Investigating Biodiversity

Question 1

What are the genetic methods of classifying organisms?

Answer 1

• DNA comparisons – DNA Sequencing and DNA Hybridisation
• Comparisons of mRNA sequences
• Comparison of AA sequence in common proteins
• Immunological comparisons (antibodies)

Question 2

How can DNA be used to classify organisms?

Answer 2

Changes in DNA are caused by mutations.
• Stretches of DNA can be determined by sequencing
• The more differences there are the less closely related two species are as
they will have evolved separately for a longer period of time.

Question 3

What is DNA hybridisation?

Answer 3

DNA Separates when heated, and
then recombines to form the original
strand when left to cool.
• All strands within a DNA mixture will
pair up with their partners eventually,
but some may anneal to form hybrid
DNA
• They are heated again - higher the
denaturing temperature the more
similar the DNA is.

Question 4

Why do we compare amino acid sequences?

Answer 4

• Amino acid sequence is determined by DNA
• The similarity between the amino acid sequence of the same protein
in different species will also indicate how closely related they are.

Question 5

Cytochrome c is more useful
than haemoglobin for studying
how closely related different
organisms are. Suggest one
reason why.

Answer 5

1. All organisms respire / have
   cytochrome c
2. (Cytochrome c structure) is
   more conserved / less varied
   (between organisms)

Question 6

What is intraspecific variation?

Answer 6

variation within a species e.g. antibiotic resistance in a species of bacteria

Question 7

What is interspecific variation?

Answer 7

variation between different species e.g. thickness of blubber in seals and sea lions

Question 8

Give a method for random sampling (3 marks)

Answer 8

• Create a grid using two tape measures
• Create random coordinates using a random number generator
• Take samples where two random coordinates intersect
• Repeat to calculate a mean