classification

• the hierarchy of classification

  -kingdom

  -phylum

  -class

  -order

  -family

  -genus

  -species
• virus kingdom

  viruses are harmful organisms that are very small.

  do not need food and cannot reproduce on their own.

  border-line between living and non-living as they can only reproduce when they are present inside living organisms.

  all parasites -> they reproduce in a host.

  
• bacteria kingdom

  unicellular organisms.

  do not have a nucleus = prokaryotic.

  reproduce by binary fission + asexually.

  
• protist kingdom

  -unicellular organisms.

  -eukaryotic cells

  -live in many different habitats: some live solitary while others live symbiotically

  • protozoa : animal based protist. ex. amoeba
  • protophyta : plant based protist. ex. chlorella
• amoeba


  -a protozoa

  -feed on smaller organisms

  -pseudopodia flow around the food and engulf it. food is taken in a food vacuole in the cytoplasm.

  -oxygen is dissolved in the water round the Amoeba and goes into it by the process of diffusion.

  -asexual reproduction = binary fission.

  -contractile vacuole = needed for osmoregulation.

  
• chlorella

  -unicellular protophyta

  -found living symbiotically in hydra

  -single cup shaped chloroplast and vacuole

  -pyrenoid = organelle for starch formation and storage

  -no contractile vacuole = surrounded by a cell wall

  
• fungi kingdom

  -made up of threads known as hyphae

  -walls of hyphae = made up of chitin

  -reproduce by means of spores

  -ex: pin mould/mucor and yeast
• pin mould (mucor)

  -grows on dead, decaying matter

  -produce spores in sporangium

  -hypha = threads growing on the surface of the bread to obtain oxygen by diffusion

  -feeds by secreting enzymes from tips of the hyphae digesting externally so that food is absorbed in cytoplasm

  
• yeast

  -feeds on sugar

  -reproduces asexually by budding

  -used for fermentation

  
• plant kingdom

  -multicellular organisms

  -contain chlorophyll

  
• bryophytes

  -small plants with simple leaves

  -found in damp places

  -produce spores in capsules

  -simple structure = thallus

  -hair like structures = rhizoids found on the lower surface of the thallus -> absorb moisture

  -size is limited = absence of vascular bundles

  -very dependent on water = limited spreading

  
• pteridophyta 


  -known as ferns

  -proper roots and stems

  -mainly found in damp places

  -made up of a leaf like frond

  -produce spores on the underside of the fronds in sacs known as sori

  -xylem and phloem -> considerable spreading

  -waxy layer -> colonise drier areas

  -leaves = fronds made up of smaller leaves -> pinnae

  
• gymnosperms

  -known as conifers

  -large trees which reproduce by having seeds in cones

  -live in cold and dry climates

  -conserve water

  -produce seeds which are not enclosed in an ovary
• angiosperms

  -seed bearing flowers

  -seeds can be protected inside fruit

  -divided into 2 groups

  -seeds are formed in the ovaries of the flowers
• monocotyledons

  -fibrous root system

  -long, parallel-veined leaves

  -petals are in multiples of three

  -vascular bundles are found at the periphery of the stem

  -seed = one cotyledon

  -ex. daffodils, grasses
• dicotyledons

  -tap root system

  -broad net veined leaves

  -petals are in groups of 4 or 5

  -vascular bundles found throughout the stem

  -seed = two cotyledons

  -ex. wallflower, daisy
• animal kingdom

  -divided into 2 phyla: invertebrates and vertebrates

  
• invertebrates - coelentrates (cnidarians)


  -sac like body with single opening for mouth and anus

  -tentacles with stinging cells

  -live in aquatic environment

  -reproduce by budding

  -ex. jellyfish, hydra
• platyhelminthes (flatworms)


  -flat, thin body

  -no circulatory system

  -oxygen diffuses in and out through the body

  -suckers on head

  -most of them are parasites

  -ex. tapeworm
• nematodes (roundworms)


  -long thread like body

  -round in cross section

  -live in soil

  -unsegmented

  -ex. Ascaris
• annelids (segmented worms)


  -long, segmented body

  -digestive tract with mouth and an anus

  -hermaphrodites = possess female and male reproductive organs

  -ex: earthworms
• molluscs 


  -soft, unsegmented body

  -possess a muscular foot

  -internal or external shell

  -live in aquatic or moist environments

  -ex: squid, snails
• arthropods

  -largest phylum in the animal kingdom

  -external skeleton and jointed limbs

  
• class crustaceans

  -hard exoskeleton

  -two pairs of antennae: one pair is sensitive to touch and the other pair are sensitive to chemicals

  -compound eyes

  -grow by moulting = shedding their exoskeleton and growing another one

  -ex: lobster, crabs

  
• class insects

  -body divided in 3 parts: head, thorax, abdomen

  -one pair of antennae and three pairs of legs and specialised mouth parts for feeding

  -some insects undergo metamorphosis

  -some are pests while others are beneficial for nature

  -compound eyes

  -ex: flies, butterflies

  
• define incomplete metamorphosis

  when the adult looks exactly the same as the young.

  
• class myriapods


  -segmented body

  -one pair of legs per body segment

  -simple eyes

  -ex: centipeds and millipeds
• class arachnida

  -body divided into two parts

  -four pairs of limbs

  -no antennae but have special appendages which help in capturing prey

  -simple eyes

  -ex: spiders