4.5 - Species and Taxonomy

Question 1

what is a species

Answer 1

-a group of organisms that can (interbreed to) produce fertile offspring

Question 2

suggest why 2 different species are unable to produce fertile offspring

Answer 2

-different species have different chromosome numbers → offspring may have odd chromosome number
-so homologous pairs cannot form → meiosis cannot occur to produce gametes

Question 3

explain why courtship behaviour is a necessary precursor to successful
mating

Answer 3

● allows recognition of members of same species → so fertile offspring produced
● allows recognition / attraction of opposite sex
● stimulates / synchronises mating / production / release of gametes
● indicates sexual maturity / fertility
● establishes a pair bond to raise young

Question 4

describe a phylogenetic classification system

Answer 4

-species (attempted to be) arranged into groups, called taxa, based on their evolutionary origins (common ancestors) and relationships
-uses a hierarchy:
○ smaller groups are placed within larger groups
○ no overlap between groups

Question 5

name the taxa in the hierarchy of classification

Answer 5

1. domain (largest / broadest)
2. kingdom
3. phylum
4. class
5. order
6. family
7. genus
8. species (smallest)

Question 6

how is each species universally identified?

Answer 6

-a binomial consisting of the name of its genus and species, eg. homo sapiens

Question 7

suggest an advantage of binomial naming

Answer 7

-universal so no confusion as many organisms have more than one common name

Question 8

how can phylogenetic trees be interpreted?

Answer 8

-branch point = common ancestor
-branch = evolutionary path
-if two species have a more recent common ancestor, they are more closely related (eg. C & D)

Question 9

name two advances that have helped to clarify evolutionary
relationships between organisms

Answer 9

1. advances in genome
   sequencing → allowing
   comparison of DNA base sequences
2. advances in immunology → allowing comparison of protein
   tertiary structure (eg.
   albumin)

Question 10

describe how advances in genome sequencing have helped to clarify evolutionary relationships between organisms

Answer 10

-more differences in DNA base sequences → more distantly related / earlier common ancestor
-as mutations (change in DNA base sequences) build up over time

Question 11

describe how advances in immunology have helped to clarify evolutionary relationships between organisms

Answer 11

-higher amount of protein from one species binds to antibody against the same protein from another species → more closely related / more recent common ancestor
-as indicates a similar amino acid sequence and tertiary structure
-so less time for mutations to build up