Module 4 Chapter 31 Multiple choice questions 31.3

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. Within the Ongeim'l Tketau lake in Palau, Mastigias jellyfish medusae undergo a complex series of daily migrations. The lake is surrounded by tall trees, which cast a shadow at the eastern end of the lake in the morning and at the western end in the afternoon. The jellyfish move 350 m west to east, then back again between sunrise and sunset, and obtain most of their energy from symbiotic zooxanthellae algae contained within them. The main predator of the jellyfish is the anemone Entacmaea medusivora, which occupies only the shaded edge of the lake. Using the information provided, what is the most reliable interpretation of the jellyfish's behaviour?

The jellyfish swim towards areas with maximum light to gain optimum advantage for their symbiotic photosynthetic algae. correct incorrect

The jellyfish swim towards areas with maximum light but stop before the shadows to avoid predators at the edge of the lake. correct incorrect

The jellyfish avoid the edge of the lake because shallower water has higher concentrations of toxic hydrogen sulphide there. correct incorrect

The jellyfish prefer the centre of the edge of the lake because the water has higher concentrations of oxygen there. correct incorrect

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. The mass migration of monarch butterflies (Danaus plexippus) from their feeding grounds (in southern Canada) to their overwintering sites (in Mexico) is about 5000 km. This migration is accomplished in a series of 2–3 generations. If each butterfly can travel 40 km per day and has a lifespan of 6 weeks, how far can it migrate before it dies?

42 km correct incorrect

240 km correct incorrect

1440 km correct incorrect

1680 km correct incorrect

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