How Do Animalia, Plantae, and Viruses Differ in Structure and Function?
The kingdom is the second-highest taxonomic rank just below domain and it is divided into smaller groups called phyla. This kingdom is further classified into Animalia, Plantae, Fungi, Protista, and Monera. The organisms were organized into five kingdoms by R.H.Whittaker on the basis of cell structure, mode, source of nutrition, and body design. The five-kingdom classification is followed by India. Kingdom Animalia contains all the animals and it is the largest among the five-kingdom classification. Kingdom Plantae consists of all the plants on the earth. Viruses are not made up of living cells so they do not belong to any particular kingdom.
The Virus Comes Under Which Kingdom
Viruses do not come under any kingdom because they are submicroscopic infectious agents that replicate only inside the living cells of an organism. Viruses have an ability to infect all types of life forms like animals, plants, microorganisms including bacteria and archaea. These are found in almost every ecosystem on earth and are considered to be the most numerous type of biological entity. Virology is the study of viruses.
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Difference Between Plantae And Animalia
Kingdom Animalia
The kingdom of Animalia is composed of all animals. It is considered to be one of the vast kingdoms from all the five kingdoms. These are multicellular eukaryotic organisms. These do not have a cell wall or chlorophyll like plants. The members of the animal kingdom have a heterotrophic mode of nutrition.
The kingdom Animalia is classified into ten different subphyla based on their body design or differentiation which are as follows
Porifera - These are the organisms with holes commonly known as sponges.
Coelenterata - These are the organisms which have a hollow body cavity.
Platyhelminthes - These are also known as platforms and they have a dorso-ventrally flattened body.
Nematoda - These consist of nematodes or roundworms which have a cylindrical body shape.
Annelida - These are commonly known as segmented or ringworms having segmented cylindrical body structure.
Arthropoda - These have jointed legs and this is the largest phylum in the animal kingdom.
Mollusca - It consists of a large group of animals and has an open circulatory system.
Echinodermata - These are spiny skinned animals and have a true coelom.
Hemichordata - These organisms have soft and fragile bodies.
Chordata - These are bilaterally symmetrical and possess a notochord.
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Kingdom Plantae
This kingdom includes all the plants on the earth. These are multicellular, eukaryotes, and consist of a rigid structure that surrounds the cell membrane called the cell wall. These have a green-colored pigment called chlorophyll which is important for photosynthesis.
The plant kingdom is also divided into five subgroups which are as follows
Thallophyta - These are the plants that lack a well-differentiated body structure.
Bryophyta - These have differentiated plant bodies like stem, leaf structures.
Pteridophyta - These have well-differentiated structures such as stem, root, leaves as well as a vascular system.
Gymnosperms - These are the plants that have a well-differentiated plant body, vascular system and they bear seeds that are naked.
Angiosperms - These are the seed-bearing plants with well-differentiated plant bodies. These are commonly known as flowering plants. These are further divided based on the number of cotyledons present in the seeds.
FAQs on Kingdom Animalia, Plantae, and Viruses: Classification and Differences
1. What were the main criteria R.H. Whittaker used to propose the five-kingdom classification?
R.H. Whittaker proposed the five-kingdom classification in 1969 based on several fundamental characteristics of organisms. The primary criteria for this classification were:
Cell Structure: Whether the cells were prokaryotic (lacking a true nucleus) or eukaryotic (with a true nucleus).
Body Organisation: The complexity of the organism's body, ranging from unicellular to multicellular, and the presence of tissues or organs.
Mode of Nutrition: How the organism obtains food, such as being autotrophic (e.g., photosynthesis) or heterotrophic (e.g., absorption or ingestion).
Reproduction: The main methods of reproduction, both asexual and sexual.
Phylogenetic Relationships: The evolutionary history and connections between different groups of organisms.
2. What are the key differences between Kingdom Plantae and Kingdom Animalia?
The main differences between Kingdom Plantae and Kingdom Animalia are based on cell structure, nutrition, and mobility.
- Cell Wall: Plant cells possess a rigid cell wall made of cellulose, which is absent in animal cells.
- Nutrition: Plants are primarily autotrophic, creating their own food via photosynthesis. Animals are heterotrophic, meaning they ingest other organisms for energy.
- Mobility: Most animals are motile (can move), whereas plants are typically sessile (fixed in one place).
- Chloroplasts: Plant cells contain chloroplasts for photosynthesis, which are absent in animal cells.
3. What is the basic structure of a virus?
A virus is a non-cellular infectious particle with a very simple structure. It fundamentally consists of genetic material, which can be either DNA or RNA (but not both), enclosed within a protective protein coat known as the capsid. The capsid is built from smaller subunits called capsomeres. Some viruses also have an outer lipid layer called an envelope, which is derived from the host cell membrane.
4. Why are viruses not placed in any of the five kingdoms?
Viruses are not included in the five-kingdom classification because they are not considered truly living organisms. They exist on the borderline of living and non-living things. Viruses lack a cellular structure, cannot perform their own metabolic processes, and are unable to reproduce independently. They are obligate intracellular parasites, which means they are inert outside a living cell and can only multiply by hijacking the machinery of a host cell.
5. What is the primary mode of nutrition in Kingdom Plantae?
The primary mode of nutrition in Kingdom Plantae is autotrophic, specifically through the process of photosynthesis. During photosynthesis, plants utilize sunlight, water, and carbon dioxide to synthesise their own food in the form of glucose. This vital process occurs in the chloroplasts, which contain the green pigment chlorophyll responsible for capturing light energy.
6. How does the three-domain system of classification relate to the five-kingdom system?
The three-domain system, proposed by Carl Woese, is a higher level of classification that refines the five-kingdom system by focusing on deep evolutionary lineages. It divides all life into three domains based on ribosomal RNA gene sequencing:
Archaea: Prokaryotes, often found in extreme environments.
Bacteria: True bacteria and cyanobacteria.
Eukarya: All organisms with eukaryotic cells.
In this model, Whittaker's Kingdom Monera is split into the two domains, Archaea and Bacteria. The other four kingdoms (Protista, Fungi, Plantae, and Animalia) are all grouped under the single domain Eukarya.
7. How do organisms in Kingdom Animalia differ in their levels of organisation?
Organisms in Kingdom Animalia exhibit a wide range of complexity in their body organisation. This diversity is categorized into different levels:
Cellular Level: The simplest animals, like sponges (Phylum Porifera), have a body made of a loose aggregate of cells with a basic division of labour but no true tissues.
Tissue Level: Organisms like cnidarians (e.g., jellyfish) have cells organised into distinct tissues to perform specific functions.
Organ Level: In more complex animals like flatworms (Phylum Platyhelminthes), tissues are grouped together to form organs.
Organ System Level: The most advanced animals, from annelids to chordates, have organs that work together in functional organ systems (e.g., digestive system, circulatory system) to carry out complex life processes.
