Correct the answer **Question:**Which of the following apply to the control of bacterial growth using ultra-violet (UV) light:1. ○ Formation of purine dimers between adjacent nucleotides on an individual strand of chromosomal DNA2. ○ None of the answers apply3. ○ Formation of pyrimidine dimers between adjacent nucleotides on an individual strand of chromosomal DNA4. ● Formation of pyrimidine dimers between opposing nucleotides between two strands of chromosomal DNA5. ○ Formation of purine dimers between opposing nucleotides between two strands of chromosomal DNA**Explanation:**The question explores how UV light affects bacterial DNA, specifically through the formation of dimers. Corrective mechanisms may be disrupted when dimers, such as pyrimidine dimers, form between DNA strands, leading to control of bacterial growth. **Question:** All of the following are bacteria that cause infectious gastroenteritis as whole agent **EXCEPT:**- ☑️ All of the above apply, no exception- ⬜ E. coli O157:H7- ⬜ Shigella dysenteriae- ⬜ Campylobacter jejuni- ⬜ Salmonella typhimurium- ⬜ Staphylococcus aureus**Explanation:** This question is a multiple-choice format assessing knowledge about bacterial agents responsible for infectious gastroenteritis. The correct answer indicates that all listed bacteria are known to cause this condition, with no exceptions.

(Note: According to given guidelines, we are supposed to answer only one question. Please repost other questions as separate question) UV light is one of the agents that controls the growth of bacteria. This radiation causes inhibition of cell growth and result in gene damage due to the mutation it cause to the genetic material. Hence UV act by damaging DNA of microbes reducing their ability to multiply. Ultra-violet radiation (UV) is a physical mutagen which causes the formation of pyrimidine dimers between adjacent nucleotides on an individual strand of chromosomal DNA. UV radiation at 260 nm causes dimerization of adjacent pyrimidine bases especially thymine bases on same strand. In the presence of UV, two pyrimidines form a four membered cyclobutane ring resulting from the formation of 5, 6 double bonds. The overall structure produced is called cyclobutyl dimer. UV induced mutation usually result in deletion mutation when the mutated strand is replicated. This result in the control of bacterial growth due to disruption of essential genes which may be required in bacterial survival. Hence correct answer is: Formation of pyrimidine dimers between adjacent nucleotides on an individual strand of chromosomal DNA. Other options are incorrect because: 1. UV does not result in purine dimers. It result in pyrimidine dimers. 2. UV results in the formation of pyrimidine dimers between the adjacent bases of same strand and not between the opposing bases of two different strands. Correct answer: Formation of pyrimidine dimers between adjacent nucleotides on an individual strand of chromosomal DNA.