Chapter 19 Outline: Systematic Seeking Order Amid Diversity
19.1: How Are Organisms Named and Classified?
Naming organisms is important because it forms the basis for scientific studies. Taxonomy is the branch of science concerned with organisms’ naming criteria. Carl von Linné established the basis of modern taxonomy. A taxon is a Named group of species.
The modern taxonomy follows a two-part scientific naming approach. The Latin name shows an organism's genus and species. The Genus name is presented first, followed by the species name.
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Modern classification underscores patterns trends of evolution, and the contemporary classification processes fundamentally aim at reconstructing phylogeny.
19.2: What Are the Domains of Life?
The split in the lower tree of life creates five kingdoms:
Protista
Fungi
Plantae
Animalia
Monera
Three domain naming system accurately reflects life history. Prokaryotic organisms were found to have two distinct groups by Woese. These are Bacteria and Archaea, which differ in their nucleotide sequences of ribosomal RNA.
Domain Eukarya has four groups of organisms:
Animals
Plants
Fungi
Protists
19.3: Why Do Classifications Change?
The emergence of the three-domain classification system indicates that the evolutionary relationships which are the bases of classification are subject to change.
The designation given to species will change when new information emerges.
Originally, systematists believed that there are two species of elephants, African and Indian. However, after research, it was ascertained that the African elephant species could be divided into two: the savanna and forest elephant.
Applying the species classification criteria can be difficult because it uses the concept of sexual reproduction as the basis of defining species. Thus, it is not possible to define asexual organisms.
19.4: How Many Species Exist?
About 15,000 species are defined annually, while at the moment, there are about 1.6 million species.
Scientists approximate the number of species to be about 8.7 million species are in existence.
The Earth's biodiversity is defined by the species living in it.
5% are prokaryotes and protists
About 20% are plants and fungi
The rest are animals
Chapter 22 Outline: The Diversity of Plants
22.1 What Are the Key Features of Plants?
Key Feature of Plants:
Plants are photosynthetic
Plants have multicellular dependent embryos
Plants have alternating multicellular haploid and diploid generations
22.2 How Have Plants evolved?
Plants belong to a large clade called charophytes: store food as starch and their cells are made of cellulose.
Plants' ancestors, protists, lived in water.
Early plants invaded the land, which posed a challenge.
Plant bodies evolved to defy gravity and drying by developing roots, wax cuticle, stomata, xylem, phloem, and lignin.
After invading the Earth, plants had to evolve their sex cells to be non-water reliant for dispersion and protection.
The evolution of plants is associated with smaller gametes.
22.3 What Are the Major Groups of Plants?
The two major groups of plants are nonvascular and vascular plants
Vascular plants are known as tracheophytes, while nonvascular plants are called bryophytes
Nonvascular plants lack conducting structure
Do not have roots, stems, or leaves but have rhizoids
Rhizoids: rootlike anchoring structures
Body size is limited
Plants include liverworts, hornworts, and mosses
There are two types of reproductive structures, archegonia, and antheridia, and both are located in the same plant
Archegonia: produces eggs
Antheridia produces sperm
Vascular plants have conducting cells that are used to provide support.
Vascular plants are distinguished by xylem and phloem.
Vascular plants are divided into two groups.
Seedless
Seed plants
Seedless plants include mosses, horsetails, and ferns.
Seed plants are characterized by two important aspects: pollen and seeds
Pollen grains: carry sperm-producing cells dispersed by wind
Seeds: have three parts, embryonic sporophyte plant, food supply for the embryo, an outer coat for protection
Gymnosperms: Nonflowering plants
Angiosperms: flowering plants and are characterized by
Flowers
Fruits
Broad leaves
22.4 How Do Plants Affect Other Organisms?
Plants have an impact on the landscape and atmosphere as they grow, survive, and reproduce.
Other inhabitants of plant earth reap immense benefits from plants.
Ecological role: Play a role in the provision of food, soil formation, and water that are key sustainers of life on Earth.
Capturing energy through photosynthesis enables them to make food.
Maintenance of atmosphere.
Building and protection of soil.
Contributes to the moisture content of the universe
Humans depend on plants for luxuries and other necessities such as food, shelter, medicine, and pleasure.
Reflection
Instructions: Write your responses below in the green boxes.
NOTE: The green boxes will expand when you type to the end of them.
1. Questions. After reading Chapter 19 and 22, write one question from each chapter that you have about the information. Go to the Discussion Board for Week 6 and post one or both of your questions below.
| Chapter 19 Question | Question 1: What contributions did Linnaeus and Darwin make to modern taxonomy? Carolus Linnaeus is often described as the father of taxonomy. Taxonomy refers to the system of categorizing and naming organisms. One of the major contributions of Linnaeus was the development of the hierarchical system of classifying organisms. On the other hand, Darwin is known as the originator of the school of evolutionary taxonomy majorly because he acknowledged the genealogy and similarity as two-fold, synergistic criteria for classification. Darwin held that genealogy is the foundation of classification. |
| Chapter 22 Question | What is meant by "alternation of generations"? What are two generations involved? How does each reproduce? The alternation of generations is also known as metagenesis. This is a kind of life cycle associated with plants and algae that belong to the groups Archaeplastida and Heterokontophyta that have discrete haploid and diploid characteristics. The reproduction phases are either morphologically or chromosomally distinct. A diploid sporophyte will reproduce through haploid spores. The spores will then divide by mitosis to form haploid gametophyte plants. Gametophyte will produce male and female gametes by mitosis. Male and female gametes will fuse, forming diploid zygotes, which will be divided by mitosis to develop diploid sporophytes. |
2. Interesting Sections. Look at the Case Study, Science in Action, Health Watch, and Links to Everyday Life sections in each chapter. Pick ONLY one section from each chapter and, in 3 sentences, explain why that particular section was interesting to you.
| Why was this section interesting to you? | |
| Chapter 19 Section | Section 19.4 was interesting to me because it made me appreciate how species-rich the Earth is and that only about 18% of species are known. Considering the nature of scientists’ work, naming at least 50% of species will take many years to name all species. |
| Chapter 22 Section | Section 22.4 was interesting because it gives one insight into how plants contribute to the larger ecosystem. Plants influence different spheres of life on Earth, such as the provision of food, shelter, and other aspects. I have appreciated that if plants were eradicated from the planet Earth, there would be no more life for animals. |
3. Design Perspective. Choose something in each chapter and explain in no more than three sentences how that information points to the designing work of a Creator. You will use these Design Perspective responses in your Critical Assignment, the Design Perspective Paper
| How does this information point to the designing work of a Creator? | |
| Chapter 19 | That there could be 8.7 million species and only 1.6 million are known shows how the Creator valued diversity. The rich diversity of species that are known and unknown makes the Earth look magnificent. Factoring that each organism a role on this planet evidences that the Creator is a master designer. |
| Chapter 22 | The role of plants on Earth shows that Creator had His creation plans well-thought-out. I think that the Creator intended plants to play an ecological role because they are the primary source of food. This is because plants play a crucial role in maintaining the sustainability of planet Earth. |
