4.2.2 - CLASSIFICATION AND EVOLUTION Flashcards
List the taxonomic hierarchy in order, starting at the top
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
What are the five kingdoms? And give an example of each
Prokaryotae - bacteria
Protocista - algae
Fungi - moulds, yeasts, mushrooms
Plantae- mosses, ferns, flowering plants
Animalia - molluscs, insect, reptiles, birds, mammals
What are the general features of the Prokaryotae kingdom?
- Unicellular
- no nucleus
- less than five micrometers
What are the general features of the Protocista kingdom?
- eukaryotic cells
- usually live in water
- single-celled or simple multicellular organisms
What are the general features of the Fungi kingdom?
- eukaryotic
- chitin cell wall
- saprotrophic (absorb substances from dead or decaying organisms)
- single-celled or multicellular organisms
What are the general features of the Plantae kingdom?
- eukaryotic
- multicellular
- cellulose cell walls
- can photosynthesise
- autotrophic (produce their own food)
What are the general features of the Animalia kingdom?
- eukaryotic
- multicellular
- no cell walls
- heterotrophic (consume plants and animals)
How is an organism’s scientific name created using the binomial system?
- first part is the Genus (capital letter)
- second part is the species (lower case letter)
e.g. humans - Homo sapiens
Names are always written in italics or underlined if handwritten
What is phylogeny?
The study of the evolutionary history of groups of organisms
What does a phylogenic tree show?
The relationship between members of a family of species
What evidence were the first classification systems solely based on?
Early classification systems only used observable features (things you can see) to place organisms into groups (e.g. whether they lay eggs, can fly)
What is a disadvantage of basing early classification systems on observable features?
Scientists don’t always agree on the relative importance of different features and groups based solely on physical features may not show how related organisms are
What other evidence is there showing how similar organisms are
- Observable features AND other evidence
- Molecular evidence - similarities in proteins and DNA
- Embryological evidence - similarities in the early stages of an organism’s development
- Anatomical evidence - similarities in structure and function of different body parts
- Behavioural evidence - the similarities in behaviour and social organisation of organisms
What does new technology mean for new discoveries?
New technologies (e.g. new DNA techniques + better microscopes) can result in new discoveries being made and the relationships between organisms being clarified
Scientists can share their new discoveries in meetings and scientific journals. How organisms are classified is continually revised to take account of any new findings that scientists discover
Describe one way in which scientists could use molecular evidence to determine how closely gibbons are related to humans.
Scientists can compare the sequence of DNA bases between humans and gibbons
Describe three differences between organisms in the Bacteria and Archaea domains
The enzyme RNA polymerase is different in Bacteria and Archaea
Archaea have similar histones to Eukarya, and not Bacteria
The bonds of lipids in cell membranes of Bacteria and Archaea are different
+ development and composition of flagella are also different
What is variation?
The differences that exist between individuals. Every individual organism is unique (even clones - like identical twins - show variation)
What is continuous variation?
When the individuals in a population vary within a range - there are no distinct categories. E.g. humans can have any height within a range (139cm, 175cm, 185.9cm, etc) not just tall or short
What is discontinuous variation?
When there are two or more distinct categories - each individual falls into only one of these categories, there are not intermediates
E.g. blood group in animals, plant colour and seed shape
Explain how variation can be caused by genes.
- Different species have different genes
- Individuals of the same species have the same genes, but different versions (alleles)
- The genes and alleles of an organism is its genotype
- The differences in genotype result in variation in phenotypes - the characteristics displayed by an organism
- Examples of variation caused only by genetic factors include blood group in humans and antibiotic resistance in bacteria
- You inherit your genes from your parents. This means variation caused by genetic factors is inherited
Explain how variation can be caused by the environment.
- Variation can be caused by differences in the environment, e.g. climate, food, lifestyle
- Characteristics controlled by environmental factors can change over an organism’s life
- Examples of variation caused only by environmental factors include accents and whether people have pierced ears
Explain how variation can be caused by both genes and the environment.
- Genetic factors determine the characteristics an organism’s born with, but environmental factors can influence how some characteristics develop
- e.g. height - genes determine how tall an organism can grow (e.g. tall parents tend to have tall children) but diet or nutrients can accept how tall an organism actually grows
- e.g. flagellum - genera determine if a microorganism can grow a flagellum, but some will only start to grow them in certain environments (e.g. if metal ions are present)
What is convergent evolution
The process whereby organisms that are not closely related independently evolve to have similar features as a result of having to adapt to similar environments
Define adaptation
Variations or characteristics that enhance the survival of an organism in an environment
What are the types of adaptation
- Physiological
- Anatomical
- Behavioural
Define physiological adaptation
Biological processes within the organism
Define anatomical adaptation
Structural or physical features
Define behavioural adaptation
The way an organism behaves
Define ecological niche
The match of a species to a specific environmental condition
What is interspecific variation
- variation between species
e.g. the lightest species of bird is the bee hummingbird, which weighs approx. 1.6 g on average. Heaviest bird is ostrich, which can weigh up to 160 kg (x 100000)
What is intraspecific variation?
- Variation within a species
e.g. individual European robins weigh between 16g and 22g and show some variation in many other characteristics including length, wingspan, colour + beak size
What are the three different groups of mammals?
- Placental mammals
- Marsupials
- Monotremes (egg-laying)
What is convergent evolution?
When two species evolve similar characteristics independently of one another as they’ve adopted to live in similar environmentsm
What four observations were made by Darwin about the world around him
[development of natural selection]
- Organisms produce more offspring than survive
- There’s variation in the characteristics of members of the same species
- Some of these characteristics can be passed on from one generation to the next
- Individuals that are best adapted to their environment are more likely to to survive
What is Darwin’s theory of evolution by natural selection?
- Individuals within a population show variation in their phenotypes
- Selection pressure create a struggle for survival
- Individuals within better adaptations are more likely to survive + have reproductive success
- Over time, the proportion of the population possessing the advantageous adaptations increases
- Over generations this leads to evolution as the favourable adaptations increases become more common in the population
What are selection pressures?
Environmental factors such as predation, disease + competition
What did Wallace contribute to the theory of evolution?
- Independently came up with idea of natural selection + wrote to Darwin about it
- He and Darwin published their poacher on evolution together + acknowledged each other’s work - though didn’t always agree about the mechanisms involved with natural selection
- Wallace’s observations provided lots of evidence to support the theory of evolution by natural selection
^— e.g. he realised that warning colours are used by some species to deter predators from eating them
Outline fossil recorded evidence to support evolution
- Fossils are remains of organisms preserved in rocks
- By arranging fossils in chronological order, gradual changes in organisms can be observed that provide evidence of evolution
Outline DNA evidence to support evolution
- Closely related species diverges more recently
- Evolution is caused by gradual changes in the base sequence of an organisms’ DNA
- Organisms that diverges away from each other more recently should have more similar DNA, as less times has passed for changes in the DNA sequence to occur
^— not just nuclear DNA analysed, by mitochondrial DNA too
Outline molecular evidence to support evolution
- Similarities in other molecules provide evidence, not just DNA
- Scientists compare amino acid sequences in proteins + compare antibodies
- Organisms that diverges more recently have more similar molecules as less times as passed for changes in proteins + other molecules to occur
Explain how pesticide resistance in insects occurs
- There is variation in a population of insects
- Genetic mutations create alleles that make some insects naturally reistant to a pesticide
- If the insect population is exposed to that pesticide only the individuals with resistance with survive to reproduce
- Alleles that cause the pesticide resistance will be passed on to the next generation + so the population with evolve - more individuals carry the allele than the previous generation
[SOME FOR DRUG RESISTANCE IN MICROORGANISMS]
State the implications of pesticide resistance in insect for humans
- Crop infestations with pesticide-resistant insects are harder to control - some insects are restraint to lots of different pesticides
- If disease-carrying insects (e.g. mosquitos) become pesticide resistant, the spread of disease can increase
- A population of instead could evolve resistant to all pesticides in use
^— to prevent this new pesticides need to be produced - TAKES TIME + MONEY
State the implications of drug resistance in microorganisms for humans
- Infections caused by drug-resistant microorganisms are harder to treat, especially if the microorganism is resistant to lots of different drugs
- Potentially, a pathogen could become resistant to all drugs we currently use against it
^— new drugs need to be developed = TIME + MONEY
