4. General characteristics
1. Fungi have no chlorophyll
so cannot make their own food by
photosynthesis
How do fungi
feed?
1. As parasites
2. As saprophytes
5. Parasites:
(feed on a living
host, causing it
harm)
Saprophytes:
(feed on dead and
decaying matter)
Parasitic fungi on (i)
nails and (ii) trees.
(i) (ii)
6. 2. Fungi do not produce
flowers. Reproduce by
spores.
3. Fungi are mainly found in
damp and shady places.
7. Question: SEP, 2011
Give a biological explanation for each of
the following statements.
Fungi are rarely found in brightly lit
environments. (3)
Do not photosynthesise.
Lack a waxy cuticle – avoid drying up by
avoiding such environments.
8. 4. The basic unit of a fungus is a hypha
and not a cell.
A. nucleus
B. cell wall
C. cytoplasm
D. vacuole
A hypha (plural = hyphae) is a thread-like
structure having a cell wall made of chitin.
Part of a hypha
10. A network of hyphae: a
mycelium
hyphae are either white or grey
A hypha grows out of
a germinating spore
Mycelium
11. Two types of hyphae:
feeding hyphae:
are horizontal
reproductive
hyphae: are erect
12. Mucor
belongs to the group of fungi called moulds –
it is a pin mould
lives on damp, organic (has carbon) matter
such as:
bread
leather
fruit
leaf litter
horse dung
13. Structure of Mucor
Spores in
sporangium
Erect
reproductive
hypha
Sporangium
(spore case)
Feeding
hypha
15. Spores are:
i) small & light:
to be carried easily by
the wind or insects
ii)numerous:
to increase chances
of survival
16. Nutrition in Mucor
3. Nutrients are
absorbed from all
over the hyphae.
1. Extracellular
enzymes from
growing tips.
2. Digestion takes place
outside the body.
18. Fungi are useful:
1. Decay dead material and are important to
recycle nutrients in the soil
2. Decompose sewage
3. Are used to make the antibiotic penicillin
4. Are eaten e.g. mushrooms
5. Yeast is useful to make bread, wine and beer
19. Fungi are harmful:
1. Parasitic fungi causes diseases
in animals and plants
2. Spoil food, clothes, leather and walls
Athlete’s foot in
humans
Rusts in wheat
20. Let us study YEAST:
1. Structure
2. Economic importance
21. A single yeast cell
cell wall
nucleus
cytoplasm
vacuole
Yeast is a unicellular fungus
26. 1. Dough making
flour, yeast, sugar &
water are mixed to
make a dough
Water must be warm and
NOT boiling. WHY?
27. The living yeast cells
multiply and
ferment the sugar to
give off carbon
dioxide gas
After 1 hour in a warm
place the dough has
risen.A close-up of the dough.
28. What happens to the
alcohol during baking?
It evaporates on baking.
SEP 2013
Explain why it is important to
produce a very sticky dough after
mixing the ingredients together. (2)
Carbon dioxide remains inside the
dough. The gas makes the dough
expand.
29. The ‘holes’ in the
bread are made by
the carbon dioxide
bubbles.
This gives the bread a
‘light’ texture
SEP 2013
What happens to the
yeast when the dough
is baked in the oven?
Why? (2)
Dies. The heat kills it.
30. Question: SEP, 2007
Give biological reasons for the following
statement:
Yeast is added to flour for the pizza dough to rise.
(2)
Yeast releases carbon dioxide by fermentation. As
carbon dioxide escapes, it makes the dough rise.
31.
32. Barley seeds are
soaked in water so that
enzymes are made
Enzymes convert the
stored starch into
sugar
33. the seeds are crushed with water
the resulting liquid is boiled with hops to
give it a flavour
36. Question
The main stages in the brewing of beer are
given in the diagram below.
Stage B
Barley or other cereal grains germinatedStage A
Stage C
Stage D
Stage E
Germinated grains crushed in water
Yeast added to solution (from Stage B) and
mixture placed in closed vats fitted with
one-way exit valve
Yeast dies and falls to bottom
Liquid bottled
a) Name the
principal
carbohydrate
stored in
cereal grains
(Stage A).
Starch
37. b) What conditions are needed for the
barley to germinate?
Water, a correct temperature, oxygen
c) Describe the action of the yeast on the
solution in Stage C. (3)
Yeast ferments the sugar into carbon
dioxide, ethanol and energy. The
process is anaerobic.
38. d) Why were the vats closed and fitted with
one-way exit valves in Stage C? (3)
To prevent microbes & oxygen from
entering. To allow carbon dioxide to
escape or else the fermenter bursts.
e) What was the most likely cause of death
of the yeast in Stage D? (Assume that the
supply of food was adequate.) (1)
Ethanol.
43. What is the use of an ‘airlock?
allows CO2 to escape
prevents microbes from entering
44. Why does the balloon inflate?
As yeast
ferments the
sugar, CO2 is
released.
45. Question: MAY, 2004
The apparatus used to make wine was
sterilised before being used. Why is
sterilisation of the apparatus important?
To kill bacteria as they can convert
ethanol into ethanoic acid. Vinegar
would be produced instead of wine.
47. Question: MAY, 2012
Some winemakers add sucrose to
unfermented grapes. What is the effect of
this sucrose addition on the alcohol
content of the wine produced? (1)
Increase in alcohol content.
48. Question: SEP, 2007
1) Humans have used yeast to produce
pizza dough. Describe briefly TWO
other beneficial ways in which yeast
has been utilised by human beings for
economic benefits. (4)
2) Suggest TWO advantages and ONE
disadvantage for yeast cells when
included in these processes. (3)
49. Other uses of yeast:
As SCP (single cell protein)
In genetic engineering experiments
50. Question: SEP, 2012
Yeast is a fungus.
a) Give ONE characteristic of fungi. (2)
b) Name the type of asexual reproduction
performed by yeast cells. (1)
c) Give ONE disadvantage of asexual
reproduction. (2)
