the number of cases of Lyme disease in humans in France in 2003 and 2015.

(2)

A group of researchers investigated a food chain on a piece of waste ground. 

Clover   →   slug   →   starling (a bird)

The researchers made various counts / estimates, as follows:

• An estimate of the number of clover plants growing on the waste ground
• An estimate of the number of slugs feeding on the clover
• A count of the number of starling appearances on the waste ground over a 6-hour period

Table 1 shows the results of the investigation and some of the researchers' calculations. 

Table 1

Calculate the missing values X and Y in Table 1.

Ecologists agree that approximately 90% of biomass is lost from one trophic level to the next. 

Suggest two reasons why the data in Table 1 gave a 'percentage of biomass lost' value of only 61% between the slugs and the starlings.

In a similar study on another piece of ground, the researchers estimated the number of clover plants in the area of waste ground to be 17 600 plants.

The area of the waste ground was measured accurately using GPS technology and found to be 2 200 m².

The quadrats used by the researchers were 0.5m × 0.5m square.

Given that the researchers actually counted a total of 880 clover plants, calculate the number of quadrats that they sampled in this area of waste ground. 

Give two suggestions why calculations of the type in Table 1 are often subject to error. 

Figure 1 below shows a food chain from the Weddell Sea, an area of the Southern Ocean off the coast of Antarctica. 

Figure 1

Human fishing activity has removed large amounts of sea bass, which is a popular food in many countries. 

There is some debate about the effect this would have on the numbers of Antarctic squid and icefish in the Weddell Sea. Some scientists believe that the numbers of squid and icefish will decrease, whilst others claim that squid and icefish numbers will not be affected. 

Explain both sides of this debate.

(1)

(2)

Part of the Weddell Sea food chain from Figure 1 in (a) is shown below in Figure 2, which includes data on the biomass of the organisms that form part of that food chain. 

Figure 2

Draw and label a pyramid of biomass for this food chain. 

Using the data from Figure 2, complete Table 2 below to show the percentage efficiency of each biomass transfer of the Weddell Sea.

Table 2

Explain why the conversion of shrimp biomass into sea bass biomass is more efficient than that of sea bass biomass into Weddell seal biomass in the cold Weddell Sea.