How is sunlight  both harmful and beneficial?
351777
Sunlight helps to to metabolize vitamin D, warms the planet to a pleasant temperature conducive to life, and provides a direct energy source for solar power, and is a great source of energy for chloroplasts, which happen to be how plants excrete oxygen that we breathe.  Basically, we would be dead without the sun.\n\nSunlight also has ultraviolet light and various other radiations, most of which are currently blocked by our ozone layer.  Sticking with ultraviolet light, sunlight can damage the skin, leading to skin cancer.  Too much exposure can result in dehydration and death.  Increased amounts of ultraviolet light may also interrupt the chloroplast processes in plants, such that too much will cause plants to die instead of producing oxygen.
207951
Plants can sustain photosynthesis (and release oxygen) from any lightsource that has enough energy. But plants can also get stressed by too much light and actually get sick. They might also grow in unnatural ways, like growing sprouts all over, if "fed" the wrong amount of light for too long periods of time. \n\nPlants are tuned to natural light during ordinary hours but some plants can even "OD" on sunlight. When the sun shines too hot during a hot day they sometimes shutdown photosynthesis and begin to perspire. \n\nIt all comes down to what kind of plant it is. An ordinary house plant should release oxygen if the artificial light is not too intensive.
345649
You need to be under a doctors care and by all means stay out of bright light--long sleeves, a hat etc---bright flourescent lighting is also bad for you.  There are many methods of treatment -- you can check it out on line in the medical areas.
1161684
Well, it depends on which organisms you are looking at. First of all, light/the sun is absolutely essential for all life on the planet, as the sun provides the energy for photosynthesis to take place, which allows the production of glucose. This glucose is then transmitted to consumers who eat the plants.\n\nin terms of humans, light/sunlight is actually pretty essential for the production of vitamin D, because radiation from the sun actually causes skin cells to produce Vitamin D. A deficiency in this vitamin can cause rickets or osteoporosis. So, basically sunlight is important for humans for normal bone growth. Also, the light also affects how light/dark one is, because of tanning. Tanning/darkening of the skin occurs when the body creates more melanin to protect the body.
452427
solar radiation - UV rays are damaging to the DNA of skin cells and can result in cancer
164339
The sun tends to lighten all pigments.  That's why it makes hair lighter (as well as construction paper, stuffed animals, and most other things you leave in direct sun light).  It's a chemistry thing that I sort of vaguely understand, but I'm not going to try to explain it.\n\nHowever, the UV radiation stimulates the cells in your skin to release extra pigment to protect your skin from the harmful effects of the radiation (sunburn, DNA damage, etc.).  The extra pigment makes your skin darker.  This part I could explain in a lot more detail if you want to hear it :-P
1183093
sun bathing is radiation. sun radiation travel through space(no air in space so it is pure radiation energy transfer), travel through air (in there also radiation is dominant ) then get in to your skin\n\nstroform is a good insulater. it has hollo set of chambers. in chambers covection can be done but cells prevent transfer of air further and convection is stoped. in the other hand conduction is prevented due to poor conductivity of material. radiation is not a problem when heat difference is not too much high and because radiation generated from a object is is propotional to absolute heat  of the object. in case of very high temperature allumenium foil is used to limit radiation.
602571
The sun is not the source of ALL the energy - just almost all of it.  \n\nLight is a form of energy, most of our light is from the sun but we do recieve a tiny fraction of light from the other stars in the sky - that is why we can see them.\n\nBut the sun does supply almost all the energy.\nThe sun radiates light and other forms of energy which hits the earth and some is absorbed (some is also reflected).  Much of the absorbed light becomes heat - this is why it is hotter in the sunshine than the shade.\nSunlight also allows plants to obtain energy by a process called photosynthasis which happens in leaves and green stalks (like on a cactus).  It is this energy from sunlight which allows plants to grow.  All living things use this energy from plants via the food chain.\nFuels (like coal and oil) come from the remains of plants and animals and thus the energy was originally from the sun.\n\nThere are sources of energy which don't come from the sun such as geothermal power (this is heat from the centre of the earth which is created by pressure) and there are even organisms which live deep in the ocean which do not need any sunlight to survive (they are chemotrophic bacteria which survive around active volcanic vents in the sea floor).  \nBut to all intents and purposes a good 99% of all the energy comes from the sun.\n\nI hope this helps you with your homework!
896536
Plants must have light to grow.  It doesn't necessarily have to be sunlight. Artificial light is a great to grow most plants too.  Photosynthesis is what causes plants to exchange necessary nutrients to create growth but each have unique abilities to utilize whatever light source is available.
240281
The electromagnetic spectrum is just a classification of the various types of light. So you are asking whether the sun uses light? Well, it certainly *emits* a lot of light and there is a lot of electromagnetic radiation (i.e. light) inside the sun, but past that, it's not clear what you want.
406219
its mostly in the way you perceive that day but at the same time sunlight exposure increases seratonin production in the brain thereby putting you in a better mood.
363967
No reason you shouldn't. Sunlight helps activate Vit. D. The only reason you would is if you are taking some medication that can cause problems when you expose yourself to UV waves. There are to many for me to mention here. If you have a list though I would be glad to tell you.
851726
Sunlight is necessary for plants to grow, and to provide energy to warm the earth's atmosphere. Light intensity controls plant growth. Light duration affects plant flowering and animal/insect habits.\n\nNow, during photosynthesis, sunlight energy is used to power chemical reactions that combine water with the air's carbon dioxide to form starchy carbohydrate. In other words, during photosynthesis, sunlight energy is stored in carbohydrate for later use. Here's the simplified chemical formula for photosynthesis:\n\n6CO2 + 12H2O + sunlight ---> 6O 2 + C6 H12O 6 + 6H2 O\nor...\ncarbon dioxide + water + sunlight ---> \noxygen + carbohydrate + water \n \n\nSome carbohydrate remains in the leaf but mostly it's transported elsewhere in the plant, perhaps into the stem, or maybe into special underground storage areas, such as the potato plant's potatoes.
1099466
According to Reuters Health article \n\n" a Little Bit of Sun May be a Good Thing: Experts" by Anne Harding, researchers spoke at the annual meeting of the American Association of the Advancement of Science, on the positive effects of solar radiation on the human body. Dr. Michael Holick of Boston University School of Medicine noted that vitamin D helps keep bones strong, and helps control cell growth. \n\nBut don't overdo it. Too much sun without protection can damage your skin. No need to spend hours and hours at the beach. But do make sure to spend some time, every season, in the sun to keep your body strong and healthy. And getting some sun is another reason to lace up those running shoes, get out the door, and go for a run.\n\nMelanoma skin cancer is caused by too much sun exposure but keep in mind everyone's skin is different and offers different levels of protection due to their amout of pigment in their skin. Black people can stay in the sun much longer than white people due their high amount of pigment in their skin. Black people do still burn and do still get skin cancer however, just that their at a lower risk of it. Bottom line here is to get some sun regularly and then cover up! I am not positive that sunblock stops the production of Vitamin D so you might want to ask that question. Good luck!
272099
Sun is the source for light and light is needed and is used by plants for photosynthesis. by photosynthesis plans prepare their own food which helps them to grow and we humans eat plants as well as animals so if we have light then everything is possible....
557230
to maximize surface area for the collection of sunlight and minimize weight and material used. also, yes it helps transport water and nutrients.
805678
Depends on the bacteria.  Light can damage cells.  UV light is used to kill bacteria, and a single cell has very little defense to the sun's light, oppose to multicellular creatures.  On the otherhand there is more food in the light.  Especially for cyanobacter, who needs light to survive.  My guess is that there is a lot more bacteria in the dark, because their are alot more dark places.