Answer: Water erosion
A scientist observes the ocean tides moving large amounts of sand away from the beach is a evidence for natural process which is known as water erosion. Water erosion is a process of removal or detachment of upper soil layers from its's original place due to the effect of water. The rate of erosion may be rapid or slow depending upon the soil, the landscape and weather conditions. The beach exhibit sandy soil whose particles are not connected or aggregated with each other and not with the surface over which it is present. Therefore, sand being loose soil is taken away by oceanic tides due to water erosion.
Crossing over happens in Meiosis 1 only. In Prophase 1 a cells chromatin (chromatin = chromosomes that have not condensed yet) condense and pair up forming homologous chromosomes (paired = XX (2 chromosomes together)). When this happens segments/ alleles of the chromosomes pairing up swap over. This creates genetic diversity as each chromosome is different, it has parts from its pair. This leaves every chromosome unique and individual.
I hope this helps, sorry some of the vocab is rather technical. By the way I would suggest watching the
'Crash Course: Meiosis' on YouTube, this really helped me when I was learning this topic. :D
Here where i live the trees are like that it is always raining so your answer would be: Trapical Rain Forest
Coevolution happens when the genetic development between two or more species affects the evolution of each other. An example would be hummingbirds and bird-pollinated (ornithophilous) flowers. The ornithophilous flowers give nourishment to the birds with their nectar that has high sugar content. The birds in return aids in the pollination of these flowers.
Koalas benefit from tress because then can climb on them to keep away from danger such as other ground predators, Trees can also serve as a food source for them to eat in day to day life.