Photosynthesis

Katydids are insects that are green and look like the leaves that they feed on. The photograph shows a katydid.

Explain how katydids affect the growth of the plants that they feed on.

Explain how katydids have evolved to look like leaves.

Plants produce their own food by photosynthesis.

Give the balanced chemical symbol equation for photosynthesis.

The table gives data from an investigation that measured the mass of carbon dioxide (CO₂ released globally between 1990 and 2014.

Plot a line graph to show the mass of CO₂ released globally between 1990 and 2014. Use a ruler to join your points with straight lines.

Calculate the percentage increase in the mass of CO₂ released globally between 1990 and 2014.

percentage increase =_........

Give three negative effects of increased levels of CO₂ in the atmosphere.

The concentration of CO₂ in the atmosphere has increased. Explain how plants may limit this increase.

A scientist does an experiment using a photosynthetic organism and bacteria. The photosynthetic organism lives in water and has a spiral chloroplast. The bacteria need oxygen to survive. The scientist shines different colours of light on the photosynthetic organism and adds the bacteria to the water. The diagram shows the location of the bacteria during the experiment.

Use the information from the diagram to suggest two conclusions that can be made about photosynthesis.

The scientist concludes that bacteria are living organisms. Explain how the diagram supports this conclusion.

Name two structures found in bacteria.

NASA (the National Aeronautics and Space Administration) is investigating how to grow plants on space stations. As part of their investigation, NASA scientists looked at the effect of using different types of lamp on the rate of photosynthesis in spinach plants.

Explain why the scientists expected a link between rate of photosynthesis and biomass produced.

The scientists measured the rate of photosynthesis and the biomass produced for different types of lamp. The table shows their results.

Plot a bar graph to show the biomass produced for each type of lamp.

Suggest why the rate of photosynthesis and the biomass produced do not follow a similar pattern.

Suggest which lamp would be best for a spinach grower to use in his glasshouse.

Name three factors, other than light, that would affect the rate of photosynthesis.

Suggest why NASA is investigating how to grow plants in space stations.

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 amount of light falling on plant leaves is an abiotic (non-living) factor that affects photosynthesis.

Give the balanced chemical equation for photosynthesis.

The leaves of plants that live in the shade (low light) are different to the leaves of plants that live in full sunlight.

Suggest why leaves from plants that live in the shade are darker green than leaves from plants that live in full sunlight.

Explain why leaves from plants that live in the shade are thinner than leaves from plants that live in full sunlight.

The rate of photosynthesis changes during the day.

Explain the factors that affect the rate of photosynthesis in the early morning.

Explain the factors that affect the rate of photosynthesis in the early afternoon.

Describe how you could compare the rate of photosynthesis in two different plant species.

A student investigates the effect of carbon dioxide concentration on the rate of photosynthesis in a water plant. The graph shows the student’s results.

Put an X on the graph to show where carbon dioxide limits the rate of photosynthesis.

Write the word equation for photosynthesis.

The student’s method allows her to make a valid and reliable comparison of the rate of photosynthesis at different carbon dioxide concentrations.

Give the independent variable in her investigation.

Suggest a variable the student needs to control in her investigation.

Explain how the student could make sure her results are reliable.

4 (a) Nile tilapia are fish. Their body colour is controlled by a single gene. The allele N produces normal body colour and the allele n produces pink body colour. Diagram 1 shows the phenotypes and the genotypes of Nile tilapia. normal body colour (NN) normal body colour (Nn) pink body colour (nn)

Diagram 2 shows all the possible crosses between the phenotypes and genotypes of Nile tilapia parents.

The table gives some descriptions of offspring. Complete the table by giving the number of crosses that would produce each description of offspring. The first one has been done for you.

Tilapia are farmed in many parts of the world to provide a source of protein. Farmers build large ponds and fill them with fish. The ponds are exposed to sunlight and the farmers add manure to help the growth of the fish. Some of the water in the ponds is changed every day.

Suggest how sunlight and manure help the growth of the fish.

Suggest why some of the water is changed every day.

A fish farm contains 6000 fish. The average (mean) increase in mass of a fish over a period of 32 weeks is 700 g. Estimate the total mass of fish, in kg, that the fish farm could produce after 32 weeks.

Plants make food by the process of photosynthesis.

Write a balanced chemical symbol equation for photosynthesis.

The leaf of a plant is adapted to carry out photosynthesis. Explain how the following parts of the leaf are adapted for photosynthesis.

palisade mesophyll layer

spongy mesophyll layer

guard cells

A student uses this method to show that starch is produced during photosynthesis. Step 1 put a potted plant in a dark cupboard for 24 hours Step 2 then put the plant in bright sunlight for 12 hours Step 3 remove a leaf from the plant and put it in a beaker of boiling water for 30 seconds Step 4 put the leaf in a boiling tube containing hot ethanol for 10 minutes Step 5 wash the leaf in cold water and put it on a white tile Step 6 add enough iodine solution to cover the leaf and observe the change in colour

Explain why the student put the plant in a dark cupboard for 24 hours in step 1.

Describe how the student could carry out step 4 safely.

State the colour of the leaf observed in step 6.

The student concludes that starch is produced by photosynthesis in the leaf. State a suitable control that she should use to make her conclusion valid.

Plants need to absorb mineral ions from the soil to enable them to produce other biological molecules. Complete the table by giving the missing information.

Plants obtain their nutrition by photosynthesis.

Write the balanced chemical symbol equation for photosynthesis.

Explain how the rate of photosynthesis is affected by changes to abiotic (non-living) factors throughout the day.

Explain how very high temperatures might reduce the growth of plants.

A student investigated the effect of red, green and blue light on the rate of oxygen production of a water plant. She used the apparatus shown.

The student shone different coloured lights on the plant. She measured the rate of oxygen production, for each colour, by counting the number of bubbles released per minute. The results are shown in the table.

Give two reasons why the data in the table are reliable.

Suggest how the student could modify the apparatus to measure the rate of oxygen production more accurately.

Name the independent variable in this investigation.

The student changed the colour of the light but kept the intensity the same. Give three other variables that she should keep the same in order to make the comparison of oxygen production valid.

The photograph shows an organism called lichen growing on the surface of a tree.

Lichens are unusual because they consist of a fungus and an algae living together.

The fungus grows hyphae that help it feed by saprotrophic nutrition. Explain what is meant by the term saprotrophic nutrition.

The diagram shows a fungal hypha with parts labelled A to D.

Which letter labels the part made from chitin?

Which letter labels the part made from glycogen?

Algae are green organisms that carry out photosynthesis.

Name the molecule that makes algae look green.

Write the word equation for photosynthesis.

Caroline investigated how light affected photosynthesis by looking at changes in carbon dioxide levels. She placed 2 cm³ of orange hydrogen carbonate indicator solution into three test tubes. She put a leaf in two of the test tubes, which were then firmly sealed with a bung. These leaves were similar in size and were taken from the same plant. She wrapped one of the test tubes in foil to prevent light entering. The third test tube was firmly sealed with a bung but was without a leaf. She left the three test tubes in the conditions shown in the diagram for two hours. They were then shaken gently and the leaves were removed.

Hydrogen carbonate indicator solution is orange in normal air. It changes colour to red as the carbon dioxide level decreases. It changes to yellow as the carbon dioxide level increases. The colour of the indicator solution in each test tube was recorded. Her results are shown in the table.

C orange red

Explain the colour change observed in test tube C.

Explain the purpose of test tube B.

Caroline set up a fourth test tube that contained a leaf and was exposed to dim light. After two hours the colour of the indicator solution in this test tube remained orange. Explain why.

Caroline carried out another experiment to investigate the effect that light intensity has on the rate of photosynthesis in a water plant.

Suggest how she could change her independent variable.

Suggest how she could measure her dependent variable.

Suggest how she could ensure that her results were reliable.