Answer:
D
Explanation:
Fossils tell us where they came from.
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These changes can be natural, such as through variations in the solar cycle.
<h3>Climate history</h3>
Clam shells
2. 800,000 years ago
Ice cores
1. 150 million years ago
Oldest rocks in the world
5. 3.8 billion years ago
Tree cores
3. 10,000 years ago
Ocean sediments
4. 200 million years ago
With this information we can conclude that these changes may be natural, such as through variations in the solar cycle. But since 1800, human activities have been the main driver of climate change, mainly due to the burning of fossil fuels like coal, oil and gas.
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Answer:
A. Molecular changes such as extracellular signals on extracellular ligands can result in quick changes in cell behaviour. One example is insulin. Upon insulin binding on the receptor on the cell membrane, the cell release GLUT4 transporters (for muscle cells) to increase uptake of glucose.
B. Slow changes in cell behaviour can be observed for other lipophilic hormones or intracellular receptors such as glucocoortoid or estrogen which reacts with receptors in the cells.
C. Insulin is required to maintain a constant blood glucose level and hence levels of insulin has to be mediated in correspondence to the blood glucose levels. Fast acting signalling is thus required for homeostasis of blood glucose levels. Where for such lipophilic hormones such as steriods, glucocortoid, these hormones tend to have a longer lasting effect and hence results in a slow change.