chapter 10 (relatedness)

Question 1

process of fossilisation

Answer 1

• animal/plant dies
• the body is covered in sediment the soft tissues decomposed and the hard body structures become fossilised by permineralisation
• the sedimentary layers accumulate and the resultant pressure forms sedimentary rock
• the earth’s movement raise the layers of the rocks to the surface
• the rock erodes exposing fossilised body structures.

Question 2

increase the likelihood of fossilisation

Answer 2

areas of rapid sediment accumulation , constant cool temperatures, low oxygen availability, low light exposure

Question 3

relative dating

Answer 3

a dating technique used to determine the relative ages of fossil by comparing its position to other fossils or rock in surrounding rock strata

Question 4

absolute dating

Answer 4

a dating technique used to determine the absolute age of a fossil by measuring the relative amounts of radioisotopes to their products

Question 5

index fossils

Answer 5

• a group of widespread fossils which existed for a short period and have a known age
• can be used to reference and easily determine the age of unknown fossils
• best index fossils: physically distinctive, have a large population, existed in many geographical areas, lived within a known short period of time

Question 6

transitional fossil

Answer 6

a fossil that shows traits that are common to both its ancestral group and its descendant group

Question 7

mould fossil

Answer 7

• fossil formed when a living thing decomposes underneath sediment
• creating a cavity in the shape of the dead organism

Question 8

cast fossil

Answer 8

fossil formed when a mould fossil is filled with sediment

Question 9

trace fossil

Answer 9

• fossil or structure indicating the presence of organisms
• rather than the organisms themselves (e.g. nests, footprints, and burrows)

Question 10

Radioisotope series

Answer 10

• Carbon-14 - nitrogen-14
  5 730 years 1 000 - 50 000 years
  Organic materials
• Uranium-235 - lead-207
  700 million years 1 million - 4.5 billion years
  (used together with U-238 - Pb-206 dating)
  Uranium-containing materials (shells, corals)
• Uranium-238 - lead-206
  4.5 billion years 1 million - 4.5 billion years
  (used together with U-235 - Pb-207 dating)
  Uranium-containing materials (shells, corals)
• Potassium-40 - argon-40
  1.3 billion years 100 000 + years
  Igneous (volcanic) rocks

Question 11

Homologous structures

Answer 11

• are physical evidence of divergent evolution
• the evolutionary process where two or more populations of a single species accumulate enough genetic differences to be classified as different species.

Question 12

Analogous structures

Answer 12

are structures that serve similar biological functions but are not derived from a common ancestor

Question 13

Vestigial structures

Answer 13

are structures found within organisms that once served a purpose for an organism’s ancestors but due to changing selection pressures have lost their original function and are no longer required for survival.
(e.g human coccyx/tailbone)

Question 14

Molecular homology

Answer 14

is the study of the similarities between organisms at a DNA and amino acid level