1. true
2. false

Actually, gluten-free foods often contain a lot of sugar and few nutrients.

1. true
2. false

Actually, you lose just as much heat per square inch through your head as you do through the rest of your body.

1. true
2. false

Intelligence is unrelated to the relative size of a person's brain.

1. true
2. false

The fossil record shows a gap of about 65 million years between the last non-dinosaurs and the <i>Homo</i> genus to which humans belong. Avian dinosaurs (aka birds) and humans live alongside one another.

1. yes, often
   no
2. rarely

Lightning often repeatedly strikes the same high trees or buildings, sometimes in the course of a single storm.

1. yes
2. no

From at least the 6th century BCE, mathematicians such as Pythagoras in Greece had determined that the world was round. Educated people in Columbus' own time were aware that the world was round. Proving that the world was round was definitely not one of the purposes of Columbus' voyages.

1. red
   blue
2. green

Just as outside your body, your blood is red inside it too. The veins look blue because subcutaneous fat allows only blue light to penetrate skin as far as the veins.

1. yes
   no
2. depends on the human

Humans and modern apes both evolved from a common ancestor, but people did not evolve from the ape species we have today.

1. no
2. yes

Despite the common belief that brain cells are irreplaceable, a 1999 study showed that the brain actually can create new cells.

1. A hypothesis is a random guess. A theory is an educated guess.
2. A hypothesis is a potential explanation for how something works. A theory is already well-supported by evidence.

Hypotheses are testable statements that offer a potential answer to a question, and they can be examined through the scientific method. Theories have been tested, and can incorporate hypotheses that have been proven to be true.

1. true
2. false

In science, an experimental error isn't necessarily synonymous with a mistake. For example, the term could refer to a statistical or systematic error. If that's the case, scientists can account for the error when they write up the results.

1. yes, always
2. not usually

According to NASA's Website, other man-made objects such city lights often are visible from space, but the Great Wall usually isn't.

1. He or she would die instantly.
   He or she would feel a sting from the impact but would live.
2. Nothing. The penny would burn up on the way down.

A penny would not seriously injure a person on the ground, due to its small mass and inability to pick up great speed, but it would hurt to be hit by one.

1. false
2. true

Actually, at 250 miles above Earth, gravity is only reduced by 10 percent. When astronauts appear to float in orbit, they're actually falling, but they're moving too fast sideways to land.

1. It grows back thicker.
   It grows back faster.
2. It’s the same as it was before.

Studies show that shaving or cutting hair doesn't affect either its thickness or its rate of growth.

1. Open the windows to reduce the air pressure.
   Keep the windows closed.
2. Open windows only on one side of the house.

In a tornado, opening the windows actually makes the inside of the house more vulnerable to the wind's force. So keep them closed and run for cover.

1. yes
   no
2. It was one of several factors.

There is evidence that climate change helped to cause the decline of Maya civilization, but it wasn't the only factor. Overpopulation and constant warfare played their parts, too.

1. There is one universe, but life exists on many planets.
   There are parallel universes.
2. An entire world exists underground that no one has discovered yet.

The Many Worlds Interpretation, a hypothesis developed by theoretical physicist Hugh Everett in the 1950s, offers the idea of multiple universes to reconcile conflicts between quantum physics and observable phenomena.

1. true
2. false

Burning fossil fuels puts more carbon in the atmosphere, but the total amount on Earth remains the same.

1. It gradually dissolves.
   It forms a giant soup of floating garbage.
2. It melts.

Plastic refuse becomes part of giant floating garbage "gyres" in the ocean.

1. faster
   slower
2. same speed

The Earth's spin is fastest at the equator, so you move with it fastest there.

1. The shape and design of the toilet.
2. The spinning of the Earth.

The Earth's spin influences the directions of things like huge weather systems. But when it comes to something as little as a toilet, the toilet itself gets the credit.

1. They're dying.
   They're far away.
2. Their light is traveling through turbulence.

As light from a star moves through the Earth's atmosphere, it travels through turbulence. We interpret this as twinkling.

1. Virtually all of it
   10 percent
2. 25 percent

Humans use virtually every part of their brain, and most of it is continually active.

1. gray
   pink
2. multiple colors

While people often refer to our brains as "gray matter," there actually are gray, white, black and red areas and structures in the brain, at least while a person is alive.

1. North Star
   Orion
2. Sirius

People think it's Polaris (the North Star), but Sirius (the Dog Star) actually is the brightest.

1. the Earth's tilt
   the Earth's distance from the Sun
2. the Earth's rotation

The earth's axial tilt causes the change of seasons.

1. true
2. false

That's what the word "theory" might mean to a layperson. But to scientists, a theory generally is an explanation for something that's backed by evidence and can be used to make accurate predictions. For instance, the theory of gravity.

1. Coal
   Emeralds
2. Graphite

Diamonds form deep in the Earth from a pure form of carbon called graphite.

1. It's expanding.
   It's decreasing.
2. It is staying the same.

The Antarctic ice cover is 18 percent thinner than it was in the 1990s.

1. true
2. false

The far side of the Moon actually receives as much light as the part we can see.

1. not if it has a high sugar or salt content
   yes, always
2. not if you pick it up in less than five seconds

A 2012 British study revealed that little or no bacteria survived on the surfaces of foods with a high sugar or salt content when they were dropped on the floor.

1. true
2. false

There is no proven link between vaccines and autism. A 1990s study published in the British medical journal The Lancet, which purported to show such a link, was later found to be false and deceptive, and it was retracted by the publication.

1. true
2. false

Although there are some connections between the hole in the ozone and global warming, these are two completely different things ... and neither of them is the primary cause of the other.

1. plutonium
   helium
2. strontium

In nuclear fusion, four hydrogen atoms combine to form helium.