Natural selection

9.What is the main source of variation within a species?

10.Which of the following is an example of natural selection in action?

11.In the context of natural selection, what does 'fittest' mean?

12.A population of rabbits lives in a cold climate. Which trait would be most advantageous for survival?

13.In a population of rabbits, some have thicker fur and some have thinner fur. If the climate becomes colder, which rabbits are most likely to survive and reproduce?

14.A population of beetles lives in a forest with both brown and green leaves. After several generations, the beetle population becomes mostly green. Which statement best explains this change?

15.A scientist measures the beak depth of finches on an island before and after a drought. The table shows the average beak depth. What conclusion can be drawn? | Time | Average beak depth (mm) | |------|------------------------| | Before drought | 8.5 | | After drought | 10.2 |

16.A population of bacteria is exposed to an antibiotic. Most bacteria die, but a few survive and reproduce. After several generations, the entire population is resistant to the antibiotic. Which statement explains this?

17.In a species of moth, there are two colour forms: dark and light. In a polluted area where trees are covered in soot, dark moths are more common. Which graph best shows the change in moth population over time?

18.In an experiment, a scientist places equal numbers of brown and green beetles in a tray with brown soil. After one hour, a bird is allowed to eat beetles for five minutes. The scientist then counts the remaining beetles. Which result would support the theory of natural selection?

19.A population of bacteria is treated with an antibiotic. Most bacteria die, but a few survive and reproduce. After several generations, the entire population is resistant to the antibiotic. Which statement best explains this?

20.In a population of rabbits, some have thick fur and some have thin fur. If the climate becomes colder over many years, which outcome is most likely?

21.A scientist measures the beak depth of finches on an island before and after a drought. The data shows that average beak depth increased after the drought. Which conclusion is best supported?

22.In a species of moth, there are two colour forms: dark and light. In a polluted area where trees are covered in soot, dark moths are more common. Which graph best shows how the proportion of dark moths would change over time if pollution continues?

23.A student investigates whether a particular antibiotic is effective against a strain of bacteria. They grow bacteria on agar plates, add antibiotic discs, and measure the zone of inhibition. After three days, they observe bacteria growing inside the zone. What is the most likely explanation?

24.Which of the following is required for natural selection to occur?

25.What is the original source of the variation that natural selection acts upon?

26.In a population of plants, some individuals produce a toxin that deters herbivores. A new species of herbivore arrives that is unaffected by the toxin. What is the most likely long-term outcome for the plant population?

27.A farmer sprays a field with pesticide to kill insects. Most insects die, but a few survive. After several generations, the insect population is no longer affected by the pesticide. This is an example of:

28.Which of the following best describes natural selection?

29.In natural selection, what does the term 'fittest' mean?

30.A population of bacteria is exposed to an antibiotic. Most bacteria die, but a few survive and reproduce. After several generations, the entire population is resistant to the antibiotic. This is an example of:

31.A scientist measures the beak depth of finches on an island before and after a drought. The data shows that average beak depth increased after the drought. Which conclusion can be drawn?

32.In an experiment, a student places equal numbers of brown and green beetles in a tray with brown soil. After one hour, a bird is allowed to eat beetles for five minutes. The student then counts the remaining beetles. Which result would support natural selection?

33.A farmer sprays a field with pesticide to kill insects. Most insects die, but a few survive. After several generations, the insect population is no longer affected by the pesticide. This is because:

34.Which of the following best explains how giraffes evolved long necks according to natural selection?

35.In a population of beetles, some are brown and some are green. They live in a forest with brown leaves. A bird predator is introduced. Which outcome is most likely after many generations?

36.A farmer sprays a field with pesticide. Most of the insects die, but a few survive and reproduce. After several generations, the insect population is no longer affected by the pesticide. Which statement best explains this?

37.A scientist measures the beak depth of finches on an island before and after a drought. The table shows the average beak depth. Before drought: 9.5 mm. After drought: 11.2 mm. What conclusion can be drawn?

38.In an experiment, a student places 50 brown beetles and 50 green beetles in a tray with brown soil. A bird is allowed to eat beetles for 5 minutes. The student counts the remaining beetles. Which result would support natural selection?

39.A population of bacteria is treated with an antibiotic. Most bacteria die, but a few survive and reproduce. After several generations, the entire population is resistant to the antibiotic. What is the original source of the resistance?

40.In a species of moth, there are two colour forms: dark and light. In a polluted area where trees are covered in soot, dark moths are more common. Which graph best shows the change in moth population over time after pollution increases?

41.Natural selection explains how species change over time.

42.All individuals within a species are exactly the same.

43.What is the main reason for variation within a species?

44.In a forest with brown leaves, why are brown beetles more likely to survive than green beetles?

45.Place the following steps of natural selection in the correct order:

46.Which of the following are required for natural selection to occur? (Select all that apply)

47.Match each term to its correct description.

48.Natural selection can lead to the development of new species over many generations.

49.Match each term on the left with its correct description on the right.

50.Put the following steps of natural selection in the correct order, starting with the first step.

51.Complete the sentence using the correct term.

52.In a population of 100 beetles, 20 are brown and 80 are green. The environment has brown soil. If brown beetles have a 90% chance of surviving to reproduce and green beetles have a 50% chance, how many brown beetles are expected to survive?

53.Describe what is meant by 'survival of the fittest'.

54.Describe how giraffes evolved to have such long necks according to natural selection.

55.In a population of 100 beetles, 20 are brown and 80 are green. The environment has brown soil. If brown beetles have a 90% chance of surviving to reproduce and green beetles have a 50% chance, how many brown beetles are expected to survive?