Page 133 - Biology_F5

Biology for Advanced Level Secondary Schools

Cell membrane Procedure
Cell wall Pyrenoid
Cytoplasm (a) Collect fresh Spirogyra from fresh
water ponds or slow moving water
streams, and put it into a watch
glass.
FOR ONLINE READING ONLY
(b) Add a drop of water on a clean slide
using a dropper, and using an office
pin pick a few threads of Spirogyra
and mount them on the slide.

(c) Separate the strands using a pin to
Mucilage Nucleus Vacuole
Chloroplast remain with a few threads. Cover
your specimen with a coverslip.
Figure 3.18: Structure of a Spirogyra
(d) Place the slide under a light
Adaptations of Spirogyra to its mode of microscope for observation.
life (e) Notice the wide variety of
Spirogyra is able to live and thrive in its chloroplast types and the small,
environment due to the following adaptive round, colorless pyrenoids on some
features:
(a) It has pyrenoids for storage of starch. or all the larger chloroplasts.
(b) It has a large vacuole for osmo (f) Based on your observation, describe
regulation. the structure of Spirogyra.
(c) It has chlorophyll a and b for
photosynthesis, hence it is an autotroph.
(d) It has mucilage layer to protect it from Exercise 3.8
desiccation and infection. 1. Describe the ways in which
(e) It has a cellulose cell wall for strength Spirogyra is adapted to its mode of
and protection. life.

2. Explain the role of Spirogyra in
oxygen balance in freshwater habitat.
Activity 3.2: Observation of Spirogyra
under a light microscope 3. With examples, explain why do
taxonomists sometimes regard
Materials Spirogyra as a plant.
Fresh Spirogyra, microscope, slides,
slide cover, dropper, office pin, watch 3.4.2 Economic importance of kingdom
glass, and beaker containing water Protoctista
Protoctista are mostly aquatic organisms
found in sea, freshwater and moist soil.

Form Five Student’s Book
126