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Scientists studying fossils in an ancient lake bed have an almost perfect fossil record ranging more than 5000 years - VCE - SSCE Biology - Question 10 - 2015 - Paper 1
Question 10
Scientists studying fossils in an ancient lake bed have an almost perfect fossil record ranging more than 5000 years. In this fossil record, there are two forms of a... show full transcript
Worked Solution & Example Answer:Scientists studying fossils in an ancient lake bed have an almost perfect fossil record ranging more than 5000 years - VCE - SSCE Biology - Question 10 - 2015 - Paper 1
Step 1
10a. Explain how the fossils in different sediment layers provide evidence for the changing environment.
Answer
The characteristics of the fish fossils collected from various sediment layers offer insight into the evolutionary changes in fish forms corresponding to the lake's environmental conditions. The fossils in the lowest layer show characteristics resembling those found in freshwater today. This suggests that at that time, the lake was likely freshwater. The top layer, containing the youngest fossils, indicates a shift towards salinity, representing a transition back to freshwater conditions in the lake.
Step 2
10b. Describe how the stickleback fish with smaller pelvices are better adapted to their environment.
Answer
The stickleback fish with smaller pelvices and no spines exhibit greater agility and speed, allowing them to evade predators effectively. These adaptations enhance their survival as young fish, enabling them to reproduce more successfully, thus leading to the proliferation of offspring with similar advantageous traits.