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Edusmart Science Middle School Assessment Answer Keys Information: Answer keys for Edusmart Science Middle School Assessments are provided as an aid for grading printed copies of the SAS assessments when the Print option is chosen. For each multiple choice item, the correct answer choice is indicated, and an explanation is given explaining why this answer choice is the best choice for the question being asked. An explanation is also provided in the Answer Keys for the Figure It Out, open­ ended response questions that appear at the end of the Click ‘N Tick version of the SAS assessments. The software program did not include a print version of the Figure It Out but if needed, these open ended questions can be printed from the answer key, for distribution to students. Suggested Strategies for Using the Assessments: 1. The printed assessment can be used as both a pre­test and as a post­test to measure how much learning has occurred following instruction using an Edusmart Science instructional module. Give the printed assessment to students prior to viewing the module. Grade the assessments, but do not share the results with the students. Once instruction is completed, give the printed version of the assessment again as a post­test and grade it. The difference between the pre­test and post­test scores indicates how much learning has occurred. 2. Allow students to work in groups and to use notes from their journals to complete the assessment. However, students must justify their answer choices by explaining their choices in writing. They must provide a reasonable explanation for why they chose one answer and did not choose the other three. This creates science discourse as students discuss their answer choices and must use reasoning to defend their choices. 3. If assessment items contain graphics, such as pictures or charts and graphs, require students to label all parts of the graphic, and write notes telling everything they know about it before reading the question. Chances are, by the time they read the question, they’ll already know the answer and will not be as easily mislead by a good, but incorrect distracter.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key G7­Life Science ­ Photosynthesis and Energy Conversion 1. Correct Answer: A Explanation: Leaves contain more chloroplasts and more stomata for gas exchange. 2. Correct Answer: B Explanation: Oxygen is a product of photosynthesis, not a reactant or raw material. 3. Correct Answer: B Explanation: Carbon dioxide is necessary to make glucose, the product of photosynthesis 4. Correct Answer: C Explanation: Chlorophyll does not absorb all wavelengths of light; it only absorbs the red and blue wavelengths. Since green is reflected back to your eyes, chlorophyll appears green. 5. Correct Answer: D Explanation: Needle­like leaves lessen water loss due to evaporation, while widespread shallow roots quickly absorb water after it rains. These adaptations increase plant A’s chances of surviving and being able to reproduction in dry areas. This is why there is an abundance of species A plants growing, but very few species B plants growing in this area. 6. Correct Answer: C Explanation: Broad leaves are an adaptation for maximizing exposure to light. 7. Correct Answer: A Explanation: A waxy cuticle is there to prevent water loss. Stomata allow water loss. 8. Correct Answer: D Explanation: Without leaves to carry on photosynthesis, the seedlings did not have the energy needed to grow and survive. 9. Correct Answer: C Explanation: The label Q is for root hairs. Root hairs provide more surface area for plants to absorb water. 10. Correct Answer: D Explanation: The purpose of photosynthesis is for plants to make glucose that they can use for energy necessary for life processes like growth.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Photosynthesis and Energy Conversion Figure it out Question: A student exposed six plants to colored light. Three plants were grown in red light and three plants in green light. Which plants should grow better? Explain your answer.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Photosynthesis and Energy Conversion Figure it out Solution: Plants will grow better in red light because chlorophyll will not absorb the wavelengths of green light. The plants in green light will not be able to absorb energy, so they will not be able to carry our photosynthesis. Without the glucose produced by photosynthesis, the plants will die.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key G7­Life Science ­ Cycling of Matter 1. Correct Answer: B Explanation: Matter cannot be created or destroyed, and there are no alternative sources of matter. 2. Correct Answer: D Explanation: Plutonium is not a nutrient needed for life on Earth. 3. Correct Answer: C Explanation: Oxygen combines with hydrogen in the water cycle, to form H2O, or water. Oxygen combines with carbon in the carbon cycle, to form CO2, or carbon dioxide. Oxygen also combines with nitrogen in the nitrogen cycle to produce NO3, or nitrate. 4. Correct Answer: B Explanation: Amino acids are produced in the nitrogen cycle. 5. Correct Answer: A Explanation: Carbon is an important element as it forms the basis of all living organisms. 6. Correct Answer: C Explanation: Phosphorus is used to form DNA and RNA. 7. Correct Answer: B Explanation: Through the process of decay, decomposers put nutrients back into soil, making those nutrients available for plants to use again. 8. Correct Answer: A Explanation: By composting, you are assisting in cycling nutrients back into the ecosystem. 9. Correct Answer: D Explanation: Humus is earthy, dark, crumbly substance made from the remains of plants and other once­living materials. 10. Correct Answer: C Explanation: Compositing creates humus, which restores depleted nutrients in the soil.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Cycling of Matter Figure it out Question: Menander, a Greek playwright, wrote, “All things come from earth, and to earth they all return”. How does the cycling of matter support this quote?
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Cycling of Matter Figure it out Solution: The law of conservation of mass states that matter is neither created nor destroyed. Life is dependent on matter and nutrients that come from the earth. When organisms die, their bodies decompose, and the nutrients are released back into the soil.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key G7­Life Science ­ Energy Flow in Ecosystems 1. Correct Answer: B Explanation: Plants absorb light energy emitted by the Sun and convert it into chemical energy in the form of glucose. 2. Correct Answer: B Explanation: Glucose is a product of photosynthesis. It does not contribute to the process of photosynthesis. 3. Correct Answer: B Explanation: Glucose and oxygen are the only products of photosynthesis. Plants use water, carbon dioxide, and energy from the Sun to produce glucose. Oxygen is given out during this process. 4. Correct Answer: C Explanation: Photosynthesis occurs in the leaves of plants, in special units called chloroplasts. 5. Correct Answer: C Explanation: A vulture is a tertiary consumer or carnivore. It feeds on secondary consumers. Primary consumers are organisms that are adapted to eating plants parts. 6. Correct Answer: A Explanation: Decomposers, such as bacteria or fungi, break down dead organic matter into forms that can be used by plants. 7. Correct Answer: B Explanation: Energy flows from a lower trophic level to a higher level in food chains and food webs. 8. Correct Answer: A Explanation: An energy pyramid also indicates the decrease in biomass from one trophic level to the next. 9. Correct Answer: C Explanation: Plants consume the most amount of solar energy. They are found at the bottom of the energy pyramid. 10. Correct Answer: A Explanation: Plants are not indirect users of the Sun’s energy. They use it directly to make food for the plant in the form of sugars.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Energy Flow in Ecosystems Figure it out Question: If the organisms in this food chain were arranged in an energy pyramid, which organism would have the least amount of total energy available? Which organism starts the flow of energy?
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Energy Flow in Ecosystems Figure it out Solution: The coyote is a tertiary consumer in the food web; hence it receives the least amount of energy and forms the topmost level in the energy pyramid. The shrubs and cacti begin the flow of energy as they are producers and form the bottom or first level in the energy pyramid.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key G7­Life Science ­ Organic Compounds and the Living World 1. Correct Answer: D Explanation: Organic compounds are carbon­based compounds. Only molecule D has carbon atoms in it. 2. Correct Answer: D Explanation: Enzymes can cause chemical changes in the food during the process of digestion. Chewing food in your mouth is an example of a physical change. There is no change taking place in the food in the processes described in B and C. 3. Correct Answer: B Explanation: Enzymes in the small intestine can chemically digest a carbohydrate molecule. As a result, a large carbohydrate molecule would be broken down into smaller pieces that can be easily absorbed through the intestinal wall. 4. Correct Answer: A Explanation: Both physical and chemical transformation of the food begins in the mouth. Chewing food results in a physical change to the food, and the action of salivary enzymes result in a chemical change. 5. Correct Answer: B Explanation: Enzymes are protein molecules that control all chemical changes that take place inside our body. 6. Correct Answer: B Explanation: In test tube B, the enzymes in saliva will break down the starch to simple sugars. Therefore, only test tube A will test positive for starch. 7. Correct Answer: B Explanation: Carbohydrates are organic compounds that contain carbon, hydrogen, and oxygen. 8. Correct Answer: C Explanation: Sulfur is an element that is present only in some proteins. Carbohydrates and lipids do not contain sulfur. The egg is the only food item which contains proteins; therefore, it is the only food item which is likely to contain sulfur. 9. Correct Answer: B Explanation: Proteins form the structural framework of our body, and are the most abundant organic compound in our body.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited 10. Correct Answer: A Explanation: A carbohydrate molecule is made up of the elements carbon, hydrogen,and oxygen that are usually present in the ratio 1:2:1.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Organic Compounds and the Living World Figure it out Question: Gelatin is a protein that forms a solution when mixed with warm water. When cooled, this protein solution sets or gels forming a jelly­like substance. Fresh strawberries can be added to strawberry­flavored gelatin that has begun to gel to make the filling for strawberry pie. However, when fresh pineapple is added to a gelatin mixture that has started to gel, the gelatin instantly breaks down and liquefies and will not gel. What could possibly explain the difference?
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Organic Compounds and the Living World Figure it out Solution: Fresh pineapple contains an enzyme that breaks down or “digests” the protein in gelatin preventing it from forming a gel. In fact, fresh pineapple juice is sometimes used to tenderize meat prior to cooking.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key G7­Physical Science ­ Force, Work and Energy 1. Correct Answer: B Explanation: Work is done when a force applied on an object moves the object in the direction as the force. The amount of work done is obtained by multiplying the force applied by the distance the object moves. 2. Correct Answer: C Explanation: Work done is equal to the product of the force applied on an object and the distance the object moved. Force is measured in newtons and distance is measured in meters. Therefore, the unit for measuring the amount of work done is a newton­.meter which is also called a joule. 3. Correct Answer: A Explanation: Work is done only when a force applied moves an object in the direction of the force. The boy was standing still and the force he applied did not move the box. So, no work was done by the boy. Work done = 40 N x 0 m = 0 J 4. Correct Answer: B Explanation: No work is done if the force applied does not move the object. In Situation 1, the force is applied in a downward direction. The box cannot move in the direction of the force because it is resting on the floor. Similarly the box cannot move in Situation 3 because it is placed against a wall. In Situation 2, it is possible that the force applied will move the box in the direction of the force, in which case work will be done. 5. Correct Answer: B Explanation: The amount of work done is the product of the force applied and the distance moved in the direction of the force. A force of 100 newtons was used to move the box through a distance of 5 meters. Work done = 100 newtons x 5 meters = 500 joules 6. Correct Answer: D Explanation: Simple machines like the ramp help to make work easier by multiplying force or changing the direction of the force, but they do not reduce the amount of work done. The amount of work done is the same in both situations. If the force is reduced by half then the distance moved will be twice as much. Work done without ramp = Work done using a ramp 100 newtons x 2 meters = 50 newtons x ___ meters 200 joules = 50 newtons x 4 meters
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited 7. Correct Answer: A Explanation: You require less force to push an object up a ramp than to lift it up directly. Greater the length of the ramp, lesser the force required to push the object up. 8. Correct Answer: C Explanation: Work done is the product of the force applied and the distance moved in the direction of the force. In both the cases, this product is equal to 80 joules. Therefore, Harry and Joshua do the same amount of work. 9. Correct Answer: B Explanation: It is easier to apply a downward force than an upward force. The pulley changes the direction of the downward force and helps Harry to lift up the water from the well. However, this pulley does not change either the amount of force applied or the total amount of work done. 10. Correct Answer: B Explanation: Energy cannot be created or destroyed. It can only be transferred and transformed. The energy used by Joshua came from the food he ate. This energy is stored as chemical energy in his muscles. When Joshua lifts the weights, he does work on them. Some of the energy is transferred to the weights and is stored as potential energy. Some of the energy is transferred to the surroundings as heat and is lost.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Physical Science ­ Force, Work and Energy Figure it out Question: In an experiment Harry used a pulley to lift a box that weighed 20 Newtons through a height of 2 meters. He measured the force required to lift the box and the distance moved by the force and recorded his measurements in a table. Do you think his measurements are accurate? Explain your answer.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Physical Science ­ Force, Work and Energy Figure it out Solution: If Harry’s measurements were accurate, the work done by the pulley is 40 Joules and the work done on the pulley is 30 Joules. According to the law of conservation of energy, the output energy can never be greater than the input energy which means the work done by the machine can never be greater than the work done on it. Therefore, we can conclude that Harry’s measurements must be incorrect.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key G7­Life Science ­ Forces Affect Plant Growth 1. Correct Answer: B Explanation: Geotropism is the movement of a plant in response to gravity. Roots are positively geotropic because they grow in the same direction as the force of gravity; towards the center of Earth. 2. Correct Answer: A Explanation: Geotropism is a plant’s response to Earth’s gravitational field. 3. Correct Answer: D Explanation: Turgor pressure is the force water exerts on the cell walls of a plant cell, helping to support a nonwoody plant so it stands upright and keeps its shape. Without turgor pressure, a plant wilts. 4. Correct Answer: A Explanation: Both germination and turgor pressure are the result of a pushing force. Germination begins when a seedling soaks up enough water that causes the embryo to swell and PUSH the seed coat apart, and turgor pressure is the force of water PUSHING outwards on a plant’s cell wall. 5. Correct Answer: C Explanation: When a seed soaks up water, it starts to swell and grow, exerting a force that pushes outwards. This force splits the seed coat and enables a seedling to emerge. 6. Correct Answer: C Explanation: Turgor force is the force exerted outward on a cell wall by the water contained in a plant. Turgor force causes a nonwoody plant to be rigid, or stand upright. 7. Correct Answer: D Explanation: In order for motion to occur in any living or nonliving object, a force must be applied. 8. Correct Answer: A Explanation: Negative geotropism is the upward growth of a plant’s stems and leaves against the force of gravity. Positive geotropism, on the other hand, is the downward growth a plant’s roots in the same direction as the pull of gravity, towards the center of Earth.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited 9. Correct Answer: C Explanation: Turgor pressure is the force exerted outwards by water stored in plant cells. If a plant does not have enough water in its cells, it will wilt. Because almost all the plants in Area A are wilted, you can infer that the area received little or no rainfall compared to the other areas. 10. Correct Answer: B Explanation: Roots growing downward toward the center of Earth is an example of positive geotropism because the roots are moving in the same direction as the force of gravity.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Forces Affect Plant Growth Figure it out Question: Jesse’s bought his mom a potted plant for her birthday. She really likes the plant, but is not a good gardener, so she thinks the plant will start to wilt. Jesse assures her that something as simple as a “force” can help the plant keep its shape. Explain which force Jesse is talking about and how that force helps a plant keep its shape.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Forces Affect Plant Growth Figure it out Solution: The force Jesse is talking about is turgor force. When a plant is watered, water collects in the plant cells and pushes outward against the cell wall. This “turgor force” helps to keep a plant rigid so it can keep its shape.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key G7­ Life Science ­ Catastrophic Events and Ecosystems 1. Correct Answer: B Explanation: Tornadoes, floods, and hurricanes are weather events. Volcanoes and earthquakes are events created by the movement of Earth’s surface. 2. Correct Answer: B Explanation: Since storm surges come from the ocean, the salinity of freshwater will increase. This added salt content will hinder the growth of freshwater plants. 3. Correct Answer: D Explanation: Ecosystems can be small or large with borders that are not obvious or fixed. They include all the biotic and abiotic things within a particular area. 4. Correct Answer: C Explanation: During a storm surge, a lot of sediment is eroded from the shore and from inland areas. This sediment can cover up and smother many living things in the region. 5. Correct Answer: D Explanation: Flooding has a mostly positive effect on natural areas that have adapted to periodic flooding. Human communities that are located near areas that flood periodically are often damaged by the flooding. 6. Correct Answer: C Explanation: Fires in a forest ecosystem can affect both the biotic and abiotic parts in the ecosystem. 7. Correct Answer: A Explanation: Floods can eliminate plants that are not tolerant to flooding. 8. Correct Answer: C Explanation: Fire burns all the organic matter in the forests and releases nutrients. These nutrients mix with the soil, resulting in nutrient recycling. 9. Correct Answer: C Explanation: The longleaf pine cones open up and release seeds only at very high temperatures. If fire is suppressed, the pine cones will not be able to release the seeds. This will lead to a decline in their number.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited 10. Correct Answer: C Explanation: Since plant A suffers after a hurricane and thrives after a heavy rainfall, it does best in low salinity water and soil. Since plant B thrives in a hurricane and suffers after heavy rainfall, it does best in high salinity water and soil.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­ Life Science ­ Catastrophic Events and Ecosystems Figure it out Question: A hurricane hit the Gulf Coast of Texas near an estuary at the mouth of a large river. Two years later, the same estuary was flooded by unusually heavy rainfall upriver. Compare the impacts of the two events on the estuary ecosystem.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­ Life Science ­ Catastrophic Events and Ecosystems Figure it out Solution: The storm surge of the hurricane would increase the salinity of the water in the estuary, while the flooding would decrease the salinity. The hurricane would result in a short­term decrease of freshwater organisms. The flooding would not decrease the freshwater organisms. In the short­term, both events would increase the overall amount of water in the estuary. The hurricane may deposit eroded sediment from the shoreline into the estuary, which could bury and kill organisms.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key G7­Earth and Space Science ­ Slow Changes in Ecoregions 1. Correct Answer: D Explanation: Oxidation is the result of a chemical reaction between iron and oxygen. Oxidation in rocks alters their chemical composition. Therefore, oxidation is an example of chemical weathering. 2. Correct Answer: A Explanation: Weathering is any process that breaks down rock into smaller pieces. Mechanical weathering breaks down rocks by physical means, changing the size, but not the composition of the rock. Chemical weathering breaks down rock through chemical reactions, changing the composition of the rock. 3. Correct Answer: A Explanation: Abrasion is the process in which rocks are worn down by friction. In this example, we know that the stones were worn down because they reduced in size, and there is a layer of sediment left at the bottom of the jar. We can also deduce that there was friction between the stones because the jar was shaken several times each day. 4. Correct Answer: A Explanation: Abrasion is the rubbing of one object or surface against another. When Jennifer shakes the jar full of stones, the stones rub against one another, causing the stones to slowly wear away. 5. Correct Answer: D Explanation: Deposition is the process in which material such as sediment is added to a landform, building up Earth’s surface. Sand dunes, alluvial fans, and deltas are all examples of deposition because they build up Earth’s surface. A canyon is formed when Earth’s surface is worn away. Weathering and erosion are processes that carve out canyons. 6. Correct Answer: B Explanation: Bubbles indicate that some kind of chemical reaction is taking place. Chemical weathering is the process that breaks down rocks through chemical reactions; therefore, the bubbling rocks are probably being chemically weathered. 7. Correct Answer: D Explanation: Saltation is the process in which wind causes particles of sand to bounce across a surface. Each particle, in turn, causes the neighboring particle to bounce and move in the direction of wind.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited 8. Correct Answer: B Explanation: Both deltas and alluvial fans are the result of deposition, but a delta is a deposit at the mouth of a stream or river, while an alluvial fan is a fan­shaped deposit at the base of sloping surface on dry land. 9. Correct Answer: A Explanation: When moving water, wind, or ice slow down, or stop, the particles they were carrying, drop or settle on Earth’s surface. Because the water is traveling the slowest at point A, that is probably the point where most deposition is taking place. 10. Correct Answer: B Explanation: Acid rain falls to Earth when precipitation in the atmosphere picks up pollution, such as sulfuric acid emitted from factories. Because it is acidic, it speeds up the process of chemical weathering.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Earth and Space Science ­ Slow Changes in Ecoregions Figure it out Question: What role does water play in the process of erosion and deposition?
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Earth and Space Science ­ Slow Changes in Ecoregions Figure it out Solution: Running water picks up and carries up loose, weathered materials as it flows over Earth’s surface. The faster the water flows; greater is the amount of materials transported by running water. When water slows down or stops flowing, the materials it was carrying drop down, or settle, building up the Earth’s surface.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key G7­Earth and Space Science ­ Watersheds 1. Correct Answer: D Explanation: Water drains through a watershed to the lowest point. Because the lowest point is the ocean, water that enters the watershed at the top of the snow­capped mountain will eventually travel all the way to the ocean. 2. Correct Answer: C Explanation: According to the information presented in the graph, the number of incidents of stream pollution decreased the same year the mayor mailed out the pamphlets, and continued to remain low every year the pamphlets were mailed. 3. Correct Answer: D Explanation: Watersheds make up every part of Earth’s surface. 4. Correct Answer: D Explanation: Watersheds are geographic areas in which rain, snow, sleet, or hail is collected and drained to a certain area such as a river, stream, lake, or ocean. Watersheds are also referred to as drainage basins. 5. Correct Answer: A Explanation: Boundaries of a watershed are the highest points in the area and determine which way the water will flow when it falls to Earth’s surface. 6. Correct Answer: D Explanation: Reading a book is least likely to affect watersheds. Airplanes emit exhaust into the air that can be carried by rain into watersheds; cutting down trees can speed up erosion in watersheds; chemicals from fertilizers can be washed away with runoff and carried into rivers and streams. 7. Correct Answer: C Explanation: Both surface and groundwater can be polluted through human activities. Groundwater is polluted indirectly when water dissolves pollutants on Earth’s surface and infiltrates the soil, carrying the pollutants to the groundwater. Surface waters can be polluted directly and indirectly. 8. Correct Answer: D Explanation: Water coming out of a faucet is captured in the basin and travels to the lowest point of a sink ­ the drain. Similarly, water captured in a watershed drains to the lowest source in the area, usually a stream, river, lake, bay, or ocean.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited 9. Correct Answer: B Explanation: All watersheds, no matter how big or how small, drain water to the lowest point in each watershed. 10. Correct Answer: C Explanation: Sediments are small pieces of rock, silt, sand, and plant or animal matter. Evaporation is the process of a liquid changing into gas. Because sediments are solids, they do not evaporate out of water.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Earth and Space Science ­ Watersheds Figure it out Question: A truck carrying chemicals overturns on a highway in the desert. The area is flat and there is not a stream in sight. Can the chemicals affect the water in the local watershed? Defend your answer.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Earth and Space Science ­ Watersheds Figure it out Solution: Yes, the chemicals can affect the water in a number of ways. Although it doesn’t rain often in the desert, when it does rain, water will flow across the surface of the road, picking up any chemicals that remain from the crash and carrying them to a river or stream far away. In addition, because water is a solvent, it might dissolve the chemicals instead and carry the contaminants over land, or infiltrate the soil and carry the pollutants to the groundwater.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key G7­Earth and Space Science ­ Life in Our Solar System 1. Correct Answer: A Explanation: The amount of gravitational pull a planet has depends partly on the planet’s mass. The more massive a similarly sized planet is, the stronger the gravitational pull. 2. Correct Answer: A Explanation: Ozone is the form of oxygen made up of three oxygen atoms (O3) that absorbs the harmful radiation from the Sun; therefore, if harmful radiation is being absorbed in the stratosphere, ozone must be present. 3. Correct Answer: B Explanation: Nitrogen makes up 78% of Earth’s atmosphere, oxygen makes up 21%, and other gases such as carbon dioxide and water vapor make up about 1%. 4. Correct Answer: A Explanation: Like the glass panes on a greenhouse, the atmosphere lets sunlight in but does not let all the heat produced by the sunlight back out again, making temperatures comfortable for life to exist on Earth. 5. Correct Answer: D Explanation: Carbon dioxide absorbs heat radiated off of Earth’s surface and water vapor absorbs heat coming directly from the Sun. Without greenhouse gases, heat would escape back into space and Earth’s average temperature would be a lot colder. 6. Correct Answer: C Explanation: The oxygen we breathe is made up of two oxygen atoms. Ozone is made up of three oxygen atoms. Ozone high in the atmosphere protects us from harmful radiation coming from the Sun. 7. Correct Answer: A Explanation: Gravitational pull is directly related to mass. The gravitational pull on Jupiter is stronger than on Earth, because Jupiter much more massive than Earth. Mercury has less gravitational pull because it is smaller and less massive compared to Earth. 8. Correct Answer: C Explanation: Earth is the third planet from the Sun, just the right distance to keep the planet from getting too hot or too cold.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited 9. Correct Answer: D Explanation: The ozone layer, high in the atmosphere, is a form of oxygen that absorbs harmful radiation coming from the sun. 10. Correct Answer: B Explanation: Engineers have developed a Water Recycling System for the International Space Station that takes wastewater produced from daily activities, such as brushing teeth and washing hands, and purifies it through machines to be used again.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Earth and Space Science ­ Life in Our Solar System Figure it out Question: The chart below compares some of the features found on Earth and Mars. Based on the information in the chart, do you think Mars can support life? Defend your answer.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Earth and Space Science ­ Life in Our Solar System Figure it out Solution: Mars cannot support life as we know it from the following reasons:
· The atmosphere of Mars contains very little oxygen, the element all living things need to survive.
· Mars is farther from the sun; therefore, temperatures are mostly like a lot cooler.
· Plants, the basis of food chains, probably would not receive enough light to undergo photosynthesis.
· Mars does not have enough liquid water to support life, and the only water found is frozen. Living things need liquid water to transport food, eliminate waste, and carry out chemical reactions to grow and move.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key G7­Life Science ­ Diversity of Life 1. Correct Answer: B Explanation: The more variety there is in an ecosystem, the better chance it has to sustain itself over time because it is more able to withstand external stresses such as disease, extreme weather, or detrimental human activities. 2. Correct Answer: A Explanation: An ecosystem is a community of all the living and nonliving things that interact in a particular area. 3. Correct Answer: C Explanation: The more varied and diverse an ecosystem is, the better chance it has to withstand outside environmental stresses. Because Ecosystem B has a greater number of different plant and animal species compared to Ecosystems A and C, it has the best chance of sustaining itself. 4. Correct Answer: D Explanation: The term “abiotic” means nonliving. Water availability, rainfall, and temperature are nonliving; therefore, they are abiotic factors that influence the environment. Animals are biotic, or a living part of an environment. 5. Correct Answer: D Explanation: A desert environment is typically hot and dry with sandy soil. A tan coyote with short fur would be best suited for such an environment because its coloration would help it blend in, and its thin, short fur would prevent it from becoming over­heated. 6. Correct Answer: C Explanation: A seed without adaptations to survive dry and cold environmental conditions could be best suited for life in a tropical rain forest because warm temperatures and abundant rainfall are common throughout the entire year. 7. Correct Answer: C Explanation: All the marks showing the locations of the crabs are concentrated on the southern side of each island. No crabs were found on the eastern, western, or northern beaches; therefore, the southern beaches must have an environment that is better suited for the crab. 8. Correct Answer: A Explanation: Environments are typically categorized according to the amount of rainfall they receive annually, and the average temperature
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited 9. Correct Answer: C Explanation: Both are grasslands, but savannas are found in warm or hot climates, while temperate grasslands are found in areas with warm summers and cool winters. 10. Correct Answer: B Explanation: Based on the information in the graph, both the tundra and desert received about 10 inches of rain last year.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Diversity of Life Figure it out Question: The pictures below show the feet of two very different organisms. The first foot is webbed and the second foot is covered with thick, white fur. Without knowing anything else about the organisms, which type of environment do you think each is best adapted? Explain your answer.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Diversity of Life Figure it out Solution: Webbed feet enable an organism to swim quickly through the water; therefore, the organism with webbed feet is best suited for a marine or aquatic environment. The organisms with thick, white, fur is probably best suited for life in an Arctic environment, such as the tundra, because the thick fur can help to protect it from the cold. The white color can also help it to blend in with snow on the ground, so it can approach prey, or hide from predators.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key
G7­Life Science ­ Ecological Succession 1. Correct Answer: C Explanation: Ecological succession is the gradual change in plant and animal life in an ecosystem over time. Ecological succession may occur rapidly or slowly. 2. Correct Answer: A Explanation: Because secondary succession occurs in areas where an ecosystem previously existed, the soil generally has a lot of nutrients allowing plants to grow more quickly than in the nutrient­poor soil associated with primary succession. 3. Correct Answer: C Explanation: Primary succession takes place when plants and animals grow and develop in previously barren areas, such as volcanic islands or bare rock. 4. Correct Answer: C Explanation: A climax community is a stable community that typically has a large, diverse population of living things. Because the diagram in this answer has a more diverse and developed community compared to the other answer choices, it best represents a climax community. 5. Correct Answer: C Explanation: Secondary succession occurs in areas where an ecosystem previously existed, but was destroyed or damaged by events such as forest fires, landslides, floods, or clear­ cutting. 6. Correct Answer: D Explanation: The information on the horizontal axis shows that as the age of the ecosystem increases, the number of species increased from 0 to 25,000 species. 7. Correct Answer: C Explanation: Pioneer species are species that develop best when there is little or no competition for resources; therefore, pioneer communities are dominant during the early stages of ecological succession. 8. Correct Answer: A Explanation: As ecological succession progresses, more nutrients are available because of the organic matter left behind by the previous species. With more nutrients available, more species move in to establish a habitat.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited 9. Correct Answer: C Explanation: Ecological succession usually begins in areas where there is no biological community. Natural disasters, such as flooding, forest fires, and volcanic eruptions, can clear the land, causing the process of ecological succession to begin. Rain showers do not typically clear the land. 10. Correct Answer: C Explanation: During the process of ecological succession, organisms die. When they die, they decompose, adding more nutrients to the soil. As more nutrients become available, more organisms move in. An area that contains a lot of different plant and animal species most likely contains nutrient­rich soil.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Ecological Succession Figure it out Question: The volcanic island on the left gradually changed into the lush, tropical island you see on the right. Scientists who are studying the island have discovered that the plant and animal species that lived on the island 200 years ago, are the same species found on the island today. In what stage of ecological succession is the island?
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Ecological Succession Figure it out Solution: The island has a stable community of plants and animals; therefore, it has reached the last stage of ecological succession called a climax community. This is evident because the population of species on the island has not changed during the past 200 years. A community reaches stability when the same species exist for hundreds or even thousands of years. In addition, tall trees, such as the ones found on the island, are typically the dominant species in a climax community.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key G7­Life Science ­ Using Dichotomous Keys 1. Correct Answer: B Explanation: Danielle is classifying, or grouping and categorizing the coins by type. 2. Correct Answer: C Explanation: Traits are used to identify and classify organisms. 3. Correct Answer: D Explanation: Over half of the animal kingdom species are arthropods. 4. Correct Answer: D Explanation: A salamander is an amphibian; one of the groups of the animal kingdom. 5. Correct Answer: C Explanation: The chart shows that only these three animals share all of the same traits. These animals are arthropods. 6. Correct Answer: C Explanation: The chart shows that a jellyfish has none of these traits. 7. Correct Answer: A Explanation: The raptor­like beak is best for tearing flesh because it is curved and sharp. 8. Correct Answer: A Explanation: A dichotomous key is a tool based on observable traits. None of the other items are tools used by scientists. 9. Correct Answer: B Explanation: The term comes from the Greek “dich­” and “temnein.” This became the Latin “dichotomos” meaning “divided into two parts.” 10. Correct Answer: C Explanation: Color, size and shape are very general traits. Plants grow and can change color and shape depending on environmental conditions and the season. In addition to leaf type, there are other physical features, like twigs and bark, that can be used as part of a dichotomous key for trees.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Dichotomous Keys Figure it out Question: Consider the following imaginary animals. They are similar, but each is a unique kind of animal. Use the dichotomous key to identify each animal by name.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Dichotomous Keys Figure it out Solution: This key first divides animals into two groups, those with ears and those without. Within each of these subgroups, there are further distinctions based on other traits such as number of legs, or whether or not there is a tail, a hump, or a nose. A. Taurus necaudi B. Taurus caudus C. Taurus sixleggus D. Taurus reddi E. Taurus nosmellum F. Taurus humpis
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G7­Life Science ­ Variability and Survival 1. Correct Answer: D Explanation: Natural selection is the process in which only the organisms best suited to an environment survive. If only brown lizards are able to reproduce and survive, they are an example of an organism best suited to a particular environment. 2. Correct Answer: A Explanation: An adaptation is a physical, behavioral or physiological change that happens gradually over generations, enabling the species to survive in its environment. 3. Correct Answer: A Explanation: Variations or differences in physical, behavioral, or physiological traits, helps species and populations survive. 4. Correct Answer: C Explanation: Organisms migrate for one of the three following reasons ­ to reproduce where babies have a better chance of surviving, to find or get more food, or to find a more suitable climate if it gets too hot or too cold. 5. Correct Answer: B Explanation: Based on the information in the graph, the population of the green spiders is the only population increasing. The population of all the other spiders is decreasing over time; therefore, the green spiders are most likely best suited for this particular habitat. 6. Correct Answer: A Explanation: Because habitats overlap, there are many different organisms in each habitat, each competing for the same resources. 7. Correct Answer: B Explanation: If there was no variation in the size of the species and predators ate only that one particular size, the species would most likely become extinct. In addition, once the species became extinct, the predators ability to survive would also be threatened as their food source would no longer be available. 8. Correct Answer: A Explanation: Migration and hibernation are both responses to a change in environment that help organisms and species survive.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited 9. Correct Answer: A Explanation: Bioluminescence is the process in which chemicals within an organism’s body produce light. This trait helps some organisms attract mates, attract prey, or warn off predators. 10. Correct Answer: D Explanation: When it gets too cold, a ground squirrel needs to eat more food to keep warm, but food is often hard to find during the winter. Therefore, ground squirrels hibernate, or become inactive for the purpose of conserving energy until more food becomes available again.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Variability and Survival Figure it out Question: The table below shows how a specific wolf population gradually changed over time. Based on the information in the table, how do you think this population of wolves’ environment changed over the past 500 years? What evidence in the table supports your hypothesis?
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Variability and Survival Figure it out Solution: The environment probably changed from a warm climate to a cool climate, because the wolves’ traits today are better suited for a cool climate. An increase in weight and long, thick fur helps protect wolves from cold climates. White fur can help camouflage wolves in the snow so they can hunt for prey, or hide from predators.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key G7­Life Science ­ Natural Selection and Selective Breeding 1. Correct Answer: C Explanation: Organisms best adapted to a particular environment have the best chance of surviving, reproducing, and passing on those favorable adaptations or traits to the next generation. 2. Correct Answer: D Explanation: Selective breeding is the process in which organisms are bred for the purpose of passing on specific or favorable traits to the next generation. 3. Correct Answer: A Explanation: Natural selection is the process in which only the organisms best suited to an environment survive. The pictures best demonstrate natural selection, as brown mice were the only ones that were able to survive and reproduce over time. 4. Correct Answer: C Explanation: The statement describes how to breed organisms with specific traits to influence the traits of the next generation. This process is called selective breeding. 5. Correct Answer: C Explanation: The information on the graph indicates that natural selection is taking place at Burke Lake because the population of finches with thin beaks increased over time, while the population of finches with wide beaks decreased over time. This trend indicates that thin­beaked finches are better suited to the environment at Burke Lake. 6. Correct Answer: D Explanation: Selective breeding is the process of breeding organisms with specific traits to influence the traits of the next generation. Labrador retrievers are easy to train but shed a lot of fur. Poodles are not as easy to train, but shed very little fur. Breeders crossed the two species hoping the next generation would have the best genetic traits of both dogs. The result was the development of a new breed called a labradoodle; a dog that sheds very little fur, and is easy to train. 7. Correct Answer: B Explanation: Humans choose the organisms that will reproduce during selective breeding in order to influence specific traits they would like to see passed down to future generations. [
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited 8. Correct Answer: B Explanation: Selective breeding is the process in which organisms are breed for the purpose of passing on specific or favorable traits to the next generation. Inbreeding is a type of selective breeding that crosses two organisms with similar genetic traits. Hybridization is a type of selective breeding that crosses two organisms with different genetic traits. 9. Correct Answer: D Explanation: Red coloring is most likely an advantageous trait, because the population of red ladybugs increased over 15 years, while the population of yellow, spotted ladybugs decreased. The red­colored ladybugs appear to be better suited to this particular environment. 10. Correct Answer: B Explanation: Hybridization is a form of selective breeding in which two organisms with different genetic traits are bred so that the offspring will inherit the best traits from both parents.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Natural Selection and Selective Breeding Figure it out Question: There was a large population of woodpeckers living in a forest. Some of the woodpeckers had long beaks, some had short beaks. During a very rainy year, the bark on most of the trees in the forest grew very thick. Only the woodpeckers with the longest, strongest beaks could drill deep enough into the thick bark to find the insects they depend on for food. Woodpeckers with short beaks could not drill in deep enough to reach the insects. If the rainy weather continues for several years, what do you expect would happen to the woodpecker population because of natural selection?
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Natural Selection and Selective Breeding Figure it out Solution: Woodpeckers with shorter beaks will not be able to get enough food to survive and reproduce. Only those woodpeckers with the longest, strongest beaks would live long enough to reproduce and pass their traits. There is a high probability that most of the offspring will also have longer, stronger beaks. Over time, if the rain continues, the entire population of woodpeckers will have longer, stronger beaks.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key G7­Life Science ­ Internal Structural Adaptations 1. Correct Answer: C Explanation: Hibernation is a physiological adaptation that helps some organisms survive long periods of cold weather when food is most scarce. 2. Correct Answer: A Explanation: Structural adaptations are adaptations which deal with the structure or body of an organism. 3. Correct Answer: C Explanation: Since thick fur is a visible structure, it is an external adaptation. 4. Correct Answer: B Explanation: Gills allow fish to breathe underwater by taking in oxygen and expelling carbon dioxide. 5. Correct Answer: C Explanation: Hollow bones make the skeleton of the bird light enough to fly. 6. Correct Answer: A Explanation: Xylem is the straw­like tissue that transports water from the roots throughout the plant. 7. Correct Answer: B Explanation: Phloem transports sugar produced during photosynthesis from the leaves throughout the plant. 8. Correct Answer: A Explanation: Webbed feet help an organism to push against the water and swim. 9. Correct Answer: B Explanation: The sharp, pointy, curved beak allows a bird to grasp and tear meat. 10. Correct Answer: C Explanation: The thick, white fur helps the polar bear camouflage itself in the snow. It also helps the bear warm.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Internal Structural Adaptations Figure it out Question: Cacti are one of the few plants that can live in the desert. What are some structural adaptations that allow a cactus plant to thrive in this hot, dry environment? Explain how each adaptation helps cacti survive.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Internal Structural Adaptations Figure it out Solution: Sharp Spines: a) Discourage animals from eating them. b) Downward­pointing spines help to direct rainwater to the roots of the plant. c) Help to reflect light away from the cactus stem, lowering the stem’s temperature. d) Some spines trap in a layer of air next to the cactus stem, which helps to prevent water evaporation. e) Provides shade to the stems of the cactus keeping it cool. f) Allow photosynthesis to occur in drought like conditions. Roots: Close to surface of the soil to take in as much water as possible during rainfall. Leaning: Some cacti lean to the south to minimize the surface area that is exposed to the drying effect of the sun. Plant Body: Some cacti are thick. This helps them retain water. Other cacti have pleats or folds that allow them to expand to hold more water. Stems: Have a waxy coating to prevent water loss.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key G7­Life Science ­ Human Body Systems 1. Correct Answer: C Explanation: Lungs remove the waste products­carbon dioxide and water vapor. The kidneys remove wastes like salts, excess protein, and water from the blood, which collect as urine. Urea containing wastes of protein­breakdown passes out through the skin. The heart pumps blood throughout the body, and has no direct excretory function. 2. Correct Answer: B Explanation: The center of the bone is a hollow space that contains a soft tissue called marrow. The marrow in bones produces blood cells. A disease affecting the bone marrow will result in a problem with the production of blood cells. 3. Correct Answer: D Explanation: The function of the digestive system is to carry out the process of breaking down food into simpler substances that can be used by cells. The mouth, the esophagus, the stomach, the small intestine, and the large intestine are some of the main organs in the digestive system. 4. Correct Answer: B Explanation: The cerebellum has most likely been affected. It is positioned in the lower part of the brain on the back side of the skull. The cerebellum controls muscle coordination and balance. Injury to this part of the brain can cause slurred speech and difficulty standing. It is important to wear protective head gear whenever it’s possible that a head injury might occur. 5. Correct Answer: A Explanation: In the small intestine, the nutrients from food are absorbed into capillaries through tiny threadlike structures called villi. 6. Correct Answer: C Explanation: An artery is a blood vessel that carries blood away from the heart. A vein carries blood to the heart. 7. Correct Answer: D Explanation: The skeletal system is made up of bones that support the body, give it shape, and enable movement from place to place. The muscular system is made up of all the muscles of the body that cause movement of body parts.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited 8. Correct Answer: B Explanation: The skeletal system is made up of bones that support the body, give it shape, and enable movement from place to place. But bones cannot move unless skeletal muscles move them. All systems including the skeletal system and the muscular system are controlled by the nervous system. 9. Correct Answer: C Explanation: Chewing is the first step in mechanical digestion. Food is broken into small pieces by the teeth. The tongue pushes food around to help further break it up. 10. Correct Answer: D Explanation: Within the lungs, tiny air sacs called alveoli exchange gases between the air and the blood. Since the incoming air is rich in oxygen, the oxygen from incoming air passes into the blood. The blood coming to the alveoli in the lungs is filled with carbon dioxide, so the carbon dioxide passes from the blood into the lungs.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ The Human Body Figure it out Question: What would happen if the muscles of the heart and the stomach were voluntary muscles?
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ The Human Body Figure it out Solution: If the muscles of the stomach were voluntary, we would have to “think” and consciously move our food through the stomach and the intestines. Similarly, if the heartbeat was under our control, we would have to consciously make an effort to contract and relax the muscles for each beat. Considering how important these two organs are for life, if we “forgot” to move our food or make our heartbeat, we would not survive!
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key G7­Life Science ­ Cell to Organisms 1. Correct Answer: A Explanation: If cells did not specialize, every living organism would be made up of only one cell because it would have to perform all the necessary functions for life. 2. Correct Answer: C Explanation: The cell is the smallest and least complex structure listed. Cells work together to form tissues. Tissues work together to form organs, which work together to form organ systems. Organ systems work together to form an organism. 3. Correct Answer: B Explanation: A paramecium is unicellular. Its one cell performs all necessary functions for life. 4. Correct Answer: B Explanation: The lungs, heart, stomach, and brain are all made up of more than one type of tissue. An organ is a structure made of different types of tissue that must work together. 5. Correct Answer: A Explanation: Although plant roots contain all types of tissues, their main function is to absorb water and minerals. Other functions such as absorbing light, releasing oxygen, and performing photosynthesis take place in the leaves. 6. Correct Answer: D Explanation: Flowers are the reproductive organs in plants, because they give rise to seeds. 7. Correct Answer: C Explanation: By definition, a digestive system is an organ system. So it must contain organs with different specialized functions. 8. Correct Answer: B Explanation: The movement of materials is called transport. It’s is not necessary to have a circulatory system to transport materials. A circulatory system is found in more complex organisms.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited 9. Correct Answer: A Explanation: A leaf, no matter what size or shape, is always a plant organ. There is not enough information to determine whether the leaves are from plants that produce seeds in flowers or whether they can be found in the United States. Plants do not contain epithelial tissues. 10. Correct Answer: D Explanation: Animals also have reproductive organs like ovaries and testes, transport organs like heart and blood vessels, organs that use light, like eyes, but only plants produce seeds.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Cell to Organisms Figure it out Question: The picture below shows the root system of a plant known as a mangrove tree. It is very different from most root systems, because much of the root system is above the ground. Based on what you know about the function of a root system, why do you think mangrove trees have root systems above the ground? Explain your answer.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Cell to Organisms Figure it out Solution: When the roots of a tree are found in water, there is not a lot of sediment or soil to help support the plant. Plants that live in water or water­logged soil need much more support than plants growing in your garden. Plants like a mangrove tree grow roots descending from the trunk and branches of the shoot system, providing a stable support for the tree.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key G7­Life Science ­ Plant Vs Animal Cell 1. Correct Answer: C Explanation: As per the principles of the cell theory, new cells can only come from pre­ existing cells and cannot develop from nonliving things. 2. Correct Answer: B Explanation: Both prokaryotic and eukaryotic cells have a jelly­like material called cytoplasm, which is enclosed by a cell membrane. 3. Correct Answer: C Explanation: Cellular respiration is the process by which energy is produced in a cell. Most of the reactions for cellular respiration take place in the mitochondria in a eukaryotic cell. 4. Correct Answer: A Explanation: When the cells are kept in water, both cells will absorb water. But unlike plant cells, animal cells do not have a rigid cell wall, so they will burst after sometime. 5. Correct Answer: B Explanation: The cell theory was formulated only after scientists were able to observe cells under the microscope. 6. Correct Answer: D Explanation: The nucleus controls all activities that take place inside the cell, just as the central nervous system controls everything that takes place inside the human body. 7. Correct Answer: D Explanation: The cell wall and chloroplast are structures present only in a plant cell. Cell A has no cell wall and no chloroplast, whereas, Cell B has a cell wall and chloroplast. 8. Correct Answer: B Explanation: Plant cells generally have big vacuoles inside them. 9. Correct Answer: C Explanation: The cell membrane is a semipermeable membrane and only allows certain substances to pass through it. 10. Correct Answer: A Explanation: According to the cell theory, all living organisms are made up of cells. As these organisms are not made up of a cell, they should be categorized as nonliving.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Plant Vs Animal Cell Figure it out Question: Three different types of cells ­ A, B and C were studied. It was found that cell A did not have any mitochondria, cell B had a few, and cell C had many mitochondria present inside. What can you tell about the type of cell and its activity based on this information?
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Plant Vs Animal Cell Figure it out Solution: Total lack of mitochondria is a characteristic of prokaryotes. Cell A is a prokaryotic cell, whereas, Cell B and C are eukaryotic cells. The number of mitochondria in a cell depends on the cell's energy demands. Cells with particularly heavy energy demands, such as muscle cells, have more mitochondria than other cells with low energy demands, like the kidney cell. Therefore, cell B is a type of cell with less energy demands, and Cell C is a type of cell with heavy energy demands.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key G7­Life Science ­ Stimulus and Response 1. Correct Answer: B Explanation: A response is the resulting act of a stimulus. 2. Correct Answer: C Explanation: Senses allow us to detect stimuli. Without senses we are unable to be stimulated, which is necessary to respond. 3. Correct Answer: D Explanation: The flash is a stimulus that occurs outside of your body; therefore, it is an external stimulus. 4. Correct Answer: C Explanation: Pain comes from within the body; therefore, it is an internal stimulus. 5. Correct Answer: D Explanation: The rabbit’s action of running and hiding is in response to the fox chasing it (the stimulus). 6. Correct Answer: A Explanation: Homeostasis is the body's ability to regulate its inner environment in response to fluctuations in the outside environment. 7. Correct Answer: C Explanation: Phototropism is when a plant grows toward the Sun so that its leaves can absorb maximum light energy for photosynthesis. 8. Correct Answer: B Explanation: The animal must decide between fighting or running, both of which require the use of muscles. 9. Correct Answer: D Explanation: Any behavior that does not have to be taught, such as spider’s ability to spin a web, is called an instinct. 10. Correct Answer: B Explanation: The student was not born with the knowledge but acquired it by being taught; therefore, this is an example of a learned behavior.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Stimulus and Response Figure it out Question: When can cause a baby to respond by crying­an internal or external, stimulus or both? Support your answer with examples.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Stimulus and Response Figure it out Solution: A baby crying could be a response to an internal or external stimulus. The baby could be hungry, which is an example of an internal stimulus, or the baby could have been frightened by a loud noise, which is an example of an external stimulus.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key G7­Life Science ­ Heredity and Genes 1. Correct Answer: C Explanation: Chromosomes are located inside the nucleus of all eukaryotic cells. 2. Correct Answer: D Explanation: Each and every cell in a living organism has DNA or genetic information stored inside it. 3. Correct Answer: B Explanation: Each of the cells in the human body has the same kind of genes regardless of their function, shape, and size. Other than reproductive cells, all cells in the human body have the same number of chromosomes. 4. Correct Answer: B Explanation: Other than reproductive cells, all the cells in a particular organism will have the same number of chromosomes. 5. Correct Answer: B Explanation: Twins generally resemble each other because they inherit the same set of genes from their parents. 6. Correct Answer: B Explanation: Chromosomes come in pairs and an organism gets one chromosome of each pair from its mother and another from its father. This always results in an even number. 7. Correct Answer: A Explanation: Picture A has characteristics of both the dalmatian and the bulldog. 8. Correct Answer: D Explanation: Each gene is present in pairs and an organism gets one copy of each gene from both its parents. 9. Correct Answer: B Explanation: A is a nucleus, B is a chromosome, C is DNA, and D is a gene. Genes are segments of DNA on a chromosome located inside the nucleus. 10. Correct Answer: D Explanation: Though the number of chromosomes in both a lima bean and opossum are the same, they have different genes located on the chromosomes. The way an organism looks depends on the kind of genes and not their chromosome number.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Heredity and Genes Figure it out Question: During crime investigations, the police collect drops of blood, skin fragments, hair, and other clues from the scene of the crime. How are crime investigators able to solve the case based on this evidence?
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Heredity and Genes Figure it out Solution: The samples collected from the crime scene are used for DNA analysis and are then compared with the DNA samples of the suspects. This gives investigators an idea of whether the suspect was present at the crime scene or not to help them solve the case. Just like your fingerprints, each person has a unique DNA; 99% of a cell’s DNA is identical between individuals, but the remaining 1% is different and that is what is used to identify a person. Scientists focus on this part of DNA and use it to generate a pattern, like a unique supermarket barcode. This process is referred to as DNA fingerprinting.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited Answer Key
G7­Life Science ­ Types of Reproduction 1. Correct Answer: A Explanation: Vegetative propagation is the development of a new plant, from the roots or stem of another plant. 2. Correct Answer: D Explanation: Offspring of a paramecium has the same genetic information because binary fission is a type of asexual reproduction. They are smaller, because the parent cell split in half. 3. Correct Answer: D Explanation: Spores are cells that are genetically identical to the one parent that released them. This is an example of asexual reproduction. 4. Correct Answer: A Explanation: Starfish can reproduce asexually by fragmentation. If the fragment contains a portion of the central disk, a whole new starfish can regenerate from each fragment. 5. Correct Answer: A Explanation: Strawberry plants can reproduce by vegetative propagation. Vegetative propagation is the development of a new plant from the roots or stem of another plant. 6. Correct Answer: A Explanation: In asexual reproduction, offspring are always genetically identical to one another. 7. Correct Answer: C Explanation: Organisms such as bread molds and mushrooms can reproduce asexually by forming spores. 8. Correct Answer: A Explanation: Sexual reproduction requires two parents. In the other examples, only one parent is necessary. 9. Correct Answer: D Explanation: Vegetative propagation is the development of a new plant from part of another plant. Although it was broken into fragments, reproduction by fragmentation only occurs in animals.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited 10. Correct Answer: D Explanation: The formation of seeds requires genetic information from two parents, so it is sexual reproduction.
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Types of Reproduction Figure it out Question: What effect would there be on the offspring produced, if asexual reproduction was the only form of reproduction?
© 2010 Edumatics Corporation. Reproduction or copying in any form is prohibited G7­Life Science ­ Types of Reproduction Figure it out Solution: If asexual reproduction were the only form of reproduction, there would be no genetic variation among the off spring. Without genetic variation, some species could possibly die out as they would have less opportunity to adapt to changes in their environment.
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