The Digestive System: Understanding Nutrition, Enzymes, Absorption & Health

Unit 1: The Digestive System

Understand: Keywords:
1. What are the seven food groups and their role in Nutrition, Nutrients, Food, Groups, Fats,
a healthy balanced diet. Carbohydrates, Proteins, Minerals, Vitamins,
2. The chemical tests to detect the presence of Fibre, Water, Digestive, System, Physical,
proteins, lipids, carbohydrates or sugar in
foods. Chemical, Villi, Breakdown, Absorption,
3. What the recommended daily amounts of Nutrients, Amino acids, Glucose, Fatty acids,
vitamins and minerals are in a healthy diet. Glycerol, Obesity & Malnutrition.
4. The role of the digestive system and its key
organs during the physical and chemical
breakdown of food.
5. The role of enzymes during the chemical
breakdown of foods.
6. How enzymes function as catalysts.
7. The role of the villi tissue in the absorption of
nutrients from the gut into the blood.
8. The fate of these nutrients in the body and their
assimilation into cells and tissues.
9. The health consequences of overeating and
under eating.
10. The importance of getting the balance right.

Science Interactive LTD Copyright 2005

Overview of the digestive system
The digestive system is a collection of cells, t________ and organs that function together
to breakdown and absorb the daily essential nutrients, minerals and vitamins required for
healthy growth and development. The digestive system is able to breakdown proteins, fats
and carbohydrates prior to their absorption into the bloodstream. These large food
molecules are broken down into smaller molecules by both physical and chemical
d________. Name a cell, tissue and organ that belongs to the digestive system ?

The digestive system: Word bank: tissues digestion

Diagram of the digestive system Organ Function (complete table)
Mouth Chews foods, using canines, incisors and molars.

Oesophagus __________________________________ ?
Stomach __________________________________ ?
Liver __________________________________ ?
Small Intestine __________________________________ ?
Large Intestine __________________________________ ?
Rectum __________________________________ ?
Anus __________________________________ ?


Dietary intake of foods
Our dietary intake of foods like proteins, carbohydrates and lipids should provide us with
the correct amount of c________ energy to maintain our daily activities, growth (if we are
children) and repair. An adult male requires about 10,500 kilojoules per day, equivalent to
about 100 joules per second. This is the same energy that a 100 watt light bulb uses. Taking
too much energy, by perhaps consuming too much raw sugar or fat, can lead to weight
gain, high blood pressure and eventually o________.

Daily energy requirements: Word bank: chemical obesity

Dietary intake, assimilation and respiration
Dietary energy
Diagram Respiration Respiration

C6H12O6 6H2O

Mitochondria Energy

6O2 6CO2
Growth & reproduction

Assimilation

10,500 kJ/day (adult male)

Notes All the chemical energy, vitamins and minerals that we require are provided by a balanced diet.
Overeating or under eating, eating too little vitamins and minerals can cause many health problems in
adults and children. It is estimated that one in four adults in the Britain will be clinically obese by 2010.


Deficiency diseases
Your diet needs to be b____________, providing all the necessary v_________ and minerals
that you require for healthy growth and development. In some areas of the World, poor diets
lacking in just one or two minerals or vitamins causes deficiency diseases. Scurvy is a good
example of a deficiency disease that was common amongst sailors during the 17 th and 18th
centuries. This disease was caused by a lack of vitamin C contained in fresh fruit and
vegetables, then unavailable during the long sea voyages. Scurvy can lead to bleeding of gums
and the general deterioration of muscles and joints.
Deficiency diseases: Word bank: balanced vitamins

Vitamin C Calcium Vitamin D Vitamin A
Diagram

Deficiency Scurvy Osteoporosis Rickets Night blindness
Notes Scurvy: Gums begin to bleed and old wounds begin to open. Limes were carried and included in a sailors
diet to avoid scurvy. Osteoporosis: A diet lacking in calcium leads to poor teeth and bone development. In
older age, bones become weak and break easily. Ricketts: A lack of vitamin D causes soft bones during a
child’s growth. This disease is known as rickets. Vitamin D is produced by the skin during the summer
months. Night blindness This is a result of too little vitamin A in the diet.


A balanced diet
The amount of energy (kJ) we consume through our diet and the recommended daily amount of
m________ and v___________ we need for normal healthy growth and development is given
by the table below. Notice that these values depend on our age, our sex, when female if we are
pregnant or lactating and even our lifestyles. The amount of e_______ we need can also
depend on the type of job we have, for example a labourer digging roads will require more
energy from their diet than someone who works in an office. Look at the information given by
the table and answer the questions.

Daily vitamin, mineral and energy requirements: Word bank: minerals vitamins energy

Sex Age Energy Body Wt. Protein Vit A Vit C Vit D Iron Calcium
Units Years kJ kg g mg mg ug mg mg
Male 15 12500 59 59 1.1 60 10 12 12000
Male 35 10500 80 63 1 60 10 10 10000
Female 15 9750 55 44 0.8 60 8 15 12000
Female 35 9750 63 50 0.8 60 8 15 12000
Female (pregnant) 35 + 1000 + 12 60 0.8 70 10 30 13000
Female (lactating) 35 +2000 63 65 1.3 75 12 15 14000

Questions: 1: Why does a 15 year old male require more energy than a 35 year old male.
2: Why do females require more iron than males.
3: What role does vitamin C and calcium play in the body.
4: Why do you require less vitamin D in the summer when compared to winter.
5: Why does a lactating female require the most protein in her diet.


Nutrition and food groups one
There are seven basic food groups essential for a healthy d______. The three main food groups
p________, fats and carbohydrates provide us with all the energy requirements as well as
having specific functions in the body. Carbohydrates should make up about 55% of your total
daily kilojoule intake. Too much fat in your diet can lead to blocked a_______ and obesity.
Protein is required most during p_______ in adolescents for growth and repair. Compare the
diets of a body builder, adolescent female and male and a pregnant female, how might they
differ ?

Proteins, carbohydrates and lipids: Word bank: diet proteins arteries puberty

Proteins Lipids Carbohydrates
Diagram

Function For growth and repair. During Store of energy. Insulates the Converted readily to glucose by
puberty protein demand is very body against the cold. High lipid carbohydrase enzymes found in
high. Why do body builders diet lead to atherosclerosis and mouth saliva and the small
take a high protein diet ? obesity. 1 in 5 adults are obese. intestine. Glucose is then respired
in cells.

Sources Animal flesh, Soya bean ____________________ ______________________
and nuts. ___________________? _____________________?


Nutrition and food groups two
The other four food groups, although they do not provide the body with any energy, are all
essential for healthy g_______ and development. A balanced diet supplying all the necessary
vitamins and minerals comes from eating a diet containing low fat meat, plenty of
carbohydrates, fresh f_____ and vegetables. Many foods sold in supermarkets now have
vitamins and minerals added to them, so that we can all take our recommended daily amount.

Vitamins, minerals, roughage and water: Word bank: growth fruit

Vitamins Minerals Roughage Water
Diagram

Function Healthy tissue growth Healthy tissue growth Helps keep regular Correct hydration is
and development. and development. A bowel movements. A essential for every cell
Lack of vitamins lack of iron causes low fibre diet and of course normal
leads to deficiency anaemia of the blood. increases the risk of blood pressure. How
diseases like scurvy Low calcium affects contracting large much water should you
and rickets. bone growth. bowel cancer. drink every day ?

Sources All fresh fruit and _______________ ______________ _________________
vegetables. ______________? _____________? ________________?


Food tests one
The presence of proteins, starch, sugars and l_______ in foods can be tested for by using
‘food tests.’ Scientists test foods for the presence of each of these food groups so they can
provide nutritional information on their food products. Where is this information normally
found on a packet of crisps or a chocolate bar ?

Food tests: Word bank: lipids

Protein Lipid Starch Sugar
Diagram

Test Biuret’s test Paper test Iodine test Benedict's test
Add 5cm3 of copper Place a small amount Place 6 drops of iodine Add 5cm3 of benedict’s
sulphate and 5cm3 of of tested food on water on food sample. solution. Heat tube in
sodium hydroxide. paper. Allow to dry. hot water for 5 minutes.

Paper goes clear with lipids
Result Control Positive Control Positive Control Positive

lipid food test


Food tests two
Starch, a polymer of g_______ is found in many foods including all cereals and most
vegetables. Starch is broken down by the carbohydrase e________ to glucose. In this
form, glucose is readily absorbed and transported to the many billions of cells in the body.
Glucose is oxidised with oxygen during cellular respiration to provide energy essential for
life. Although glucose is essential for cellular respiration, which disease might you suffer
after years of eating a high glucose diet ?

Testing for starch in foods: Word bank: glucose enzyme

Starch solution Corn Apple Sucrose solution
Diagram

Results Starch ? Starch ? Starch ? Starch ?
Yes Yes Yes Yes
No No No No


Function of the digestive organs one
Each organ or tissue in the digestive system has a specific function that helps break down the
three main food groups (proteins, lipids and carbohydrates) into small molecules so they can be
a_________ into the blood stream. The majority of e___________ that chemically breakdown
foods are released by the pancreas into the small intestine. After carbohydrate, protein and lipid
breakdown, their products; sugars, amino acids, fatty acids and glycerol are absorbed across
the villi into the blood stream. Why can only small food molecules like glucose cross from the
gut into the blood ?
Digestive organs: Word bank: absorbed enzymes

Teeth Food pipe Stomach Small intestine
Diagram

Notes Chews food and secretes Sends contents to Adds acid and proteases Most enzymes are found
salvia which lubricates stomach by squeezing to begin protein here. Lipids, proteins
the food and contains the chewed food (bolus) breakdown. The stomach and carbohydrates are
enzyme carbohydrase, This process is called has a pH of around 2. broken down before they
which begins to break peristalsis. Gravity also This also kills any are absorbed into the
down carbohydrates. helps this process. bacteria found in food. blood across the villi.


Functions of the digestive organs two
All nutrients including amino acids and glucose and other food groups including water,
minerals and vitamins are absorbed by the v______ found in the small intestine. The
remaining organs of the digestive system including the large intestine and colon remove
water from undigested material, helping to form a solid stool. The rectum stores the waste
faeces until its excretion via the anus. Blood takes the nutrients to the l_______ where they
are processed and sent via the circulatory system, the billions of cells in the human body.

Digestive organs: Word bank: villi liver

Liver Pancreas Large intestine Rectum and anus
Diagram

Notes Processes all nutrients The pancreas is found The large intestine The rectum stores the
like amino acids, glucose, behind the stomach. absorbs and recycles solid waste which
fatty acids and glycerol. The pancreas makes water. The stool begins contains undigested food
Also breaks down excess and releases all the to become solid. This (fibre), bacteria, water
amino acids forming enzymes found in the makes it easier to store and broken down blood
urea. small intestine. by the rectum. cells.


Physical digestion
The breakdown of proteins, carbohydrates and lipids begins with chewing. Humans have a
mixture of c_______, incisor and molar teeth which are designed to cope with a varied
diet, which includes animal flesh and vegetables. Our canines and incisors tear and rip
food. Our molars, with their flat profile are designed to grind and chew fibrous vegetable
matter like root vegetables and fruits. How does a high sugar diet affect our teeth and lead
to tooth decay ?

Human teeth and physical digestion: Word bank: canine

Teeth Human teeth Brushing
Diagram

Notes Humans have two sets of The tooth (incisors, canines and Modern toothpaste now
teeth. Your milk teeth are molars) are capped with white enamel. contains fluoride which
replaced when you are This is made from calcium carbonate helps control oral bacteria
about eight years old. Your and is the hardest substance in the and prevents tooth decay.
final molars appear in your body. It can be eroded by acids found Always have a 6 monthly
twenties. in foods or produced by oral bacteria. check-up at the dentist.


Enzymes and chemical digestion
Digestive enzymes break down large f_____ molecules into smaller ones. Enzymes are all
proteins, and are very specific, only having one substrate like a protein or a lipid. They
behave like c_________, able to speed up the rate of reaction and can be recycled by the
digestive system. There are three main types of enzymes found in the digestive system:
proteases, carbohydrases and lipases. Look at the table below to find out the function and
location of each type ?
Types of digestive enzymes: Word bank: food catalysts lipases

Proteins Carbohydrates Lipids
Diagram

Enzymes Proteases Carbohydrases L_________
-stomach -salivary -pancreatic
-pancreatic -pancreatic

Products Amino acids Sugars Fatty acids and glycerol


How enzymes function one
For proteins, lipids and c____________ to be absorbed from the small i_________,
into the blood, they must be broken down into small molecules. Digestive enzymes
breakdown food chemically. An enzyme’s substrate will bind to the enzyme’s
a_________ site where chemical bonds are broken producing smaller molecules
which can then be absorbed into the b________ stream.

How enzymes break down food molecules: Word bank: carbohydrates intestine active blood

Stage one Stage two Stage three
Diagram
SubstrateSubstrates
Products

Enzyme substrate complex

active site active site active site
Enzyme (catalyst) Enzyme Enzyme (can be reused)
Products

Notes Step one Step two Step three

Substrates like proteins, Chemical bonds are broken New products like glucose are
carbohydrates and lipids bind by the enzyme to form formed which then leave the
to the enzyme’s active site. monomers. enzyme’s active site.


How enzymes function two
Enzyme are biological catalysts which will increase the rate of b__________ of proteins,
carbohydrates and lipids without be used up themselves. Enzyme catalysts are able to lower the
activation energy required for new products like sugars and amino acids to be produced from
substrates like carbohydrates and proteins. The reaction takes place in an area of the enzyme
which is called the active site.
Carbohydrases, Lipases, Proteases Enzymes are biological catalysts
Not used up during the reaction Lower the activation energy

Enzymes as biological catalysts: Word bank: breakdown

Breakdown of carbohydrates by carbohydrase
Diagram Carbohydrase + Carbohydrate Carbohydrase + sugar molecules
Sugar
e Sugar
ra t Sugar
hyd
rbo Sugar
Ca
Sugar
Catalyst
Enzyme Catalyst
Enzyme

active site
active site active site
active site

Notes Substrates like carbohydrates collide and temporarily bind to the enzyme’s active site on its surface. The
bonds in the substrates are weakened by the enzyme. The bonds are broken and new products are formed.
These products (sugar) then leave the enzyme’s active site, leaving the enzyme catalyst unchanged and able
to participate in further reactions.


How enzymes function three
A human body contains many hundreds of different enzymes found inside cells and as part of
the d_________ system. Without enzymes, which catalyse the breakdown of nutrients like
proteins, carbohydrates and fats, digestion would be too slow to support all your functions.
Like many of the inorganic catalysts, enzymes lower the activation energy and increase the rate
of reaction without being used up. With enzymes, the rate of reaction increases as the
t___________ increases, doubling for every 10oC rise in temperature. However, above
approximately 40oC, enzymes are denatured or destroyed and will stop working altogether.
Name three types of enzymes found in the human gut ?

Biological enzymes as catalysts: Word bank: digestive temperature

How enzymes speed up the rate of reaction Heat sensitive enzymes

With inorganic catalyst
Substrates with
sufficient energy to
form new products

Rate of reaction
With enzyme With enzyme

Without enzyme

0 Temp oC 40 60 80 100

A catalyst will lower the activation required for substrates to react As you increase the temperature by 10 oC the
with one another to form new products. The graph above shows how rate of reaction doubles until around 40-45 oC
by adding a catalyst, the activation energy shifts to the left increasing where the high temperature denatures or
the number of successful collisions and therefore increasing the rate of destroys the enzyme. Inorganic catalyst like
reaction. Enzymes are highly specific for their substrate. iron and nickel are not temperature sensitive.


Using enzymes as catalysts
Enzymes are used in a wide variety of industrial applications. Enzymes found in yeast cells are
used for f___________ sugar during alcohol production and making bread. Enzymes found in
the bacteria lactose bacillus are used to produce lactic acid from milk lactose. This is the first
step in the production of cheese and dairy yoghurts. Other enzymes are found in modern
biological w_________ powders that digest stains on clothing. These modern washing powders
work at relatively low temperatures (<40oC) and are energy efficient because you don’t need to
use high water temperatures. What temperature would be best to produce cheese from milk ?

Biological enzymes as catalysts: Word bank: fermenting washing

Alcohol Washing powders Bread manufacture
Diagram

Notes Yeast is an essential bacteria All biological washing Yeast is used during bread
containing enzymes used to powders contain enzymes that making. The carbon dioxide gas
ferment sugar from grape, fruit help with the removal of food produced during the respiration
or wheat into alcohol. stains. These enzymes digest of wheat sugars and
Fermentation of sugar must be and breakdown the stains at carbohydrates cause the bread
done in an oxygen free very low temperatures... dough to rise. This gives the
environment. below 40 C.
o
bread its light texture.


Absorption of nutrients by the villi
Once proteins, lipids and carbohydrates are broken down into amino acids, sugars, fatty acids and
glycerol, absorption into the blood stream takes place in the small intestine. The small intestine is
well designed for absorption of n___________ into the blood stream. It has a thin lining, large
s_________ area and a good blood supply. The surface area of the small intestine is about 10
metres squared. To achieve this huge surface area, the small intestine has a folded lining, is very
long and contains millions of tiny microscopic villi. These are finger like projections which
increase the surface area and help nutrient absorption into the blood.
Absorption across the villi into the blood stream: Word bank: nutrients surface

Small intestine Features of the small intestine villi (Villi (x 10,000 Magnification))
Diagram
Fatty acids
glycerol

Glucose
Amino acids

Artery

Lymph vessel Vein

Notes There are many millions of villi found on the surface of the small intestine. They have thin walls and have a
very rich blood supply. Amino acids and glucose are absorbed into the blood. Fatty acids and glycerol are
absorbed into the lacteal, which then drains into the lymph system.


Breakdown of foods along the digestive tube
The digestive system is simply a long tube where large nutrient molecules are converted to
small molecules. In the small intestine, nutrients like g_________ and amino acids are absorbed
across the villi into the hepatic artery. Here they travel to the liver and are either used
immediately, stored or assimilated into your cells. Look at the overview of digestion and find
out where protein, carbohydrate and lipid digestion occurs ?

Overview of digestion: Word bank: glucose proteins water

Digestive system
Key
P_______ ? G________ ?

Carbohydrate Fatty acids and glycerol

Lipids Waste

W_______ ? Stool

Amino acids Blood cells

Hepatic artery

to the liver

Oesophagus Small intestine Large intestine Rectum Anus
Stomach


Assimilation of nutrients
After the digestion of proteins, carbohydrates and lipids by the digestive system, g_________
and amino acids are absorbed across the villi into the hepatic artery. Here they travel to the
liver and are either used immediately, stored or assimilated into your cells. Glucose is either
respired or stored in muscle and liver as glycogen. Amino acids are used to build p______ like
enzymes. Excess amino acids are broken down by the liver to form urea. Fatty acids and
glycerol, which are absorbed into the lymph system are used to make cell membranes, some
hormones or are stored under the skin. What two hormones control the amount of glucose in
your blood stream ?
Word bank: glucose proteins

Nutrientsystem Small intestine
Digestive assimilation: Nutrient use

Respiration C6H12O6 6H2O
Liver
Mitochondria Energy

6O2 6CO2
Cells
Blood stream

Fat

Assimilation
Glucose
Amino
acids
Fatty acids
& glycerol Glucose Amino acids Fatty acids Muscle


Getting the balance wrong one
A healthy balanced diet should provide you with the right amount of chemical energy,
vitamins and minerals. It should also be relatively low in f___ and protein (adult) and high
in carbohydrates. Eating too much fatty or sugary foods, low in vitamins and minerals for
long periods of time may lead to health problems later on in life. D______,
atherosclerosis, obesity and heart disease are all associated with eating a poor diet. It is
estimated that obesity will be the number one killer in the next twenty years in Britain.

Consuming the wrong foods: Word bank: fats diabetes

Pizza Chips Fast Food Sweets and chocolates
Diagram

Notes With an ever increasing choice of cheap fatty fast foods, children are now more overweight
and less fit when compared to children of the seventies. Obesity, diabetes and in some cases
heart disease are now no longer diseases of the old. Children need to avoid ‘junk food’ and eat
a more balanced diet containing the right quantities of all of the seven food groups.


Getting the balance wrong two
Your brain regulates your appetite and signals when you are h______. Your body is able
to regulate the amount of chemical energy that you take over many years. Consuming
foods high in sugar and fat and low in bulk tend to upset the right balance. Excess
chemical energy in your diet leads to greater assimilation, weight gain and eventually
obesity. Some individuals who are grossly obese, store upwards of a million additional
kilojoules in their body as f___. What health consequences does obesity in humans cause ?

Over consumption of nutrients: Word bank: hungry fat

Dietary intake in excess of daily requirements
Dietary energy Respiration
Diagram Respiration

C6H12O6 6H2O

Mitochondria Energy

Assimilation
6O2 6CO2
Obesity

Dietary intake in excess of
10,500 kJ/day (adult male)

Notes All the chemical energy, vitamins and minerals that we require are provided by a healthy balanced diet.
Overeating or under eating, eating too little vitamins and minerals can cause many health problems in
adults and children. It is estimated that one in four adults will be clinically obese by 2010.


Getting the balance wrong three
Poverty, drought, disease and war can lead to the failure of crops and livestock. In severe cases
of famine, for example the famine in Ethiopia in 1984, millions of people may starve to death.
The very old and y_______ are particularly vulnerable. Malnutrition can lead to low body
weight, weak immune systems and poor development in children. Famine and malnutrition is
still widespread in Africa. Live 8 is now putting pressure on the eight richest countries (G8) to
reduce Africa’s debt burden. This should reduce the level of poverty and starvation in Africa.

Under consumption of nutrients: Word bank: young

Dietary intake below daily requirements
Dietary energy Respiration
Diagram Respiration

C6H12O6 6H2O

Mitochondria Energy

6O2 6CO2
Malnutrition

Dietary intake below
10,500 kJ/day (adult male) Assimilation

Notes Malnutrition in Africa and other developing countries is common place where daily income is less than
one pound a day. Many children have less food than they require to live. It is estimated that every three
seconds someone dies because of starvation.


Getting the balance right one
Over the last 200 years, here in Western Europe our life expectancy has increased partly due to
our healthy diets. Eating a low fat, medium protein, high fibre and carbohydrate diet containing
lots of minerals, v________, fresh fruit and vegetables is important so that we maintain our
correct b_____ weight. In schools, less junk food and more freshly prepared meals are now
being offered to pupils, due to parental pressure and Jamie Oliver, the famous chef who has
begun to campaign for better school diners.

Good lifelong eating habits: Word bank: body weight

Dietary intake in excess of daily requirements
Diagram Healthy growth and development over your lifetime requires sensible eating and a balanced diet.

Respiration

Malnutrition

Assimilation
Dietary intake at 9,750 kJ/day

Notes A balanced diet is important for our long life expectancy. Overeating or under eating, eating too little
vitamins and minerals can cause many health problems in adults and children. In order to reach your old
age, eat a healthy balanced diet...its that simple !


Getting the balance right two
Our dietary intake of foods like p________, carbohydrates and lipids should provide us
with the correct amount of chemical energy to maintain our daily activities, growth (if we
are children) and repair. An adult male requires about 10,500 kJ per day, equivalent to
about 100 joules per second. This is the same energy that a 100 watt light bulb uses. Also
research shows, that eating five portions of f____ and vegetables a day reduces the risk of
developing heart disease, colon cancer and obesity. How can you get children to eat more
fruit and vegetables ?

Healthy diets: Word bank: proteins fruit

Steamed potatoes Carrots Fresh fruit Cereals
Diagram

Notes Eating sufficient quantities of fresh fruit and vegetables helps us avoid many of the lifestyle diseases
like obesity, cancer and diabetes. It is recommended that we all eat at least five portions of fruit and
vegetables every single day. Fruit and vegetables are an excellent source of all the minerals and
vitamins that we require like vitamin C. This helps us to avoid deficiency diseases like scurvy.


Extension questions and homework
1: Define the following terms: Physical digestion, Chemical digestion, Enzymes, Excretion, Nutrients, Minerals,
Vitamins, Fibre, Absorption, Assimilation & Catalyst.
2: Look at the diagram of the three endocrine glands. Complete the table.
Roast potatoes Boiled potatoes Fried potatoes

Cooking method Healthy option Rich in minerals and vitamins
Roasting
Boiling
Frying

3: Answer the following questions:
a) The type of teeth we find in an animals mouth can tell us some information on their diet...how.
b) What is peristalsis and how does saliva help this process.
c) Acid is added to food in the stomach, what is the function of stomach acid. What is the pH of stomach acid.
d) Draw a flow chart to show what happens to food as it passes from the mouth to the anus.
e) What is the function of bile during the digestion of lipids. Where is it produced.
f) What enzyme breaks down carbohydrates to glucose. Where is this enzyme found along the gut.
g) What’s the role of the intestine’s villi and where do nutrients travel once they’ve reached the blood stream.


4: Look at the information in the table below. Use the following table to answer questions a to d.
Person Energy (kJ) Protein (g) Carbohydrate (g) Fats (g) Iron (mg) Vitamin C (mg)
Male 10 -12 10800 30 230 45 45 20

Female 10 -12 9700 28 220 39 56 20

Adult male 12900 39 256 54 76 35

Pregnant female 14500 45 260 35 150 40

a) Describe any differences between males and females in children and adults.
b) What role do proteins, carbohydrates, fats, vitamin C and iron play in the human body.
c) Why does the pregnant female require huge quantities of iron and protein.
d) What would a male doing an active job require in kJ/day.

a) Most western diets contain too much fat and salt. What health problems will this cause.
b) Why is tooth enamel the hardest substance in the human body.
c) What are the four main types of teeth. Is there a relationship between the diet an animal has and the types of
teeth they have.
d) Which type of teeth are not present in your milk set, but are present in your permanent set.
e) What causes tooth decay. Draw three diagram to show the main stages of tooth decay.
f) Compare the causes and effects of starvation and overeating in humans.
g) What health problems are caused by obesity in humans.


6: Look at the information in the table below. Complete the table.
Vitamin /mineral Rich food sources Function in the body Deficiency disease

A Carrots, milk and dairy products Good eyesight and skin Poor vision and skin

C Tissue repair and immune system

D Fish oil, dairy and made by body in sunlight Rickets

Iron Red meat and liver

Calcium Strong teeth and bones Soft bone and teeth

a) Write a paragraph to explain the action of enzymes in digestion. Include the following words: Protease,
Amylase, Absorption, Proteins, Carbohydrates, Lipids, Amino-acids, Fatty-acids, Glycerol, Glucose, Blood,
Capillaries and Villi.
b) What do you think is the main enzyme needed to break down the following foods: Fish, Bread, Butter, Rice, &
Chicken.
c) Look at the diagram of the digestive system. Match the organs to the
following functions:
(i) Absorbs water (ii) Contains proteases and acid (iii) Stores faeces (iv)
Allows faeces to pass out of the rectum (v) Joins the throat to the stomach (vi)
Most absorption of nutrients happens here (vii) Where most food molecules are
broken down (viii) down by pancreatic enzymes. (ix) Stores and release bile.

Internet:
Go to google.co.uk and find how glucose is used by cells during cellular respiration. Cut and paste a diagram to
show how cells use sugar during cellular respiration. What are the end products and how are they excreted.

The Digestive System: Understanding Nutrition, Enzymes, Absorption & Health

The Digestive System: Understanding Nutrition, Enzymes, Absorption & Health

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