1)magnification goes by 10x (read 10 times), 100x,1000x and some goes 10,000x
2)Always focus first using lowest power possible first, switch to medium power (100x) after it's focused on low power(10x), on 100x, use the small knob to focus it more. DO NOT touch the bigger nob when in medium or high power. Switch to high power (100x) when it is focused on medium power, again focus again using the small knob on high power.
3) So it doesn't gather dust and fog up the lense? that one should be self explanatory
A dichotomous key helps you identify unknown specimens based on their traits because there are only two options available per trait. Selecting one from the two options (usually contrasting characteristics) from each step leads to smaller and smaller groups until the option is reduced to single and unique trait of an organism.
Considering you need to identify an organism. So, on the top of they key is animal with options: (a) with red blood cells and (b) no red blood cells. The option you will select is no red blood cells and under option b, you’re given two choices again: (a) hard bodies and (b) soft bodies. You’ll select soft bodies, then two options again are given: (a) with shell and (b) without shell. The option you’ll select would be without shell, and so on.
Keratinized, <span>stratified columnar, </span>