Evidence for evolutionIB MYP Biology: Subtopic test

1. 1
   Palaeontologists have found fossils in layers of sedimentary rock in Pakistan and Egypt that record the history of whales. The oldest fossils, about 50 million years old, show a wolf-sized animal with four legs that lived partly on land. Younger fossils show animals with shorter back legs and paddle-like front limbs. The youngest fossils show animals with bodies like modern whales and only tiny hind-limb bones.

   (a)

   In undisturbed layers of sedimentary rock, where are the oldest fossils usually found?

   [1 mark]

   • AIn the top layer, nearest the surface
   • BIn the same layer as the youngest fossils
   • CIn the deepest layers, at the bottom
   • DOnly in rock formed from cooled lava

   (b)

   What does the sequence of whale fossils show?

   [1 mark]

   • AWhale ancestors changed gradually over millions of years
   • BWhales appeared suddenly with no ancestors
   • CLand animals are turning into whales today
   • DAll whales are the same age

   (c)

   Explain why the fossil record is incomplete.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   The front limbs of a human, a bat, a whale and a horse look very different and are used for different jobs: grasping, flying, swimming and running. However, when anatomists compare the bones, each limb contains one upper-arm bone, two lower-arm bones, a group of wrist bones and a series of finger bones, arranged in the same basic pattern.

   (a)

   What term describes bones with the same basic arrangement in different animals, even if they have different functions?

   [1 mark]

   • AAnalogous structures
   • BVestigial structures
   • CFossil structures
   • DHomologous structures

   (b)

   What does the similar bone pattern suggest about these four animals?

   [1 mark]

   • AThey live in the same habitat
   • BThey share a common ancestor
   • CThey eat the same food
   • DThey all evolved from bats

   (c)

   Explain how the limb bones support the idea that these animals evolved from a common ancestor, even though the limbs have different uses.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Cytochrome c is a protein used in respiration by almost all living organisms. Scientists compared the order of amino acids in cytochrome c from different species with the human protein and counted the positions where the amino acids differ. For the chimpanzee there were 0 differences, for the rhesus monkey 1, for the dog 10, for the chicken 13 and for the tuna 21.

   (a)

   Describe the pattern in the data and explain what it suggests about how closely related each species is to humans.

   [3 marks]

   (b)

   A student concludes: 'Dogs have 10 differences and tuna have 21, so humans evolved from dogs.' Evaluate the student's conclusion and suggest one way to strengthen the evidence.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A national science museum is building a gallery about how ideas about evolution have changed and how they are used today. One panel compares the nineteenth-century ideas of Jean-Baptiste Lamarck and Charles Darwin. Another panel explains how health agencies now compare the DNA of influenza viruses collected around the world to decide which strains to include in each year's flu vaccine.

   (a)

   Compare Lamarck's and Darwin's explanations of how giraffes came to have long necks, and give one piece of evidence against Lamarck's idea.

   [6 marks]

   (b)

   Discuss and evaluate the use of DNA comparisons to track how influenza viruses change in order to choose the strains for each year's vaccine. Give a justified conclusion.

   [6 marks]

   Total for question 4: 12 marks

End of questions