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Year 11 Human Biology
Unit 1.5 - Nutrient Procurement
Chapter 5 Text Questions - Solutions
FOCUS QUESTIONS
1. Difference between mechanical and chemical digestion.
Mechanical is the physical breakdown of the food. Eg tearing, ripping.
Chemical is where enzymes are used to break the food down. Eg Amylase.
2.
(a) Why is digestion necessary for some compounds?
Because they are too large to be absorbed into the bloodstream.
(b) What compounds in foods have to be chemically digested?
Carbohydrates, protein, and lipids
(c) What compounds don't have to be chemically digested?
Glucose, fibre, water and vitamins.
3.
(a) Parts of the digestive system.
Mouth, tongue, pharynx, oesophagus, liver, stomach, small intestine, large intestine, pancreas, rectum,
anus, gall bladder.
(b) Which aren't the alimentary canal?
Mouth, tongue, liver, pancreas, gall bladder. (These are associated organs)
4. Describe how the structure is suited to the following functions.
(a) Ingestion of food
Mouth cavity holds the food whilst it's chewed
(b) Movement of food along the canal.
The canal is made up of 4 layers with circular and longitudinal muscle to push the food along.
(c) Mechanical Digestion of food.
The teeth are sharp and the muscles of the canal churn the food.
(d) Chemical Digestion of food.
Secrete enzymes and gastric juices from the lining of the canal and associated organs.
(e) Absorption of food.
The villi have a large surface area and the small intestine is long in length.
(f) Elimination of indigestible material.
The rectum holds the material and it's then passed out through the anus.
5. The structure of each of the 4 types of teeth & their function.
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Incisors - chisel sharp for biting and cutting.
Canines - Conical shape for tearing
Molars & Pre-molars - Broad crowns with rounded cusps for grinding.
6. Functions of saliva.
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Lubricates the mouth & food
Dissolves food so taste receptors can be stimulated.
Form Bolus
Amylase breaks down starch, chemical digestion.
Contains anti-bodies that kill bacteria.
7. Explain the function of the following:
(a) Gastric Juice:
Digestion in the stomach
(b) Bile:
Digestion of fats
(c) Pancreatic Juice:
Digestion of organic compounds
(d) Intestinal Juice:
Digestion of carbohydrates, proteins and lipids.
8.
(a) Blood supply to the liver.
From two arteries, the Hepatic artery and the hepatic portal vein.
(b) Functions of the liver
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Blood glucose regulation
Deamination
Fat conversion
Bile formation
Plasma protein formation
Production of blood clotting factors
Storage
Toxin and hormone breakdown
Heat production
9. What gives the small intestine its large surface area?
The folds of the intestine and the numerous villi.
10.
(a) Differences in absorption of fatty acids & glycerol compared to others.
Fatty acids and glycerol are absorbed by diffusion, the others by active transport.
(b) Differences in absorption of water compared to monosaccharides.
Water by osmosis in the villi.
11. What happens to substances absorbed in the:
(a) Capillaries
Carried to the hepatic portal vein.
(b) Lacteals
Transported in the lymph system.
12.
(a) The defecation process.
The semi-solid material is pushed into the rectum by peristalsis. The rectum's stretch receptors are
stimulated triggering the defecation process. The sphincter muscles relax passing the material through.
(b) What materials are contained in the faeces?
Undigested food, cellulose, bacterial, bile pigment, cellular remains.
13. Difference between constipation and diarrhoea.
Constipation is where defecation is difficult, diarrhoea is frequent defecation of watery faeces.
APPLY YOUR KNOWLEDGE:
1. Why do baby's contain rennin, where adults don't?
Because babies have more milk protein compared to adults.
2.
(a) What are Vestigial Organs?
Unused organs
(b) Wisdom Teeth & appendix.
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Wisdom Teeth =
Appendix = Cellulose digestion
3. Would a person be able to swallow upside down?
Yes due to peristalsis pushing the food towards the stomach.
4. A Meal of sausages & fried potato chips
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Sausages ð Protein by pepsinogen
Fat by lipase
Potato chip ð Fat by lipase
Potato by amylase.
5. Why does digestion occur in 3 places?
So more digestion can occur and it takes a long time to break food down.
6.
(a) What does enzyme specific mean?
They will act on one substance.
(b) Examples
Amylase only breaks down starch. etc
7. Explain why the small intestine has a larger surface area than the
large intestine.
Because it's folded and longer than the large intestine so more absorption can occur.