CLASSIFICATION AND EVOLUTION Flashcards
Classification
Arranging organisms into groups based on their similarities and differences
Makes it easier for scientists to identify them
Taxonomy
Study of classification
Taxonomic hierarchy
Domain Kingdom Phylum Class Order Family Genus Species
The five kingdoms
Prokaryotae- bacteria, prokaryotic, unicellular, no nucleus
Protoctista- algae, protozoa, eukaryotic, usually live in water, single celled or simple multicellular
Fungi- moulds, yeasts and mushrooms, eukaryotic, chitin cell wall, single celled or simple multicellular, saprotrophic
Plantae- mosses, ferns, flowering plants, eukaryotic, multicellular, cellulose cell walls, photosynthesise, chlorophyll, autotrophic
Animalia- molluscs, insects, fish, reptiles, birds, mammals, eukaryotic, multicellular, no cell wall, heterotrophic
Types of evidence
Molecular- similarities in proteins and DNA, DNA storage and sequence of bases, sequence of amino acids
Embryological evidence- similarities in early stages of an organisms development
Anatomical evidence- similarities in structure and function of different body parts
Behavioural evidence- similarities in behaviour and social organisation
Three domain system
Large super kingdoms above kingdoms in the taxonomic hierarchy
Archaea and bacteria- cells without a nucleus
Eukarya- cells with a nucleus
How did the three domain system come about
Molecular evidence- enzyme RNA polymerase is different in bacteria and archaea. Archaea have similar histones to eukarya
Cell membranes evidence- bonds of lipids in cell membranes of bacteria and archaea are different, development of flagella also different
What is the three domain system an example of
How scientific knowledge is always changing and improving
Variation
Differences that exist between individuals, every organism is unique
Interspecific variation
Variation between species
Intraspecific variation
Variation within species
Continuous variation
When individuals in a species vary within a range
Discontinuous variation
Two or more distinct categories
Genetic factors leading to variation
Same species- same genes- different alleles
Differences in genotype lead to differences in phenotype
Blood group, antibiotic resistance
Inherited
Environmental factors leading to variation
Differences in the environment
Accents/piercings
Genetic and environmental factors leading to variation
Born with but environments influence how the characteristics develop
Weight- nutrient availability
Flagellum- genes determine if they grow or not but some only start to grow in certain environments
Adaptations
Organisms have features that increase their chances of survival and reproduction and also the chances of offspring reproducing successfully
Adaptations develop due to evolution by natural selection
Behavioural adaptations
Way an organism acts to increase survival
Possums play dead
Scorpions dance before mating
Physiological adaptations
Processes inside the body which increase chances of survival
Brown bears hibernate
Some bacteria produce antibiotics
Anatomical adaptations
Structural features
Otters- streamline shape
Whales- thick layer of blubber
Marsculpial mammals
Kangaroos
Short gestation period
Don’t develop a full placenta
Born early in development and climb into mothers pouch where they become attached to the teat and receive milk
Placental mammals
Humans
Longer gestation period
Develop a placenta during pregnancy which allows the exchange of nutrients and waste products
Born fully developed
Evolved differently and independently on different continents
Marsupial and placental moles aren’t closely related, list their similar adaptations
Live in tunnels underground Burrow to reach food supply Small/non existent eyes No external ears Scoop shaped paws Claws for digging Tube shaped body Cone shaped head
Who came up with the theory of evolution by natural selection
Charles Darwin
Darwin’s observations
Organisms produce more offspring than survive
Variation of characteristics of the same species
Some characteristics passed on from generations
Individuals best adapted to their environment are more likely to survive
Darwin’s theory
Individuals in a population show variation in their phenotypes
Selection pressures create a struggle for survival
Individuals with better adaptations are more likely to survive and have reproductive success
Overtime, the proportion of the population possessing the advantageous adaptations increases
Over generations, this leads to evolution as the favourable adaptations become more common
Alfred Russell’s theory of evolution
Warning colours are used by some species (butterflies) to deter predators from eating them which is an example of an advantageous adaptation
Evidence supporting evolution
Fossil records- remains of organisms preserved in rocks, shows gradual change
DNA evidence- closely related species diverged more recently, evolution is caused by gradual changes in the base sequence of an organism’s DNA, organisms that diverged more recently have less change in DNA
Molecular evidence- sequences of amino acids in proteins and comparing antibodies
Evolved resistance (pesticides)
Pesticides- chemicals that kill pests.
There is a variation in the population of insects
Genetic mutations create alleles that make some insects naturally resistant to a pesticide
Only resistant individuals will survive and reproduce, these alleles are passed on and the population evolves
Evolved resistance (drugs)
Pathogens have become resistant to specific drugs
Infections caused by resistant microorganisms are harder to treat
New drugs need to be developed
Takes time and money
