Question

Which of the following groups of organisms is most closely related to the kingdom Fungi? a. the animal kingdom b. the green algae c. the land plants d. the bacteria e. the archaea

Short answer

Most closely related kingdom to Fungi is the animal kingdom.

Step-by-step solution

Understanding the Taxonomic Hierarchy

The taxonomy of life forms or organisms is divided into different hierarchical levels. From highest to lowest, these levels are: domain, kingdom, phylum, class, order, family, genus, and species. Each level contains organisms with common characteristics.

Understanding the Kingdom Fungi

The kingom Fungi includes organisms such as mushrooms, molds, and yeasts. Fungi are typically multicellular, eukaryotic organisms. They have cell walls made of chitin. They are heterotrophic, typically digesting food in their environment by secreting enzymes.

Comparing Fungi with Other Kingdoms/Groups

When comparing these characteristics with the groups listed in the answers: a. The animal kingdom: Animals are multicellular, eukaryotic organisms. However, unlike fungi, animals do not have cell walls and are not decomposers but consumers. b. The green algae: These are mostly aquatic, photosynthetic organisms. There may be cell wall, but it is not made of chitin. c. Land plants: Plants also have cell walls and carry out photosynthesis. However, plant cell walls are made of cellulose, not chitin, and they are autotrophic. d. Bacteria: Bacteria are prokaryotic, not eukaryotic, and mostly unicellular. There is a cell wall, but the constitution is different. e. The archaea: They are prokaryotic like bacteria. They are distinguished from bacteria primarily based on RNA sequences.

Identifying the Most Closely Related Organism

None of the organisms listed in the options are exactly similar to Fungi, however, among the available choices, the organisms that are most closely related to fungi are the 'animal kingdom'. They share more common characteristics and both belong to the same domain, Eukarya.

Key concepts

Taxonomy

Taxonomy is the science of classifying and naming organisms into organized categories, making it easier to understand and study the diversity of life. This classification follows a hierarchical system comprising several levels: domain, kingdom, phylum, class, order, family, genus, and species. Each level—or taxon—includes organisms sharing a set of common characteristics.
For example, humans belong to the domain Eukarya, kingdom Animalia, and so on down to the species level, Homo sapiens. Within taxonomy, similar organisms are grouped together based on shared features, allowing scientists to understand relationships between different organisms.

• Domain is the highest taxonomic rank.
• Kingdom is the second highest and is divided into several categories like animals (Animalia), plants (Plantae), and fungi (Fungi).

The study of taxonomy helps in tracing evolutionary relationships among organisms, allowing us to see how closely related they are on a genetic level. For example, humans and fungi are part of the same domain, Eukarya, indicating a distant evolutionary relationship.

Eukaryotic Organisms

Eukaryotic organisms are defined by having complex cells with a nucleus enclosed within a membrane. This is one of the main characteristics distinguishing them from prokaryotic organisms, which lack a defined nucleus.

• Eukaryotic cells have organelles like mitochondria and the endoplasmic reticulum.
• They can be either unicellular or multicellular, such as plants, animals, and fungi.
• They share a more organized structure compared to prokaryotes.

Eukaryotic organisms are an incredibly diverse group, ranging from amoebae to humans. The kingdom Fungi is part of this domain, emphasizing that fungi, like animals and plants, have cells with a nucleus. This cellular structure supports complex biological processes and allows for the increased complexity in growth and reproduction compared to prokaryotes.

Heterotrophic

Heterotrophic organisms cannot produce their own food and instead rely on consuming other organisms or organic matter. This is a key characteristic of both the animal kingdom and fungi.

• Fungi digest food externally by secreting enzymes into their environment, breaking down complex organic material into simpler molecules that can be absorbed.
• Animals are consumers, feeding on plants, fungi, or other animals.

Unlike autotrophic organisms, such as plants that can make their own food through photosynthesis, heterotrophs depend on an external food source. This makes fungi similar to animals in terms of nutrition, as both require organic substrates to obtain the necessary nutrients for growth and energy.

Animal Kingdom

The animal kingdom, scientifically known as Animalia, encompasses a wide variety of multicellular, eukaryotic organisms. Unlike plants and some other kingdoms, animals lack cell walls. This absence of a rigid cell structure allows them greater flexibility and motility.

• Animals are primarily heterotrophic and must consume organic matter for energy.
• Most possess specialized tissues and organ systems.
• They reproduce primarily through a process called sexual reproduction.

Despite differences in cell wall structure and mode of nutrition, animals and fungi share some fundamental characteristics as they both belong to the domain Eukarya. This shared domain suggests a degree of genetic relationship, which is why fungi are considered more closely related to animals than plants, bacteria, or archaea.