BOT350: Lab Quiz #2
Name: ___________________________
lab:
9:00am
11:00 (rm3077)
11:00 (rm3089)
2:00pm
You are looking to get some lab experience during the summer and have volunteered to
help your TA, Todd, who is working on an unidentified leaf spot of apple.
He is trying to use _______________
_________________ , the 4 step process to prove
that an organism is the cause of a disease. You suspect that the organism causing the
disease might be a fungus, so you look for hyphae and fruiting structures that are the
(signs / symptoms) of the pathogen. You make a wet mount from the diseased tissue, but
you don’t see any evidence of a fungus. Instead, you see ________________________
which suggests that you have bacterium.
Next, you decide to isolate the bacterium in pure culture. Using sterile technique, you
take tissue from the (center / edge) of the lesion, place it in sterile water, macerate the
leaf material, and allow the suspension to settle for 10 minutes. With a sterile bacterial
loop, you streak the suspension out onto a (differential / selective) medium that allows
the leaf spot bacterium to grow with characteristics that distinguish it from other bacteria.
After allowing the suspected pathogen to grow for 2-3 days, you streak the cells from a
single colony onto nutrient agar to get it in pure culture.
Now that you have the bacterium in pure culture, you perform a Gram stain and find that
the bacteria are stained red, indicating that they are (gram negative / gram positive). To
find out more, you take your bacteria to your resident electron-microscopy lab. The
electron-micrograph shows a bacterium with a single ( polar / peritrichous ) flagellum.
Next, to prove that this bacterium is the cause of the leaf spot, you
___????______________ leaves of a healthy apple tree with the bacterium, wait several
days and then examine the leaves for symptoms similar to those on the initial disase
sample.