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Lesson 7.3 Workbook B Copyright by Pearson Education, Inc., or its affi liates. All rights reserved.101

7.3 Cell Transport

Lesson Objectives Describe passive transport. Describe active transport.

BUILD VocabularyA. The chart below shows key terms from the lesson with their definitions. Complete the

chart by writing a strategy to help you remember the meaning of each term. One has been done for you.

Term Definition How Im Going to Remember the Meaning

Diffusion Movement of particles from an area of higher concentration to an area of lower concentration

Diffusion happens when the concentrations of particles are different.

Facilitated diffusion

Diffusion of molecules through a protein channel

Hypertonic Solution with more solute than another solution

Hypotonic Solution with less solute than another solution

Isotonic Two solutions that have the same amount of solute

Osmosis Diffusion of water through a selectively permeable membrane

B. As you work through this lesson, you may find these terms in the activities. When you need to write a key term or a definition, highlight the term or the definition.

Facilitate means help. A protein channel helps diffusion occur in facilitated diffusion.

Hyper- means more or above. A hypertonic solution contains more solute than another solution.

Hypo- means less or below. A hypotonic solution contains less solute than another solution.

Iso- means equal or the same. Two solutions are isotonic if they have the same amount of solute.

Water is H2O, and osmosis starts with O. Osmosis is the movement of water through a membrane.

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membrane

water

solute particles

Osmosis

water movement

Diffusionof

SoluteParticles

solute particle movementnumber of solute particles should be the same on bothsides of the membrane

number of solute particles does not change, just level of water

Passive Transport Active Transport

BUILD UnderstandingCompare/Contrast Table Use a compare/contrast table when you want to see the similarities and differences between two or more objects or processes. Select words or phrases from the box to complete the table comparing passive and active transport.

diffusion energy required exocytosis osmosis endocytosis energy not required facilitated diffusion protein pumps

Passive TransportDiffusion is the movement of particles from an area of high concentration to an area of low concentration. Osmosis is the diffusion of water through a selectively permeable membrane. Study the beakers at the right. The arrows between beakers tell you what process is occurring. 1. In the beakers on the right,

draw the result of the described process. Draw changes in water levels. Draw changes in the number of solute particles. Remember to draw on both sides of the membrane.

2. Look at the top left beaker. What would happen if the membrane did not allow water or solute particles to pass through it?

diffusionenergy not requiredfacilitated diffusion

osmosis

endocytosisenergy required

exocytosis protein pumps

The solutions would stay the same. Neither water nor solute particles would move

through the membrane.

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facilitated diffusion

Glucose molecules

active transport

Molecule tobe carried

Energy

Moleculebeing carried

Active TransportFacilitated diffusion takes place when a substance diffuses across the cell membrane through a protein channel. Active transport takes place when the cell uses energy to carry a substance across the cell membrane against a concentration difference.

Follow the directions. 1. Label each diagram as either facilitated diffusion or active transport.

Answer the questions. Circle the correct answer. 2. Which process can move molecules from a lower concentration solution on one side of

the membrane to a higher concentration solution on the other side?active transport facilitated diffusion

3. Which process does not require energy?active transport facilitated diffusion

4. What does the word facilitated mean in facilitated diffusion ?hindered helped

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Lesson 7.4 Workbook A Copyright by Pearson Education, Inc., or its affi liates. All Rights Reserved.109

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7.4 Homeostasis and Cells

Lesson Objectives Explain how unicellular organisms maintain homeostasis. Explain how multicellular organisms maintain homeostasis.

Lesson SummaryThe Cell as an Organism Sometimes a single cell is an organism. Single-celled organisms must be able to carry out all the functions necessary for life.

Unicellular organisms maintain homeostasis, relatively constant internal conditions, by growing, responding to the environment, transforming energy, and reproducing.Unicellular organisms include both prokaryotes and eukaryotes.Unicellular organisms play many important roles in their environments.

Multicellular Life Cells of multicellular organisms are interdependent and specialized.The cells of multicellular organisms become specialized for particular tasks and communicate with one another to maintain homeostasis.Specialized cells in multicellular organisms are organized into groups. A tissue is a group of similar cells that performs a particular function. An organ is a group of tissues working together to perform an essential task. An organ system is a group of organs that work together to perform a specific function.The cells of multicellular organisms communicate with one another by means of chemical signals that are passed from one cell to another. Certain cells form connections, or cellular junctions, to neighboring cells. Some of these

junctions hold cells together firmly. Other cells allow small molecules carrying chemical signals to pass directly from one cell

to the next. To respond to a chemical signal, a cell must have a receptor to which the signaling

molecule can bind.

The Cell as an OrganismFor Questions 15, complete each statement by writing the correct word or words. 1. The term refers to the relatively constant internal physical and chemical

state of a living cell. 2. Unicellular prokaryotes, called , are adapted to living in a remarkable

number of different places.

3. Some unicellular eukaryotes, called , contain chloroplasts.

4. Yeasts are unicellular , which are eukaryotes.

5. Other unicellular eukaryotes include and algae.

homeostasis

bacteria

fungi

protozoans

algae

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homeostais

bacteria

algae

fungi

protozoans

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6. How do single-celled organisms maintain homeostasis?

7. Why is maintaining homeostasis particularly important to single-celled organisms?

Multicellular Life 8. How are the cells of a multicellular organism like a baseball team?

9. How does a multicellular organism maintain homeostasis?

10. Complete the table by describing the functions of the specialized cells.

Examples of Specialized Cells

Type of Cell Name of Specialized Cell Part Function of Specialized Cell Part

cells that line the upper air passages in humans

cilia sweep mucus, debris, and bacte-ria out of lungs

pine pollen grains wings enable pollen grains to float in the slightest breeze

They maintain homeostasis by growing, responding to their environment, transform-

ing energy, and reproducing.

Because they consist of only one cell, loss of homeostasis by a single-celled organism

would mean the immediate death of the organism. They do not have any other cells

that can perform the activities of life for them.

A multicellular organism has many different types of cells with different shapes that

specialize in one of the functions that keep the organism alive. A baseball team has

different players who each specialize in one of the jobs that must be done so the team

can function.

A multicellular organism maintains homeostasis by having specialized cells that must

maintain their own homeostasis and cooperate with other cells. This requires the cells

to communicate with one another. Each cell in a multicellular organism contributes to

the overall homeostasis of the organism.

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They maintain homeostatis by growing, responding to their environment, transforming energy and reproducing

Because they consit of only one cell, loss of hemostais by a single celled organisms would mean the immediate death of the organism they do not have any other cells that can perform the activites of life for them.

a multicellular organism has many diferent types of cells with dierent shapes that specialize in one of the functions that keep the organism alive. a baseball team has dierent players who specializw in one of the jobs that must be done so the team can function

sweet mucus, debris, and bacteria out of lungs

enable pollen grains to oat in the slightest breeze

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11. The Venn diagram below consists of four concentric circles. Complete the diagram to show the relationships among four levels of organization of life. Use the terms cells, organ, organ system, and tissue.

12. Starting with the outermost circle of the diagram, explain how each level is related to the next level within each circle.

13. What is the name of the areas that hold adjacent cells together and enable them to communicate?

14. On the Venn diagram above, where would you add a circle that represents the organism level of life? Where would you add a circle that represents another organ of the same organ system?

Organ systems are made of one or more organs. Organs are made up of one or more

tissues. Tissues are made up of many cells with similar shapes and functions.

Cellular junctions

A circle that represents the organism level of life should be drawn outside of the

outermost circle for an organ system. A circle that represents another organ of the

same organ system would be drawn within the organ system circle but would be

separate from the series of circles that represent the organs already shown in the

Venn diagram.

Cells

Tissue

Organ

Organ system

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organ systems are mode of one or more organs. organs are made up of one or more tissues. tissues are made up on many cells with similar shapes and functions.

a circle that represents the organism level of life should be drawn outisde of the outmost circle of an organ system. A circle the represents another organ of the same organ system would be drawn within the organ system circle but would be seperate form the series of circles that represent the organs already shown