TOPICS 1–3

ANSWER KEY

BLM 2-1, Is a Candle Alive?/Skill Builder

BLM 2-2, Parts of a Compound Light Microscope/Overhead Master

Goal: Students complete a Venn diagram to compare a candle with a human in relation to the characteristics of living things. Answers Students’ diagrams will vary. However, students must be able to justify the placement of characteristics within their diagrams. Analyze 1. Be open to a variety of student responses, as long as students can support their assertions with reasonable explanations. For instance, a candle cannot reproduce itself. However, the flame that comes from a lit candle can “reproduce” if a piece of paper or another candle is held to the flame. There is no need to emphasize whether students’ answers are right or wrong. Rather, engage them in discussion to make it clear that there may be more than one viewpoint.

Goal:Use this overhead as a teaching aid when discussing the parts of a microscope. Answers not applicable

BLM 2-3, The Compound Light Microscope/Reinforcement Goal:Students review the function of the different parts of the compound light microscope. Answers All answers in the table on the next page are taken from page 106 of SCIENCEFOCUS™ 8.

2. No, a candle is not alive, although it may be possible to apply many of the characteristics of living things to candles. The main reason candles are not alive is that they are not made of cells. Microscope part

Function

eyepiece

The part you look through. It has a lens that magnifies the object, usually by 10 ×.

tube

Holds the eyepiece and the objective lenses at the proper working distance from each other.

revolving nosepiece

Rotating disk that holds two or more objective lenses. Turn it to change lenses. Each lens clicks into place.

objective lens

Magnifies the object. Different lenses provide different levels of magnification.

fine-adjustment knob

Use with medium- and high-power magnification to bring the object into sharper focus.

coarse-adjustment knob

Moves the tube or stage up or down to bring the object into focus. Use it only with the low-power objective lens.

stage

Supports the microscope slide. Clips hold the slide in position. A hole in the centre of the stage allows the light from the light source to pass through the slide.

condenser lens

Directs light to the object being viewed.

diaphragm

Controls the amount of light reaching the object being viewed.

light source

Lights the object being viewed.

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TOPICS 1–3

ANSWER KEY

BLM 2-4, Use and Care of a Microscope/Information Handout Goal: This BLM instructs students on the proper use and care of a microscope. Answers not applicable

BLM 2-5, Calculate Magnification/Problem Solving Goal: Students practise calculating the magnifications of different microscope lens combinations. Answers 1. The magnification would be 10 × 10 = 100× 2. (a) Combine the ocular lens (10×) with the lowpower lens (4×) for a magnification of 40× . (b) Combine the ocular lens (10×) with the medium-power lens (10×) for a magnification of 100×. (c) Combine the ocular lens (10×) with the highpower lens (40×) for a magnification of 400×. 3. The total magnification would be 15 × 40 = 600× 4. Total magnification = (Ocular lens magnification) × (Objective lens magnification)

2. Size of happy face in first circle is 2.5 cm. Size of one happy face in the second circle is 1.25 cm. Size of one happy face in the third circle is 0.83 cm. Size of one happy face in the fourth circle is 0.625 cm. Part B The diameter of the field of view is 2500 µm.

BLM 2-8, Cell Size/Assessment Goal: Students are assessed on their abilities to estimate the size of cells in a field of view. Answers 1. (a) A field of view is the area seen through the eyepiece. (b) A diameter is the distance across a circle. 2. (b) The circle is 3 cm or 30 mm in diameter. 3. (a) 3 cm or 30 mm (b) 3 cm or 30 mm (c) 0.3 cm or 3 mm (d) Divide the diameter of the circle (3 cm) by the number of cells. 4. Span of 1 cell = Diameter of circle Number of cells 40 mm = 4 mm = 10

BLM 2-6, Using Microscopes: A Partner Checklist/Assessment

BLM 2-9, The Parts of a Plant Cell/Vocabulary Check

Goal: Student partners assess each other’s proper use, care, and knowledge of microscopes. Answers not applicable

Goal: Students review the vocabulary relating to plant cells by labelling a diagram. Answers A. cell membrane E. cell wall B. cytoplasm F. chloroplast C. nucleus D. vacuole

BLM 2-7, Estimating the Size of Microscopic Objects/Skill Builder Goal: Students develop skills for estimating the size of objects under the microscope. Answers Part A 1. Students’ estimates will vary.

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TOPICS 1–3

ANSWER KEY

BLM 2-10, The Parts of an Animal Cell/Vocabulary Check Goal: Students review the vocabulary relating to animal cells by labelling a diagram. Answers A. cell membrane B. cytoplasm C. nucleus

D. vacuole

BLM 2-11, Topics 1–3 Test/ Assessment Goal: To assess understanding of Topics 1–3. Answers: 1. cell

17. The width of the paramecium in the diagram is about 1/5 of the field or view. 1/5 of the actual field of view is 1/5 × 1.5 mm or 0.3 mm. (Depending on the students’ approximation of the amount of the field of view the paramecium takes up, their answers may vary. Accept any reasonable answer.)

2. chlorophyll

3. cell membrane

4. electron microscope

5. multicellular

6. B

7. P

8. B

9. B

10. P

16. (a) Answers will vary, but may include the following: – Living organisms need food for energy. – Organisms reproduce. – Organisms grow. – Organisms produce wastes. – Organisms respond to their environment. (b) Answers will vary depending on the function and organisms chosen. For example, food for energy: some plants have broad leaves that enable the plant to collect the most sunlight to make food; a wolf has sharp canine teeth for tearing meat.

11. B 12. Description Used for focusing at low power.

Name

Letter

Coarse adjustment knob

C

Allows you to switch magnification.

Revolving nosepiece

F

Stage

H

Eyepiece or ocular lens

A

Diaphragm

J

Supports microscope slides. Lens closest to the eye. Controls the amount of light reaching the object.

13. Steps should be in the following order: 5, 3, 4, 1, 2 14.

Eyepiece magnification

Objective magnification

Total magnification

10×

4×

40×

10×

10×

100×

10×

40×

400×

Short Answer 15. Answers will vary, but may include ideas similar to the following: – A car does not grow. Construction on an assembly line is not growth. – A car does not reproduce. – A car does not respond without a driver to initiate the response.

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TOPICS 4–5

ANSWER KEY

BLM 2-12 Designing a Cell Membrane/Science Inquiry Goal:Students design cells with membranes that are permeable, impermeable, and selectively permeable. Answers

Analyze 4. It is best for cells to have selectively permeable membranes. It is necessary for cells to let certain molecules in for its survival, but it is also necessary for cells to keep toxic molecules out.

Part A 1. This type of membrane lets all substances through. 2. This type of membrane only lets certain substances through. 3. A cell needs to be selective in order to keep out harmful (toxic) substances, letting only the good substances in. Part B outside cell

inside cell

inside cell

outside cell

outside cell

lets in only certain molecules

molecules

keeps others out

free exchange of molecules

clearly too big to fit Cell 1 — impermeable

inside cell

Cell 2 — permeable

Cell 3 — selectively permeable

BLM 2-13, Relating Diffusion to the Particle Theory/Reinforcement

BLM 2-14, A Diffusion Flowchart/ Science Inquiry

Goal: Students review their knowledge of diffusion. Answers

Goal: Students explore the concept of diffusion using a flowchart. Answers: Analyze 1. Diffusion is the movement of the particles of a substance from an area of high concentration to an area of low concentration. Diffusion occurs through the random movement of the individual particles and continues until the particles are evenly distributed.

Part A 1. particles 2. moving

3. vibrate 4. faster

6. high, low 5. slowly

Part B Students’ diagrams should indicate that particles in a liquid are not very densely packed together. Particles in a gas should be even less packed together than in a liquid. For example, if students draw ten liquid particles, they should represent about four or five gas particles in the same-size space. The gas particles should be spaced apart from each other. Students should also indicate that the particles are in motion. There would be more particle motion in the gas than in the liquid.

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2. The food colour would diffuse more quickly because there are more particles available to diffuse.

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TOPICS 4–5

ANSWER KEY

3. Diffusion occurs faster in the hot water. Hot water molecules move faster than cold water molecules. Therefore, the increased agitation of molecules in the hot water increases the agitation, or speed, at which the food colour particles diffuse in the hot water. 4. In situations where it is necessary, diffusion keeps cells from having either too high or too low a concentration of a certain substance. For instance, when an amoeba produces carbon dioxide as a waste product, the concentration within the amoeba will be greater than the concentration within the water that surrounds it. Diffusion helps to restore the proper balance of carbon dioxide by allowing some carbon dioxide to diffuse out of the amoeba.

BLM 2-15, Tracing a Drop of Water through a Plant/Reinforcement Goal: This page helps students follow the path of water through a plant. Answers In sequence, the charts should be filled in to read: droplet encounters root (or root hair); osmosis occurs and droplet enters root hair from soil; droplet enters xylem tissue; travels to shoot system; enters an organ, such as a leaf; may leave organism through transpiration.

BLM 2-16, Specialized Cells — Using a Web as a Graphic Organizer/Skill Builder Goal: Students explore and organize their knowledge about specialized cells using a web organizer. Answers 1. Cell specialization refers to different types of cells having different tasks or functions within a larger organism. 2. Students’ drawings should be similar to illustrations/photographs from pages 138–139, SCIENCEFOCUS ™8 3. Nerve cells: have long, branched fibres. This aids the nerve cell’s specialized function of carrying signals from one part of the body to another.

Muscle cells: are elongated and thin. The function of a muscle cell is to shorten when it contracts. The shape of the cell allows it to stretch and shorten without losing its elasticity. Red blood cells: have a thin, disklike shape. This gives them a large surface area to pick up large amounts of oxygen. This aids the red blood cells specialized function of carrying oxygen in the bloodstream. Bone cells: secrete a matrix in which the cell lives, so cell is solid. The matrix is what strengthens and supports the cell to provide the rigidity necessary for the strength of the bone. Skin cells: are thin, flat, and interlocking. This aids the function that skin has to serve as a barrier to keep water, bacteria, etc. out of the body.

BLM 2-17, Organization in Biology/ Reinforcement Goal: Students use this page to review their knowledge of organization in biology and then use a concept map to show different organs that contribute to the digestive system. Answers 1. tissue: groups of similar cells having a common function 2. organ: a structure composed of at least two (and often more) types of tissue 3. system: a group of organs that work closely together to accomplish or perform a common purpose 4. organism: the living independent individual 5. Students will probably know many of the organs from everyday experience or previous studies. Some of their answers may include: stomach, pancreas, liver, tongue, mouth, large intestine, small intestine, and salivary glands.

BLM 2-18, Understanding Body Tissues/ Reinforcement Goal: This page helps students in identifying the four main types of body tissue. Answers 1. • Muscle tissue is found in various places. Much of our body contains skeletal muscles, those that are attached to our bones and allow

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TOPICS 4–5

ANSWER KEY

movement such as walking and running. Other important areas that students should know about include the heart and the blood vessels, the digestive system (muscles in the lining of the gut contract to help move food along the digestive tract and cause contractions of the stomach). Muscles are associated with many other parts of our bodies, such as our eyes and skin (which can cause, for example, hair to stand erect to produce goose flesh). • Epithelial tissue covers every body surface (so the skin is the common example students know), as well as the surface of every structure that faces an internal cavity. Thus, the cavities themselves (such as the chest and abdominal cavities) and the structures within the cavities (e.g., heart, lungs, stomach, liver, spleen, pancreas) are lined with epithelial tissue. • Nerve tissue is present in all areas of our bodies except for the epidermis. (Some students may then wonder how we can feel sensations. The nerve endings in the dermis have an association with special cells in the epidermis, called Merkel cells, that participate in sensory perceptions.) It can connect signals between the brain and any other part of the body. • Connective tissue examples that students may know about include bone, blood, tendons, and cartilage. Connective tissue, like bones, provides support. Blood transports substances throughout the body. 2. Students’ answers will probably be similar to the information found in Figure 2.24, page 142 of SCIENCEFOCUS™ 8. Accept any other appropriate answers. 3. It is beneficial because the different tissues have different roles or functions. Multicellular organisms require such specialization for proper functioning. 4. Students may give many examples (A limb involves connective tissue, muscles, and nerves; the stomach has muscles, epithelial tissues and nerves.)

BLM 2-19, Tissues Found in Plants/ Reinforcement Goal: Students use this page to review the types of tissues in plants and their functions.

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Answers 1. A plant needs to transport minerals and water from its roots to other cells of its body. 2. A plant needs to transport sugars from its leaves to other cells of its body. 3. Different tissues are required to perform different functions. 4. Xylem transports water and minerals. These substances move from the roots toward other parts of the plant, so the general direction is up. 5. Sugars are transported by the phloem. Direction is from the leaves to other parts of the plant, so it is generally down. 6. Epidermal tissue protects the outside of the plant.

BLM 2-20, Testing Your Knowledge about Plants/Assessment Goal: This page tests students’ knowledge of plants. Answers Part A 1. Both are vascular tissues of a plant. Phloem conducts sugars and xylem conducts water and nutrients. 2. The shoot system is the above-ground part of the plant that supports the leaves and reproductive system. The root system is below ground and anchors the plant. Both contain xylem and phloem. 3. Tissues are groups of similar cells that perform a common function (e.g., xylem). An organ is a structure composed of at least two (and often more) types of tissue (e.g., a leaf). 4. Palisade cells and epidermis are both present in a leaf. Palisade cells form the layer underneath the epidermis that contains large numbers of chloroplasts and is where most photosynthesis occurs. The epidermis forms a protective covering over the plants. Part B 1. (e), 2. (d), 3. (g), 4. (f), 5. (c), 6. (a), 7. (b) Part C 1.(b), 2. (a), 3. (a), 4. (c), 5. (c)

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TOPICS 4–5

ANSWER KEY

BLM 2-21, Topics 4–5 Test/ Assessment Goal: To assess your understanding of terms and concepts in Topics 4–5. Answers: Across (a) permeable (d) osmosis (f) xylem (g) transpiration Down (a) phloem (b) root hairs (c) diffusion (e) system (g) tissue (h) organ

13. Water enters the root hairs by osmosis. This water then enters the xylem tissue, where the pressure of the water entering the roots pushes the water up through the tube-like cells of the tissue. During the process of transpiration, water vapour is released through openings in the leaves. This pulls the water up into the leaves. 14. The concentration of water inside the cells of the potato will be higher than the concentration of water outside the cells. Thus, more water will move from the area of high concentration (inside the cell) to the area of lower concentration (outside the cell), causing the potato slice to lose water and go limp.

2. O 3. T 4. T 5. S 6. S 7. O 8. T 9. Terms should be in the following order: 5, 1, 3, 2, 4 10. Answers will vary depending on the organ chosen. 11. (a) A root system supplies water and minerals to the plant. It also anchors the plant in the ground. (b) Any 2 of: – Root hairs have a large surface area and/or there are numerous root hairs to allow more surface where osmosis can take place. – Xylem cells are shaped like tubes so they can transport water up the root. – Branches of the root and root hairs spread out to help anchor the plant. 12. A tree can grow in a variety of environments. A tree can grow much larger.

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117

TOPICS 6–7

ANSWER KEY

BLM 2-22, Organ Systems in Humans: The Digestive System/ Vocabulary Check Goal: This activity provides an opportunity to reinforce understanding and use of terms related to the digestive system. Answers 1. Refer to Figure 2.26 on page 146 of the student textbook. 2. The esophagus connects the mouth and stomach. 3. The pancreas produces insulin. 4. Absorption of nutrients occurs mostly in the small intestine.

5. The lungs are the main organs of the respiratory system. 6. It is the system that allows the exchange of gases required for proper cellular function (takes in oxygen and releases carbon dioxide). 7. Each of the structures performs one or more specific role that is required for the proper and efficient exchange of gases. 8. They are so numerous to maximize the surface area available for exchange. 9. Yes, smoking does harm the respiratory system. Various substances inhaled during smoking remain in the lungs, reducing their efficiency, and increasing the chances of diseases such as lung cancer and emphysema.

5. The small intestine is connected to the stomach at one end and the large intestine at the other end. 6. It is the system that takes in nutrients for the body. 7. Saliva has two main functions. It helps moisten food so that it can be swallowed more easily, and it contains enzymes that begin the breakdown of starches. 8. The stomach digests food both by chemical action and physical action, and it serves as a temporary storage area so that the intestines receive a more or less constant amount of food to handle. 9. Each of the structures performs one or more specific role that is required for the proper digestion and absorption of nutrients.

BLM 2-24, Organ Systems in Humans: The Circulatory System/ Vocabulary Check Goal: This activity provides an opportunity to reinforce understanding and use of terms related to the circulatory system. Answers 1. Refer to Figure 2.28 on page 147 of the student textbook. 2. Capillaries connect the arteries and veins. 3. Arteries transport blood away from the heart. 4. Veins transport blood toward the heart.

BLM 2-23, Organ Systems in Humans: The Respiratory System/Vocabulary Check Goal: This activity provides an opportunity to reinforce understanding and use of terms related to the respiratory system. Answers 1. Refer to Figure 2.27 on page 146 of the student textbook. 2. The trachea connects the mouth to the lungs. 3. The diaphragm plays a main role in breathing. Students may also give the rib muscles as an answer. 4. Gas exchange occurs in the alveoli.

5. The left atrium receives blood from the lungs. 6. It is the system that ensures all cells receive nutrients and get rid of their wastes. The circulatory system also helps fight disease and serves a role in communication by circulating hormones throughout the body. 7. Heart, arteries, veins, and capillaries make up the circulatory system. 8. Gases that enter or leave the bloodstream must diffuse through membranes. The thin nature of these vessels ensures efficient diffusion. 9. The right atrium, right ventricle, left atrium, and left ventricle are required because the heart must actually accommodate two cycles, one for the lungs and another for the body.

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147

TOPICS 6–7

ANSWER KEY

BLM 2-25, The Respiratory and Circulatory Systems/Reinforcement Goal: Students relate the connection between the circulatory and respiratory systems. Answers 1. trachea: 20 mm; bronchus: 12 mm; bronchiole: 0.5 mm

7. They are similar in that they are closely associated with capillaries for exchange of material, and they are adaptations to increase the surface area available for exchange. 8. Many villi and air sacs are required to maximize the surface area for exchange. 9. Students should draw a diagram similar to Figure 2.31 on page 149 of the student textbook.

2. The tiny air sacs are called alveoli. 3. The tiniest tubes are the capillaries. 4. The capillaries closely surround each alveolus. These two structures are separated only by very thin walls, so that gases can be efficiently exchanged. 5. Diffusion is the movement of particles in gases and liquids from areas of high concentration to areas of low concentration. 6. The substances that cross from one system to the other do so by diffusion. 7. Oxygen and carbon dioxide are exchanged.

BLM 2-26, The Digestive and Circulatory Systems/Reinforcement Goal: Students review the way that food enters the body. Answers 1. Students’ answers will vary. Examples include: the bloodstream carries away carbon dioxide from cells; it supplies cells with oxygen and nutrients; it helps to maintain a constant body temperature; it helps in the fight against disease; and it circulates hormones for communication. 2. The exchange occurs in the intestines. 3. To digest means to break down or reduce something to a convenient size. 4. The process that allows food particles to pass from the intestine to the circulatory system is called absorption. 5. The main functions of the digestive system are digestion (the breaking down of food into a size that allows it to pass into the bloodstream) and absorption (the passage of nutrients into the bloodstream).

BLM 2-27, How Well Do You Know Your Systems?/Assessment Goal: This quiz tests students’ knowledge of the body’s systems. Answers Part A 1 (d), 2 (f), 3 (e), 4 (b), 5 (a). 6 (c) Part B 1. Diffusion is the movement of particles in gases and liquids from areas of high concentration to areas of low concentration. An example is the diffusion of dissolved gases between the respiratory and circulatory systems. 2. Absorption is the passage of dissolved food particles from the digestive system to the circulatory system. An example is water, which carries the food particles. 3. A hormone is a chemical messenger circulated by the circulatory system that has an effect on another part of the body. An example is insulin, which helps control sugar levels in the blood. Part C 1. Alveoli and villi are similar in that they represent a mechanism for increasing the surface area available for the exchange of substances, and they are both very closely linked to capillaries. They differ in that alveoli are part of the respiratory system and villi are part of the digestive system. Students might also say that the circulatory system surrounds the alveoli but is within the villi. 2. Oxygen and carbon dioxide are both gases present in the body. They are similar also in that they are exchanged in the respiratory system. They differ in that oxygen is a substance required by respiration, whereas carbon dioxide is a waste product of respiration.

6. The villi are small projections of the internal surface of the intestinal wall.

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TOPICS 6–7

ANSWER KEY

3. The trachea and an artery are both tubes. The trachea, however, is part of the respiratory system and takes air toward the lungs. An artery is part of the circulatory system and carries blood away from the heart.

BLM 2-28, Journey of a Red Blood Cell/Overhead Master Goal: Use this overhead to help students understand how blood circulates in the body. Answers: not applicable

BLM 2-29, You Are What You Eat/ Reinforcement Goal: Students review their understanding of the foods they eat and their effects on health. Answers 1. A nutrient is a chemical substance that is taken in through diet and that provides the body with energy and materials used in building required structures (e.g., for growth and repair of tissues). 2. Nutrient

Function in body

Food source

carbohydrate

main source of quick energy

plant foods or food derived from plants that are rich in carbohydrates

proteins

provide substances for building and repair of structures (growth, repair of tissues)

animal-derived foods (meat, fish, eggs)

fats

also a source of energy but can be stored by the body to supply energy over long term

animal-derived foods

too much of some substances as well. Surplus fat, for example, will be stored by the body, which may lead to increased weight, meaning the body’s systems will have to work harder than they should.

BLM 2-30, Design Your Own “Extraterrestrial”/Design Your Own Investigation Goal: This BLM has students use their knowledge on biological systems to design their own biologically correct “extraterrestrial.” Answers Students’ creatures will vary. Encourage them to be as creative as possible. The only restriction should be that their creatures conform to the biological rules that they have learned about in Unit 2; that is, they should take into consideration such factors as surface area-to-volume relationships, and the need for an organism to supply all of its cells with the nutrients and other substances required to maintain life (in other words, the need for systems in multicellular organisms). Also, students should take into account the sorts of adaptations required by an organism. If, for example, their creature is terrestrial then the creature must have features that permit it to live on land (rather than gills and fins, for instance). Nearly any adaptation may be accepted, so long as the student can support it with biological examples.

BLM 2-31, Topics 6–7 Test/ Assessment Goal: To assess your understanding of Topics 6–7.

3. Before a race the ideal food for a marathon runner is one that provides plenty of carbohydrates, which the runner will need for energy. 4. Minerals, vitamins, and water and required for a healthy body. 5. Eating a healthy diet is important for helping to maintain the body’s internal environment and providing the required substances for repair. The body’s ability to maintain its health is influenced by

Answers: 1. excretory 2. digestive 3. respiratory 4. circulatory 5. Students’ answers will vary. Following is an example of a chart. Relationship of Systems and Organs/Structures System

Name

circulatory

heart, artery, vein

respiratory

lungs, diaphragm, alveoli

digestive

stomach, small intestine, liver, salivary glands, pancreas, gall bladder

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ANSWER KEY

6. Students’ answers may be similar to the following: exercise → increased need for oxygen → increased heart rate → increased supply of oxygen to the muscles. 7. Students answers may vary, but may include: – a drawing of a pop bottle with balloon inserted. Labels and/or sentences should state how pushing in on the plastic bottle causes the balloon to deflate because of increased pressure, and releasing the pressure inflates the balloon as air is drawn in. – a sketch of the respiratory system. Labels and/or sentences should state how the diaphragm moving down causes a pressure decrease inside the chest cavity, thus inflating the lungs, and how they move up to increase the pressure and cause the expulsion of air. 8. (a) alveoli (b) villi (c) Both structures are small projections that greatly increase the amount of surface through which food or gases may pass. They do this without taking up much space. 9. (a) Smoke and other pollutants cause an irritation of the lining of the respiratory system. This causes the mucus cells to produce a lot of mucus. Over time, the irritated lining becomes inflamed. Eventually the mucus producing cells multiply, and the lining of the airways become narrowed and blocked. (b) Nicotine causes the blood vessels to constrict. This raises blood pressure and increases heart rate. Students may also mention that carbon monoxide completes with oxygen in the lungs putting further stress on the respiratory and circulatory systems.

150

10.Students’ graphs should be similar to the following: Effect of Exercise on Heart Rate 120

individual class average

110 Heart rate

TOPICS 6–7

100

90

80

70

At rest

After exercise

1 min after exercise

5 min after exercise

11. (a) Exercise increases heart rate. (b) heart rate (pulse) (c) Students’ answers may vary, but might include type of exercise and length of time of exercise.

BLM 2-32, Unit 2 Test/Assessment Goal: To assess your understanding of Unit 2. Answers: 1. b 2. d 3. c 4. c 5. d 6. c 7. a 8. b 9. a 10. d 11. a 12. b 13. d 14. b 15. c 16. d 17. b

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TOPICS 6–7

ANSWER KEY

28. Students’ graphs should be similar to the following:

18. c 19. a 20. c 21.

Rise of Water Over Time 100

Microscope Parts and Functions

90

Function

Letter

objective lenses

G

magnifies objects at different powers of magnification

arm

E

connects the base and the tube

tube

B

holds the eyepiece and the objective lenses at the proper distance

revolving nosepiece

F

allows for the changing of lenses

22. Multicellular organisms are able to adapt to a wider range of environments. Multicellular organisms are able to grow larger. 23. 1.5 mm/about 7 cells = about 0.2 mm. 24. Answers may vary, but may include ideas similar to the following: – A diet high in fats may cause a build up of fatty deposits on the inside of arteries. This may result in blood clots, which can lead to strokes, or limited blood flow to the arteries, causing a heart attack. – A high salt diet may lead to high blood pressure and the risk of stroke. – A low fibre diet may lead to a slowing of digestion, which may irritate the intestine. This may lead to cancer. 25. (a) Your heart rate would increase and/or your rate of breathing would also increase. (b) nervous system and respiratory system 26. (a) manipulated variable: type of exercise (b) responding variable: heart rate (pulse) (c) controlled variables: person doing the exercise, length of time exercising, amount of rest between exercise, starting heart rate

80 Height in cm

Name

70 60 50 40 30 20 10 0

12

24

36

48

60

72

Time in hours

29. (a) osmosis (b) The concentration of sugar is greater inside the carrot than outside, so the water moves through the semi-permeable membrane to the inside of the carrot. (c) The level of the water would not change. 30. Students’ paragraphs will vary, but may include ideas similar to the following: Nicotine in cigarettes can constrict the blood vessels in the circulatory system, raising blood pressure and increasing the risk of stroke. The lining of the respiratory system may become irritated, causing a build up of mucus and conditions such as bronchitis and emphysema. Cigarette smoking is the leading cause of lung cancer in the respiratory system. Cigarette smoking causes a build up of carbon monoxide, which decreases the blood’s ability to deliver oxygen to all body systems.

27. Answers will vary. Following is one example using a chart. Organism

Structure

Mechanism to move liquid

Amoeba

cell membrane

diffusion

Plant

xylem, phloem

osmosis and transpiration

Animal

vessels (arteries and veins)

heart pumps the blood

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