CRT Study Guide A well-known scientist who built the most powerful microscope of his time was __________________________. His invention was considered.

CRT Study Guide

• A well-known scientist who built the most powerful microscope of his time was __________________________.

• His invention was considered a major contribution to science.

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van Leeuwenhoek

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• Bacteria, which is made of ____________ ___________, are known to be the simplest organisms.

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single cells

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• Most cells have a ___________. This cell structure is sometimes called the “brain” of the cell because its function (job) is to “control all of the cell’s activities.” It controls how and when the cell grows, develops, and divides.

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nucleus

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• The __________ ____________ is a cell structure that is common to both plant and animal cells. Its function (job) in both is to “control the movement of substances into and out of the cell.”

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cell membrane

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• _____________________ is a jelly-like substance found in plant and animal cells. It fills most of the cell and has other cell structures floating in it. It is made up mostly of water.

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cytoplasm

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• When an organism is made up of many cells and different kinds of cells, each kind of cell has a special______________________. For example, blood cells have a different job than muscle cells. They each have a different job to do, and that keeps us alive and healthy.

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function

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• There are two cell structures that are found ONLY in plant cells. They are ______ ________ and the ___________________. You will never find these cell structures in animal cells!

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cell wall and

chloroplasts

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• When sunlight passes through a prism, the light _______________________________________ called the visible spectrum.

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separates into different colors

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•When light colors are ______________, we CANNOT see the color.

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absorbed

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•The “bending of light as it moves from one material to another” is known as ______.

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refraction

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• Farsighted means a person CAN see far away (distant) objects clearly, but close (nearby) objects look blurry. Glasses with ____________ lenses correct farsighted vision.

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convex

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• The part of the eye that light passes through to help us see nearby objects is called the ____________.

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• lens

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• On a rainy day, you may observe a ______________ in the sky as light passes through raindrops. This is because raindrops are like tiny prisms in the air.

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rainbow

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• If you see an object such as a green car, you know that the color green is the color that is reflected…not absorbed. You will not see the colors that are absorbed. Therefore, when you look at grass, you know that __________ is not absorbed.

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green

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• The function of the _____________ in the human eye is to “control the amount of light that enters the pupil.”

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iris

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• We know that a ___________ reflects the most light of common household objects. That is why you can see your own image, as well as other images of differing colors, in one.

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mirror

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•The _________ is the part of the eye that bends light rays.

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cornea

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•The “bouncing back of light from a surface” is known as ________________.

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reflection

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• When you see your image in a mirror, ________________ are bouncing back from the surface of the mirror. This is what allows you to see your reflection.

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light rays

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• A person who can see nearby objects clearly but cannot see distant objects is nearsighted. A nearsighted person’s vision would be corrected by wearing glasses that have ____________ lenses.

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concave

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• Tilting a mirror in front of your face so that you are changing the angle of the light ray hitting the mirror, prevents you from seeing your own face but instead ___________________.

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another image

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• Contact lenses are a type of corrective lens for people who “need glasses”. They work to correct vision because they are very similar to the ___________ in the human eye.

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• cornea

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• The reason you SEE colors of objects is that the object is reflecting the light color that you are seeing. It absorbs all the other light colors of the visible spectrum. So, when you notice that an apple is red, you know that it is _____________________________.

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reflecting light