(b) R. Whittaker
R.H. Whittaker proposed a five kingdom classification system. The five kingdoms are Monera, Protista, Fungi, Plantae, and Animalia. Species are the basic unit of classification. The organisms that have the same characteristics and can breed with each other to produce fertile offspring are known to belong to the same species.
- Bacteria occur everywhere and they are microscopic in nature.
- They possess a cell wall and are prokaryotic.
- The cell wall is formed of amino acids and polysaccharides.
- Bacteria can be heterotrophic and autotrophic.
- They are unicellular and eukaryotic organisms.
- Some of them have cilia or flagella for mobility.
- Sexual reproduction is by a process of cell fusion and zygote formation.
- The fungi are filamentous, excluding yeast (single-celled).
- Their figure comprises slender, long thread-like constructions called hyphae. The web of hyphae is called mycelium.
- Some hyphae are unbroken tubes which are jam-packed with multinucleated cytoplasm. Such hyphae are labelled Coenocytic hyphae.
- The other type of hyphae has cross-walls or septae.
- The kingdom Plantae is filled with all eukaryotes which have chloroplast.
- Most of them are autotrophic in nature, but some are heterotrophic as well.
- The Cell wall mainly comprises cellulose.
- All multicellular eukaryotes which are heterotrophs and lack cell wall are set aside under this kingdom.
- The animals are directly or indirectly dependent on plants for food.
- Their mode of nutrition is holozoic.
- Many of the animals are adept for locomotion.