CIE A Level Biology复习笔记18.1.4 Kingdoms

• The domain Eukarya can be divided into 4 kingdoms:
  • Protoctista
  • Fungi
  • Plantae
  • Animalia
• Organisms from each of the four kingdoms have distinct characteristics and features, but share similarities in that they have cells with membrane-bound nuclei separating genetic material from the cytoplasm, and compartmentalisation within their cells as a result of the presence of other organelles

The four kingdoms within the Eukarya domain: protoctista, fungi, plantae and animalia

Kingdom Protoctista

• All Protoctista are eukaryotic, and this broad group of cellular life encompasses all eukaryotic cells that do not belong to the other three eukaryotic kingdoms
• Members of this kingdom show great diversity in all aspects of life including structure, life cycle, feeding and trophic levels and well as modes of locomotion
• Protoctists can exist as single-celled organisms or as a group of similar cells
• A group of Protoctista known as protozoa possess cells similar to animal cells
  • Their cells have no cell wall
• Another group of Protoctista known as algae possess cells similar to plant cells
  • Their cells have cellulose cell walls and chloroplasts
• Stentor roseli is a protoctist that has flagella all over its body which help it feed and move

Kingdom Fungi

• The oldest organism in the world is thought to be a fungus aged somewhere between 1500 - 10,000 years old
• All fungi are eukaryotic cells
• The cells of fungi:
  • Possess non-cellulose cell walls (often made of the polysaccharides chitin and glucans
  • Don’t have cilia
• Fungi are heterotrophs:
  • They use organic compounds made by other organisms as their source of energy and molecules for metabolism
  • They obtain this energy and carbon by digesting dead/decaying matter extracellularly or from being parasites on living organisms
• Fungi reproduce using spores that disperse onto the ground nearby
• Fungi have a simple body form:
  • They can be unicellular (like the common baker’s yeast Saccharomyces cerevisiae
  • Some consist of long threads called hyphae that grow from the main fungus body (mycelium)
  • Larger fungi possess fruiting bodies that release large numbers of spores
• The mould found on bread is actually a fungus: bread mould fungus Rhizopus nigricans

The structure of a fungus with its hyphae, mycelium and fruiting bodies

Kingdom Plantae

• Plants are multicellular eukaryotic organisms
• Plant cells:
  • All have cell walls composed of cellulose
  • Possess large (and usually permanent) vacuoles that provide structural support
  • Are able to differentiate into specialized cells to form tissues and organs
  • Possess chloroplasts that enable photosynthesis (not all plant cells have chloroplasts)
  • Can sometimes have flagella
• They are autotrophs
  • This means they can synthesize their organic compounds and molecules for energy use and building biomass from inorganic compounds
• Plants have complex body forms
  • They have branching systems above and below the ground
• Bristlecone pines are found in the USA, it is estimated that some of them could be 3000 years old

Kingdom Animalia

• Animals are also multicellular eukaryotic organisms
• Animal cells:
  • Are able to differentiate into many different specialised cell types that can form tissues and organs
  • Have small temporary vacuoles (for example, lysosomes)
  • Have no cell walls
  • Sometimes have cilia
• They are heterotrophs
  • They have a wide range of feeding mechanisms
• They have a wide range of body forms:
  • Communication within their complex body forms takes place through a nervous system and chemical signalling
• Blue whales are the largest living animal species