1. constant speed is a steady speed from start to finish, instantaneous is not constant from start to finish.
2. The average speed of the marble is 5 m/s (meters per second).
3. Rider 1 will arrive at the destination before Rider 2.
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Answer:
Nyctophobia
Explanation:
Nyctophobia is known as the fear of darkness
Ans.
Cell-to-cell communication allows signalling of essential substances between the plant cells, which are surrounded by cell walls. The molecules used by plants for long-distance signalling are known as hormones, such as auxin, ethylene, and gibberelin.
These hormones are secreted by one plant cell and received by another plant cell, where it exerts it affect. Thus, the correct answer to be fill in the blank is 'option A). hormones.'
B and C are correct - A is incorrect as natural selection affects any generation of species. D is also incorrect as any species population change in an ecosystem inevitably affects another, even if it isn't a predator-prey relationship.
