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Life Science U3-L5 How Cells Work

Unit 3 Review: How Cells Work

You've taken a living thing apart down to its atoms, watched molecules cross a membrane, and followed energy from the sun into a cell. Here's all of it in one place, and two questions you'll have to answer for yourself.

Teacher Notes

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Lesson Goal

Bring the four Unit 3 lessons together, check which parts hold and which need a second read, and finish by writing about how a membrane lets some things through and what happens to a lake's consumers when its producers die.

Key Concepts

Every question here is tied to one of the four lessons and the hint says which one, so a wrong answer is directions to the right page and not a mark against the student.

The two written questions at the end are the real test of whether the unit landed. The lake question in particular needs Lesson 3 understood, not memorized: consumers can't make their own food, so they depend on producers.

Key Vocabulary

Element
Something made of only one kind of atom, which can't be broken down into anything simpler.
Compound
Two or more elements bonded together.
Carbohydrates
Organic compounds made of carbon, hydrogen and oxygen, such as sugars and starch.
Enzymes
Proteins that speed up chemical reactions in cells without being changed.
Selectively permeable
Letting some substances pass through while stopping others.
Diffusion
The movement of molecules from an area where they are crowded to an area where they are less crowded.
Osmosis
The diffusion of water through a selectively permeable membrane.
Active transport
Materials moving through a cell membrane that require the cell to use energy.
Photosynthesis
Using energy from sunlight to build glucose out of carbon dioxide and water, giving off oxygen.
Cellular respiration
Using oxygen to break glucose down and release the energy stored in it.
Biodegradable
Able to break down easily in the environment.
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Before You Start

The Words

The words this lesson uses. Tap a card to see what it means, then come back to them whenever a question uses one.

Part One

The Questions

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Questions about the story you just read. Pick your answer straight off, or press Find it in the story if you would rather hunt for the sentence first.

Part Two

Vocabulary Check

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The word cards are at the top of this page. Look back at them as often as you need, then answer.

When you finish: write the answers out in your own words — not copied word for word from the choices. Saying it your own way is the part that proves you understood it. Then use Print Answer Sheet for a one-page record of what was answered and scored.
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