10
6
This question is about enzymes.
Choose words from the list to complete the sentences.
Each word may be used once, more than once, or not at all.
amino acids
amylase
bacteria
biological
fatty acids
glucose
humidity
lipase
living
protease
salivary
temperature
All enzymes are proteins. Proteins are made of
catalyst.
An enzyme acts as a
and pH.
Inorder to work rapidly, enzymes need the correct
An example of an enzyme that works in the acidic conditions in the stomach is
Acidic conditions will kill many of the
Salivary
present in food.
stops working in acidic conditions.
Fats are broken down by
[7
[Total: 7]
(b) State how young animals use the substances listed in Table 7.1.
protein
fa
carbohydrate
calcium
water
[5
12
(c) An adult eats a high-fat diet.
State two health problems that could be caused by eating a high-fat diet.
2
[2]
12
6
Fig. 6.1 shows a section through a tooth.
G
H
Fig. 6.1
(a) State the names of structures F,G and H.
Write your answers on Fig. 6.1.
[3]
(b) (0) State two functions of teeth.
1
2
[2
6
3
(a) The boxes on the left contain the names of components of the diet.
The boxes on the right contain the functions of these components in the body.
Draw one straight line to link each component of the diet to its correct function.
Draw four lines.
component of the diet
function
calcium ions
bone formation
fat
growth of muscles
protein
insulation
vitamin D
[4]
16
(d) Protein can be broken down into amino acids.
() List four chemical elements that are always found in protein.
2
3
4
[2]
(i) State the name of the organ in the human body that breaks down excess amino acids.
[1)
(e) Fig. 6.2 shows some chemical reactions that are catalysed by enzymes.
The enzyme catalysing the reaction is shown on the arrow.
Complete Fig. 6.2 by filling in the names of the four missing molecules.
amylase
starch
protein
amino acids
lipase
and
fats
Fig. 6.2
(3]
[Total: 17]
8
3
Enzymes help to digest food in humans and are produced by different parts of the alimentary
canal.
(a) The box on the left contains a sentence beginning.
The boxes on the right contain somne sentence endings.
Draw two lines to make two correct sentences about enzymes.
are carbohydrates.
are catalysts that slow down reactions and remain unchanged.
are catalysts that speed up reactions and are changed.
Enzymes
are catalysts that speed up reactions and remain unchanged.
are lipids.
are proteins.
(2]
(b) Fig. 3.1 is a diagram showing an enzyme and several different substrate molecules.
O.
enzyme
Fig. 3.1
State the letter of the molecule that is most likely to be the substrate for this enzyme.
[1]
(c) Enzymes are involved in chemical digestion in humans.
Define the term chemical digestion.
[2]
10
(d) Fig. 3.2 is a graph showing the effect of changes in pH on the activity of four different enzymes,
U
to X.
U
W
enzyme
activity
1
2
3
A
6
5
7
10
8
11
pH
Fig. 3.2
The pH values in different parts of the alimentary canal were measured.
Table 3.1 shows the pH values found in the different parts of the alimentary canal.
(i) Use the information in Fig. 3.2 to state the letter of the enzyme that would be most
active in each part of the alimentary canal.
Table 3.1
part of the
alimentary canal
pH values
duodenum
5.5
ileum
8.0
mouth
6.7
stomach
1.5
enzyme letter
(2]
(ii) The duodenum and ileum are part of the small intestine.
State the name of one part of the large intestine.
[1]
11
(e) The acid in gastric juice provides an acid pH for enzymes.
(i) State one other function of the acid in gastric juice.
[1]
(ii) State the name of the acid that is found in gastric juice.
[1]
() Table 3.2 shows the names of some enzymes, the substrate they act on and the products of
the reaction they are involved in. It also shows the organ that secretes the enzyme.
Complete Table 3.2.
Table 3.2
substrate
enzyme
amylase
products
the enzyme
starch
fatty acids and glycerol
protease
organ that secretes
pancreas
amino acids
[6
[Total: 16]