Labelled diagram showing the process of conjugation in Spirogyra (See page 338, Graham et al.,
2014; New International edition) (10)
2
,1.2 Advantages of algae (any 4)
1. Algae form the basis of the aquatic food chain.
2. Algae are an important source of food for humans and animals.
3. Algae yield a large variety of substances that can be used industrially, commercially and
domestically.
4. Algae yield compounds that are used in medicines.
5. Because algae are rich in nutrients, they can be used as fertiliser.
Disadvantages of algae
1. Algae may obstruct the gills of fish and cause their death.
2. Blooms impart smells and tastes to the water and increase the cost of water purification.
3. Some algae and cyanobacteria may secrete toxic compounds that can poison humans and
animals.
4. The decomposition of algae may lead to oxygen depletion, causing fish deaths. (8)
1.3 Terrestrial biomes (further reading: from page 483-509 Plant Biology, 2nd edition or 530-581-
New International edition)
a) Tropical forests
More than 200 cm annual rainfall with warm-hot temperatures year-round.
Thin soil cannot support continued cropping, and cannot resist erosion.
Rapid decomposition and nutrient cycling.
b) Deserts
Characterized by low moisture levels and precipitation that is infrequent and
unpredictable from year to year.
Wide daily and seasonal temperature fluctuations.
c) Chaparral/Mediterranean
Hot, dry summers and cool, moist winters.
Fires common component of landscape.
d) Savannas
Communities of grasses, seasonal herbaceous flowering plants, and open savannas.
Large daily and seasonal temperature fluctuations.
Frequent grass fires.
e) Tundra
Short growing season.
Treeless, frigid plain found in the very northern regions.
Water locked up much of the year.
Low biological productivity, low diversity, and low resilience
f) Taiga/Coniferous forest
Needle-like leaves with waxy coatings
g) Temperate deciduous forest
Occur throughout the world where rainfall is plentiful.
Deciduous trees shed leaves when water is scarce or ground is frozen
h) Grasslands
3
, Typically found in regions with flat or rolling terrain and have grass as their major
form of vegetation. (12)
QUESTION 2
2.1 See figure 22.14 (page 413, Plant Biology 2nd edition, 2006) or figure 14 (Page 471, Plant
Biology New International edition, 2014).
(15)
4
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