Year 10 Science · Unit 1 · Lesson 14

Evidence for Evolution, Molecular and Biogeographical

Foundation Worksheet

Name

Date

Class

Learning Goals

Explain how DNA similarity between species provides evidence for common ancestry.
Describe how a molecular clock works and what it can tell us about evolutionary divergence.
Explain why Australian marsupials evolved differently from placental mammals elsewhere.

Warm Up

Fill the gap

Choose the correct word from the word bank to complete each sentence.

cytochrome c molecular clock biogeography common ancestor convergent evolution antibiotic resistance marsupials species distribution

The study of the geographical distribution of species and its connection to evolutionary history is called . Australia became geographically isolated around 50 million years ago, which is why evolved there independently of placental mammals. When two unrelated species independently evolve similar traits to suit similar environments, this is called . Scientists use the concept of a to estimate when two species last shared a , based on the rate of neutral DNA mutations. The protein is identical in humans and chimpanzees, reflecting how recently they diverged. The evolution of bacteria that can survive exposure to drugs is an example of and demonstrates that evolution is occurring right now.

Your Turn

Match each term to its definition or example

Draw a line connecting each term on the left to its correct definition on the right. Or write the matching letter next to each term.

Term	Your answer	Definition / Example
Molecular clock		A. A protein conserved across species; identical in humans and chimpanzees, differs by 45 amino acids between humans and yeast.
Biogeography		B. Australian mammals such as the sugar glider and North American flying squirrel, similar adaptations, different ancestry.
Marsupial		C. Uses rate of neutral DNA mutation to estimate when two species last shared a common ancestor.
Convergent evolution		D. Studies how the geographical location of species reflects their evolutionary history.
Cytochrome c		E. MRSA bacteria surviving doses of methicillin, observable evolution in hospitals today.
Antibiotic resistance		F. A mammal whose young are born early and complete development in a pouch; kangaroo, koala and wombat are examples.

Show What You Know

1. Humans share approximately 98.8% of their DNA with chimpanzees but only 85% with mice. What does this difference in DNA similarity tell us about our evolutionary relationships with each species?

Recall 2 marks

2. Explain why antibiotic resistance in bacteria is considered evidence that evolution is happening today.

Recall 2 marks

Wrap Up

In one sentence, what was the main idea of this lesson?