- Created by: Harry
- Created on: 18-05-14 09:30
Characteristics of the five kingdoms
- Animalia – animals are multicellular, do not have cell walls, do not have chlorophyll, feed heterotrophically (heterotrophs can't make their own food)
- b) Plantae – are multicellular, have cell walls, have chlorophyll, feed autotroprically (autotrophs can make their own food)
- c) Fungi – multicellular, have cell walls, do not have chlorophyll, feed saprophytically (saprophytes feed off dead organisms and decaying material)
- d) Protoctista – unicellular (single celled), have a nucleus, protoctista include algae
- e) Prokaryotes – unicellular (single celled), have no nucleus e.g. bacteria
Viruses are not included in the five kingdoms because they cannot reproduce themselves, have a protein coat containing fewer genes, invade cells and make them reproduce the invading virus
Characteristics of the Phylum Cordata
- All include a spine and a nerve cord
- They all have throats
- Have a tale above the anus (is too short to notice on humans)
Vertabrates are examples of phylum cordata, and are divided into five classes:
Animals are placed into theses five classes due to:
- Oxygen absorbtion methods - lungs, gills and skin
- Reproduction - internal or external => ovaparious (lay eggs) or viviparous (give birth to live young)
- Thermoregulation - Homeotherms ('warm blooded') or poikilotherms ('cold blooded')
Problems associating vertebrates to a specific gro
- Has a bill like a duck
- Is homeothermic
- Lays eggs but suckles its young
- Is difficult to classify, but is closer to being a mammal than any of the four other verebrate groups
How animals are adapted for survival - dry/cold ar
Due to many factors:
- Changes to surface area => heat/water transfer factor => desert animals tend to have a large surface area/volume ratio => allow excess body heat to be readily lost. This helps overheating, partially as they do not sweat as much and produce smaller volumes of conc. urine
- Changes to surface area => Animals in colder areas have a smaller surface area/volume ratio to reduce heat loss to minimise heat loss
- Thickness of insulating coat => Desert animals have a thinner coat => aids heat loss
- Thickness of insulating coat => Arctic animals have a very thick coat => minimises heat loss
- Amount of body fat => Desert animals have thin layers of body fat => aids heat loss
- Amount of body fat => Arctic animals have layers of fat/blubber => minimises heat loss AND acts as an energy store (has a very high calorific value)
- Camoflage => Desert animals have sand-coloured coats => good for hiding from predators
- Camoflage => Arctic animals have white fur to blend in with the arctic background => increases chances of killing
Darwin's theory of natural selection
- variation – most populations of organisms contain individuals which vary slightly from one to another, those with superior characteristics are more likely to survive,
- b) over-production – most organisms produce more young than will survive to adulthood ensuring some will survive,
- c) struggle for existence – because populations do not generally increase rapidly in size there must therefore be considerable competition for survival between the organisms,
- d) survival - those with advantageous characteristics are more likely to survive this struggle,
- e) advantageous characteristics inherited – better adapted organisms are more likely to reproduce successfully passing on the advantageous characteristics to their offspring
- f) gradual change – over a period of time the proportion of individuals with the advantageous characteristics in the population will increase compared with the proportion of individuals with poorly adapted characteristics, and the poorly adapted characteristics may eventually be lost.
- Continuous variation is when a particular characteristic of an individual lies within a range with no distinct category.
- Discontinuous variation occurs when a particular characteristic of the species fits into a few particular and specific categories with no range of variation.
How speciation occurs
A species is group of similar organisms that can interbreed to give fertile offspring.
Speciation is the development of a new species and can happen when populations of the same original species becomes so different (genetically) that they can no longer interbreed to give fertile offspring.
Speciation can occur via isolation – two populations of a species become separated, eg geographically,
In the two geographical regions, the climate might be different, the other plants and animals may be different.
However, if each population can survive, by the process of natural selection, two distinct species can evolve (or perhaps one population remains the same, but the other has to adapt to a different environment).