4

UNIT 2

Questions 4 – 5

Figure 1 accompanied an article in a magazine explaining the pungent (hot, spicy) effect of Indian
mustard powder on nose and palate. The enzymes referred to in the figure are substances which
control chemical activity in living things.

Figure 1

4

Figure 1 indicates that uncrushed Indian mustard seed

A

is pungent.

B

contains allyl isothiocyanate.

C

contains myrosinase and sinigrin.

D

contains no enzymes.

5

Of the following, the best explanation for the pungency of Indian mustard powder is that crushing the seed

A

brings myrosinase, sinigrin and water together to produce the pungent substance allyl isothiocyanate.

B

breaks down allyl glucosinolate into the pungent substance allyl isothiocyanate, with the release of
water.

C

causes the enzyme myrosinase to turn into the pungent substance allyl isothiocyanate.

D

causes the enzyme myrosinase to produce sinigrin, which then turns into the pungent substance allyl
isothiocyanate.

=

=

= =

Why mustard tastes hot

Indian mustard seeds

CH

2

CH

2

CH

2

CH

2

N C

S and glucose and sulfate

CH

C

S

glucose

enzyme

water

allyl isothiocyanate in meal
or mustard paste
volatile and pungent

allyl glucosinolate
(sinigrin) in seeds

N

O

SO

3

CH

crushing the seed releases
the enzyme myrosinase

mustard meal or condiment