Which Kingdom in Whittaker's five-kingdom classification includes unicellular eukaryotes?
AMonera
BProtista
CFungi
DPlantae
Answer:
B. Protista
Read Explanation:
Whittaker's Five-Kingdom Classification System
- The Five-Kingdom Classification System was proposed by Robert H. Whittaker in 1969. This system is widely accepted due to its comprehensive and logical grouping of organisms.
- It classifies organisms based on several key criteria:
- Cell structure (prokaryotic or eukaryotic)
- Thallus organization (unicellular or multicellular)
- Mode of nutrition (autotrophic, heterotrophic - saprophytic, parasitic, holozoic)
- Reproduction
- Phylogenetic relationships (evolutionary history)
- The five kingdoms are:
- Monera
- Protista
- Fungi
- Plantae
- Animalia
Kingdom Protista
- Kingdom Protista includes all single-celled eukaryotes.
- Protists exhibit a diverse mode of nutrition, including:
- Autotrophic (e.g., photosynthetic algae like diatoms, dinoflagellates, Euglena)
- Heterotrophic (e.g., protozoans like Amoeba, Paramecium)
- Mixotrophic (combining both, e.g., Euglena)
- They possess a well-defined nucleus and membrane-bound organelles, distinguishing them from prokaryotic organisms in Kingdom Monera.
- Some protists have cilia, flagella, or pseudopodia for locomotion.
- Reproduction in protists can be both asexual (e.g., binary fission) and sexual (e.g., zygote formation).
- This kingdom acts as a connecting link between prokaryotes (Monera) and the other three multicellular eukaryotic kingdoms (Fungi, Plantae, Animalia).
Other Kingdoms (Brief Overview for Comparison)
Kingdom Monera
- Comprises all prokaryotic organisms (bacteria and cyanobacteria/blue-green algae).
- They are typically unicellular and lack a true nucleus and membrane-bound organelles.
Kingdom Fungi
- Includes heterotrophic eukaryotic organisms, primarily multicellular (except yeast, which is unicellular).
- They are characterized by a cell wall made of chitin and obtain nutrients through absorption (saprophytic or parasitic).
Kingdom Plantae
- Consists of multicellular eukaryotic autotrophs.
- They have a cell wall made of cellulose and primarily produce food through photosynthesis.
Kingdom Animalia
- Composed of multicellular eukaryotic heterotrophs.
- They lack cell walls and obtain nutrients through ingestion (holozoic nutrition).
- Most members are motile.