--- title: "Quick check: evidence, new species and evolution today" subtitle: "Year 10 Biology · Evolution · Lesson 7" --- # Quick check: evidence, new species and evolution today **Name:** {{field-24}} **Date:** {{field-15}} **Class:** {{field-15}} > **Key question:** Whales have finger bones. Bacteria shrug off drugs. What do they have in common? :::teacher-note **In one sentence:** A self-test on the lines of evidence for evolution, speciation and extinction, and evolution in present populations (AC9S10U02, nodes 3, 4 and 5, taught in class; node 3 a hinge). **Students should be able to say:** I can give three kinds of evidence for evolution. I can explain how a new species can form and why one goes extinct. I can use natural selection to explain antibiotic resistance. **Width:** the unmarked parts are the floor every student does (Engage, Explore, Explain, Evaluate). Typical and Wider sections add contexts, not difficulty. Students work in the online tutorial alongside this sheet. ::: ## Evidence :::keep-together ### Evidence or not? **Is it evidence for evolution?** Groups: Evidence, Not evidence - Fossils in layers, with simpler forms in older rock: {{field-15}} - Similar bones in a human arm, a bat wing and a whale flipper: {{field-15}} - DNA more similar between closely related species: {{field-15}} - Related animals living in the same region, such as Australian marsupials: {{field-15}} - Two animals that are the same colour: {{field-15}} ::: :::teacher-note **Answer:** Fossils in layers, with simpler forms in older rock → Evidence; Similar bones in a human arm, a bat wing and a whale flipper → Evidence; DNA more similar between closely related species → Evidence; Related animals living in the same region, such as Australian marsupials → Evidence; Two animals that are the same colour → Not evidence ::: :::keep-together ### Why several? **Why do scientists place so much weight on several lines of evidence?** ☐ Independent kinds of evidence all point to the same conclusion, which makes it much more reliable ☐ Each is a different theory ☐ More evidence is always better, whatever it shows ☐ One line is enough ::: :::teacher-note **Answer:** Independent kinds of evidence all point to the same conclusion, which makes it much more reliable Fossils, anatomy, DNA and distribution come from different methods, so agreement is strong support. ::: :::keep-together ### What each shows **Match each line of evidence to what it shows.** A. Those animals share a common ancestor B. Living things have changed over time, in order C. Species evolved where their ancestors lived, cut off from elsewhere D. How closely related they are {{columns 60% 40%}} {{rows 1}} | Part | Letter | |---|---| | `Fossils in rock layers` | | | `Similar bones in an arm, a wing and a flipper` | | | `How similar species' DNA is` | | | `Marsupials found mostly in Australia` | | ::: :::teacher-note **Answer:** Fossils in rock layers → B. Living things have changed over time, in order; Similar bones in an arm, a wing and a flipper → A. Those animals share a common ancestor; How similar species' DNA is → D. How closely related they are; Marsupials found mostly in Australia → C. Species evolved where their ancestors lived, cut off from elsewhere ::: ## Past diversity :::keep-together ### New species **A population is split by a new mountain range. Over a long time the two groups face different conditions. What might happen?** ☐ Natural selection acts differently on each, and they may become separate species ☐ Each group changes because its members try to suit their new home ☐ Nothing changes ☐ The groups merge ::: :::teacher-note **Answer:** Natural selection acts differently on each, and they may become separate species Isolated groups cannot share genes, and different pressures favour different traits, so they can diverge until they no longer interbreed. ::: :::keep-together ### Extinction **Why do species go extinct?** ☐ They never go extinct naturally ☐ They choose to stop reproducing ☐ They are always the weakest species ☐ The environment changes faster than the population can adapt, or it has no helpful variation ::: :::teacher-note **Answer:** The environment changes faster than the population can adapt, or it has no helpful variation Selection can only act on variation that already exists. If no individuals can survive the change, the species dies out. ::: :::keep-together ### Fossil timeline **What does the fossil record show about species over time?** ☐ Fossils show only species that are now extinct ☐ All the species alive today are found in the oldest layers ☐ Species appear and disappear at different times in the rock layers ☐ The deeper the layer, the bigger the animals ::: :::teacher-note **Answer:** Species appear and disappear at different times in the rock layers Layers show the order in which groups appear and vanish, which fits change over time. ::: ## Evolution now :::keep-together ### Resistant bacteria **Antibiotics kill most bacteria in an infection, but a few resist. What happens next?** ☐ Nothing: resistance cannot spread ☐ The bacteria decide to resist ☐ The resistant bacteria survive and reproduce, so the population becomes more resistant ☐ The antibiotic makes the bacteria resistant ::: :::teacher-note **Answer:** The resistant bacteria survive and reproduce, so the population becomes more resistant The antibiotic is the selection pressure. Resistant bacteria already existed by chance, and the treatment leaves them to multiply. ::: :::keep-together ### Pesticide **A farmer sprays the same pesticide for years and it works less well. Why?** ☐ The insects moved away ☐ The insects learned to ignore it ☐ The pesticide wore out ☐ Insects that happened to resist survived and bred, so resistance became common ::: :::teacher-note **Answer:** Insects that happened to resist survived and bred, so resistance became common Selection pressure over many generations raises the share of resistant individuals. ::: :::keep-together ### Individuals or populations? **Which statement about evolution is correct?** ☐ Evolution only happened in the past ☐ Populations change over generations; individuals do not evolve in their lifetime ☐ Evolution has a goal ☐ Individuals change to suit their surroundings ::: :::teacher-note **Answer:** Populations change over generations; individuals do not evolve in their lifetime Individuals do not change their genes to fit; the proportions of traits in the population change as some survive and reproduce more. ::: :::keep-together ### Why so many species? **Why are there millions of different species today?** ☐ All of today's species have existed unchanged since life began ☐ New species stopped forming once humans appeared ☐ Every species has been evolving towards being human ☐ Over billions of years, natural selection in different environments has split populations into many species, and it still goes on ::: :::teacher-note **Answer:** Over billions of years, natural selection in different environments has split populations into many species, and it still goes on Today's biodiversity is the result of the same processes still at work: variation, selection and isolation. ::: ## Exit ticket :::keep-together **Explain in two sentences how bacteria become resistant to an antibiotic.** {{lines-3}} ::: :::teacher-note **Answer:** Some bacteria already have resistance by chance. The antibiotic kills the others, so the resistant ones reproduce and become common. :::