evolution

• Competition - organisms (animals and plants) have to compete with each other for access to limited resources
• Animals compete for: food & water, mates(reproduction), territory
• plants compete for: nutrients/water(prevent deficiencies), sunlight(photosynthesis), space(shade limits photosynthesis)
• Adaptation - different characteristics that allow an organism to be successful in the environment and survive
• Cactus


  -wide stems to store water

  -spikes all over the plant to protect itself from other organisms

  -wide spread root system that can collect water from a large area/underground

  -thick waxy cuticle to prevent excess water loss

  -small leaves to reduce surface area and water loss

  -reduced number of stomata to reduce water loss
• various organisms are adapted for their best survival.
• Trees


  -grow quickly in spring(wet and warm)

  -they lose leaves in winter to save energy

  -fallen leaves provide warmth and protection

  -leave decompose and nutrients can be reused
• How are animals adapted to survive the winter?

  -hibernation, animals find a safe warm area to sleep through winter

  -they grow thick fur, to keep warm

  -migration, animals move somewhere warmer with more food availability
• Interdependence-when a predator feed on one type of prey so if ne decreases so does the population of the other.
• variation - different characteristics within a specie
• bear variations

  -brown bear

  -polar bear

  -panda bear

  -honey bear

  -koala bear
• inheritance variation-variation of characteristics passed on from parents to off-springs through DNA

  -hair

  -eye colour

  -height
• environmental variation- variation in characteristic caused by changes to your surrounding and lifestyle, made by choice

  • tattoos
  • dying hair
  • favourite colour
• continuous variation-characteristic that vary over a range of values

  • height
  • weight
  • hand span
• discontinuous variation- characteristics that can only take certain values(categorical)

  • eye colour
  • hair colour
  • blood type
• continuous data can be plotted on a scatter graph/line graph/histogram
• discontinuous data can be plotted on a bar chart
• gametes - sperm, male), egg, female)
• characteristics are inherited through DNA from our parents (50% from the male and 50% from the female) to produce a genetically different organism (off-spring)
• female(50%) > egg cell > fusion < sperm cell < male (50%)

  fertilisation

  ^

  off-spring(100% DNA)
• gene - a section of DNA that codes for a specific characteristics
• DNA - long double helix of genetic material
• chromosome - condensed packages of DNA
• The average human have 46 chromosomes (23 pairs)
• organism >cell > nucleus > chromosome> DNA > gene
• xx = female

  xy = male
• natural selection is a process of organisms best adapted to their environment, surviving and pass on there genes to off-spring (survival of the fittest)
• charles darwin first observed and recorded evolution though natural selection. (finches)
• Steps of natural selection:

  1. variation
  2. adaption
  3. reproduction
  4. evolution
• evolution - a change in inherited characteristics over time with in a specie though natural selection.
• extinction - when no more individuals from a particular specie are left on earth.
• extinct animals:

  • dodo
  • Tasmanian tiger
  • saber-tooth tiger
  • wooly mammoth
  • white rhino
• causes of extinction: diseases, destruction of habitats, introduction of a new predator, hunting, environment
• fossil - preserved remains or preserved traces of long dead organisms
• fossil record - name given to the collection of fossils we have found so far
• gene banks - stores of genetic material from organisms that are important to science and conservation
• the number and placement:

  • how organisms have changed over time (or not)
  • when these organisms have lived
  • what conditions were like when that organism was alive
• Polar bear

  • thick fur to protect itself from cold weather
  • thick layer of fat as an insulator
  • large paws to grip and catch food
  • fur to camouflage