Lesson Notes By Weeks and Term v5 - Grade 11

Lesson Video

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Performance objectives

• Define biodiversity and its importance in South Africa.
• Outline the binomial system of nomenclature.
• Describe the hierarchical classification system.
• Explain phylogeny and cladistics for evolutionary relationships.
• Discuss the characteristics of the five kingdoms.

Lesson summary

This week, we embark on an exciting journey to explore the incredible diversity of life on Earth, specifically focusing on plants and animals. Understanding this diversity and how we classify it is crucial for several reasons. Firstly, it helps us appreciate the intricate web of life that sustains us. Secondly, it's vital for effective conservation efforts; knowing what species exist and where they are allows us to protect them. Thirdly, understanding evolutionary relationships helps us unravel the history of life.

Lesson notes

2.1 Biodiversity and its Importance: Biodiversity, short for biological diversity, refers to the variety of life on Earth at all its levels, from genes to ecosystems, and the ecological and evolutionary processes that sustain it. It encompasses the number, variety, and variability of living organisms. Why is it important?

Ecosystem Services: Biodiversity underpins essential ecosystem services such as pollination (think of the role of bees and other insects in pollinating our crops), nutrient cycling (carried out by bacteria and fungi in the soil), water purification (provided by wetlands), and climate regulation (forests acting as carbon sinks).

Food Security: A diverse range of crops and livestock provides food security and resilience against pests and diseases. Indigenous knowledge systems in South Africa often rely on biodiversity for traditional medicines and food sources.

Economic Value: Many industries, including agriculture, tourism, and pharmaceuticals, rely on biodiversity. Ecotourism in South Africa's national parks contributes significantly to the economy.

Ethical Considerations: Many believe that all living organisms have an intrinsic value and a right to exist. Preserving biodiversity is a moral imperative.

Resilience: Ecosystems with high biodiversity are more resilient to environmental changes and disturbances such as droughts, floods, and climate change.

Example: The Fynbos biome in the Western Cape is a hotspot of biodiversity, with a high concentration of endemic plant species. Its survival is crucial for maintaining water resources in the region and supporting the livelihoods of many communities. 2.2 Binomial Nomenclature: Binomial nomenclature, or "two-name naming", is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages. The first part identifies the genus to which the species belongs; the second part identifies the species within the genus.

Genus: The genus name is always capitalized.

Species: The species name is always written in lowercase.

Italics: Both names are italicized or underlined.

Example: Homo sapiens (humans), Panthera leo (lion), Protea repens (sugarbush protea).

Significance: Universality: Provides a standardized, unambiguous name for each species recognized globally, avoiding confusion caused by common names that vary regionally.

Stability: Although classifications may change, the scientific name generally remains stable, even if the species is moved to a different genus.

Informative: The genus name indicates the evolutionary relationships between species. 2.3 Hierarchical Classification System: The hierarchical classification system groups organisms into increasingly inclusive categories based on their evolutionary relationships.

The main levels are: Kingdom: The broadest category.

Phylum (Animals) or Division (Plants): Groups organisms with a similar body plan.

Class: Groups organisms within a phylum/division with shared characteristics.

Order: Groups organisms within a class with more specific similarities.

Family: Groups of closely related genera.

Genus: A group of closely related species.

Species: The most specific level, a group of organisms that can interbreed and produce fertile offspring.

Mnemonic Device: King Philip Came Over For Good Spaghetti (Kingdom, Phylum, Class, Order, Family, Genus, Species)

Example: Let's classify a lion (Panthera leo): Kingdom: Animalia Phylum: Chordata (possessing a notochord at some stage)

Class: Mammalia (possessing mammary glands, hair)

Order: Carnivora (meat-eating)

Family: Felidae (cats)

Genus: Panthera (big cats)

Species: leo (lion) 2.4 Phylogeny and Cladistics: Phylogeny: The evolutionary history of a species or group of related species. It represents the pattern of descent from common ancestors.

Cladistics: A method of classifying organisms based on shared derived characters (synapomorphies). It uses cladograms (branching diagrams) to represent evolutionary relationships.

Cladogram: A branching diagram showing the cladistic relationship between a number of species. In cladistics, organisms are categorized by shared derived characteristics which can be traced to the group's most recent common ancestor and are not present in more distant ancestors.

Key terms: Derived character: A trait that evolved in the lineage leading up to a clade and sets members of that clade apart from other individuals.

Ancestral character: A trait that was present in the common ancestor of a group.

Clade: A group of organisms that includes an ancestor and all of its descendants. A clade is also called a monophyletic group.

Example: Consider the evolutionary relationships between birds, reptiles, and mammals.