No. Most don't. But a neutron star that continues to accumulate mass can. For example if 2 neutron stars collide they can form a black hole. We detected one of these mergers on August 17, 2017.

One that doesn't accumulate mass will, in theory, slowly lose mass until it explodes into a white dwarf in about 10^(38) years (if proton decay is real). Since the universe is much younger than that, this hasn't happened yet.

It does.

But mane-made light is more effective because it is more powerful. Our atmosphere blocks a lot of the sun's UV rays. Also organisms evolved with sunlight, so they have developed mechanisms to resist and repair the damage.

But enough sunlight will kill most microorganisms.

However, your skin has pores. Sidewalks have micro-fissures. There are places where microorganisms can hide from direct sunlight.

So the sun will deplete their numbers, but won't eradicate them.

Assuming that the planet is bigger than the moon, then the planet would have a much larger impact on the moon than the moon would have on the planet.

Look at the moons of Jupiter and Saturn. They are squeezed and compressed by the planet's gravity, which causes volcanism. Io is the extreme example, as it is closest to Jupiter. But Ganymede has a liquid ocean under it's ice largely because the gravity of the nearby planet is squeezing it and the friction is warming up the interior.

Also tidal locking is a thing. That's good for your story. A moon that is tidally locked to it's planet (like ours is) will always face the planet. From our perspective the moon doesn't rotate, it's always showing us the same face. That's why the moon has a dark side. Not because it's literally dark, but because before we invented spacecraft no one had ever seen it, it was unknown.

So your theoretical moon would have the city always facing the planet, to remind the planet's inhabitants of what happened (although it would likely be much to far away to make out the city). It could also be a sulphurous volcanic wasteland, much like the surface of Io due to tidal effects.

As for the moon's effect on the planet, that depends on the size of the moon and how close it is to the planet. Too close and too large and tidal effect will break the moon apart. You seem to have settled on a small, close moon which likely would have very little effect on the larger planet. As an example the 2 small moons of Mars have almost no effect on the planet at all.

Our moon causes ocean tides on Earth. It may also have an effect on plate tectonics, not so much with moving them, but may be at least part of what's keeping them apart and not allowing them to bind together (The jury is still out on that one, the oceans being subducted and releasing water seems to play a much larger role). On the other hand, the Earth caused the moon to become tidally locked and also causes a regular pattern of moonquakes.

You aren't talking about the Mormons, are you?

She doesn't pee. Apparently her kidneys shut down and other processes are used to remove toxins from the blood without wasting water.

She doesn't sweat.

The only water she loses is from respiration. This quickly forms ice on the surface of her den, which solidifies and creates a physical barrier that hinders further moisture from leaving.

She's using her fat reserves, she'll emerge having lost 30% of her weight. Part of the biological process of breaking down fat into energy releases water. For instance, the equation for breaking down triglycerides is:

C^(55)H^(104)O^(6) + 78 O^(2) --> 55 CO^(2) + 52 H^(2)O + energy

Only the pregnant female polar bears dens. Technically they don't hibernate, as their body temp does not fall and her heart rate does not drop. But she will stay in the den from around October until around May, not eating and not leaving, while she gives birth to her cubs and feeds them for the first few months.

Largely, they hibernate in dens that they dig themselves. They'll use a ready-made cave and save themselves the digging, but typically they dig one themselves. They may return to the same den year after year.

Polar bears can't dig into the ground because of permafrost, so they dig into a snow mound and den in there.

Just do an image search of "bear den" and you'll see loads of pictures.

Humans? No. For ethical reasons there probably never will be.

But they have done it with other things such as bacteria. They've even created an entirely new organism by creating DNA from scratch with just a few genes and inserting it into a bacterial cell that had it's DNA removed.

It's actually crazy how much viral DNA has been absorbed by the human genome. Roughly 4% of our genes actually code for something, so 4% of our entire genome is what's necessary to make a human being.

8% of our genome comes from viruses. That's double what it takes to make a person. And since it takes a lot less DNA to make a virus than it does to make a human, that's a whole lot of viral DNA.

None of it codes to make a virus anymore, that replication feature has been deactivated. A lot of it is just "junk DNA" that doesn't do anything. But some of it is necessary for human survival.

As an example, we are mammals only because of viral DNA. An early proto-mammal absorbed some DNA from a virus. That virus originally caused nearby cells to fuse together to create a wall around itself which blocked the white blood cells from finding it. That virus no longer exists, but it's DNA got absorbed into the germ cell DNA of it's host and passed along to it's offspring. 200 million years later that DNA is used to create the placenta, which is a fused cell wall that allows nutrients to pass from the mother's blood to the childs, but blocks the mothers immune system from finding and attacking the child. It's what all mammals use to feed and protect their fetuses. It's what allows live birth to happen. So the only reason why humans don't lay eggs is because we absorbed some viral DNA.

The universe is mostly not matter. It's about 63% dark energy. What little matter there is is mostly dark matter. Only about 20% of all matter is not dark matter.

Of that 20% of matter that's not dark matter, it's mostly Hydrogen. Hydrogen makes up about 80% of all non-dark matter in the universe. The remaining 20% is mostly Helium, which makes up about 19.8% of that 20%.

So that means that everything else, all carbon, all iron, all oxygen, and nitrogen, everything that we are made of and everything that out planet is made of (excepting the hydrogen in things like water) is made of a vanishingly small and rare subset of what's available in the universe.

95% of the universe is dark matter and dark energy. Of the 5% that's left 4% is hydrogen, and Helium takes up most of the remaining 1%. We and our entire planet (excepting the Hydrogen bound up in water and other minerals) are made of less than 0.001% of the universe.

The Calcium in your bones, the Iron in your blood, the Carbon in your food, the Oxygen that you breath, even the ground that you walk upon, all of it is so rare as to be almost impossible.

And coyotes only came over in the 1980's, so they didn't affect the founder population at all.

There were no predators on the island for the moose (outside of the brown black bear, which isn't particularly good at taking down a moose). That helped them to quickly reproduce and spread.

The annual quota for moose hunting in Newfoundland is 27,667 animals, and that quote is about 60% met, which means 16-17 thousand are removed every year. Of note they weren't hunted at all (legally) before 1930.

By talking to plants you're exhaling Carbon Dioxide from your breath onto their leaves, which can help them grow.

The jury is still out on whether music does anything to plants. Some studies show effects on certain species, other studies show no or negligible effect. No one has yet proposed a mechanism where plants, which don't have ears or a nervous system, but may be able to sense pressure changes, could be affected by noise.