species and taxonomy

Question 1

species

Answer 1

a group of individuals that can interbreed to produce fertile offspring

Question 2

situations in which the definitions of species does not work

Answer 2

1. Organisms that reproduce asexually, eg. bacteria.
   
   2. Extinct species from the fossil record.
   3. Organisms in different geographical locations.
   4. Some organisms do produce fertile offspring, but it’s so rare that we consider them separate species. Eg 1 = Asiatic lion v Tiger, Eg 2 = Coyote v Dog.

Question 3

courtship behaviour

Answer 3

In many species, the male and the female are very different in appearance.

Females choose mates based on appearance and display.

Behaviour patterns can be:
Visual - colour / movement
Auditary - sounds of certain pitch / frequency
Chemical - secrete pheromones

Question 4

taxonomy

Answer 4

is the science of naming and classifying organisms

organisms are named in latin using two names

name of genus - 1st letter uppercase
name of species - 1st letter lowercase

Question 5

hierarchical system of classification

Answer 5

non-overlapping categories - lots of smaller categories

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Question 6

3 domains

Answer 6

prokaryotes

archaea

eukarya

Question 7

4 domains in eukaryotes

Answer 7

animalia - no cell wall

plantae - cellulose cell wall

fungi - chitin cell wall

protictista - unicellular eukaryotes

Question 8

phylogenetic trees

Answer 8

Phylogenetic trees show evolutionary relationships between organisms.
In the past, this was done based on appearance.

Very misleading, because:
distantly related organisms can look similar because they are adapted to the same environment (convergent evolution).
closely related organisms can look different eg. the pentadactyl limb of mammals is adapted to be fins (whale), wings (bat), or hoof (divergent evolution).

Nowadays, this is done by using biochemical / genetic techniques.

Question 9

using phylogenetic trees

Answer 9

We use information obtained from:

1. Comparison of DNA base sequences
2. Comparison of RNA base sequences
3. Comparison of Amino acid sequence of proteins 

The logic is that more closely related organisms (ie, organisms with a more recent common ancestor) will have more similar DNA, therefore more similar RNA, and therefore more similar proteins.

The more genes / RNA / proteins used for comparison, the more accurate will the resulting tree be.

Question 10

genetic / biochemical methods to determine evolutionary relationships

Answer 10

1. DNA Methods
   a. DNA Hybridisation
   b. DNA Fingerprinting (comparing length / size of genes)
   c. Comparing DNA Base Sequences
   
   2. Comparison of RNA base sequences
   3. Protein Methods
      a. Comparing length / size of proteins
      b. Immunoprecipitation
      c. Comparing amino acid sequences of proteins.

Question 11

genome sequencing

Answer 11

Three types of sequence data are used to investigate evolutionary relationships
DNA
mRNA
Amino acids (of a protein)

Question 12

sequencing technology

Answer 12

can determine the order of DNA bases, mRNA bases and amino acids within an organism’s genome

This technology is especially useful for comparison with an extinct species (using ancient DNA) or when distinguishing between species that are very physically similar

Question 13

what will scientists do

Answer 13

Scientists will choose specific proteins or sections of the genome for comparison between organisms
Looking at multiple proteins or multiple regions of the genome will allow for a more accurate estimate of evolutionary relatedness
Note the protein used needs to be present in a wide range of organisms and show sufficient variation between species
Cytochrome c is often used as it is an integral protein to respiration (in the electron transport chain) which is used by all eukaryotic organisms

Question 14

similarity from sequence data

Answer 14

For all types of sequence data it can be said that the more similar the sequences, the more closely related the species are

Two groups of organisms with very similar sequences will have separated into separate species more recently than two groups with less similarity in their sequences

Species that have been separated for longer have had a greater amount of time to accumulate mutations and changes to their DNA,mRNA and amino acid sequences

Sequence analysis and comparison can be used to create family trees that show the evolutionary relationships between species

Question 15

immunology

Answer 15

The proteins of organisms can also be compared using immunological techniques
The protein albumin is found in many species and is commonly used for these experiments

Question 16

immunology method

Answer 16

Pure albumin samples are extracted from blood samples taken from multiple species
Each pure albumin sample is injected into a different rabbit
Each rabbit produces antibodies for that specific type of albumen
The different antibodies are extracted from the different rabbits and are then mixed with the different albumin samples
The precipitate (antibody-antigen complexes) resulting from each mixed sample is weighed

Question 17

immunology results

Answer 17

The greater the weight of the precipitate, the greater the degree of complementarity between the antibody and albumin
For example, antibodies produced against human albumin will produce a larger amount of precipitate when exposed to chimpanzee albumin than when exposed to rat albumin because humans are more closely related to chimpanzees

Question 18

DNA fingerprinting

Answer 18

gel electrophoresis separates DNA fragments according to size

this allows you to compare whether a particular gene is present in different closely-related species

not very accurate because gene lengths can vary due to presence of introns

The more genes you use, the more accurate your tree will be.

Question 19

3a Protein lengths / sizes comparison (ie, protein fingerprinting)

Answer 19

gel electrophoresis is a method by which proteins or DNA can be separated according to size

this allows you to compare whether a particular protein is present in different closely-related species

not a very efficient method of determining phylogeny - protein may not be produces by the species at the same time - thus the species may produce the protein without the experimenter knowing it

Question 20

what are the advantages of courtship behaviour

Answer 20

individuals can recognise sexually mature members of their own species of the opposite sex, synchronise mating, form a pair bond, and successfully breed <3

Question 21

define classification

Answer 21

the process of arranging organisms into groups

Question 22

what system is used to give species a universal name

Answer 22

binomial naming system

Question 23

what are the two components to a binomial name

Answer 23

generic name = the genus the organism belongs to - two closely related species will share the same genus

specific name = the species the organism belongs to

Question 24

how are binomial names handwritten

Answer 24

the first letter of the generic name should be capitalised and the rest lower case

should be underlined if handwritten

italics if types

Question 25

what is phylogenetic classification

Answer 25

the process of arranging organisms into groups based on their evolutionary origins and relationships

Question 26

how can we clarify evolutionary relationships between organisms

Answer 26

analyse their molecular differences

advantages in immunology / genome sequencing provide a clear picture of how related two organisms are

Question 27

explain hierarchical classification

Answer 27

groups within groups

no overlap between groups