Q3. In the Grand Canyon, scientists have found fossils of several different groups of organisms.
The diagram shows the number and age of the fossils that the scientists found.
The width of each shaded area shows the number of fossils found.
accept 2 physical factors or 2 biological factors or one of each for full marks
examples of biological factors such as predators (allow hunters), disease / named pathogen, competition lack of food / mates, cyclical nature of speciation / isolation / lack of habitat or habitat change
If no other answers given allow natural disaster / climate change / weather change / catastrophic event / environmental change for 1 mark
(c) older fossils simpler
to gain the mark there must be implication of change
change (with time)
(d) insufficient / no evidence / no remains or fossils survive
ignore no people were there
allow no proof
M3. (a) remains of an organism or bone / shell / hard part of an organism / impression
further detail – eg in rock / from a long time ago
if numbers, greater or equal to hundreds of years
allow made of minerals
ignore over time
ignore fossil are rocks
(b) (i) D
(iii) predation / disease / lack of food / competition / loss of habitat /
climate change / catastrophic event – or volcanic eruption / flood /
drought / temperature change / weather change / ice age / change in atmosphere
ignore human effects
ignore pollution effects / acid rain
allow natural disaster
(c) C = ‘widest’ thickest / widerthicker column or more fossils
(of type C found)
allow biggest / er
(d)members of the groups have similar physical structures
extra box ticked – cancel
M4. extinct (NOT fossils)
each for 1 mark
M5. (a) increased by about 7 times / from 600 to 4300 / by 3700
(b) Marks awarded for this answer will be determined by the Quality
M6. (a) there is a lack of valid / reliable evidence
because the early organisms were soft bodied or because remains were
destroyed by geological action
(b) populations of salamanders became isolated / separated
by areas between mountains
there was genetic variation in these isolated communities
natural selection acted differently on these isolated communities
eventually resulting in interbreeding being no longer possible and so
new species have been formed
M7. (a) (i) D
for 1 mark
(ii) D Y (both) or C X (both) or B W (both)
for 1 mark
(b) N.B. answers must relate to fossils providing evidence
show types of animals / plants that no longer exist / named ref eg dinosaur
show changes in types (of animals / plants) similar fossils found in rocks of similar age
reference to sequence of change
e.g. horse / limb
any two for 1 mark each
M8. (a) mud
(b) idea that living things have changed (over time)
do not allow ‘dating’
do not credit ‘evolved’
allow ‘compare the skeleton’
E2.(a) (i) Less than one third of the students could give an adequate explanation of how the fossil of the dinosaur footprint might have been formed. Answers were very mixed, but most students who gained a mark did so by describing the way in which the footprint was made by treading in soft mud. Many wrote that the fossil was formed from dinosaur bones, even though the question told them that it was a footprint.
(ii) Many students gained a mark for reference to bones, shells or whole animals trapped in ice or amber. Just over one third of students were able to give an adequate description of a method of fossil formation.
(b) Nearly all students knew at least one possible cause of extinction, with approximately half being able to give two causes, ranging from physical factors such as flooding, volcanic activity, asteroid collision, drought, or an ice age, to biotic factors such as predation, disease or competition for food.
(c) Less than one third of students were able to explain how changes in fossils with time might give evidence for evolution. Very few made the point that older fossils were simpler. Failure to score was often because of the use of the word ‘evolve’ to mean change: ‘ evolution ’ was given in the question and so ‘evolve’ could not gain credit. There were vague references to adaptation to the environment, which often referred to just a single organism rather than to organisms changing over time.
(d) Many answers here were vague or confused. There was confusion between the origin of life and the origin of the universe. Some answers referred to conflicting theories about how life began on earth or stated that there were no people there to record events! A little over half the students were able to explain that there was insufficient evidence, such as a lack of suitable fossils.
E3. (a) As the diagram indicated, a fossil is likely to have been formed from an organism that was alive millions of years ago (rather than just “many years”). Details, such as being an impression (e.g. a footprint) or being formed in rock, were also acceptable as part of the answer. Most students were able to make at least one correct point, but less than half could give two.
(b) What should have been obvious from the diagram proved to be so for only three-quarters of the students who correctly selected group D as the group of organisms which were first to evolve. Slightly more realised that the diagram gave evidence that group B was now extinct. Most students were also able to suggest an environmental factor that might have caused extinction, such as predation, lack of food, competition or some catastrophic event.
(c) Around three-quarters of students successfully described that group C’s fossils were the most common 10 million years ago (or that this group had the widest band in the diagram for that time). Some students merely re-stated the words of the question and so gained no credit.
(d) Around two-thirds correctly selected the fact that having similar physical structures would indicate that all four groups of organisms had evolved from a common ancestor.
E4. Very well answered by most candidates with a small minority reversing “extinct” and “fossils”.
E8. This proved to be a good opening question for most candidates. It produced generally high scores.
(a) The majority of candidates were able to score full marks. In a few cases however, the candidates had not followed the instructions in the rubric concerning the method of indicating their answers. In general, the candidates’ intentions were clear but in a few cases there were so many crossings out, ringing and re-writing that it was difficult for examiners to decide what the candidate had intended.
(b) This proved to be more demanding, with only a minority of the candidates realising that evidence came from a comparison between fossils and present day specimens. Most of the other candidates either talked about the dating of fossils or left the question unanswered.