Interdependence

The grasslands of Africa are an example of an ecosystem.

Fig. 11.1 shows a food chain within this ecosystem.

Fig. 11.1

Name an example of each of the following in the food chain shown in Fig. 11.1.

A primary consumer.

An abiotic component.

Describe the role of grass as a producer in this food chain.

Organisms depend on each other for survival. This is called interdependence.

Fig. 11.2 shows a buffalo and some oxpeckers.

Fig. 11.2

Ticks are small organisms that feed on, live on and harm the buffalo.

Oxpeckers sit on the buffalo eating the harmful ticks. They also warn the buffalo if danger is nearby.

Identify the type of relationship between these organisms using ideas about interdependence.

Ticks and buffalo........

Oxpeckers and buffalo........

15* The graph shows the changes in population of a predator and its prey.

Describe and explain the trends in the graph. Identify the predator and the prey using evidence from the graph to support your choice.

The picture is of a sword-billed hummingbird feeding on a flower.

• The hummingbird feeds on nectar from the flower.

• The flower benefits because the hummingbird transfers pollen from one flower to the next.

• This helps the flower to reproduce and develop seeds.

Which word describes the interdependence between the hummingbird and the flower?

competition mutualism parasitism predation

The long beak of the hummingbird is an adaptation that helps the bird to feed. The bird’s ancestors had shorter beaks.

Complete the sentences about the long beak of the sword-billed hummingbird.

The ancestors of the sword-billed hummingbird showed........ in beak length.

Members of the species with longer beaks fed on more nectar.

This meant they were more likely to........

The allele for longer beaks was passed on to the next........

Over time, all the hummingbirds evolved to have longer beaks.

This process is called natural........

Lions hunt and eat antelopes.

Which row correctly describes lions in this relationship?

The picture is of a sword-billed hummingbird feeding on a flower.

• The hummingbird feeds on nectar from the flower.

• The flower benefits because the hummingbird transfers pollen from one flower to the next.

• This helps the flower to reproduce and develop seeds.

What word describes the interdependence between the hummingbird and the flower?

The long beak of the sword-billed hummingbird is an adaptation that helps the bird to feed. The bird’s ancestors had shorter beaks.

Explain how the sword-billed hummingbird may have evolved to have a long beak. Include ideas about natural selection.

Plasmodium is a microbe that causes the disease malaria in humans. Humans act as a host for plasmodium.

Which term describes the relationship between plasmodium and humans?

A Consumer

B Mutualism

C Parasitism

D Predation

Complete these sentences about different factors that affect the ecosystem.

Use the words or phrases in the list.

abiotic biotic carbon dioxide food oxygen

pH in soil predators temperature

Living organisms affecting the ecosystem are known as........ factors.

Physical factors that affect living organisms are described as........ factors.

Physical factors that can directly affect the rate of photosynthesis include

........ and........ concentration.

A student investigates the relationship between bean plants and the bacteria that live in the roots of the bean.

They think the bacteria live inside root nodules.

Fig. 12.1 shows root nodules on a bean plant.

Fig. 12.1

The student takes a thin section of the nodule and looks at it under a light microscope.

Fig. 12.2 shows bacteria inside the root nodule.

Fig. 12.2

Describe how to take a thin section of the nodule and prepare it to view under a light microscope.

The bacteria were not visible clearly using a light microscope.

The student found an image taken using a different type of microscope.

Fig. 12.3 shows this image.

Fig. 12.3

The maximum resolution of a light microscope is 200 nm.

What type of microscope is used to take this image?

The bacteria live inside the bean plant cells in root nodules. The bacteria are able to take nitrogen gas from the air and turn it into nitrates. The plants use nitrates to make amino acids.

Explain the relationship between the bacteria and the bean plant. Include ideas about photosynthesis in your answer.

Cheetah hunt and kill zebra, then feed on the zebra meat.

Which term describes this feeding relationship?

A Competition

B Mutualism

C Parasitism

D Predation

Mutualism and parasitism involve two different organisms living together.

Which statement describes the difference between mutualism and parasitism?

A Both organisms benefit from living together in mutualism, only one benefits in parasitism.

B Both organisms benefit from living together in parasitism, neither benefit in mutualism.

C Neither organism benefits from living together in parasitism, both benefit in mutualism.

D One organism benefits from living together in mutualism, both benefit in parasitism.

Lichens are made up of a fungus and algae living together. The fungus gets nutrients from the algae and algae is sheltered by the fungus.

Which term describes this type of relationship?

A Competition

B Mutualism

C Parasitism

D Predation

Look at the diagram of the water cycle.

Complete these sentences about the diagram.

Choose words from the list.

combustion evaporation photosynthesis precipitation

run-off respiration transpiration

Arrows labelled A represent the process of........

Arrows labelled B represent the process of........

Arrows labelled C represent the process of........

How many predators does the shrimp have in this food web?

When plant material is decomposed by fungi, there is an increase in temperature.

Complete the sentences to explain why.

Choose words from the list.

endothermic excretion exothermic

respiration photosynthesis

During decomposition fungi release energy from the plants by the process of

........

This process releases energy as heat because the reaction is

........

Dogfish and minnows are fish that live in lakes.

Dogfish build nests to lay their eggs in. Minnows lay their eggs in the same nests as dogfish.

The dogfish protect the nest from predators.

Minnows move in and out of the nest. This helps to remove harmful bacteria and get oxygen to the eggs.

Dogfish usually eat minnows. When the dogfish have eggs they do not eat minnows.

Dogfish have two different interactions with the minnows.

Write down the names of these two types of interactions.

Describe when each interaction takes place.

One of the interactions benefits both minnows and dogfish.

Explain how.