The main purpose of the Mayo Clinic experiment was a. to reduce the symptoms of HIV in cats b. to make cats immune to FIV c. to make cats glow in the dark
The antiviral gene came from a. monkeys b. jellyfish c. mice
The goal of the “glow” gene was a. to make the experiment more interesting for the researchers b. to attract media attention and raise money for HIV c. to test the results of the antiviral gene
Discussion/essay questions
Weird science experiments often make the news. Have you heard any other stories of strange or unusual experiments?
Transcript
In 2011, scientists at the Mayo Clinic began an experiment. They were trying to use a gene to prevent feline immunodeficiency virus, or FIV, in cats. FIV is genetically similar to HIV in humans. If scientists could use genetic engineering to make cats immune to FIV, they might also be able to reduce human deaths from HIV and AIDS. The scientists modified cat eggs with an antiviral gene from monkeys. They paired this gene with a jellyfish gene that causes bioluminescence, which is a natural ability to glow in the dark. The goal of the “glow” gene was to help the scientists test their results. If the kittens glowed, the scientists would know that the antiviral gene had been activated. The experiment created three glow-in-the-dark cats with cells that showed immunity to FIV. These cats also passed both genes on to their own kittens.
As a teenager, Einstein wondered what would happen if a human could chase a. a beam of light b. a train c. a clock
Einstein’s 1905 theory is called a. general relativity b. special relativity c. universal relativity
The speed of light is a. constant b. variable c. relative
Discussion/essay questions
Most scientists think that time travel to the past is probably not possible. However, time dilation means that time travel to the future would be possible if we could move very fast. What would you do if you could time travel? Do you think it would be more interesting to travel to the past or the future?
Transcript
When Albert Einstein was a teenager, he wondered what would happen if a human could run fast enough to chase a beam of light. This thought experiment led to his 1905 theory of special relativity. Einstein’s theory showed that time was not universal. People could experience time differently if they were moving very fast. This effect is called time dilation. Einstein used a few scientific laws to support his theory. The first was that speed is relative. Two trains travelling at the same speed in the same direction stand still relative to each other. However, experiments before Einstein had already proved that the speed of light is always 300,000 kilometres per second. This is true no matter how fast the observer moves. Even if a person could chase a beam of light, the light would always outrun them by the same speed. Einstein realized that because the speed of light was constant, another variable had to change. This variable was time. Since Einstein published his theory, experiments have shown that clocks run slower at high speeds.
Joseph von Fraunhofer discovered that a. passing light through a prism would create a rainbow b. light could behave as a particle c. there were dark lines in the colour spectrum made by the Sun
Absorption lines happen when a. a cool gas absorbs photons b. a hot gas releases photons c. photons pass through empty space
Scientists can study absorption lines to find out a. the masses of stars b. the distances between stars c. the chemicals present in stars
Discussion/essay questions
Do you know any interesting facts about light? What optical illusions or “tricks of the light” have you seen?
Transcript
In 1814, a German physicist named Joseph von Fraunhofer passed light from the Sun through a prism to create a colour spectrum. He noticed that there were dark lines blocking out certain colours in the spectrum. Today, scientists call these lines absorption lines. Absorption lines happen when particles of light, called photons, move through a cool gas. The atoms and molecules in the gas absorb some of the photons and block certain colours of light. When an atom absorbs a photon, it shows up as a dark line in the colour spectrum. The photons that get absorbed are not random. Every element absorbs specific wavelengths of light, which means every element also has a unique pattern of absorption lines. Scientists can study these lines to find out which chemicals are present in stars and planets.
Tetrachromacy causes people to a. be more sensitive to blue light b. see perfectly in the dark c. distinguish more colours than the average person
Tetrachromacy has only been found in a. women b. young children c. artists
Scientists test for tetrachromacy by a. taking a DNA sample b. observing a person’s reactions to bright light c. asking a person to sort nearly identical colours
Discussion/essay questions
Do you think you see colours the same way as other people? Is this possible for us to know?
Transcript
Tetrachromacy is a rare genetic condition that causes some people to see more colours than usual. Most people have three types of cones in their eyes, which are sensitive to red, green, and blue light. However, tetrachromats have four. This allows them to see millions of colours that the average person can’t distinguish. So far, very few true tetrachromats have been identified, and all of them are female. This is because the gene for an extra cone is found on the X chromosome. If men experience the same mutation, they are likely to become colourblind instead. Scientists test for tetrachromacy by asking people to sort nearly identical colours by similarity. The average person will likely change their answer, but a tetrachromat will always sort these colours the same way.
The camera obscura was a. a device that took photographs on silver sheets b. a low-cost camera that anyone could buy c. a dark room that projected an image through a hole
The first permanent photograph was taken in a. 1800 b. 1826 c. 1900
A daguerreotype was a. a photograph taken using colour film b. a digital photograph stored as a set of numbers c. a photograph taken on a silver sheet
Discussion/essay questions
What are some ways that society has been changed by the ability to take pictures?
Einstein’s theory of special relativity states that a. it is impossible for something to travel faster than light b. light travels at an accelerating speed c. the light from stars reaches Earth almost instantly
A light-year is a measure of a. time b. distance c. energy
The closest star to the Sun is about a. 4.25 light-years away b. 299 light-years away c. 1000 light-years away
Discussion/essay questions
Einstein’s theory of special relativity also states that speed can change the way we experience time. Do you think time travel will ever be possible? Why or why not?
Transcript
Einstein’s theory of special relativity states that it is impossible for anything to travel faster than light. In a vacuum, light travels at a constant speed of 299,792,458 metres per second. Scientists use the speed of light to measure distances between stars in space. A light-year is a unit that represents the distance that light can travel in a year. Even the closest stars and exoplanets are removed from our solar system by several light-years. Proxima Centauri, the closest star to the Sun, is about 4.25 light-years away. Some visible stars are thousands of light-years away. This means that the night sky is an image of the past. In fact, it is possible that some of the stars we can see no longer exist.
Brown dwarfs look like a. planets b. stars c. asteroids
Brown dwarfs are different from stars because a. they use deuterium for fusion b. they don’t have cores c. they reach extremely high temperatures
It is difficult to find brown dwarfs because a. they don’t orbit anything b. they are smaller than most planets c. they emit very little light
See answers below
Discussion/essay questions
Scientists are always learning more about space. What do you think will be discovered in the future?
Transcript
A brown dwarf is a type of celestial object that can’t be classified as a planet or a star. Although brown dwarfs look more like planets, they form the same way stars do. A star is created when a cloud of gas and dust begins to compress. The intense force of gravity causes the star’s core to fuse atoms together, producing helium. Fusion is what causes a star to shine. Early in its life, a star fuses atoms of deuterium. It begins to use regular hydrogen as its core gets hotter. However, brown dwarfs never reach this stage. They stay at low temperatures and fuse deuterium until they run out. Brown dwarfs produce very little light, which makes them hard to find. Scientists first theorized about brown dwarfs in 1963, but didn’t observe any until 1995.
Circadian rhythms respond to changes in a. light b. temperature c. gravity
Melatonin is a hormone that helps with a. energy b. memory c. sleep
Some people struggle to fall asleep because a. their brains make too much melatonin b. their brains make melatonin later in the night c. their brains make melatonin too early in the day
See answers below
Discussion/essay questions
Do you think you get enough sleep? Why or why not? What are your sleeping habits?
Do you think it’s possible for society to accommodate for people with different sleeping patterns?
Transcript
A circadian rhythm is a natural clock that helps control our bodily processes. Humans’ circadian rhythms keep track of time by detecting changes in the light. When the sky becomes dark enough, the brain receives a signal to produce melatonin, a hormone that helps us fall asleep. However, not all circadian rhythms are the same, and some people’s brains do not produce sufficient melatonin until later in the night. People who naturally stay awake later often struggle with the work and school hours of modern society. Circadian rhythms can also be disrupted by unnatural light, such as the blue light that comes from screens. For this reason, many people report getting less sleep than they need.
Redshift is one example of how reality can depend on our interpretation. While an observer standing still might be able to see an object change colour, an observer moving at the same speed as the object would not. Can you think of some other situations where different people might interpret reality differently?
Transcript
Redshift is an effect created by light waves. It causes the colour of an object to become redder as it moves away from an observer. This is because red light has the longest wavelength of all the colours on the visible spectrum. Redshift is not something that humans often see, because an object must be travelling very fast to visibly change colour. However, we can observe a similar effect with sound waves, when the pitch of a car horn changes as the car drives away. Redshift is important because it has helped astronomers make observations about the universe. In 1929, the redshift of galaxies caused astronomer Edwin Hubble to discover that the universe is expanding. Today, astronomers also use redshift to find the locations of planets outside of our solar system.
Have you ever seen bioluminescent creatures in real life?
Transcript
Bioluminescence is a phenomenon that creates displays of light in nature. It can often be seen in oceans. This light is actually created by organisms in the environment. Certain marine animals have a chemical in their bodies called luciferin, which reacts with oxygen and produces light. Some organisms use bioluminescence to scare away predators, while others use it to attract mates. Bioluminescence is especially common in deep water, because it allows organisms to navigate and communicate in the dark. However, marine animals are not the only organisms that can produce light. Fireflies are bioluminescent insects that can be found on almost every continent.
The human perception of colour is caused by the way our eyes to light. While humans can see many different colours, light that is visible to humans only makes up a small amount of the light in the . This is because of the limits of the photoreceptors in our eyes. Human eyes contain types of photoreceptors known as cones, which are responsible for detecting coloured light. Because light is made up of , each type of light has a different wavelength. Cones can pick up on these wavelengths, which is how we differentiate between colours. Humans have three types of cones in our eyes – known as red, green, and blue cones. We can see any colour of light with a wavelength within the range of those cones. However, light outside of the visible range – such as infrared and ultraviolet light – can’t be seen by the human eye. Though this light is invisible to us, it isn’t invisible to every . Different animals have different amounts of cones in their eyes. Dogs, for example, only have two types of cones, and therefore can’t see as many colours as we can. An animal known as the mantis shrimp, however, has sixteen types of cones. That means that its range of visible light is much wider than ours, and it can see colours we can’t even .
Comprehension questions
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Discussion/essay questions
Many scientists have wondered if we all see the same colours, or if we have learned to call different colours the same names. One person could possibly call a colour “red” that another person sees as blue. We have no way of proving or disproving this, because it is difficult to describe what a colour looks like. Do you think it is possible that we all have a different perception of colours?
Transcript
The human perception of colour is caused by the way our eyes respond to light. While humans can see many different colours, light that is visible to humans only makes up a small amount of the light in the universe. This is because of the limits of the photoreceptors in our eyes. Human eyes contain types of photoreceptors known as cones, which are responsible for detecting coloured light. Because light is made up of waves, each type of light has a different wavelength. Cones can pick up on these wavelengths, which is how we differentiate between colours. Humans have three types of cones in our eyes – known as red, green, and blue cones. We can see any colour of light with a wavelength within the range of those cones. However, light outside of the visible range – such as infrared and ultraviolet light – can’t be seen by the human eye. Though this light is invisible to us, it isn’t invisible to every species. Different animals have different amounts of cones in their eyes. Dogs, for example, only have two types of cones, and therefore can’t see as many colours as we can. An animal known as the mantis shrimp, however, has sixteen types of cones. That means that its range of visible light is much wider than ours, and it can see colours we can’t even imagine.
