IGCSE Coordinated Science: Animal Nutrition

IGCSE Coordinated Science: Animal Nutrition

1. State what is meant by the term balanced diet and describe a balanced diet related to age, sex, and activity of an individual.

Balanced diet: A balanced diet is a diet which consists of all nutrients in the food pyramid to suitable proportions.

Food pyramid:

Your diet should be determined by three main factors:

• Age
• Sex
• Activity

2. Describe the effects of malnutrition in relation to starvation, coronary heart disease, constipation, and obesity

Malnutrition is a condition where certain nutrients of a balanced diet are missing, in excess, or taken in the wrong proportions.

E.g. Overconsumption of fatty foods is an example of malnutrition.

• An example of malnutrition isn’t necessarily the typical African child who is starving. That is ONE example of malnutrition. The obese person who eats McDonalds 7 meals a week, 3 meals a day is also suffering from malnutrition.

Starvation

• Starvation is a pretty common concept that we are all familiar with. This is a problem occurring in many third world countries, where starvation occurs when a person has a severe deficiency of energy, nutrient and vitamin intake.

• Prolonged starvation may cause organ damage, and if not treated properly, death. Approximately 6 million people a year die of hunger.

Coronary heart disease

• This problem is less seen in third world countries but more in MEDC’s where over-abundance of food intake is the problem.
• Coronary heart disease, as you will learn in Unit 5, speaking in terms of diet, is caused by an over-abundance of intake of fatty foods, and what happens is that the cholesterol and “bad” things deposit and eventually form a clog in the arteries, hence preventing proper blood flow in the body (more of this in Unit 5).
  Get quality help now

  

  Bella Hamilton

  Verified

  Proficient in: Science

  5 (234)

  “ Very organized ,I enjoyed and Loved every bit of our professional interaction ”

  

  +84 relevant experts are online

  Hire writer

Constipation

• Constipation occurs when one finds it difficult to …..Let’s say….relieve oneself. Bowel movements are obstructed.

Common causes

• Lack of fibre intake.
• Lack of water intake

Obesity

• A person is considered obese if his/her body weight is 20%above the standard body weight.
• Again, this is a problem that is more often seen in MEDC (More Economically Developed Countries), where an over-abundance of food intake is the problem.
• An over-abundance of calorie intake, increased dependence on fast food and sugary foods have accelerated the number of obese people.

3. Define ingestion as taking substances (e.g., food, drink) into the body through the mouth.

• Ingestion: Taking substances into the body through the mouth

4. Define egestion as passing out of food that has not been digested, as feces, through the anus.

• Egestion: The passing out of good that has not been digested, as feces, through the anus.

5. Identify the main regions of the alimentary canal and associated organs including mouth, salivary glands, esophagus, stomach, small intestine: duodenum and ileum, pancreas, liver, gall bladder, large intestine: colon and rectum, anus.
6. Describe the functions of the regions of the alimentary canal listed above, in relation to ingestion, digestion, absorption, assimilation, and egestion of food.

• Mouth: Where the food enters. Food has to enter somewhere before they can be digested right? There are other purposes of your mouth that isn’t biology related, and hence we won’t discuss it here.
• Salivary Glands: These secrete amylase, which breaks down starch into maltose, so the substance can more easily be digested.
• Esophagus & Stomach: : After the food has been digested, it is now in a round, small mass. It then travels down the esophagus and the stomach by a process called Peristalsis. Gastric juice in the stomach will then start digesting the protein.
• Small intestines: After 1-2 hours a resulting thick liquid called chyme is produced. The chyme enters the duodenum, and is mixed with digestive enzymes in the pancreas. Eventually, this is passed down the small intestines.
• Chyme is absorbed into blood when digested.
• Water and minerals are reabsorbed into the blood in the colon.
• Liver: The liver produces bile, which emulsifies (mixture of two or more liquids) fats, to allow absorption. Bile is stored in the gallbladder where it is then released to small intestine via bile duct.
• Pancreas: Pancreas makes pancreatic juice. This secretes important enzymes for digestion such as amylase, pancreatic lipase, and forms of proteases.
• Anus: Stored feces are eliminated from the body through the anus, via the process egestion.

7. Define digestion as the break-down of large, insoluble food molecules into small, water-soluble molecules using mechanical and chemical processes.

• Digestion: Break-down of large, insoluble food molecules into small, water-soluble molecules using mechanical and chemical processes.

8. Identify the types of human teeth and describe their structure and functions.

Functions of teeth:

• Enamel: Covers tooth crown. Enamel is VERY hard (harder than bone), and prevents the tooth from decaying.
• Dentin: Located under the enamel, this looks quite similar to bone. Not as hard as enamel.
• Pulp: Found at center of tooth, and contains blood vessels, nerves and soft tissues which delivers nutrients to your tooth.

Types of teeth:

Incisors: Eight teeth at the front and center of food.

Purpose:

• Bite food

Canine: You have four canines. Sharpest teeth

Purpose:

• Ripping
• Tearing

Premolar : You have four pre-molars on each side of your mouth.

Purpose:

• Chewing
• Grinding

Molars: You have eight molars in total. Same function as premolar, just different location (refer to diagram)

Purpose:

• Chewing
• Grinding

9. State the causes of dental decay and describe the proper care of teeth.

Causes:

• Tooth decay is caused by a combination of bacteria and food.
• A stick substance called plaque which contains bacteria is constantly being formed in your teeth.
• When bacteria feed on the sugars you eat, it forms acids.
• Over a prolonged period of time, the acids starting destroying the tooth enamel, hence causing tooth decay.

Treatment:

• Brush teeth frequently.
• Get fillings
• Schedule regular dentist appointments
• Eat less sugary foods.

10. State the significance of chemical digestion in the alimentary canal in producing small,soluble molecules that can be absorbed.

The food that you want to be digested in the small intestine can’t just be digested immediately.

11. Outline the role of bile in emulsifying fats to increase the surface area for the action of enzymes.

• When food is in the stomach, it then travels to the small intestines
• The stomach is acidic, but the digestive enzymes in the small intestines work best in alkaline conditions
• Here is where bile comes in.
• Bile is an alkaline substance produce in the liver and then stored in the gallbladder
• Bile is then secreted in the small intestine, and its function is to “emulsify” fat, the purpose to give a larger surface area for the enzyme lipase to work on.

12. State where, in the alimentary canal, amylase, protease, and lipase enzymes are secreted.

• Amylase: Stomach and small intestine.
• Protease: Stomach
• Lipase: Primarily found in pancreas, but also found in mouth and stomach.

13. State the functions of a typical amylase, a protease, and a lipase, listing the substrate and end products.

These are all pancreatic enzymes which serve a specific function.

Amylase:

• Breaking down complex carbohydrates into simple sugars.
• This is important so the body can use these sugars for energy (particularly respiration)

Protease:

• There are many types of proteases, such as trypsin. However, you don’t really have to know that.
• In small intestine, protease guide with the breakdown of protein in amino acids

Lipase

• Help digest fats
• Help with absorption of fat by breaking down triglycerides into fatty acids, which can easily be absorbed.

14. Define absorption as movement of digested food molecules through the wall of the intestine into the blood.

• Absorption: Movement of digested food molecules through the wall of the intestine into the blood

15. Describe the structure of a villus, including the role of capillaries and lacteals.

• Capillaries: The nutrients that are absorbed through the wall of the small intestine get absorbed by the capillary network within the villi and they will come together to form the hepatic portal vein that goes directly to the liver for processing.
• Lacteal: This is also a capillary. What the lacteal does is that it absorbs fats in the villi of the small intestine.

16. Describe the significance of villi in increasing the internal surface area of the small intestine.

• These are finger-like projections.
• Very small, approximately 1mm long.
• Each villi is made up of even smaller microvilli

Villi:

• Increase internal surface area of the intestinal walls.
• Larger surface area for absorption
• This is particularly useful because digested nutrients pass into the villi.
• This increased surface basically means that the distance travelled by nutrient molecules is decreased, hence allowing for more efficient absorption of nutrients.

17. Identify the small intestine as the region for the absorption of digested food.

• Digested food is absorbed in the small intestine.

18. Describe the role of fat as an energy storage substance.

• One primary role of fat is to be stored in the body as an ‘energy storage substance’, containing approximately 37.8 Kilojoules per gram of fat.
• The fat can be broken down to give glycerol and fatty acids.
• The glycerol can be converted to glucose by the liver and can then be used as a source of energy.

19. Describe the role of the liver in the metabolism of glucose (glucose →glycogen).

• This process is called Glucoregulation
• Glucoregulation is the maintenance of glucose inside the body.
• Hormone insulin is very important for regulation.
• Can cause some cells to store glucose in the form of glycogen
• Its absence can cause glycogen to break down into glucose.
• Glycogen is stored and released inside the liver.