Pre-AP Biology Chapter 34 Homework
Name the type of innate behavior exhibited in the following examples.
1. __________________ You leap up after sitting down in shorts on a hot car seat.
2. __________________ A sea turtle returns to the beach where she was hatched, in order
to lay her eggs.
3. __________________ A giant clam closes its shell when a shadow falls across it.
4. __________________ A spider spins a complex, circular web.
5. __________________ A large male baboon stares at another male, then suddenly
“yawns” to reveal his long, sharp fangs.
6. __________________ When a herd of elephants arrives at a waterhole, the oldest
female drinks first, followed by 3 females with calves, and finally a young male.
7. __________________ Large numbers of monarch butterflies fly south to roost in the
winter.
8. __________________ After fighting briefly with an older pack member, a young wolf
stops fighting and rolls onto her back with her tail tucked between her legs and her eyes
averted.
9. __________________ You sleep at night and go to school during the day.
10. __________________ When the days become shorter in autumn, a woodchuck enters
its den for the winter.
Name the type of learned behavior.
11. __________________ You stay with relatives who have a clock that chimes every hour.
The first two nights, the chimes keep you awake, but after that you no longer notice
them.
12. __________________ A boy receives a day-old duckling as a gift. It soon follows the
boy wherever he goes.
13. __________________ A young woman takes up archery. At first, her arrows don’t hit
the target, but after a week of practice, she is hitting the bull’s eye 50% of the time.
14. __________________ Your cat comes running to the kitchen when she hears the
sound of the can opener.
15. Suppose a dog becomes frightened every time he rides in a car. How might you train the
dog not to be afraid?
Thinking Critically
After their chicks hatch, black-headed gulls carry the eggshells away from the nest. The animal
behaviorist, Niko Tinbergen, hypothesized that this behavior makes it less likely that crow
predators will discover the nest and eat the chicks. He carried out an experiment to test this
hypothesis. Results are shown in the following table:
16. How do the results support the hypothesis?
17. Some eggs were still taken by crows even when the eggshells were 200 cm from the eggs.
Hypothesize what this shows.
18. Do you think the gulls’ behavior is instinctive or learned? Give reasons for your choice.
Is Migration Learned or Inherited?
Many birds migrate to warmer climates during the winter, sometimes to avoid excessive cold, but largely to find
food. Migration is an adaptation that increases their chances of survival.
Starting in the 1960’s, an unusual behavior pattern occurred in some German and Austrian blackcap birds. Instead
of following their normal migratory routesouth to the warm climate of the Mediterranean, about 10% of the birds
headed north to England. Researchers wanted to know if this new migratory behavior was learned or inherited.
They devised the following experiment.
In England, the researchers collected a sample of birds that had flown north for the winter. For the experiment,
these birds were taken to Germany, and were bred to produce about 40 young birds. A second, separate group of
offspring was bred from birds caught in Germany. Thus, none of the offspring in either group had ever been out of
Germany and were subject to the same environmental factors. The birds’ preferred migratory path was tested by
putting them in cups lined with typewriter correction paper. As the birds tried to take off, their feet scratched out
their preferred direction. Researchers observed that the offspring of birds that had wintered in England made
tracks in a northwesterly direction towards England. The offspring of birds that had been caught in Germany made
tracks in the standard southwesterly direction.
19. Why did researchers use offspring of the birds in each group rather than the birds they had
collected?
20. What would you conclude about the northern migration behavior?
21. Hypothesize why the first few blackcaps went to England.
22. Predict what you think would happen if the offspring of the 2 experimental groups were
allowed to interbreed. Where do you think the next generation of birds would migrate?
Applying Scientific Methods
An animal’s behavior is thought to have adaptive value. One such behavior is exhibited by the Thompson’s gazelle.
In the presence of a predator, the gazelle jumps about a half meter off the ground with all 4 legs held straight and
stiff and with the white rump patch clearly visible. This behavior is called stotting.
One behaviorist, Timothy M. Caro, devised 11 hypotheses that might explain stotting in gazelles. Here are a few of
them.
A. Stotting warns other gazelles, particularly offspring, that a predator is near.
B.
Stotting signals other gazelles to flee as a group, lessening the predator’s chances of isolating a victim
from the herd.
C.
Stotting confuses the predator, keeping it from focusing on one animal.
D. Stotting communicates to the predator that it has been seen by the gazelle.
23. Which of these 4 hypotheses do you think is most plausible? Give reasons for your choice.
Caro then set about eliminating some of the hypotheses. First, he made predictions about how the gazelles would
behave if a certain hypothesis were correct. In the table below, write Yes or No in each empty box after you
consider each of the hypotheses and how it would affect the gazelles’ behavior.
Caro continued his investigation to try to eliminate some of the hypotheses. He discovered that a solitary gazelle
sometimes stotts when a cheetah approaches.
24. Which hypotheses does this eliminate? Why?
Caro found that all stotting gazelles turn their rumps toward the predator.
25. Which hypotheses does this eliminate?
26. Explain which hypothesis now appears to be the most plausible.
27. How would this benefit the gazelle?