the digestive system

The Digestive System

Understand: Keywords:1. What are the seven food groups and their role

in a healthy balanced diet.2. The chemical tests to detect the presence of

proteins, lipids, carbohydrates or sugar in foods.

3. What the recommended daily amounts of vitamins and minerals are in a healthy diet.

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.

Nutrition, Nutrients, Food, Groups, Fats, Carbohydrates, Proteins, Minerals, Vitamins, Fibre, Water, Digestive, System, Physical, Chemical, Villi, Breakdown, Absorption, Nutrients, Amino acids, Glucose, Fatty acids, Glycerol, Obesity & Malnutrition.

Unit 1: The Digestive SystemUnit 1: The Digestive System

Overview of the digestive systemOverview 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: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 __________________________________ ?

Science Interactive LTD Copyright 2005

Word bank: tissues digestion

Dietary intake of foodsDietary intake of foodsOur 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

Growth & reproduction

Assimilation

Dietary energy Respiration

10,500 kJ/day (adult male)

C6H12O6

6O2 6CO2

6H2O

Mitochondria Energy

Respiration

Dietary intake, assimilation and respiration

Diagram

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 diseasesDeficiency diseasesYour 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:

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.


Word bank: balanced vitamins

A balanced dietA balanced dietThe 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:

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.


Word bank: minerals vitamins energy

Nutrition and food groupsNutrition and food groups oneone

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 puberty protein demand is very high. Why do body builders take a high protein diet ?

Store of energy. Insulates the body against the cold. High lipid diet lead to atherosclerosis and obesity. 1 in 5 adults are obese.

Converted readily to glucose by carbohydrase enzymes found in mouth saliva and the small intestine. Glucose is then respired in cells.

Sources Animal flesh, Soya bean and nuts.

_______________________________________?

___________________________________________?

Nutrition and food groupsNutrition and food groups two 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 and development. Lack of vitamins leads to deficiency diseases like scurvy and rickets.

Healthy tissue growth and development. A lack of iron causes anaemia of the blood. Low calcium affects bone growth.

Helps keep regular bowel movements. A low fibre diet increases the risk of contracting large bowel cancer.

Correct hydration is essential for every cell and of course normal blood pressure. How much water should you drink every day ?

Sources All fresh fruit and vegetables.

_____________________________?

___________________________?

_________________________________?

Food testsFood tests one 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:

Control Positive Control Positive Control Positive

lipid food test

Paper goes clear with lipids


Word bank: lipids

Protein Lipid Starch Sugar

Diagram

Test Biuret’s test

Add 5cm3 of copper sulphate and 5cm3 of sodium hydroxide.

Paper test

Place a small amount of tested food on paper. Allow to dry.

Iodine test

Place 6 drops of iodine water on food sample.

Benedict's test

Add 5cm3 of benedict’s solution. Heat tube in hot water for 5 minutes.

Result

Food testsFood tests two 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 ?

Yes

No

Starch ?

Yes

No

Starch ?

Yes

No

Starch ?

Yes

No

Function of the digestive organsFunction of the digestive organs oneone

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:

Teeth Food pipe Stomach Small intestine

Diagram

Notes Chews food and secretes salvia which lubricates the food and contains the enzyme carbohydrase, which begins to break down carbohydrates.

Sends contents to stomach by squeezing chewed food (bolus) This process is called peristalsis. Gravity also helps this process.

Adds acid and proteases to begin protein breakdown. The stomach has a pH of around 2. This also kills any bacteria found in food.

Most enzymes are found here. Lipids, proteins and carbohydrates are broken down before they are absorbed into the blood across the villi.


Word bank: absorbed enzymes

Functions of the digestive organsFunctions of the digestive organs two 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:

Liver Pancreas Large intestine Rectum and anus

Diagram

Notes Processes all nutrients like amino acids, glucose, fatty acids and glycerol. Also breaks down excess amino acids forming urea.

The pancreas is found behind the stomach. The pancreas makes and releases all the enzymes found in the small intestine.

The large intestine absorbs and recycles water. The stool begins to become solid. This makes it easier to store by the rectum.

The rectum stores the solid waste which contains undigested food (fibre), bacteria, water and broken down blood cells.


Word bank: villi liver

Physical digestionPhysical digestionThe 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 teeth. Your milk teeth are replaced when you are about eight years old. Your final molars appear in your twenties.

The tooth (incisors, canines and molars) are capped with white enamel. This is made from calcium carbonate and is the hardest substance in the body. It can be eroded by acids found in foods or produced by oral bacteria.

Modern toothpaste now contains fluoride which helps control oral bacteria and prevents tooth decay. Always have a 6 monthly check-up at the dentist.

Enzymes and chemical digestionEnzymes 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

-stomach

-pancreatic

Carbohydrases

-salivary

-pancreatic

L_________

-pancreatic

Products Amino acids Sugars Fatty acids and glycerol

How enzymes functionHow enzymes function oneone

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:

Substrates

Products


Word bank: carbohydrates intestine active blood

Substrate

Enzyme substrate complex

Products

Enzyme (catalyst)active site

Enzymeactive site

Enzyme (can be reused)active site

Stage one Stage two Stage three

Diagram

Notes Step one

Substrates like proteins, carbohydrates and lipids bind to the enzyme’s active site.

Step two

Chemical bonds are broken by the enzyme to form monomers.

Step three

New products like glucose are formed which then leave the enzyme’s active site.

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.

Enzymes as biological catalysts:

Carbohydrases, Lipases, Proteases Enzymes are biological catalysts

Not used up during the reaction Lower the activation energy

How enzymes functionHow enzymes function twotwo Science Interactive LTD Copyright 2005

Word bank: breakdown

active site active site

Carbohydrase + Carbohydrate

Catalyst Catalyst

Carbohydrase + sugar molecules

Carbohydrate Sugar

Sugar

Sugar

Sugar

Sugar

active site active site

Enzyme Enzyme

Breakdown of carbohydrates by carbohydrase

Diagram

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.

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:

With inorganic catalyst

With enzyme

0 Temp oC 40 60 80 100R

ate

of r

eact

ion

Substrates with sufficient energy to form new products

Without enzyme

With enzyme

How enzymes functionHow enzymes function threethree Science Interactive LTD Copyright 2005

Word bank: digestive temperature

How enzymes speed up the rate of reaction Heat sensitive enzymes

A catalyst will lower the activation required for substrates to react with one another to form new products. The graph above shows how by adding a catalyst, the activation energy shifts to the left increasing the number of successful collisions and therefore increasing the rate of reaction. Enzymes are highly specific for their substrate.

As you increase the temperature by 10oC the rate of reaction doubles until around 40-45oC where the high temperature denatures or destroys the enzyme. Inorganic catalyst like iron and nickel are not temperature sensitive.

Using enzymes as catalystsUsing enzymes as catalystsEnzymes 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:

Alcohol Washing powders Bread manufacture

Diagram

Notes Yeast is an essential bacteria containing enzymes used to ferment sugar from grape, fruit or wheat into alcohol. Fermentation of sugar must be done in an oxygen free environment.

All biological washing powders contain enzymes that help with the removal of food stains. These enzymes digest and breakdown the stains at very low temperatures... below 40oC.

Yeast is used during bread making. The carbon dioxide gas produced during the respiration of wheat sugars and carbohydrates cause the bread dough to rise. This gives the bread its light texture.


Word bank: fermenting washing

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:

Absorption of nutrients by the villiAbsorption of nutrients by the villi

Amino acids

Fatty acids

Glucose

glycerol

Vein

Artery

Lymph vessel


Word bank: nutrients surface

Small intestine Features of the small intestine villi (Villi (x 10,000 Magnification))

Diagram

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.

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:

Breakdown of foods along the digestive tubeBreakdown of foods along the digestive tube

Digestive system


Word bank: glucose proteins water

Oesophagus

StomachSmall intestine Large intestine Rectum Anus

Blood cellsAmino acids

StoolW_______ ?

WasteLipids

Fatty acids and glycerolCarbohydrate

G________ ?P_______ ?

Hepatic artery

to the liver

Key

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 ?

Nutrient assimilation:

Assimilation of nutrientsAssimilation of nutrients

C6H12O6

6O2 6CO2

6H2O

Cells

Mitochondria Energy

C6H12O6

6O2 6CO2

6H2O

Cells

Mitochondria Energy

Digestive system

Liver

Small intestine

Blood stream

Fat

Muscle

Assimilation

Respiration

Fatty acids

Glucose

& glycerol

Aminoacids

Glucose Amino acids Fatty acids

Nutrient use


Word bank: glucose proteins

Getting the balance wrongGetting the balance wrong one 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.

C6H12O6

6O2 6CO2

6H2O

Mitochondria Energy

Respiration

Obesity

Assimilation


Dietary intake in excess of


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:

Getting the balance wrongGetting the balance wrong two twoScience Interactive LTD Copyright 2005

Word bank: hungry fat

Dietary intake in excess of daily requirements

Diagram

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.

C6H12O6

6O2 6CO2

6H2O

Mitochondria Energy

Respiration

Malnutrition


Dietary intake below


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:

Getting the balance wrongGetting the balance wrong three three

Assimilation


Word bank: young

Dietary intake below daily requirements

Diagram

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.

Malnutrition

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:

Getting the balance rightGetting the balance right one one

Healthy growth and development over your lifetime requires sensible eating and a balanced diet.

Respiration

AssimilationDietary intake at 9,750 kJ/day


Word bank: body weight

Dietary intake in excess of daily requirements

Diagram

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 rightGetting the balance right twotwo

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.

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.

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.

Extension questions and homework

Cooking method Healthy option Rich in minerals and vitamins

Roasting

Boiling

Frying

Roast potatoes Boiled potatoes Fried potatoes


4: Look at the information in the table below. Use the following table to answer questions a to d.

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.

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


6: Look at the information in the table below. Complete the table.


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.

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.

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

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.


the digestive system

Documents

healthy diet

chemical energy

healthy balanced diet

deficiency diseasesyour

daily energy requirements

energy kj

little vitamins

science interactive