D. Cholinergic antagonists
No reaction would occur. because in PCR ,dNTP is crucial factor for polymerisation of primer . DAN polymerase bind to primer and template
Because you will focus past ("overshoot") your specimen. (Like using a race car as a shopping cart: it's too fast, and you'll fly past the cereal and never even see it before you realize you need to stop.) Also: you risk crushing the slide and objective against each other (on older or cheaper scopes), and that would be a costly (and embarrassing) mistake.
I think it's the nucleus. Isn't the nucleus the brain of the cell?