Classification Flashcards
What is classification
The act of arranging organisms into groups based on their similarities and differences. This makes it easier for scientists to study them.
How many taxonomic levels are there
8
What are the 8 taxonomic groups
1) domain
2) kingdom
3) phylum
4) class
5) order
6) family
7) genus
8) species
The five kingdom classification system and their general characteristics
Prokaryotae- bacteria - prokaryotic , unicellular, no nucleus, less than 5 micrometres
Protoctista - algae and Protozoa- eukaryotic cells, usually live in water, single celled or simple multicellular organisms
Fungi - moulds, yeast mushrooms- eukaryotic, chitin cell wall, saprotrophic, single/multi cellular
Plantae- mosses, ferns, flowering plants - eukaryotic, multicellular, cell walls made of cellulose, can photosynthesises, contain chlorophyll, autotrophic.
Animalia- mammals, birds, fish , insects - eukaryotic, multicellular, no cell walls, heterotrophic.
What is a saprotrophic organism
An organism that absorbs substances from dead or decaying organisms
What is the naming system used in classification
It is called the binomial system. The first part is the genus name and has a capital letter. The second part is the species name and begins with a lower case. Always written in italics unless handwritten then they are underlined.
What is phylogeny
The Study of the evolutionary history of groups of organisms
How to show relationships between organisms
Phylogenetic tree. Branches show common ancestors
What is it called when you classify organisms into groups and take phylogeny into account
Cladistics
Why is observable features not enough to place organisms into groups
Scientists do no always agree on the relative importance of different features and groups based solely on physical features may Not show How related organisms Are.
Other evidence that shows how similar organisms are
1) molecular evidence - look for similarities in genes and DNA. Similarities in base sequence and nucleotides
2) look for similarities in sequence of amino acids in proteins.
3) look for similarities in cytochrome C and Haemoglobin.
4) similarities in any of these, show close relationship.
5) look for similarities in anatomical structure, behaviour, physiology and embryology.
6) fossils can also show how organisms have evolved over time.
What is the three domain system.
In 1990, the three domain system replaced the older five kingdom system. The three domains were Eukarya, Archaea and Bacteria. Domains was the highest taxonomic level and the lower hierarchy stays the same.
Evidence that led to the proposal of the three domain system
1) molecular evidence - the enzyme RNA ploymerase is different in bacteria and Archaea. Archaea but not bacteria have similar histones to Eukarya.
2) cell membrane evidence- the bonds of the lipids in the cell membrane of bacteria and Archaea are different. The development and composition of flagellae are also different.
Most scientists agree bacteria and archaea developed seperately and archaea is more closely related to Eukarya than bacteria.
Variation definition
The differences that exists between individuals.
Types of variation
1) intraspecific- occurs within a species
2) interspefific - occurs between species
3) continuous (no distinct categories) eg height
4) discontinuous (distinct categories ) eg blood type
What can variation be caused by
1) genetic factors
2) environmental factors
3) both
How do genetics cause variation
Different species have different genes. Individuals of the same species have the same genes but different alleles. The genes and alleles make up the organism’s genotype. Differences in genotype result in variation in phenotype.
Variation only caused by genetics includes blood Type in humans and antibiotic resistance in bacteria. Genetic factors are inherited.
How does the environment cause variation
Differences in climate, Food and lifestyle can cause variation. Examples of variation caused by only environmental factors includes accents and whether people have pierced ears.
How do both genetic and environmental factors cause variation
1) height- genes determine how tall an organism can grow but diet and nutrient availability affects how tall an organism actually grows.
2) flagellum - genes determine if microorganisms can grow a flagellum but some will only start to grow them in certain environments eg if metal ions are present.
How can you compare variation between samples
By calculating means of different samples and comparing using a distribution curve.
How can you tell variation within a sample
Standard devaition tells us the spread of values about the mean.
How do adaptations make an organism better suited to their environment
1) being adopted to an environment means the organism has features that increase its chance of survival and reproduction, and the chances of its offspring reproducing successfully. Adaptations can be behavioural, physiological and anatomical. Adaptations develop by evolution by natural selection.
What are some behavioural adaptations
This is when the way an organism Acts increases its chance of survival. For example:
1) possums sometimes “play dead” when threatened by a predator.
2) scorpions dance before mating to make sure they attract a mate of the same species.
What are some physiological adaptations
These are the processes inside an organism’s body that increase its chance of survival. For example:
1) brown bears hibernate- they lower their rate of metabolism over winter. This conserves Energy so they don’t need to look for Food when it’s scarce.
2) some bacteria produce antibiotics. These kill other bacteria in the area so there is less competition and they are more likely to survive.
