B15 - Genetics and Evolution

Question 1

What do we now know Mendel’s ‘units’ as?

Answer 1

Genes/ alleles

Question 2

What was Jean-Baptiste Lamarck’s theory about evolution?

Answer 2

• Changes that an organism acquires during its lifetime will be passed on to its offspring
• If a characteristic was used a lot by an organism, it became more developed during its lifetime and would be inherited
• (e.g. if a rabbit used its legs to run a lot, they would grow long and its offspring would have long legs)

Question 3

Explain the way the fossils are formed via mineral replacement.

Answer 3

• GRADUAL REPLACEMENT BY MINERALS
  => Animal dies but teeth, shells, bones etc. don’t decay easily and last a long time when buried
  => Eventually get replaced by minerals as they decay, forming rock-like substance in shape of tooth etc.
  => Surrounding sediments also turn to rock but fossil stays distinct in the rock
  => Someone digs it up

Question 4

What is speciation and when can it occur?

Answer 4

• Speciation is the development of a new species:
  => Species separated by river/sea/mountains/city etc.
  => Each population experiences different conditions
  => Variation due to random mutations
  => Different natural selection causes different characteristics
  => A new species = these two populations cannot breed to produce fertile offspring.

Question 5

What leads to the formation of antibiotic-resistant strains of bacteria?

Answer 5

=> Reproduce quickly - Variation due to random mutations - small number resistant to antibiotics - pass on genes
=> Patients not finishing their course of antibiotics
=> Inappropriately prescribing antibiotics
=> Antibiotics used in agriculture (resistant bacteria spreads to humans via produce)
(new antibiotics take a long time to be created and the process is expensive)

Question 6

Name the groups that organisms are classified into in the Linnaean system.

Answer 6

=> Kingdom
=> Phylum
=> Class
=> Order
=> Family
=> Genus
=> Species
(King Phillip Came Over For Group Sex)

Question 7

Who proposed the ‘Three-Domain System’ of classification in 1990? What are the three domains?

Answer 7

• Carl Woese
• Archaea (primitive bacteria usually living in extreme environments)
• Bacteria (true bacteria)
• Eukaryota ( includes protists, fungi, plants and animals)

Question 8

Explain how casts and impressions fossils are formed.

Answer 8

=> Footprints, burrows, plant roots, dead animals on top of soft material like clay
=> Material hardens around them
=> (decay)
=> Impression is made in rock
=> Someone digs it up

Question 9

Explain the process of fossilisation by preservation

Answer 9

=> In amber (a clear yellow ‘stone’ of fossilised resin; sometime tree sap) and tar pits there is no W.O.W. so decay microbes can’s survive.
=> In glaciers it’s too cold for the decay microbes to work
=> Pete bogs are too acidic for decay microbes
=> When animals die in these locations, they do not decay and are preserved.