Energy & Feeding Relationships (CIE IGCSE Biology: Co-ordinated Sciences (Double Award))

Fig. 1 represents the carbon cycle.

Fig. 1

Use Fig. 1 to answer the following questions.

Name the process labelled U.

[1]

Name a group of organisms that are responsible for the process labelled W.

[1]

 List two letters that identify respiration.

[2]

 State which letter identifies photosynthesis.

State the word equation for aerobic respiration.

Suggest reasons why the mean percentage of carbon dioxide in the atmosphere has increased during the last 100 years.

• Star grass is eaten by antelope species, such as topi and Thomson’s gazelle.
• Smaller animals such as mice and grasshoppers feed on red oat grass.
• Topi and Thomson’s gazelle are eaten by predators such as cheetahs, lions and serval cats.
• Grasshoppers and mice are eaten by serval cats and tawny eagles.
• Vultures feed on dead mammals.

Fig. 1 shows part of the food web for this ecosystem.

Fig. 1

Complete the food web by writing the names of the correct organisms in the boxes in Fig. 1.

Name the trophic level of the following species.

[1]

Topi

[1]

[1]

[1]

Extended Tier Only

Explain why there are no more than four trophic levels in the food web shown in Fig. 1.

Fig. 1 shows a simple food web.

Fig. 1

Table 1 shows some of the terms that can be used to describe the organisms in the food web in Fig. 1.

Place ticks (✓) in the boxes to show the terms that can be used to describe each organism.

Table 1

[3]

State the number of trophic levels in the food web in Fig. 1.

[1]

Identify one organism that feeds at more than one trophic level.

[1]

State the term used to describe an organism that gets its energy from dead or waste organic material.

[1]

State the principal source of energy for food webs.

[1]

(i)

The sentences in the box describe the feeding relationships between four organisms. 

Use the information in the sentences to write a food chain containing these four organisms.

Do not draw pictures of the organisms.

[3]

State the principal source of energy for this food chain.

[1]

State the type of organism that gains its energy from dead organic material.

[1]

(i)

A species becomes endangered when it is at risk of extinction.

Explain two ways in which a species could become endangered.

[4]

State one way in which endangered species can be conserved.

[1]

Fig. 1 shows part of the carbon cycle.

Fig. 1

Identify the processes shown by arrows A, B and C on Fig. 1.

Choose words from the list.

(i)

On Fig. 1 draw one arrow to represent photosynthesis.

Label this arrow with a letter D.

[1]

On Fig. 1 draw one arrow to represent respiration.

Label this arrow with a letter E.

The concentration of carbon dioxide in the atmosphere is increasing.

Describe two possible causes of the increased carbon dioxide concentration in the atmosphere.  

[2]

State two adverse effects of the increase in carbon dioxide concentration in the atmosphere.

Carbon dioxide is a greenhouse gas.

State the name of one other greenhouse gas.

Describe how human activities are affecting the carbon cycle.

Fig. 1 shows a food chain that is found in the sea.

Fig. 1

State the name of the producer in this food chain.

[1]

Define the term producer.

State the name of the secondary consumer in this food chain.

[1]

State the name of the herbivore in this food chain.

[1]

State what the arrows in a food chain represent.

[1]

In some countries humans eat crabs.

Explain how the over-harvesting of crabs could affect the other organisms in the food chain shown in Fig. 1.

A type of organism gains energy from waste organic material from all trophic levels.

State the name of this type of organism.

Extended Tier only

(i)

Outline how organisms in the first trophic level of the woodland food chain produce biomass using energy from the Sun.

[3]

Explain why the fourth trophic level has the least biomass in this food chain.

[3]

The woodland is a conservation area.

Outline the possible benefits of conserving this specific area of woodland.