Week 2: Classification Flashcards
Classification
Process of sorting variety of different things into manageable groups
The study of biological classification is called
taxonomy or systematics
Why is a universally accepted system of classification important?
so scientists can identify species based on shared characteristics
Artificial Classification
sorts organisms into groups based on similar identifiable characteristics
Artificial classification is limited. why?
Because characteristics are picked on the basis of similarity in function and the current characteristics organisms have.
why are keys used in biology?
to categorise and identify organisms
Dichotomous key
Series of statements with two choices describing a characteristic of an unidentified organism
What does a natural classification system consider?
the degree of evolutionary relationships
Natural classification organises species into groups of organisms that share characteristics from a common ancestor. What are these characteristics called?
Homologous characteristics
Homologous characteristics have what?
underlying similarity of structure and position regardless of the function
why are forelimbs of mammals homologous?
all modifications of the same structure
Hierarchal Categories that organisms are grouped into are
Domain, Kindgdom, Phylum, Class, Order, Family, Genus and species
DUMB KING PHILIP CAME OVER FOR GREAT SUSHI
Hierarchical categories; these groups are known as
taxa or taxonimic levels
what is the sorting of hierarchical classification based on?
shared characteristics + molecular similarities
Highest taxonomic rank are the
Domains
3 domains of living things are
Archaea (Prokaryotes)
Bacteria (prokaryotes)
Eukarya (Eukaryotes)
Prokaryotes in terms of domains of what kingdom?
Monera
Eukarya domain is subdivided into many kingdoms including
Animalia (animals)
Plantae (plants)
Protista (protists)
Fungi
How are organisms of different kingdoms distinguished?
using different characteristics
plants are what type of autotrophs?
photosynthetic autotrophs
Plants have organelles called chloroplast and a cell wall that consists of what?
cellulose
how many estimated species of plants are there?
300000 including grasses, trees, bushes, mosses, ferns and vines
how many animal species have been discovered thus far
over 1 million
Fungi prokaryotic or eukaryotic
eukaryotic heterotrophs
Cell walls of fungi don’t have cellulose but have
chitin
Do fungi carry out photosynthesis?
no
how many fungal species are there estimated to be?
over 5 million
Protists eukaryotes or prokaryote?
eukaryote unicellular. Can be both heterotrophic and autotrophic
Protists consist of eukaryotes that aren’t plants, animal or fungi and are sometimes referred to as the
leftovers
all members of phylum (phyla for plural) have a common _______ and similar ______________
ancestor, anatomical features
Each phylum have how many classes?
one or more
subdivision of phylums into classes are based on what?
similar characteristics
class of organisms can be further subcategorised into_____ and they have more _______ characteristics than members of a class
orders, specific
Members of one family have very _______ anatomical features and _______________
similar, behavioural characteristics
members of one genus have shared characteristics that are
highly specific
most specific ranking in the taxonomic hierarchy
species
Characteristics used when classifying organisms into their grouping: are
Physical features, reproductive strategies, molecular sequencing
physical features are an expression of the
genotype and the environment
mammals seperated into 3 groups by reproductive strategies:
Placentals, Marsupials, Monotremes
Placentals:
humans, cats give birth to live young where a placenta is involved to nourish the foetus
Marsupials
kangaroo, wallaby young develops in pouch
Monotremes
platypus, echidna lay eggs
Dna is a molecule that consists of
nucleotide subunits
order of nucleobases in a molecule of dna is called its
nucleic acid sequence.
What does the nucleic acid sequence do?
codes for the production of an organisms protein molecules
Most accurate way of determining how closely related two species are is to:
compare the molecular sequences of DNA and protein molecules between the two
Degree of similarity of the cytochrome C protein necessary for aerobic respiration pathways between species indicate the
closeness of evolutionary relationships
The sequence of Cytochrome C for humans and chimpanzees match at all
104 amino acid positions
Random mutations cause changes in what?
nucleic acid sequence
Mutation of DNA causes what? And the number of random mutations increase with _______
a corresponding change in the amino acid sequence of the protein, time
Internationally accepted system to name organisms is the
binomial system of nomenclature
The first part of the nomenclature is the
name of the genus
The second part of the nomenclature specifies the
species
2 rules for nomenclature binomial system writing of a scientific name:
The first letter of genus name - Capital letter
Names both written in italics
Why is the nomenclature beneficial?
Universal language so universal collaboration
No confusion between identities of two organisms
for the easy identification of any new organism
the names provide info about the organism
and the systems ability to be updated with the discovery of new species
reproductively isolated
a species inability to produce fertile offspring with another species
2 isolating reproductive mechanisms are
Pre zygotic Mechanisms (prevention of mating from occurring)
Post zygotic Mechanisms (prevent offspring from being viable)
Pre zygotic mechanisms include
geographical separation
different mating calls + rituals
use of pheromones to attract the opposite sex
The difference in flower shape or genitalia
different seasons or times for reproduction
the inability of sperm to survive in the reproductive system
incompatibility of gametes
pollen tubes unable to grow towards ovules in a flower
Post zygotic mechanisms include
Zygote failing to develop
young failing to reach sexual maturity by dying
infertile offspring
