Human Digestive System (Cambridge O Level Biology)

Exam Questions

3 hours30 questions
1a
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4 marks

Fig. 1 shows the marine iguana, Amblyrhynchus cristatus.

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Fig. 1

(i)

Marine iguanas are reptiles.

State two features that are used to classify animals as reptiles.

[2]

(ii)

State two structures that are present in plant cells that are not present in the cells of reptiles.

[2]

1b
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5 marks

Marine iguanas feed on seaweed. Seaweed contains starch.

(i)      State the names of two parts of the digestive system where starch is digested by enzymes.

[2]

(ii)

Explain why the shape of an enzyme is important for digestion.

[3]

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2a
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5 marks

During digestion, enzymes act on different types of food to produce simpler substances that can be absorbed.

Complete Table 1 by inserting the missing information.

Table 1

food type enzyme acting on the food type simpler substances produced
Protein Protease  
  Amylase  
    Fatty acids and glycerol

2b
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4 marks

The following diagram includes some of the stages of food breakdown and descriptions of these stages.

Complete the following by drawing lines to connect each stage of food breakdown with the correct description.

Stage of food breakdown   Description
     
Ingestion   Breakdown of large insoluble molecules into small soluble ones
     

Absorption

  Digested food molecules move into the cells of the body
     
Assimilation   Digested food molecules move through the wall of the intestine
     

Chemical digestion

  Taking in food and drink through the mouth

2c
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2 marks

Enzymes are involved with the chemical digestion of food molecules.

State two parts of the digestive system where chemical digestion occurs.

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3a
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2 marks

Fig. 1 shows teeth in a human skull. 

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Fig. 1

Add label lines and labels to Fig. 1 to identify an incisor tooth and a molar tooth.

3b
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3 marks

The teeth are responsible for the physical digestion of food molecules when we chew.

(i)

Define the term 'physical digestion'.

[2]

(ii)

Describe the purpose of physical digestion.

[1]

3c
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1 mark

Other than the chewing action of teeth, state one example of physical digestion.

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4a
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5 marks

Fig. 1 shows a diagram of part of the alimentary canal and associated structures. 

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Fig. 1

(i)

State the names of the structures labelled H and J.

Write your answers on Fig. 1.

[2]

(ii)

On Fig. 1 draw label lines with letters to show:

N where faeces are stored.

P where most water is absorbed.

R where digested food is absorbed.

[3]
4b
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2 marks

(i)

State the name of the process that is defined as the movement of digested food molecules into the cells of the body where they are used, becoming part of the cells.

[1]

(ii)

State the name of the process that removes faeces from the body.

[1]

4c
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3 marks

Fig. 2 shows how the rate of reaction of a digestive enzyme changes with pH.

061032-oct-2018-paper-3-q5c-enzyme-ph-graph---sqFig. 2

(i)
Describe the effect of the increase in pH on the rate of reaction shown in Fig. 2.

[2]

(ii)
State one factor other than pH that will affect enzyme activity.
[1]

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1a
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4 marks

Fig. 1 is a diagram of the alimentary canal and associated organs.

Some parts are identified by letters.

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Fig. 1

Complete Table 1 by inserting the letter from Fig. 1 which identifies the part that carries out the function described. 

Table 1

Description of function Letter in Fig. 1
Where egestion takes place  
Where lipase is made  
Where mechanical digestion occurs  
Where the most water is absorbed  

1b
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4 marks

Cholera is a transmissible disease. 

(i)

State the type of pathogen that causes cholera.

(ii)

One of the symptoms of cholera is diarrhoea.

Describe what is meant by the term diarrhoea

[1]

(iii)

Outline the treatment for diarrhoea. 

[2]

1c
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2 marks

State two ways in which the body can defend itself against pathogens. 

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2a
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3 marks

Fig. 1 shows a section through a tooth.

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Fig. 1

State the names of structures F, G and H.

2b
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4 marks

(i)

State two functions of teeth.

[2]

(ii)

Describe the importance of teeth in the digestion of food.

[2]

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3a
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4 marks

The reactions of chemical digestion are catalysed by enzymes.

Fig. 1 shows the stages of an enzyme-catalysed reaction.

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Fig. 1

State the names of A to D in Fig. 1.

3b
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2 marks

Explain the importance of chemical digestion.

3c
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6 marks

Extended Only

Fig. 2 shows the human alimentary canal and associated organs.

The functions of some of these parts of the body are given in Table 1.

061041-may-2018-paper-4-q1c-alimentary---sq

Fig. 2

Complete Table 1. One row has been done for you. 

Table 1

Function Letter from Fig. 2 Name of Structure
Site of starch digestion    
Reabsorption of water    
Secretion of pepsin    
Site of maltose digestion    
Secretion of bile    
Storage of faeces F rectum
Secretion of lipase and trypsin    

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4
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4 marks

Fig. 1 shows the four different types of human teeth. 

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Fig. 1

Fig. 2 shows a diagram of the position of the different types of teeth in the mouth.

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Fig. 2

Complete Table 1 by writing the names, positions and functions of the different types of teeth in the mouth shown in Fig. 2.

Table 1

Name of type of tooth Letter on Fig. 2 Function
  R  
Incisor    
    Grinding
Premolar   Tearing and grinding

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5
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4 marks

Red pandas, Ailurus fulgens, and humans have a similar arrangement of teeth.

Fig. 1 shows a section through one tooth of a red panda. Fig. 2 shows the side view of the lower jaw of a red panda.

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                    Fig. 1                                                      Fig. 2

(i)

State the names of the structures labelled A to F in Fig. 1 and Fig. 2.

[3]

(ii)

State the type of digestion that breaks down large pieces of food.

[1]

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6a
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4 marks

Two functions of the alimentary canal are mechanical digestion and chemical digestion.

Outline where and how mechanical digestion occurs in the alimentary canal.

6b
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3 marks

Enzymes catalyse the reactions of chemical digestion. Table 1 gives information about chemical digestion in three parts of the alimentary canal.

Complete Table 1.

Table 1

Part of the alimentary canal Enzyme Substrate Product(s)
mouth   starch  
stomach     peptides
    fat fatty acids and glycerol
6c
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3 marks

Substances that are absorbed from the alimentary canal may enter cells and become part of the cells. 

(i)

State the storage carbohydrate made from glucose in liver cells.

[1]

(ii)

State the type of protein used in the immune system that is produced from amino acids by lymphocytes.

[1]

(iii)

Fat is produced from fatty acids and glycerol by cells in the fatty tissue beneath the skin.

State one function of this layer of fat.

[1]

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7
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6 marks

Fig. 1 shows some parts of the human body.

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Fig. 1

(i)

Use Fig. 1 to complete Table 1.

State the letter and the name of the part responsible for each function.

Table 1

Function Letter in Fig. 1 Name of the part
Produces insulin    
Produces hydrochloric acid    

[4]

(ii)

State the letter of the part of the body where egestion occurs.

[1]

(iii)

State the function of hydrochloric acid in the body.

[1]

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8a6 marks

Digestion in the human digestive system is carried out by the action of enzymes.

The diagrams each represent the action of a specific enzyme to break down a substrate into one or more end products.

Fig. 1.1 has been completed for you.

Complete Fig. 1.2 and Fig. 1.3.q1a-8-2-human-digestive-system-medium-sq-cie-o-level-biology

8b4 marks

Amino acids are the end products of protein digestion.

Describe what happens to these amino acids after digestion until they reach the liver.

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9a3 marks

The diagram shows part of the human alimentary canal and its associated organs.q9a-8-2-human-digestive-system-medium-sq-cie-o-level-biology 

Complete the three labels on the diagram by naming the structures.

9b3 marks

Describe the functions of the structure labelled F.

9c2 marks

Name structure H and describe its role in homeostasis.

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1a
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2 marks

Define the term chemical digestion.

1b
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8 marks

A student investigated the activity of the digestive enzyme pepsin. Fig. 1 shows the apparatus used in the investigation.

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Fig. 1

The appearance of the four test-tubes was recorded at 0 and 5 minutes.

The protein in the egg white solution gives the solution a cloudy appearance.

The cloudy appearance clears when the protein in the egg white solution breaks down.

Table 1 shows the results.

Table 1

Test-tube Contents Appearance at 0 mins Appearance after 5 mins
1 Egg white solution, pepsin Cloudy Less cloudy
2 Egg white solution, pepsin, hydrochloric acid Cloudy Clear
3 Egg white solution, boiled pepsin, hydrochloric acid Cloudy Cloudy
4 Egg white solution, hydrochloric acid Cloudy Cloudy

(i)
Explain the results shown for test-tubes 1, 2 and 3 in Table 1.

[5]

(ii)

Explain the purpose of test-tube 4.

[2]
(iii)

State the name of the organ in the body that produces pepsin.

[1]

1c
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3 marks

Maltase is another digestive enzyme.

Describe the action of maltase and state where it acts in the alimentary canal.

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2a
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5 marks
Fig. 1 shows the human digestive system.

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Fig. 1

(i)

Identify organ X in Fig. 1.

[1]

(ii)

Describe the function of organ X in digestion.

[4]

2b
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3 marks

Chewing on a piece of bread will result in a sweet taste developing in the mouth after a while.

Explain the reason for this.

2c
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4 marks

Protease enzymes chemically break down protein molecules.

Explain why protease enzymes cannot break down any other type of molecule.

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3a
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3 marks

The stomach produces gastric juice which contains hydrochloric acid.

Explain the importance of hydrochloric acid in the stomach.

3b
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3 marks

Normally the epithelial cells in the lining of the stomach are protected from the effects of gastric juice by a layer of mucus secreted by goblet cells found in the stomach lining.

Sometimes a type of bacteria called Helicobacter pylori can penetrate the mucus layer and cause damage to the goblet cells. This leads to the formation of a peptic ulcer.

Fig. 1 compares a healthy stomach lining with one that has been infected by H. pylori.stomach-lining

Fig. 1

Based on the information in Fig. 1, suggest how H. pylori may lead to the formation of a peptic ulcer.

3c
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2 marks

Patients suffering from peptic ulcers may receive treatment with substances called proton pump inhibitors (PPI's). These substances will suppress the cells in the lining of the stomach that produce hydrochloric acid.

Explain how PPI's could act as a treatment for peptic ulcers.

3d
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3 marks

Based on the information from part (c), suggest the effect the PPI's could have on digestion in the stomach.

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4a
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3 marks

A group of students investigated the effect of pH on the activity of amylase.

Their results are shown in Fig. 1.

starch

Fig. 1

(i)

Identify the optimum pH of amylase from Fig. 1.

[1]

(ii)

Explain your answer from part (i).

[2]

4b
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2 marks

Calculate the percentage decrease in the time taken to digest starch between pH 5 and 7. Show your working.

4c
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4 marks

Describe and explain the shape of the graph between pH 7 and 8.

4d
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5 marks

Outline the process of starch digestion in the human body.

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5a
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2 marks

Fig. 1 shows the location of the gallbladder in the human digestive system.

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Fig. 1

Explain the purpose of the gallbladder.

5b
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3 marks

The gallbladder may become inflamed or blocked by gallstones, which may cause much pain. In such cases, it is best to surgically remove the gallbladder. Doctors may recommend that patients with no gallbladder follow a low fat diet after surgery.

Suggest a possible reason for this recommendation.

5c
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2 marks

Certain vitamins are known as fat soluble vitamins. They are often found in food with a high fat content and are best absorbed into the blood along with digested lipids.

Based on the information provided in part (b) and (c), explain why people without gallbladders may develop deficiencies in these vitamins.

5d
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3 marks

Vitamin D is an example of a fat soluble vitamin. In some cases, children may need to have their gallbladders removed due to inflammation. In most cases, this will not have a significant impact on their long term health, but in some extreme cases, it might.

Suggest a possible impact that this may have on their health.

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