CHAPTER The Cell In Action SECTION 2 Cell Energy

NameCHAPTER 2ClassDateThe Cell in Action2 Cell EnergySECTIONNational ScienceEducation StandardsBEFORE YOU READAfter you read this section, you should be able to answerthese questions:LS 1c, 4c How do plant cells make food? How do plant and animal cells get energy from food?How Does a Plant Make Food?The sun is the major source of energy for life on Earth.Plants use carbon dioxide, water, and the sun’s energy tomake food in a process called photosynthesis. The foodthat plants make gives them energy. When animals eatplants, the plants become sources of energy for the animals.Plant cells have molecules called pigments that absorblight energy. Chlorophyll is the main pigment used inphotosynthesis. Chlorophyll is found in chloroplasts.The food plants make is a simple sugar called glucose.Photosynthesis also produces oxygen.READING CHECK1. Identify In which cellstructures does photosynthesistake place?Photosynthesis6CO2 6H2O light energyCarbonWaterdioxideSTUDY TIPCompare As you readthis section, make a VennDiagram to compare cellularrespiration and fermentation.C6H12O6 6O2Glucose OxygenPlant cellChloroplastTAKE A LOOK2. Identify What twomaterials are producedduring photosynthesis?Photosynthesis takes place in chloroplasts. Chloroplasts arefound inside plant cells.Copyright by Holt, Rinehart and Winston. All rights reserved.Interactive Textbook23The Cell in Action

NameSECTION 2ClassDateCell Energy continuedHow Do Organisms Get Energy from Food?STANDARDS CHECKLS 1c Cells carry on the manyfunctions needed to sustain life.They grow and divide, therebyproducing more cells. Thisrequires that they take innutrients, which they use toprovide energy for the work thatcells do and to make the materialsa cell or an organism needs.Word Help: functionto workWord Help: energythe capacity to do work3. Identify Name twoways cells can get energyfrom food.TAKE A LOOK4. Identify What twomaterials are needed forcellular respiration?Both plant and animal cells must break down foodmolecules to get energy from them. There are two wayscells get energy: cellular respiration and fermentation.During cellular respiration, cells use oxygen tobreak down food. During fermentation, food is brokendown without oxygen. Cellular respiration releases moreenergy from food than fermentation. Most eukaryotes,such as plants and animals, use cellular respiration.What Happens During Cellular Respiration?When you hear the word respiration, you might thinkof breathing. However, cellular respiration is differentfrom breathing. Cellular respiration is a chemical processthat happens in cells. In eukaryotic cells, such as plantand animal cells, cellular respiration takes place in structures called mitochondria.Recall that to get energy, cells must break down glucose. During cellular respiration, glucose is broken downinto carbon dioxide (CO2) and water (H2O), and energy isreleased. This energy is stored in a molecule called ATP(adenosine triphosphate). The figure below shows howenergy is released when a cow eats grass.C6H12O6 6O2GlucoseCellular respiration6CO2 6H2O energy (ATP)OxygenCarbondioxideWaterMitochondria5. List What three thingsare produced during cellularrespiration?Animal cellThe mitochondria in the cells of this cow will use cellular respiration to releasethe energy stored in the grass.Copyright by Holt, Rinehart and Winston. All rights reserved.Interactive Textbook24The Cell in Action

NameClassSECTION 2DateCell Energy continuedThe Connection Between Photosynthesisand Cellular RespirationCritical ThinkingCellular respirationCellular respiration releasescarbon dioxide and water.These are used by plant cellsin photosynthesis.(ATP)Lightenergy6. Apply Concepts Whatwould happen if oxygenwere not produced duringphotosynthesis?CO2 H2OMitochondrionChloroplastC6H12O6 O2PhotosynthesisPlant cellTAKE A LOOKPhotosynthesis usescarbon dioxide and waterand produces glucose andoxygen. Plant and animalcells use glucose andoxygen to make ATP incellular respiration.Animal cell7. Complete Plant andanimal cells use glucoseand oxygen to make.How Is Fermentation Different fromCellular Respiration?During fermentation, cells break down glucose withoutoxygen. Some bacteria and fungi rely only on fermentation torelease energy from food. However, cells in other organismsmay use fermentation when there is not enough oxygen forcellular respiration.When you exercise, your muscles use up oxygen veryquickly. When cells don’t have enough oxygen, they mustuse fermentation to get energy. Fermentation creates abyproduct called lactic acid. This is what makes yourmuscles ache if you exercise too hard or too long.Say ItResearch Use the schoollibrary or the Internet toresearch an organism thatuses fermentation. What kindof organism is it? Where is itfound? Is this organism useful to humans? Present yourfindings to the class.Copyright by Holt, Rinehart and Winston. All rights reserved.Interactive Textbook25The Cell in Action

NameClassSection 2 ReviewDateNSESLS 1c, 4cSECTION VOCABULARYcellular respiration the process by which cellsuse oxygen to produce energy from foodfermentation the breakdown of food withoutthe use of oxygenphotosynthesis the process by which plants,algae, and some bacteria use sunlight, carbondioxide, and water to make food.1. Identify What kind of cells have chloroplasts?2. Explain How do plant cells make food?3. Explain Why do plant cells need both chloroplasts and mitochondria?4. Apply Concepts How do the processes of photosynthesis and cellular respirationwork together?5. Compare What is one difference between cellular respiration and fermentation?6. Explain Do your body cells always use cellular respiration to break downglucose? Explain your answer.Copyright by Holt, Rinehart and Winston. All rights reserved.Interactive Textbook26The Cell in Action

CCells, Heredity, and Classification Answer Key continuedSECTION 2 CELL ENERGY2. No. Organs are made of tissues, so to have3.4.5.6.organs, an organism must have tissues.Function is the purpose of a part, or the jobthe part does. Structure is the arrangementof parts in an organism.Specialization of cells means that, inmulticellular organisms, different cellsperform different functions to help keepthe organism alive.An organ has to have two or more tissues.Tissues have to work together for an organto do a job.The life span of a multicellular organism is notlimited to the life span of any one of its cells.chloroplastsglucose and oxygencellular respiration, fermentationglucose and oxygencarbon dioxide, water, energy (ATP)Plants and animals wouldn’t have oxygen forcellular respiration. They couldn’t use cellular respiration to get energy.7. ATP1.2.3.4.5.6.Review1. plant cells2. Plant cells use carbon dioxide, water, and energyChapter 2 The Cell in Action3.SECTION 1 EXCHANGE WITH THEENVIRONMENT4.1. the movement of particles from areas of highconcentration to areas of low concentration2. by diffusion3. The 200 molecules of water have a higher4.5.6.7.concentration of water because 100% of themolecules are water.Water moves into it by osmosis.by osmosisenergyThe vesicle in the third picture should belabeled.5.6.Review1. Both involve moving large particles across2.3.4.5.the cell membrane. In endocytosis, particlesmove into the cell. In exocytosis, particlesmove out of the cell.Osmosis is the diffusion of water across asemipermeable membrane.During passive transport, particles movefrom areas of high concentration to areas oflow concentration. During active transport,particles move from areas of low concentration to areas of high concentration. Activetransport uses energy from the cell, and passive transport does not.channelsAn arrow should point from the pure waterto the water mixed with sugar.from the sun to make food by photosynthesis.Chloroplasts make food for the plant, andmitochondria break down the food torelease energy.Each process gives the other the materialsit needs. Cellular respiration uses oxygenand glucose and produces carbon dioxide,water, and ATP. Photosynthesis uses carbondioxide, water, and sunlight and producesglucose and oxygen.Cellular respiration uses oxygen to breakdown food. Fermentation does not. Cellularrespiration produces more energy than fermentation.No, if cells don’t have enough oxygen, theybreak down glucose using fermentation.When you exercise, for example, your muscle cells use up oxygen quickly. When thereis not enough oxygen left, the muscle cellsuse fermentation.SECTION 3 THE CELL CYCLE1. The cell must make a copy of its DNA.2. binary fission3. Chromatids are copies of chromosomes that4.5.6.7.are held together at the centromere.interphase, mitosis, cytokinesiseight moreprophase, metaphase, anaphase, telophasecell plateReview1. In prokaryotic cells, the DNA is on a single,circular chromosome. The DNA of eukaryotes is stored on many chromosomes.Copyright by Holt, Rinehart and Winston. All rights reserved.Interactive Textbook Answer Key14Cells, Heredity, and Classification

cells get energy: cellular respiration and fermentation. During cellular respiration, cells use oxygen to break down food. During fermentation, food is broken down without oxygen. Cellular respiration releases more energy from food than fermentation. Most eukaryotes, such as plants and animals, use cellular respiration.