V-shaped valley
As the river erodes downwards the sides of the valley are exposed to freeze-thaw weathering which loosens the rocks (some of which will fall into the river) and steepens the valley sides. The rocks which have fallen into the river help the process of corrasion and this leads to further erosion.
DNA is the molecule that contains the genetic information that is transmitted hereditary and controls the cellular functioning
My answer: Because the actual thing you might be modelling might be too small or large to replicate, (for example you cannot draw a plant cell TO SCALE because it’s way too small to see with a bare eye).
And if the item is too big, you won’t be able to fit it in a small space; if you were to draw it or create it in 3D.
I hope this helps!
Sorry if the response is too short, try rewording if you need to :)
Anxiety, overexcitement, inability to focus, poor coordination, and shaking are common side effects of substance abuse. The class of drugs includes cocaine, nicotine, ecstasy, and amphetamines.However, any drug when used that can cause euphoria or feeling “high” can become a drug of abuse.