Question

Lab Exercise - Ultraviolet Light-Lethal Effects Please review the below videos as well as read introduction, materials, methods & procedures in the lab manuals and answer the following questions. https://www.youtube.com/watch?v=z4arnMlhbpE&app=desktop https://www.youtube.com/watch?v=OMN9ZGSHZW 1) Why was half of each plate covered with an index card? 2) Suppose you've tested the effect of UV radiation on bacterial growth for E. coli vs. S. aureus plates. How did the growth on E. Coli plates differ from the growth on the S. aureus plates that were exposed to UV light for the same amount of time? Explain. 3) Describe the damaging effects of UV radiation on living cells. 4) What types of damage to human tissues can result from prolonged exposures to UV radiation? What protective measures can be taken to limit these types of damage, both during the experiment and in everyday life?

Answer 1

Answer

Q1

The half portion of dish was covered to prevent exposure to UV Ray's. To keep that half as a control.

Q3

UV Ray's damage living cells by damaging DNA. UV causes formation of thiamine dimmers. This diners are very stable and resistant to repair. At last accumulation of such dna errors culminate in mutation or cell death. UV Ray's can cause skin cancers, sun burns etc.

Q4

Prolonged exposure to UV rays can cause skin cancer. Sun burn, heat stroke etc can also result.

Also UV can damage retina and thus affect vision.

Protective clothing, sunscreens with more than 15, using umbrellas, reforestation etc can help prevent exposure. Sun glasses can prevent uv damage to eyes.

Q2

Ecoli has got a capsule.

Ecoli is gram negative and staph aureus is gram positive.

S.aureus has got no cell wall.

Even MRSA can be killed by uv.