Question at position 14 Why does wearing sunscreen reduce cancer risk? It doesn't; sunscreen causes mutation and actually increases cancer risk.Sunscreen can reduce the chance of mutations caused by exposure to UV radiation present in sunlight.Sunscreen can repair damaged DNA.Sunscreen can activate checkpoints in skin cells.Sunscreen can prevent cells with mutations from being destroyed.Clear my selection

Question

BlackTom AI · Accepted Answer

Sunscreen absorbs and/or reflects ultraviolet (UV) radiation, reducing the number of UV photons that reach skin cell DNA and thereby lowering the probability that UV-induced mutations will occur.

1) Relevant knowledge points and concepts
- UV radiation (UVB and UVA) from sunlight can directly damage DNA (UVB causes cyclobutane pyrimidine dimers and 6-4 photoproducts) and indirectly cause oxidative damage (primarily UVA), both of which can introduce mutations.
- Accumulated mutations in proto-oncogenes or tumor suppressor genes can initiate skin cancers (basal cell carcinoma, squamous cell carcinoma, melanoma).
- Sunscreens contain chemical absorbers or physical blockers (e.g., zinc oxide, titanium dioxide) that prevent many UV photons from reaching the epidermis.
- DNA repair pathways and cellular checkpoints exist but are not activated or created by sunscreen; sunscreen’s role is preventive.

2) Step-by-step reasoning
- Step 1: Sunlight contains UV photons that reach skin. 
- Step 2: UV photons are absorbed by DNA bases, forming lesions (e.g., CPDs). 
- Step 3: If lesions are misrepaired or bypassed during replication, permanent mutations result. 
- Step 4: Repeated mutations increase cancer risk. 
- Step 5: Applying sunscreen lowers the flux of UV photons hitting skin cells, so fewer DNA lesions form, reducing the chance of mutation and lowering cancer risk.

3) Calculations/intermediate steps
- No numeric calculation is required here; the logical intermediate steps are the chain from reduced photon exposure → fewer DNA lesions → fewer mutations → lower cancer risk.

4) Why the correct answer is correct
- The correct option states that sunscreen reduces the chance of mutations caused by UV radiation. Because sunscreen blocks or absorbs UV, it prevents the initial DNA damage that leads to mutation-driven carcinogenesis, so it reduces cancer risk.

5) Why other options are incorrect
- "It doesn't; sunscreen causes mutation..." is false: sunscreens reduce UV exposure and thus reduce mutation risk; properly formulated sunscreens do not cause mutations.
- "Sunscreen can repair damaged DNA." Sunscreen is not a repair mechanism; cellular enzymes do that.
- "Sunscreen can activate checkpoints in skin cells." Checkpoints are cellular responses; sunscreen does not activate them.
- "Sunscreen can prevent cells with mutations from being destroyed." That would be harmful; sunscreen does not prevent apoptosis or immune clearance of mutated cells.

6) Conclusion
The correct answer is: "Sunscreen can reduce the chance of mutations caused by exposure to UV radiation present in sunlight." This explanation confirms and supports the provided answer.

类似问题

Which of the following serve to increase the surface area of a cell for absorption and/or secretion?

Question at position 1 The fluid part of the cell is calledCytoskeletonCytosolCytoplasm

Question at position 12 The cells of the epidermis that produce pigment to help protect deeper cells and tissues from UV light areMerkel cellskeratinocytesLangerhans cellsmelanocytesClear my selection

A human body is composed of trillions of , of which there are about 200 different types with varying functions that help to carry out life processes.

Question at position 2 What is the smallest unit that can carry out the processes of life?CellsOrgansMoleculesAtomsClear my selection

Question at position 1 All of the different cell types within a person's body have different genes.are genetically identical.perform all of the same functions.have exactly the same cell structure.Clear my selection

Choose an option that correctly completes the statement below. Membrane extensions containing microfilaments that increase surface area to facilitate absorption are called __________.

Which of the following terms means pertaining to within the cell?

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单