8.4 BIODIVERSITY

Learning Outcomes

At the end of lesson, students should be able to:1. Explain the meaning of ‘biodiversity’.2. Explain the need for classification of organisms.3. State the five kingdoms used in the classification of organisms.4. Identify the main characteristics of organisms in each kingdom5. List examples of organisms in each kingdom6. State the hierarchy in the classification of organisms using

examples7. Explain through examples, the method of naming organisms

using Linnaeus binomial system8. Explain the importance of biodiversity.

Definition

• Biodiversity refers to the diverse species of plants and animals interacting with one another on Earth.

The Need for Classification of Organisms - Taxonomy

• Taxonomy: A branch of Biology concerned with identifying, describing and naming organisms.

• Systematic method to classify plants and animals based on similarities and characteristics.

• Enables organisms to be identified easily and accurately.

• Enables communication among scientist.• Allow information about a particular organism to

be found more readily.

Kingdoms

• There are five kingdoms used in the classification of organisms.

Monera

• Prokaryotic organisms.• Unicellular.• Have cell walls but lack of both membrane-

bound nuclei and organelles.• Can be photosynthetic and non-

photosynthetic.

• Examples:

• Examples:

Cyanobacteria (blue-green algae)

Bacteria

Protista

• Eukaryotes – unicellular or multicellular organisms, and each cell has a distinct membrane-bound nucleus.

• Some have cell wall and some do not.• Multicellular protist have no specialised cells

to perform specific function.• Nutrition: Can be either heterotrophic and

autotrophic or both.

• Examples:

Spirogyra sp.Alga

Seaweed Amoeba sp.

Fungi

• Heterotrophic multicellular eukaryotes.• Some are unicellular.• Cell wall of fungi contain a material called

chitin.• Main bodies consist of network of thread-like

hyphae called mycelium.• Do not contain chlorophyll.• May feed saprotrophically.

• Examples:

Mushroom

Yeast

Pin mould

Plantae

• A kingdom which includes all land plants.• Immobile, multicellular eukaryotes.• Important sources of oxygen, food, clothing,

pigments, spices, dyes and drugs.

• Examples:

Fern Hibiscus plant

Palm tree

Animalia

• Multicellular heterotrophic eukaryotes.• Do not have cell wall.• Can move form one place to place.

• Examples:

Hierarchy in classification of organisms

Linnaeus binomial system

• Each organism has two names in Latin.• First name: begin with a capital letter refers to

genus.• Second name: begin with smaller letter refers

to species.• Example:– Homo sapiens [Homo: genus; sapiens: species]

Exercise 8.1

1. Describe the following modes of nutrition:a) Saprophytismb) Parasitismc) Predation

2. Explain how the relationship of prey-predator can establish a dynamic equilibrium in the environment. (Give one example in your explanation).

1. (a)saprophytic organism does not synthesize food by itself.