Unit 3 - Topic 1 - Classification Processes

Question 1

What is biological classification? What can it be based on?

Answer 1

Grouping of both organisms and ecosystems to show their biological relationships, evolution and diversity.

Based - different levels of:
similarity of physical features
methods of reproduction
molecular sequences

Question 2

Describe the classification system: similarity of physical features

Answer 2

Called the Linnaean system

Hierarchal structure of classifying organisms

Uses morphological features of organisms to create groups according to their similarities - features of the groups become more similar at each lower taxon

Uses binomial nomenclature to name classified organisms at Genus species level

Question 3

Describe the classification system: methods of reproduction

Answer 3

Organisms classified on methods of reproduction - two ways of classifying:
1. sexual vs asexual reproduction
2. K and r strategists

Question 4

Compare sexual vs asexual reproduction

Answer 4

Sexual:
- 2 parents
- sperm fertilises egg
- used by animals, flowering plants, some fungi
- provides genetically diverse offspring - different from parents
- time consuming

Asexual:
- 1 parent
- single organism - creates exact copy of self
- bacteria, some plants, some fungi, few animals
- identical offspring to parent - no genetic variation
- fast & easy

Question 5

Compare K vs r strategists

Answer 5

K selection:
- low growth rate, high survivability (low mortality)
- stable environment where resources maximise long-term survivability
- few offspring per brood, high level parental care
- typically larger body size - long developmental span (late maturity)

r selection:
- high growth rate, low survivability (high mortality)
- unstable environment, ecological disruption where resources used maximise reproduction
- many offspring per brood - litte parental care
- typically smaller body size - short developmental span (early maturity)

Question 6

Describe the classification system: molecular sequences

Answer 6

Called molecular phylogeny (or cladistics)

Uses DNA & amino acid sequences of proteins to compare similarity of molecular sequences across different organisms

Greater similarity in molecular sequences = more closely related

Developed after Linnaean classification system

Question 7

Define the term clade

Answer 7

A group of organisms consisting a common ancestor and all its linear descendants (which evolved from the common ancestor)

Question 8

Recall the common assumptions of cladistics

Answer 8

3 common assumptions:
1. Change in characteristics occur