Life On Earth Flashcards Preview

Biology > Life On Earth > Flashcards

Flashcards in Life On Earth Deck (12)
Loading flashcards...

Major stages in evolution of living things
Old men play pianos every cloudy Monday

Organic molecules: formed in water on early earth

Membranes: developed to isolate and protect the system of large organic molecules- evolved to contain Nucleic acids and capable of self replication

Prokaryotic heterotrophic cells: nutrition from the chemicals around them- simple cell no nuclear membrane- bacteria

Prokaryotic autotrophic cells: make own food from Suns energy - simple cell no nuclear membrane- has photosynthetic pigments- photosynthetic bacteria, Cyanobacteria

Eucaryotic cells: cells containing membrane- bound nucleus and organelles developed

Colonial organisms: multicellular organisms may have originated when daughter dells bound together after cell division to form similar cells

Multicellular organisms: specialisation of function evolved- each cell has own particular function and is dependent on others



Study of life in ancient times, through fossil record


Change from anoxic to oxic atmosphere in the evolution of living things

-Early atmosphere anoxic- no free oxygen
-Evolution of procaryotic autotrophic cells(Cyanobacteria) photosynthesised and large amounts of oxygen produced
This dissolved into oceans until they became saturated
-Then reacted when iron in rocks and formed banded iron formations
-Excess oxygen moved to upper atmosphere- reactions occurred causing oxygen atoms to chemical combine to form ozone layer
- free oxygen enabled organisms to develop that could produce energy (respiration)
-more energy: more diverse+large the organisms
-formation of ozone layer provided protection from damaging UV radiation
- this enabled organisms to colonise the land



Contains chlorophyll-- photosynthesis
Forms dense mats in aquatic environments

Aquatic environments, warm temp, high availability of nutrients

Photosynthesise-- produce oxygen
Primary producers for ecosystem



Anaerobic ( don't use oxygen to produce energy in respiration)

Anoxic environments--swamps, deep soul ( no oxygen)
In digestive system of herbivores(cows)

Break down organic matter
Help break down cellulose in plant cell walls to aid digestion


Why is there a need for scientists to be able to classify organisms?

Understand relationships b/w organisms
Reflect our current knowledge of living things
Make communications to other biologists about organisms easier
Mage study of life easier


How levels of organisation in a hierarchal system assists classification

Grouping organisms into smaller groups it makes identification of individual species possible


Impact of changes in technology on development and revision of biological classification systems

High magnification light microscopes- enabled scientists to identify bacteria as having unique cellular features and creating a new kingdom monea

Electron microscope- identified internal cellular structures that eventually led to the kingdom Protista

Biochemistry using amino acids and sequencing and DNA analysis: indicated two major groups of bacteria


Binomial system in naming organisms and the relationship to the concepts of genus and species

Many organisms known by different common names in different areas

Confusing to scientists when trying to classify organisms and communicate to others

Binomial system if nomenclature- system using to specific names
Involves two words
1. Genus - capital letter, members of group very similar
2. Species- lower case, members of group have same basic characteristics, members of a species can interbreed and produce fertile offspring


Difficulties trying to classify extinct organisms

-mAy be found in fossils
Fossils difficult to classify because:
May not show enough detail
Be incomplete
May be no similar living organism which compare it
Fossil can end up with two or more scientific names if different scientists classified different parts of same fossil


How classification of organisms can assist in developing an understanding of present and past life on earth

If classified- scientists have a knowledge of the structural and functional features of the organism within each group

Progression from large groups 'kingdoms' to small groups 'genus +species ' -the members all have increasingly similar characteristics

Classification helps scientists in:


Scientific theory's relating to evolution of the chemicals of life and their significance in understanding origins of life

Theory 1: panspermia- life from outer space
Individual bacteria spores could drift across space, propelled by the pressure of light and that these were seeds of life on earth
Evidence: fossilised of ancient life found in meteronite, originated on Mars

Theory 2: soupy pond
Early atmosphere of the earth contained all necessary basic chemical compounds for life.
Evidence: Urey and miller found it contained amino acids