5 DIAGNÓSTICO
5.1 Los instrumentos de gestión educativa en donde se evidencia la gestión en
5.1.5 El proyecto educativo institucional (PEI)
Fungi 61
Ferramycin from S. rimosus Erythromycin from S. erythreus Jaweharene from Aspergillus sp.
2. In Industry
u. their vegetative body is collectively called mycellium.
in. reproduction is both asexual and sexual.
iv. fungi cause diseases like smut, rust etc to man.
v. fungi causes diseases in man and animals e.g. ringworm.
vi. fungi are highly important in medicine, industries and in agriculture.
i. Briefly explain the economic importance of fungi to man.
u. List three differences between asexual and sexual reproduction in Mucor.
How do fungi obtain nutrients from their substrates?
zetwv adult
Dutta A.C., Botany for degree stud_ ells
Idodo - Umeh (1996) College Biology - Idodo - Umeh Publishers, Benin City
Volume 1: Basic Concepts in Biology
Page
1.0 Introduction 64
2.0 Objectives 64
3.0 Characteristic Features of Algae 64
3.1 Spirogyra 66
3.1.1 Structure of Spirogyra 66
3.2 Reproduction in Spirogyra 67
3.3 Importance of Algae 69
4..0 Conclusion 69
5.0 Summary 69
6.0 Tutor - Marked Assignment 69
7.0 Further Readings and other Resources 69
63
There are several distinct divisions of the plant kingdom, which although they are not really closely related, are conveniently discussed together because they have certain features in common. Even though some of these basically simple plants appear to have bodies that have true roots, stems or leaves because they lack the vascular tissues and other characteristics of such structure in higher plants. The sex organs and sporangia are usually one celled, or if multicellular, the gametes and spores are not enclosed within a wall formed by a layer of sterile (non reproductive cells).
The members of these groups are generally called cryptogams.
Algae are Cryptogams. Cryptogams are flowerless, seedless plants. They form three main groups.
1. Thallophyta: algae, fungi and lichens.
2. Bryophyta: Liver worts e.g. marchantia and mosses e.g. funaria (polyrichum).
3. Pteridrophyta: ferns e.g. Dryopteris.
There are various kinds of algae base on their morphology and t' c pigment they contain.
On the basis of their pigments, the following groups
have beet identified• Blue green algae e.g. Nostoc, Oscillatoria
• Green algae e.g. Spiroygra
• Brown algae e.g. Fucus, sargassum
• Red algae e.g. Bartrachospermum On the basis of morphology
• Euglenoid algae e.g. Euglena
• Bacillairophytes e.g. diatoms e.g. Pinnula a, Diatoma
By the end of this unit, you should be able to:
i. Explain what algae are.
ii. List the characteristics of algae.
iii. Describe the structure of algae.
iv. Explain the reproduction of algae.
v. State the importance of algae.
vi. List the differences between algae and fungi.
Now let us commence our study of algae by examining the general characteristics of this group
1. They are simple plants without roots, stems and leaves.
2. All algae have chlorophyll. Some have blue, yellow, brown and red pigments which mask the chlorophyll.
3. Majority are non-cellular while few are multicellular. Some, such as sea weeds are large.
4. They are mainly aquatic, with a few on damp soils and shady places.
Examples are Spirogyra, Anabaena and Sargassum see fig. 8.1 5. The body of an alga in composed of a true parenchymatous tissue.
6. The cell wall of an alga is composed of a true cellulose.
7. Reserve carbohydrate is usually starch, and not glycogen as in fungi.
Algae 65
8. Algae are classified into six classes. These are:
Class I - Mycophyceae or cynophyceae or blue green algae e.g. include Nostoc, Anabeana, Oscillatoria.
Class 2 - Euglenophyceae e.g. Euglena
• Class 3 - Chlorophyceae or green algae e.g. volvox, spirogyra, witella, Zygnema
• Class 4 - Bacillariophyceae or diatoms.
• Class 5 - Phaeophyceae or brown algae, e.g. Fucus
• Class 6 - Rhodophyceae or red algae e.g. Batrachospermum Conjugation in Sypirogyra
Spirogyra
Sargassum
chloroplast (spiral) pyrcnoid mucilage
nucleus
cytoplasmic
strand vacuole
septum cell wall lining cytoplasm
Closterium (diatom) Figure 8.1 - Different forms ofAlgae 3.1 Spirogyra (Chlorophyceae)
Occurence: Spirogyra belongs to the family chlorophyceae and the order conjugates or zygnematales. It is a cosmopolitan plant which forms a tangled mass of filaments floating on stagnant fresh water, especially in ponds, ditches, springs and streams. Some species grow in running water. Such species produce a short unicellular organ of attachment, called hapteron, for anchorage on sea weeds.
Spirogyra is commonly found as bright green masses of thread-like or filamentous structures on the surfaces of waters, and is often referred to as a "pond scum".
3.1.1 Structure of a Spirogyra
Mature filament is unbranched and consists of single row of identical cylindrical cells jo
ined
end to end.Cell wall is made of cellulose and pectin.
External cell wall is covered by mucilage, making it slimy.
Cytoplasm is a thin layer with spiral bands of chloroplast.
Nucleus is suspended at the centre by strands of cytoplasm.
Chloroplast contains small nodular protoplasmic bodies called the pyrenoids.
Starch grains are deposited around each pyrenoid.
Gametes are without cilia and are called aplanogametes.
Gametes are morphologically isogamous (identical in structure) but physiologically anisogamous (ie.
gametes are different in terms of appearance and behaviour).
Figure 8.2 - The Structure of Spirogyra
Algae 67
List five characteristic features of algae.