Trophic levels

This food web comes from an African ecosystem.

What is meant by the term ecosystem ?

Identify all the producers in this food web.

Give the trophic level of the lion in this food web.

Name an organism that occurs at two different trophic levels in this food web.

Give the food chain from this web that contains four different organisms including the baboon.

Explain why the number of organisms usually decreases along a food chain.

The diagram shows a food chain.

How many consumers are shown in this food chain?

What term describes the trophic level of the snake?

Light is an abiotic (non-living) factor that affects the growth of maize.

Explain the role of light in helping the growth of maize.

Scientists measured the average (mean) daily increase in mass of maize in a square metre of a field in two different regions of the world. They also measured the daily light energy available in a square centimetre of each of the two regions. The table shows their results.

The scientists expected that the same light energy would produce the same average daily increase in mass of maize in each region of the world. However, the results show that the average daily increase in mass of maize produced in the UK was less than they expected. Calculate the average daily increase in mass the scientists expected to be produced in the UK.

average increase in mass =_........

The scientists concluded that factors other than light must be limiting the growth of maize in the UK. Name two other abiotic factors that could limit the growth of maize.

Give three reasons why not all of the energy available in the maize is transferred to the snake.

The passage describes how different organisms are classified into groups. Complete the passage by writing a suitable word or words in each of the spaces.

Plants are multicellular organisms. They have chloroplasts to carry out photosynthesis and cell walls made of_........ . They store carbohydrate as_........ or as sucrose.

Animals are also multicellular but do not carry out photosynthesis. They are able to move from place to place and are always described as_........ in food chains. They store carbohydrate as_........ .

Bacteria are single-celled organisms. They do not have a nucleus. Instead, they contain a circular_........ and smaller circles of DNA called_........ . Most bacteria feed off other living or dead organisms but some bacteria can make their own food by_........ .

Examples of bacteria include Lactobacillus, used in the production of_........

from milk, and Pneumococcus, that acts as a_........ causing the disease_........ .

The diagram shows a food web from a forest.

Use information from the food web to complete the table. The first one has been done for you.

Plant cell walls are made of cellulose. Cellulose is an insoluble molecule made from the same simple sugar as starch. The rabbit’s intestine contains bacteria that can digest cellulose. Suggest why this is an advantage for the rabbit.

The deer runs away when it sees the wolf.

Name the effector in this response.

The deer releases a hormone when it sees the wolf. Explain how this hormone helps the deer to run away.

The owl uses its eyes to find prey. The diagram shows a section through the owl’s eye.

Name the parts labelled A and B.

Describe the function of part A.

Describe the function of part B.

Name the producer in this food web.

Gazelles try to avoid being caught by lions by running away quickly. They can run at a top speed of 96 km per hour.

Calculate the distance in metres a gazelle runs in one minute at a speed of 96 km per hour. Show your working.

distance =_........ metres

Gazelles cannot maintain their top speed for a long time because a change in the type of respiration takes place in their muscle cells. Explain how this change in respiration stops gazelles from running at a top speed for a long time.

Zebras also try to avoid being caught by lions. It was thought that the striped coat of zebras helps to camouflage them. A new theory suggests the striped coat evolved because it reduces the number of biting flies that feed on zebra blood. Use your knowledge of natural selection to explain how a striped coat that reduces the number of flies feeding on zebra blood may have evolved.

Lions’ eyes are adapted to help them see in dim light.

Their eyes have a layer of cells behind the retina that reflects light which has passed through the retina. Suggest how this would help a lion see in low light intensities.

Suggest one other adaptation in the structure of a lion’s eye that helps the lion to see in low light intensities.

When a lion catches its prey it tears the meat into smaller pieces in its mouth before swallowing.

Suggest why the saliva released into the lion’s mouth does not contain amylase.

Explain how tearing the meat into smaller pieces helps digestion in the stomach.

The diagram shows part of a food web in an oak forest.

Use the information in the food web to complete the statements in the table. The first one has been done for you.

What effect would a decrease in the population size of caterpillars have on the population size of blue jays?

What is meant by the term population ?

The tick feeds on deer by sucking their blood. Name two different molecules that are found in the blood of deer that the tick could feed on.