Characteristics & Classification of Living Organisms Flashcards
Movement
an action by an organism or part of an organism causing a change of position or place
Respiration:
the chemical reactions that break down nutrient molecules in living cells to release energy for metabolism
Sensitivity
the ability to detect or sense stimuli in the internal or external environment and to make appropriate responses
Growth
a permanent increase in size and dry mass by an increase in cell number or cell size or both
Reproduction
the processes that make more of the same kind of organism
Nutrition:
the taking in of materials for energy, growth and development; plants require light, carbon dioxide, water and ions; animals need organic compounds, ions and usually need wate
Excretion:
the removal from organisms of toxic materials, the waste products of metabolism (chemical reactions in cells including respiration) and substances in excess of requirements
mnemonic to remember
MRS. GREN
A species is defined as
a group of organisms that can reproduce to produce fertile offspring
species can be classified into groups by
features that they share
all characteristics of living organisms
Movement Respiration Sensitivity Growth and development Reproduction Excretion Nutrition
binomial system where the scientific name of an organism is made up of two parts starting with:
the genus (always given a capital letter) and followed by the species (starting with a lower case letter) When typed, binomial names are always in italics (which indicates they are Latin) e.g. Homo sapiens
The sequence of classification is
Kingdom, Phylum, Class, Order, Family, Genus, Species
Originally, organisms were classified using
morphology (the overall form and shape of the organism, e.g. whether it had wings or legs) and anatomy (the detailed body structure as determined by dissection)
Organisms share features because
they originally descend from a common ancestor
As technology advanced
microscopes, knowledge of biochemistry and eventually DNA sequencing allowed us to classify organisms using a more scientific approach
DNA sequencing
Studies of DNA sequences of different species show that the more similar the base sequences in the DNA of two species, the more closely related those two species are (and the more recent in time their common ancestor is) This means that the base sequences in a mammal’s DNA are more closely related to all other mammals than to any other vertebrate groups As DNA base sequences are used to code for amino acid sequences in proteins, the similarities in amino acid sequences can also be used to determine how closely related organisms are
The cells of all living organisms contain the following:
Cytoplasm Cell membrane DNA as genetic material (either found in the nucleus or free in the cytoplasm)
Main features of all animals:
They are multicellular
Their cells contain a nucleus but no cell walls or chloroplasts
They feed on organic substances made by other living things
A typical animal cell
Main features of all plants:
They are multicellular
Their cells contain a nucleus, chloroplasts and cellulose cell walls
They all feed by photosynthesis
Main features of all fungi (e.g. moulds, mushrooms, yeast)
usually multicellular
cells have nuclei and cell walls not made from cellulose
do not photosynthesize but feed by saprophytic (on dead or decaying material) or parasitic (on live material) nutrition
draw a fungi cell
Main features of all Protoctists (e.g. Amoeba, Paramecium, Plasmodium)
Most are unicellular but some are multicellular
All have a nucleus, some may have cell walls and chloroplasts
This means that some protoctists photosynthesise and some feed on organic substances made by other living things
draw a protoctist cell
Main features of all Prokaryotes and give an example
They are often unicellular
Their cells have cell walls (not made of cellulose) and cytoplasm but no nucleus or mitochondria
bacteria
draw a prokaryote cell
Ferns:
Have leaves called fronds
Do not produce flowers but instead reproduce by spores produced on the underside of fronds
How to distinguish between monocotyledons and dicotyledons:
1) FLOWERS
Flowers from monocotyledons contain petals in multiples of 3
Flowers from dicotyledons contain petals in multiples of 4 or 5
Monocot and dicot flowers
2) LEAVES
Leaves from monocotyledons have parallel leaf veins
Leaves from dicotyledons have reticulated leaf veins (meaning that they are all interconnected and form a web like network throughout the leaf)
Monocot and dicot leaves
Features of Viruses
Viruses are not part of any classification system as they are not considered living things
They do not carry out the seven life processes for themselves, instead they take over a host cell’s metabolic pathways in order to make multiple copies of themselves
Virus structure is simply genetic material (RNA or DNA) inside a protein coat
