Classification and Evolution

Question 1

What is the order of the Linnaean classification?

Answer 1

• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species

Question 2

What are the 3 domains?

Answer 2

Archea - ancient bacteria and extremophiles
Eukarya - eukaryotes
Eubacteria - real bacteria, unicellular organisms without a nucleus

Question 3

What are the reasons for classification?

Answer 3

• Identifying species
• Predict characteristics
• Find evolutionary links

Question 4

What is phylogeny?

Answer 4

The evolutionary links between organisms

Question 5

What does a phylogenetic tree show?

Answer 5

• Evolutionary relationships
• Evolutionary timeline
• Continuous

Question 6

What are the 3 types of evidence for evolution?

Answer 6

Palaeontology - Study of fossils
Comparative anatomy - Anatomical differences between organisms (homologous structures)
Comparative biochemistry - DNA bases and amino acid sequences

Question 7

What does palaeontology show us?

Answer 7

• Simple lifeforms evolve into complex ones
• Animals need plants to survive, as plant fossils were formed before animal ones
• Find how closely related organisms are might be based on similarities or differences in structure

Question 8

What is the problem with palaeontology?

Answer 8

• Incomplete fossil record as most are discovered by accident
• Tectonic plate movements can break fossils or move them

Question 9

What does comparative biochemistry show?

Answer 9

• Important molecules are highly conserved (eg cytochrome c is involved in respiration in every living organism)
• Cytochrome c can be compared in different organisms, and closely related organisms have very similar or the same amino acid sequence for it

Question 10

What does the t test and spearman’s rank show?

Answer 10

t test - Compares mean data to see if there is a significant difference two sets of data
Spearmans rank - Find if there is a positive or negative correlation between two sets of data

Question 11

What is a null hypothesis?

Answer 11

Any relationship/correlation between two sets of data is only due to chance

Question 12

When do you reject the null hypothesis, and why?

Answer 12

When the t value is bigger than the critical value, as we are more than 95% confident that there is a significant difference

Question 13

What is the difference between intraspecific and interspecific variation?

Answer 13

Interspecific - The variation seen between different species
Intraspecific - Differences seen between the same species

Question 14

What is continuous and discontinuous variation?

Answer 14

Continuous - Numerical data, quantitative and usually represented on a line graph
Discontinuous - Grouped or distinct data, qualitative and represented with bar charts

Question 15

What are some causes of genetic variation?

Answer 15

• Dominant and recessive alleles
• Mutations (random replication error, mutagens or carcinogens)
• Meiosis in crossing over and independent assortment
• Random fertilisation as any sperm cell can fertilise any egg cell

Question 16

What are the different types of adaptations?

Answer 16

• Behavioural
• Anatomical - physical features
• Physiological - chemical processes like photosynthesis and digestion

Question 17

What is divergent evolution and convergent evolution?

Answer 17

Divergent - Two species have evolved from the same common ancestor and have homologous structures
Convergent - Two species share similar adaptations in the same habitat but have different evolutionary origin

Question 18

What are analogous structures?

Answer 18

Similar appearance and function, but different underlying structure and origin

Question 19

What are the stages of evolution by natural selection?

Answer 19

1. Pre-existing variation - There are individuals within a population that have shown different adaptations, this is due to mutations
2. Change in selection pressure - Change in environment that causes some individuals to survive, and some to die, for example a flood. Best adapted individuals can survive and reproduce
3. Pass on advantageous and favourable allele - repeated over many generations
4. Repeats leading to increased allele frequency
5. Overtime, this can lead to speciation