Monthly Archives: May 2011

Chapter 8: Classification

Linnaeus

Carl von Linne – Image Source

Learning Intention: To understand the biological system of classification and how living organisms are named and identified.

Success Criteria: Given sufficient information, you will be able to identify relationships between living organisms and classify them into their appropriate groups.

Carolus Linnaeus was a swedish botanist and zoologist who developed the system of classification that biologists still use today to order our natural world – “binomial nomenclature“. Just like large shops and warehouses that need to store huge numbers of items, biologists find it useful to classify organisms using a hierarchical system that groups the same kinds of organisms together. All living things are grouped and named using the following sytem:

  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species

The latin binomial system uses the genus and species name as a universal, unique identifier for a particular type of organism. This minimises the problem of organims that might have different common names in different parts of the world (eg. Blackbird, brown snake) and uses a one language recognisable to scientists worldwide. If two particular organisms have the same genus name, they are more closely related than two that belong to the same family but belong to different genera. However, if two organisms have the same species name, but belong to a different genus, they may not be closely related at all. The species name is more of a descriptor, so, for example, Eucalyptus citriodora is the lemon-scented gum and Backhousia citriodora is the lemon myrtle. They belong to different genera, so are not as closely related as two eucalypts or two myrtles.

Chapter 7: Sexual and Asexual Reproduction

Vegetative-reproduction 

This week we are starting the topic “Reproduction” by looking at Asexual methods of reproduction. In plants, asexual reproduction is also called vegetative reproduction.  Complete the table titled “Types of Vegetative Reproduction” using your text and activity manual. Plants that are produced by vegetative reproduction are genetically identical to their parent plants, which is a very useful trait for horticulturalists. They may use the following methods:

  • Runners (strawberries, water hyacinth)
  • Cuttings (geraniums, roses)
  • Rhizomes (underground stems, as in ferns, irises, ginger and galangal)
  • Tubers (potatoes)
  • Bulbs (daffodils, tulips, onions)
  • Suckers (underground stems that arise a distance from the parent plant eg. elm trees and blackberries)

Some other organisms also reproduce asexually: (Asexual reproduction in Animals)

  • Binary fission (Paramecium, bacteria)
  • Budding (Hydra)
  • Fragmentation (Planarians)
  • Regeneration (Echinoderms such as seastars)
  • Parthenogenisis (some lizards, aphids)

This is a useful Powerpoint presentation to learn about the methods of asexual reproduction:

Chapter 6: Distribution of Materials

tube worm respiratory system

Image Source and information about the White Christmas Tree Worm

This chapter looks at three systems: circulatory, respiratory and excretory systems.

The Circulatory System: Once food has been digested, these nutrients needs to be distributed to every cell within the body to enable cellular respiration to occur. These nutrients, as well as hormones, waste products (CO2 and urea), salts and heat are transported in the circulatory system. The circulatory system of mammals includes  a four-chambered heart, arteries, veins and capillaries that allow the movement of blood to every cell within the body.

The Respiratory System: The mammalian respiratory system includes the lungs, trachea, bronchi and alveoli that allow the transfer of oxygen and carbon dioxide between the internal blood supply and the external environment. Insects have an open respiratory system in which the air and the internal cells are in close contact, oxygen entering through spiracles and passing in to branching tubes within the organism. Don’t get confused between cellular respiration and breathing! Cellular respiration is the process that converts glucose and oxygen to energy within the cells. Oxygen is supplied to those cells by the red blood cells, which carry oxyhaemoglobin to cells and remove carbon dioxide from cells.

The Excretory System: Our kidneys are part of our excretory system, to remove nitrogenous wastes from our body. The nephron is the functioning unit that removes urea from the blood and allows water, nutrientsand salts to be re-absorbed to the body. Ureters are the tubes that carry urea from the kidneys to the bladder and urine leaves the body via the urethra.