Digestion: make soluble products, then absorb them
הוצג| English | משמעות |
|---|---|
| digestion/daɪˈdʒestʃn/ | עיכול |
| emulsification/ɪˌmʌlsɪfɪˈkeɪʃn/ | אמולסיפיקציה |
What would explain this observation?
- Chewing makes food pieces smaller, but digestive enzymes change large food molecules into soluble products. Mechanical breakdown and chemical digestion 消化 have different effects.
Build the model
- The mouth, oesophagus, stomach and intestines form a digestive pathway.
- Amylase from salivary glands, pancreas and small intestine breaks starch into sugars.
- Proteases produced in stomach, pancreas and small intestine digest proteins into amino acids.
- Lipases from pancreas and small intestine break lipids into glycerol and fatty acids.
- Small soluble products can be absorbed, mainly through the small intestine.
- digestion: Breakdown of food molecules into smaller soluble products.
- emulsification 乳化: Breaking a liquid into smaller droplets without the digestive reaction itself.
How does bile help lipid digestion?
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
Bile emulsifies lipids - breaking large droplets into many small ones with far more surface for lipase - and its alkalinity suits the small-intestine enzymes. Bile is not an enzyme and stores nothing.
Match each technical term to its precise meaning.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Bile is made in the liver and stored in the gall bladder.
- Its alkaline character helps neutralize stomach acid entering the small intestine.
- It emulsifies fat into small droplets, increasing surface area for lipase.
- Bile is not an enzyme.
- Digestion products can build new carbohydrates, proteins and lipids, and some glucose is used in respiration.
In the lab: Trace one food molecule from a digestive site through a named enzyme to its products, then to absorption and use. Use simple word equations at GCSE: protein → amino acids, and lipid → glycerol + fatty acids. AQA does not require chemical symbol equations for these digestion reactions.
Which two habits make the investigation or model in this case more defensible?
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
Stating the conditions and assumptions lets others repeat the work exactly, and recording the supporting evidence lets them check the conclusion. Hiding disagreeing results removes the evidence that could challenge a wrong conclusion, and one measurement can never establish a wider claim.
Work from known quantities
- Known: a model contains 12 identical fat droplets that are divided into 48 smaller droplets while total fat amount stays the same.
- Droplet count rises fourfold.
- The increased exposed area can increase lipase action under matched conditions, but counting droplets alone cannot calculate their total area without size information.
Your turn: A model divides 15 fat droplets into 60 smaller droplets. Calculate the count ratio final/initial.
A model divides 15 fat droplets into 60 smaller droplets. Calculate the count ratio final/initial.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
The result is 4 . Known: 15 droplets become 60 droplets with the same total fat. Count ratio = 60/15 = 4. The exposed surface rises because many small droplets have more total area than few large ones of equal volume.
Check the conclusion and its limits
- Absorption does not mean breaking the food molecule down.
- Bile helps lipase but does not itself digest lipid.
- The stomach is not the main site where every nutrient is absorbed, and digested food does not travel through the trachea.
Not true: Bile is a digestive enzyme that hydrolyses every food molecule. Bile contains no enzyme and hydrolyses nothing: it is an emulsifier that physically disperses lipid droplets. The chemical breakdown is done by lipase, helped by the extra surface bile creates.
- The mouth, oesophagus, stomach and intestines form a digestive pathway.
- Bile is made in the liver and stored in the gall bladder.
- Watch for: absorption does not mean breaking the food molecule down.
Bile is a digestive enzyme that hydrolyses every food molecule.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
Bile contains no enzyme and hydrolyses nothing: it is an emulsifier that physically disperses lipid droplets. The chemical breakdown is done by lipase, helped by the extra surface bile creates.
Breakdown of food molecules into smaller soluble products: write the technical term.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
digestion means Breakdown of food molecules into smaller soluble products.