Question

Which of the following is NOT a domain in Woese and Fox's phylogenetic tree? a. Plantae b. Bacteria c. Archaea d. Eukarya

Short answer

a. Plantae

Step-by-step solution

- Understand Woese and Fox's Phylogenetic Tree

Woese and Fox's phylogenetic tree divides all living organisms into three major domains based on differences in ribosomal RNA (rRNA). The three domains they identified are Bacteria, Archaea, and Eukarya.

- List the Given Options

The options provided are: a. Plantae, b. Bacteria, c. Archaea, d. Eukarya.

- Compare the Options with the Known Domains

Compare each option to the three domains identified by Woese and Fox. The known domains are Bacteria, Archaea, and Eukarya. Check if each option fits into one of these categories.

- Identify the Odd One Out

From the options listed, Bacteria, Archaea, and Eukarya are known domains in Woese and Fox's phylogenetic tree. Plantae is a kingdom within the domain Eukarya, not a domain itself.

Key concepts

The Three Domains of Life

Woese and Fox's phylogenetic tree revolutionized how scientists classify living organisms. Before their work, life was mainly divided into Prokaryotes and Eukaryotes. However, studies on ribosomal RNA (rRNA) led them to discover three distinct domains: Bacteria, Archaea, and Eukarya.

Each of these domains represents a major lineage of life with unique characteristics. This structure helps us better understand evolution and relationships among different organisms.

Breaking it down:

• Bacteria: Single-celled, lack a nucleus, but have a simple cell structure.
• Archaea: Similar to bacteria in structure but have unique biochemistry and genetics.
• Eukarya: Complex cells with a nucleus; includes animals, plants, fungi, and protists.

Bacteria

The Bacteria domain comprises single-celled organisms that lack a nucleus and various organelles found in eukaryotic cells. They are considered among the oldest life forms on Earth and can be found in virtually every environment.

Key characteristics:

• Simple, single-celled organisms without a nucleus.
• Contain a cell wall composed of peptidoglycan.
• Reproduce by binary fission, a simple form of cell division.
• Often have a single circular chromosome.
• Can be found in soil, water, and as part of human flora.

Bacteria play crucial roles in ecosystems, such as decomposing organic material, fixing nitrogen, or causing diseases. Some bacteria are beneficial and used in food production, biotechnology, and medicine.

Archaea

The Archaea domain is composed of single-celled organisms that are distinct from bacteria and eukaryotes. They were initially classified as bacteria but have unique genetic and biochemical traits.

Characteristics of Archaea:

• Similar in appearance to bacteria, but with significant genetic differences.
• Cell walls lack peptidoglycan and have unique membrane lipids.
• Often live in extreme environments, such as hot springs and salt lakes.
• Not known to cause diseases in humans.

Archaea are adapted to survive in harsh conditions, making them invaluable for studying life's resilience. Their unique biochemistry also holds potential for industrial applications.

Eukarya

The domain Eukarya includes all organisms with complex cells containing a nucleus. This group encompasses a wide variety of life forms from single-celled protists to multi-cellular plants, animals, and fungi.

Main features:

• Possess a nucleus that houses DNA.
• Have various organelles, such as mitochondria and chloroplasts.
• Undergo mitosis and meiosis for cell division.
• Thicker cell structures compared to bacteria and archaea.

This domain's complexity allows for diverse forms of life. Plants perform photosynthesis, fungi decompose matter, and animals have elaborate tissues and organ systems. Eukarya's adaptability and complexity make it a fascinating domain to study and understand.