Digestion

Eating too much carbohydrate can cause obesity.

Name one disease that obesity is a risk factor for.

Table 5 shows information about sugar intake and obesity in different countries.

Complete Figure 10.

You should:

• label the y-axis

• add the scale for the y-axis

• plot the data for countries C, D, E, F and G from Table 5

• draw a line of best fit.

Countries A and B have been completed for you.

Figure 11 shows information about the relationship between sugar intake and tooth decay.

Name the type of graph shown in Figure 11.

What relationship is shown between the two variables in Figure 11 ?

Tick () one box.

Sugars and starch are carbohydrates.

A student investigated the effect of temperature on the activity of amylase.

For each temperature, the student:

• mixed starch and amylase together

• added iodine solution after 5 minutes.

The iodine solution was yellow-brown before it was added to the mixture.

Table 6 shows the results.

Explain the results at 30 °C and at 90 °C.

How could the student change the investigation to find a more precise temperature that amylase works best at?

Tick () one box.

Protease enzymes are involved in protein digestion.

Different types of protease enzyme are active in different organs of the digestive system.

Complete Table 7 to identify the organ where each protease enzyme is active.

Eating too much carbohydrate can cause obesity.

Name one disease that obesity is a risk factor for.

Table 1 shows information about sugar intake and obesity in different countries.

Complete Figure 2.

You should:

• label the y-axis

• add the scale for the y-axis

• plot the data for countries C, D, E, F and G from Table 1

• draw a line of best fit.

Countries A and B have been completed for you.

Figure 3 shows information about the relationship between sugar intake and tooth decay.

Name the type of graph shown in Figure 3.

What relationship is shown between the two variables in Figure 3 ?

Tick () one box.

Sugars and starch are carbohydrates.

A student investigated the effect of temperature on the activity of amylase.

For each temperature, the student:

• mixed starch and amylase together

• added iodine solution after 5 minutes.

The iodine solution was yellow-brown before it was added to the mixture.

Table 2 shows the results.

Explain the results at 30 °C and at 90 °C.

How could the student change the investigation to find a more precise temperature that amylase works best at?

Tick () one box.

Protease enzymes are involved in protein digestion.

Different types of protease enzyme are active in different organs of the digestive system.

Complete Table 3 to identify the organ where each protease enzyme is active.

In people with severe liver disease the liver stops working correctly.

A person with severe liver disease can be treated with:

• an injection of embryonic stem cells or

• a liver transplant from a donor.

The person’s body can reject embryonic stem cells and can reject a liver transplanted from a donor.

What property of embryonic stem cells makes them suitable to treat liver disease?

Suggest one ethical reason why a person may not want an injection of embryonic stem cells.

Drugs can be used to reduce the risk of liver rejection after a transplant.

One drug contains monoclonal antibodies.

The monoclonal antibodies are specific to an antigen on the surface of liver cells.

Figure 9 shows part of the process used to create the monoclonal antibodies.

Name the three types of cell in Figure 9.

How is the mouse stimulated to produce cell type A ?

A patient with severe liver disease was given a liver transplant.

The drug containing the monoclonal antibody is given to the patient.

Explain how the monoclonal antibody stops the patient’s white blood cells from attacking the cells of the donor liver.

Give one other use of monoclonal antibodies.

Do not refer to pregnancy tests.

The liver produces bile.

Bile is needed for efficient digestion.

Where is bile stored in the human body?

Tick () one box.

Explain why a person with severe liver disease has difficulty digesting fats.

Starch and sugar are two types of carbohydrate.

Describe the chemical tests that a student could use to show if bread contains:

• starch

• sugar.

You should include the results of a positive test and a negative test for each type of carbohydrate.

A student investigated three types of bread.

For each type of bread, the student:

• put a square piece of bread into their mouth

• did not chew the bread

• recorded the time taken for the bread to taste sweet.

Table 2 shows the results.

Complete the sentences.

Choose answers from the box.

The starch in the bread was broken down by the

What was the independent variable in the investigation?

Tick () one box.

Give two conclusions that can be made from the results in Table 2.

Table 2 is repeated below.

The student improved the investigation.

Table 3 shows the results.

What did the student do to improve the investigation?

Use Table 2 and Table 3.

Calculate value X in Table 3.

Why should the student do the investigation with more people?

Tick () one box.

Cystic fibrosis (CF) is an inherited disorder caused by a faulty gene.

Where in a cell would the CF gene be found?

CF affects many organs in the body.

The main organs affected are:

• the lungs

• the pancreas

• the small intestine.

Figure 7 shows organs of the human body.

Which letters in Figure 7 show the lungs, the pancreas and the small intestine?

Tick () one box.

The pancreas produces several digestive enzymes.

CF reduces the amount of each enzyme that reaches the small intestine.

Explain why a person with CF has:

• difficulty digesting food

• difficulty gaining body mass.

Gas exchange happens in the alveoli in the lungs.

Describe three features of the alveoli that help maximise gas exchange.

CF reduces the amount of oxygen that can enter the blood from the alveoli.

Explain how a reduced amount of oxygen entering the blood will affect the human body.

Cystic fibrosis (CF) is an inherited disorder caused by a faulty gene.

Where in a cell would the CF gene be found?

CF affects many organs in the body.

The main organs affected are:

• the lungs

• the pancreas

• the small intestine.

Figure 2 shows organs of the human body.

Which letters in Figure 2 show the lungs, the pancreas and the small intestine?

Tick (✓) one box.

The pancreas produces several digestive enzymes.

CF reduces the amount of each enzyme that reaches the small intestine.

Explain why a person with CF has:

• difficulty digesting food

• difficulty gaining body mass.

Gas exchange happens in the alveoli in the lungs.

Describe three features of the alveoli that help maximise gas exchange.

CF reduces the amount of oxygen that can enter the blood from the alveoli.

Explain how a reduced amount of oxygen entering the blood will affect the human body.

Cake and bread each contain the same two types of carbohydrate.

Describe the chemical tests that could be used to show the presence of the two types of carbohydrate in cake.

Include a risk assessment in your answer.

A student investigated three types of bread.

For each type of bread, the student:

• put a square piece of bread into their mouth

• did not chew the bread

• recorded the time taken for the bread to taste sweet.

Table 2 shows the results.

What was the dependent variable in the investigation?

Give one control variable the student should have used in the investigation.

During the investigation, the bread began to taste sweet in the student’s mouth.

Explain why the bread tasted sweet.

Suggest one reason why the results of the investigation were not valid.

Do not refer to control variables in your answer.

This question is about food and digestion.

Proteins are needed to make new body cells by mitosis.

Give one reason why a person needs new body cells.

What are proteins made of?

Tick (✓) one box.

Which chemical is used to test for protein in food?

Tick (✓) one box.

What colour would be seen in a positive test for protein?

Tick (✓) one box.

Enzymes break down food molecules in the human body.

Characteristics of enzymes are linked to their function.

Draw one line from each characteristic to its effect on enzyme function.

Figure 3 shows how pH affects the rate of breakdown of protein.

Which pH does enzyme Y work fastest at?

Explain why enzyme X works best in the stomach.

Complete the sentences.

Choose answers from the box.

Enzyme Y does not break down protein at pH 6 because the shape of the enzyme has changed.

The part of the enzyme that changes shape is

the.

The change in shape means the enzyme cannot bind to

the.

Amylase is an enzyme which breaks down starch.

A student investigated the effect of pH on the rate of starch breakdown by amylase.

Figure 4 shows some of the apparatus the student used.

Describe a method to investigate the effect of pH on the rate of starch breakdown by amylase.

You should include the apparatus shown in Figure 4.

Plant cells and fungal cells are similar in structure.

Figure 10 shows a fungal cell.

Name one structure in Figure 10 which is present in both plant cells and fungal cells but not in animal cells.

Which disease is caused by a fungus?

Tick (✓) one box.

A fungal cell divides once every 90 minutes.

How many times would this fungal cell divide in 24 hours?

Some types of fungal cell are grown to produce high-protein food.

The high-protein food can be used to make meat-free burgers.

Where is protein digested in the human digestive system?

Tick (✓) one box.

Which chemical could be used to test if the burgers contain protein?

Tick (✓) one box.

Table 7 shows some information about burgers made from meat and meat-free burgers.

Evaluate the use of burgers made from meat compared with meat-free burgers in providing humans with a healthy, balanced diet.

Use information from Table 7 and your own knowledge.

Plant cells and fungal cells are similar in structure. Figure 2 shows a fungal cell.

Name one structure in Figure 2 which is present in both plant cells and fungal cells but not in animal cells.

Which disease is caused by a fungus? Tick (✓) one box.

A fungal cell divides once every 90 minutes. How many times would this fungal cell divide in 24 hours?

Some types of fungal cell are grown to produce high-protein food.

The high-protein food can be used to make meat-free burgers.

Where is protein digested in the human digestive system? Tick (✓) one box.

Which chemical could be used to test if the burgers contain protein? Tick (✓) one box.

Table 3 shows some information about burgers made from meat and meat-free burgers.

Evaluate the use of burgers made from meat compared with meat-free burgers in providing humans with a healthy, balanced diet. Use information from Table 3 and your own knowledge.

Turn over for next question

Carbohydrates are needed as part of a balanced diet.

Which formula shows glucose? Tick (✓) one box.

Which type of enzyme breaks down starch? Tick (✓) one box.

A student investigated the effect of temperature on the activity of the

enzyme amylase. Figure 7 shows the apparatus used.

This is the method used.

1. Set up the apparatus as shown in Figure 7.

2. After 5 minutes, pour the starch solution into the amylase solution and mix.

3. Remove one drop of the amylase-starch solution mixture and place onto a spotting tile.

4. Immediately add two drops of iodine solution to the amylase-starch solution mixture on the spotting tile.

5. Record the colour of the iodine solution added to the amylase-starch solution mixture.

6. Repeat steps 3 to 5 every minute until the iodine solution is yellow-brown.

Name apparatus Q in Figure 7.

Why were the starch solution and the amylase solution left for five minutes before mixing them together? Tick (✓) one box.

Figure 8 shows the results.

How many minutes did it take until the iodine solution and amylase-starch solution mixture was yellow-brown? Use Figure 8.

How could a more accurate time be obtained? Tick (✓) one box.

The student repeated the investigation at five different temperatures.

Table 2 shows the results.

Which temperature did the enzyme work quickest at? Tick (✓) one box.

Explain why the iodine solution remained blue-black in the investigation at 80 ° C.

Amylase is an enzyme that breaks down starch.

Amylase is a polymer of smaller molecules.

Name the type of smaller molecule.

Name the three parts of the human digestive system that produce amylase.

Explain how amylase breaks down starch.

Answer in terms of the ‘lock and key theory’.

A student investigated the effect of temperature on the activity of amylase.

Figure 8 shows the apparatus used.

This is the method used.

1. Set up the apparatus as shown in Figure 8.

2. After 5 minutes, pour the starch solution into the amylase solution and mix.

3. Remove one drop of the starch-amylase mixture and place onto a spotting tile.

4. Immediately add two drops of iodine solution to the starch-amylase mixture on the spotting tile.

5. Record the colour of the iodine solution added to the starch-amylase mixture.

6. Repeat steps 3 to 5 every minute until the iodine solution stays yellow-brown.

7. Repeat steps 1 to 6 using water at different temperatures.

Name two control variables the student used in the investigation.

Why did the student leave the starch solution and amylase solution for 5 minutes before mixing them?

Table 3 shows the results of the investigation.

What conclusion can be made about the effect of temperature on amylase activity between 20 °C and 65 °C?

Explain the results at 5 ° C and at 80 ° C.

Use Table 3.

The student investigated the effect of temperature on amylase activity.

Describe how the student could extend the investigation to determine the effect of a different factor on amylase activity.

Figure 11 shows where three of the same type of tumour were found in a patient.

Malignant tumours are cancers.

Describe what happens to cells when a tumour forms.

What evidence is there in Figure 11 to suggest that the tumour in the lung is malignant?

Some types of cancer can cause the numbers of blood components in a person’s body to fall to a dangerously low level.

A person with one of these types of cancer may experience symptoms such as:

• tiredness

• frequent infections

• bleeding that will not stop after the skin is cut.

Explain how a very low number of blood components in the body can cause these symptoms.

Some patients with a very low number of blood cells may be given a blood

transfusion.

A blood transfusion is where a patient receives blood from a donor.

Different people have different blood groups.

Figure 12 shows:

• the red blood cells found in people with different blood groups

• the antibodies that can be made by people with different blood groups.

Antibodies can bind to antigens that have complementary shapes.

When antibodies bind to the antigens on red blood cells, many red blood cells begin to clump together.

Each red blood cell is about 8 µm in diameter.

Many capillaries have an internal diameter of about 10 µm.

In one type of blood transfusion, only red blood cells from a donor are transferred to

the patient.

It is dangerous for a patient with blood group A to receive red blood cells from a donor with blood group B.

Explain why.

Explain why blood group O red blood cells can be given to patients with any blood group.

Table 4 shows some of the risks associated with blood transfusions.

Which risk has the lowest probability of occurring?

Tick (✓) one box.

A person has a tumour blocking the tube leading from the gall bladder to the small intestine.

Explain why this person would have difficulty digesting fat.

Lipases break down lipids. Which two products are formed when lipids are broken down? Tick (✓) two boxes.

One model used to explain enzyme action is the ‘lock and key theory’.

Figure 7 shows a model of the theory.

Explain the ‘lock and key theory’ of enzyme action. Use information from Figure 7 in your answer.

There are many different types of lipase in the human body. Why does each different type of lipase act on only one specific type of lipid molecule?

Students investigated the presence of starch and glucose in the leaves of

geranium plants. This is the method used.

1. Place two identical geranium plants on a bench near a sunny window for two days.

2. After two days:

leave one plant near the window for two more days.

place one plant in a cupboard with no light for two more days.

3. Remove one leaf from each plant.

4. Crush each leaf to extract the liquid from the cells.

5. Test the liquid from each leaf for glucose and for starch.

Describe how the students would find out if the liquid from the leaf contained glucose.

Describe how the students would find out if the liquid from the leaf contained starch.

Table 2 shows the students’ results.

Explain why the leaf in the light for four days contained both glucose and starch.

Explain why the leaf left in a cupboard with no light for two days did contain glucose but did not contain starch.

Suggest one way the students could develop the investigation to find out more about glucose and starch production in plants.

Many foods contain carbohydrates.

Figure 1 shows information about four different foods.

Which food contains the highest percentage of carbohydrate?

Tick (✓) one box.

Estimate the percentage of water found in beans.

Look at Figure 1.

Why would eating only beans provide a more balanced diet than eating only chicken?

Sugars are produced when enzymes break down starch.

What is the name of the enzyme which breaks down starch to produce sugars?

Tick (✓) one box.

Which chemical could be used to test for glucose?

Tick (✓) one box.

What colour change would be seen in a positive test for glucose?

From blue to.

People with diabetes have difficulty controlling the concentration of glucose in their blood.

The blood of four people was tested.

Table 1 shows the results.

Table 2 shows the information used to help decide if a person has diabetes.

Which person has severe diabetes?

Tick (✓) one box.

Figure 2 shows part of the human digestive system.

Glucose is absorbed into the bloodstream in part X.

Name part X.

Complete the sentences.

Choose answers from the box.

Some glucose is absorbed into the bloodstream against the concentration gradient by

the process of.

Water moves out of part Y and into the bloodstream by

the process of.

Pancreatic cancer develops when a malignant tumour grows inside the pancreas.

The pancreas produces digestive enzymes. What is an enzyme?

Carbohydrase is an enzyme produced by the pancreas.

Name two other organs in the digestive system that produce carbohydrase.

One symptom of pancreatic cancer is weight loss. Explain how pancreatic cancer may cause a person to lose weight. Do not refer to hormones in your answer.

Enzyme A and enzyme B are involved in controlling cell division in pancreatic cancer cells. Most cancer cells produce both enzyme A and enzyme B. Some people have a gene mutation that stops cancer cells producing enzyme B.

Figure 9 shows how cell division is controlled in pancreatic cancer cells.

Scientists have developed a drug that inhibits enzyme A. The drug is given to pancreatic cancer patients who have the gene mutation that stops cancer cells producing enzyme B. The drug only targets cancer cells.

Explain why the drug can be used to treat pancreatic cancer in patients with the gene mutation.

Use information from Figure 9.

Explain why the drug could not be used to treat pancreatic cancer in a patient that produces both enzyme A and enzyme B.

The drug was trialled before it was licensed for use. To improve validity of the results in the trial:

• some patients were given a placebo

• a double-blind trial was used.

Give reasons why a placebo and a double-blind trial were used.

A double-blind trial

One stage in a drug trial is to test the drug on healthy volunteers.

What is the next stage in the drug trial?

Tick (✓) one box.

A monoclonal antibody has been produced to treat pancreatic cancer.

Explain how the monoclonal antibody works to treat pancreatic cancer.

Figure 5 shows the human digestive system.

Label organs A, B and C.

Complete the sentences.

Choose the answers from the box.

Digestion is the process of breaking down large food molecules into smaller

chemical reactions.

If the temperature of an enzyme gets too high, the enzyme is

Protease is an enzyme.

Protease breaks down protein.

What is protein broken down into?

Tick one box.

Why is protein needed by the body?

Which organ in the human digestive system produces protease?

Tick one box.

Describe how you would test a sample of food to show it contains protein.

Give the reason for any safety precautions you would take.

Complete the sentence.

Choose the answer from the box.

Obesity can be caused by a diet high in.

Complete the sentence.

Choose the answer from the box.

Obesity is a risk factor for.

Earthworms are small animals that live in soil. Earthworms have no specialised gas exchange system and absorb oxygen through their skin.

What is the name of the process in which oxygen enters the skin cells?

Tick one box.

Table 3 shows information about four skin cells of an earthworm.

Which cell has the smallest difference in percentage of oxygen between the outside and the inside of the cell?

Tick one box.

Which cell will oxygen move into the fastest?

Tick one box.

Earthworms have a large surface area to volume ratio.

Suggest why a large surface area to volume ratio is an advantage to an earthworm.

The earthworm uses enzymes to digest dead plants.

Many plants contain fats or oils.

Which type of enzyme would digest fats?

Earthworms move through the soil.

This movement brings air into the soil.

Dead plants decay faster in soil containing earthworms compared with soil containing no earthworms.

Explain why.

When earthworms reproduce, a sperm cell from one earthworm fuses with an egg cell from a different earthworm.

Name the process when an egg cell and a sperm cell fuse.

Some types of worm reproduce by a process called fragmentation.

In fragmentation, the worm separates into two or more parts. Each part grows into a new worm.

What type of reproduction is fragmentation?

Table 8 shows information about some food components in cow’s milk.

How much more milk would a typical adult have to drink to get their RDA for calcium compared with the amount of milk needed to get their RDA for vitamin B-12?

Describe how a student could test cow’s milk to show whether it contains protein and different types of carbohydrate.

A scientist investigated the effect of bile on the breakdown of fat in a sample of milk.

The scientist used an indicator that is colourless in solutions with a pH lower than 10, and pink in solutions with a pH above 10.

This is the method used.

1. Add 1 drop of bile to a test tube and one drop of water to a second test tube.

2. Add the following to each test tube:

• 5 cm³ of milk

• 7 cm³ of sodium carbonate solution (to make the solution above pH 10)

• 5 drops of the indicator

• 1 cm³ of lipase.

3. Time how long it takes for the indicator in the solutions to become colourless.

The results are shown in Table 9.

Explain why the indicator in both tubes became colourless.

Give the reason why the measurement of the time taken for the indicator to become colourless might be inaccurate.

Explain the difference in the results for the two test tubes in Table 9.