Organisation and digestion flashcards

Organisation and digestion covers how living organisms are structured in a hierarchy from cells to organ systems, and how the digestive system breaks down food for absorption. Students must understand the levels of organisation: cells, tissues, organs and organ systems. The digestive system includes organs such as the stomach, small intestine and liver, each with specific roles. Enzymes are biological catalysts that speed up the breakdown of large food molecules into smaller, soluble ones. Carbohydrases break down carbohydrates, proteases break down proteins, and lipases break down fats. Students should also understand how bile emulsifies fats and the role of the stomach in producing acid. The products of digestion are absorbed into the bloodstream through the small intestine, which is adapted with villi to increase surface area.

1. Card 1

   What are the four levels of organisation in a multicellular organism, in order?

   Cells, tissues, organs and organ systems. Each level is made up of the level below it working together to carry out a function.

2. Card 2

   What is a tissue?

   A tissue is a group of similar cells that work together to carry out a particular function, for example muscle tissue contracts to cause movement.

3. Card 3

   What is the role of enzymes in digestion?

   Enzymes are biological catalysts that speed up the breakdown of large, insoluble food molecules into smaller, soluble ones that can be absorbed into the blood.

4. Card 4

   Which enzyme breaks down starch, and what is the product?

   Amylase breaks down starch into maltose (a sugar). It is produced in the salivary glands and the pancreas.

5. Card 5

   Where are proteases produced, and what do they break proteins down into?

   Proteases are produced in the stomach, pancreas and small intestine. They break proteins down into amino acids.

6. Card 6

   What does lipase do, and where is it produced?

   Lipase breaks down fats (lipids) into fatty acids and glycerol. It is produced in the pancreas and small intestine.

7. Card 7

   What is the role of bile in digestion?

   Bile is produced by the liver and stored in the gall bladder. It emulsifies fats, breaking them into tiny droplets to give lipase a greater surface area to work on.

8. Card 8

   Why does the stomach produce hydrochloric acid?

   The stomach produces hydrochloric acid to kill bacteria in food and to provide the acidic pH that stomach proteases (pepsins) need to work effectively.

9. Card 9

   How is the small intestine adapted for absorption?

   The small intestine is lined with villi, tiny finger-like projections that greatly increase the surface area, allowing digested food molecules to be absorbed into the blood quickly.

10. Card 10

    What is the function of the large intestine?

    The large intestine absorbs water from the remaining undigested food material, forming solid faeces which are then stored in the rectum before being expelled.

11. Card 11

    What is the role of the pancreas in digestion?

    The pancreas produces digestive enzymes including amylase, protease and lipase, and releases them into the small intestine. It also produces insulin to regulate blood sugar.

12. Card 12

    Why must food molecules be broken down before they can be used by the body?

    Large molecules like starch and protein are insoluble and too big to pass through the gut wall. They must be broken into small, soluble molecules to be absorbed into the bloodstream.

• Many students confuse bile with an enzyme; bile is not an enzyme and does not chemically break down fats, it only emulsifies them into smaller droplets.
• Students often state that enzymes are destroyed rather than denatured at high temperatures; the correct term is denatured, meaning the active site changes shape permanently.
• A common error is to say that digestion happens only in the stomach; in fact digestion begins in the mouth with amylase and continues throughout much of the digestive system.

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