1. Speeding up
digestion
WALT: To understand how the rate of digestion can
be increased.
Sunday, 28 September 2014
WILF:
Recall knowledge on types of enzymes and factors
which affect enzyme action. (C)
Describe how different parts of the digestive system
are adapted for the optimum pH for different
enzymes. (B)
Clearly explain the role of bile in the digestion of fats.
(A/A*)
Keywords
Bile
Surface area
Emulsify

2. What’s wrong with this?
Digestive enzymes are made by cells and break
down large molecules into smaller, insoluble
molecules so they can be absorbed in the
stomach. Carbohydrases break down
carbohydrates into amino acids. For example,
amylase is made in the stomach, pancreas and
small intestine. Proteases break down proteins
into amino acids. These enzymes are made in the
salivary glands, pancreas and large intestine.
Lipases break down fats into fatty acids and again
these are made in the pancreas and small
intestine.
Can you spot the 8
mistakes in this
answer? Underline
and write the
correct answers in
your book.

3. Investigating digestion
Test for starch?
Use iodine, a positive result
is shown as blue-black
colour.
Test for sugar (glucose)?
Use Benedict’s, a positive
result is shown as red colour.

4. B1
Link!
Adaptation in animals
(4.2)
Keywords
Surface area:
Volume
Insulation
Blubber
Camouflage
C: List three adaptations that Arctic
animals have to keep warm.
B: Describe some of the adaptations
animals living in hot and dry climates
have to help them survive.
A/A*: Explain how a small surface area
to volume ratio is a useful adaptation
shown in many arctic mammals.
Pgs. 78-79

5. pH in the digestive system
The stomach produces hydrochloric acid
(pH2).
The enzymes in the stomach (protease) have
an optimum pH of pH2.
Hydrochloric acid does not digest food but
allows enzymes to work in optimum
conditions.
Protein  amino acids

6. pH in the digestive system
Enzymes produced by the pancreas and
small intestine work best in alkaline
conditions.
So?
Bile  made in the liver and stored in the
gall bladder.
Neutralises stomach acid.

7. Task 1: Look at the
practical picture on pg
170.
Explain the results of
each test tube on how
protein is broken down.
Task 2: Describe how the
stomach protects itself
from the hydrochloric
acid it produces.
Task 3: Copy and complete
the following sentences:
Bile is produced in the…
Bile is stored in the…
Bile neutralises…
This is important because…

8. Altering the surface area
(SA)
Enzymes need the largest SA possible to
work as this will increase the rate of
reaction.
Large globules of fat provide a small
surface area for lipase to work on.

9. Digestion of Fats
Bile emulsifies the large fat globules into smaller
droplets creating a larger SA for lipase to work on.

10. Explain the role of enzymes in the digestive system and
how the digestive system is adapted for efficient
digestion. 6m

11. What’s wrong with this?
Digestive enzymes are made by cells
and break down large molecules
into smaller, insoluble molecules so
they can be absorbed in the
stomach. Carbohydrases break
down carbohydrates into amino
acids. For example, amylase is made
in the stomach, pancreas and small
intestine. Proteases break down
proteins into amino acids. These
enzymes are made in the salivary
glands, pancreas and large intestine.
Lipases break down fats into fatty
acids and again these are made in
the pancreas and small intestine.
What’s wrong with this?
Digestive enzymes are made by cells
and break down large molecules
into smaller, insoluble molecules so
they can be absorbed in the
stomach. Carbohydrases break
down carbohydrates into amino
acids. For example, amylase is made
in the stomach, pancreas and small
intestine. Proteases break down
proteins into amino acids. These
enzymes are made in the salivary
glands, pancreas and large intestine.
Lipases break down fats into fatty
acids and again these are made in
the pancreas and small intestine.