Lesson 1 | Sexual Reproduction and Meiosis Student Labs and Activities Page Appropriate For: Launch Lab 8 all students Content Vocabulary ELL 9 all students Lesson Outline ELL 10 all students MiniLab 12 all students Content Practice A 13 AL AL AL Content Practice B 14 AL OL BL Language Arts Support 15 all students Math Skills 17 all students School to Home 18 all students Key Concept Builders 19 Enrichment 23 Challenge 24 AL AL BL Lesson Quiz A 25 AL AL AL Lesson Quiz B 26 AL OL BL AL AL AL all students Assessment Teacher Support Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Answers (with Lesson Outlines) AL Approaching Level T2 OL On Level BL Beyond Level ELL English-Language Learner Teacher evaluation will determine which activities to use or modify to meet any ELL student’s proficiency level. Reproduction of Organisms 7 Name Date Launch Lab Class LESSON 1: 15 minutes Why do offspring look different? Unless you’re an identical twin, you probably don’t look exactly like any siblings you might have. You might have differences in physical characteristics such as eye color, hair color, ear shape, or height. Why are there differences in the offspring from the same parents? Procedure 1. Read and complete a lab safety form. 2. Open the paper bag labeled Male Parent, and, without looking, remove three beads. Record the bead colors in your Science Journal, and replace the beads. 4. Repeat steps 2 and 3 for each member of the group. 5. After each member has recorded his or her bead colors, study the results. Each combination of male and female beads represents an offspring. 3. Open the paper bag labeled Female Parent and remove three beads. Record the bead colors and replace the beads. Think About This 1. Compare your group’s offspring to another group’s offspring. What similarities or differences do you observe? 3. 8 Key Concept Why might this type of reproduction be beneficial to an organism? Reproduction of Organisms Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 2. What caused any differences you observed? Explain. Name Date Class Content Vocabulary LESSON 1 Sexual Reproduction and Meiosis Directions: Explain the relationship between/among the terms in each group below. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Terms How are these terms related? egg, sperm 1. fertilization, zygote 2. diploid, haploid 3. fertilization, sexual reproduction, DNA 4. homologous chromosomes, diploid 5. DNA, meiosis, homologous chromosomes 6. meiosis, diploid, haploid 7. Reproduction of Organisms 9 Name Date Class Lesson Outline LESSON 1 Sexual Reproduction and Meiosis A. What is sexual reproduction? 1. produces an offspring when genetic materials from two different sex cells combine. a. The female sex cell, a(n) , forms in an ovary. b. The male sex cell, a(n) , forms in a testis. 2. During a process called , an egg cell and a sperm cell join together. The new cell that forms is called a(n) . B. Diploid Cells 1. Organisms that reproduce sexually make two kinds of cells— cells and sex cells. 2. Body cells are ; they have pairs of chromosomes. 3. If a zygote has too many or too few , it will not develop properly. 4. Different organisms have different 5. of chromosomes. C. Haploid Cells 1. Sex cells are ; they have only one chromosome from each pair of chromosomes. 2. In , one diploid cell divides and makes four haploid cells. D. The Phases of Meiosis 1. Meiosis involves two divisions of the nucleus and the . These divisions, known as meiosis I and meiosis II, result in four haploid cells. 2. During , the reproductive cell grows and duplicates its chromosomes. 3. During meiosis I, each pair of duplicated homologous chromosomes . 4. After meiosis I, the two cells formed during this stage go through a second division of the sister 10 and cytoplasm called meiosis II. During meiosis II, separate to produce four haploid cells. Reproduction of Organisms Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. are pairs of chromosomes that have genes for the same traits arranged in the same order. Name Date Class Lesson Outline continued E. Why is meiosis important? 1. Meiosis forms sex cells with the correct haploid number of . This maintains the correct number of chromosomes in organisms when sex cells join. 2. Meiosis creates genetic variation by producing cells. F. How do mitosis and meiosis differ? 1. During and cell division, a body cell and its nucleus divide once and produce two identical cells. 2. During , a reproductive cell and its nucleus divide twice and produce four cells––two pairs of identical haploid cells. G. Advantages of Sexual Reproduction 1. Sexual reproduction produces that have a new combination of DNA. This results in genetic individuals. among 2. Genetic variation gives individuals within a population slight differences that might be an advantage if the Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 3. changes. breeding has been used to develop desirable traits in plants and animals. H. Disadvantages of Sexual Reproduction 1. One disadvantage of sexual reproduction is that organisms have to grow and develop until they are mature enough to produce cells. 2. Another disadvantage is that searching for a mate takes time and energy and might expose individuals to predators, environmental conditions. Reproduction of Organisms , or harsh 11 Name Date MiniLab Class LESSON 1: 20 minutes How does one cell produce four cells? When a diploid cell goes through meiosis, it produces four haploid cells. How does this happen? Procedure 1. Read and complete a lab safety form. 2. Make a copy of the diagram by tracing circles around a jar lid on your paper. Label as shown. 3. Use chenille craft wires to make red and blue duplicated chromosomes Diploid cell 2.5 cm long and green and yellow duplicated chromosomes 1.5 cm long. Recall that a duplicated chromosome has two sister chromatids connected at the centromere. 4. Place the chromosomes in the diploid cell. 5. Move one long chromosome and one short chromosome into each of the middle cells. Meiosis I Meiosis II 6. Separate the two strands of the chromosomes, and place one strand into each of the haploid cells. Haploid cells 1. Describe What happened to the chromosomes during meiosis I? During meiosis II? 2. Think Critically Why are two haploid cells (sperm and egg) needed to form a zygote? 3. 12 Key Concept How does one cell form four cells during meiosis? Reproduction of Organisms Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Analyze and Conclude Name Date Class Content Practice A LESSON 1 Sexual Reproduction and Meiosis Directions: On the line before each definition, write the letter of the term that matches it correctly. Each term is used only once. 1. production of an offspring through the combination of egg and sperm A. diploid cell B. egg C. fertilization 2. female sex cell 3. male sex cell D. haploid cell E. homologous chromosomes F. meiosis 4. joining of egg and sperm 5. the cell formed by fertilization G. sexual reproduction H. sperm I. zygote 6. body cell or zygote, which has pairs Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. of chromosomes 7. male or female sex cell that has only one chromosome from each pair 8. process by which one diploid cell divides into four haploid cells 9. two chromosomes that have genes for the same traits in the same order Directions: On the line before each statement, write T if the statement is true or F if the statement is false. 10. Sexual reproduction produces offspring that is identical to the parents. 11. The nucleus divides in meiosis I and again in meiosis II. 12. During meiosis, the number of chromosomes in each cell stays the same. Reproduction of Organisms 13 Name Date Class Content Practice B LESSON 1 Sexual Reproduction and Meiosis Directions: Answer each question or respond to each statement on the lines provided. 1. Define sexual reproduction. 2. What are male and female sex cells, and where are they made? 3. Explain what a zygote is. Use the terms egg cell, sperm cell, and fertilization in your explanation. 5. Which process divides one diploid cell and makes four haploid cells? How many times does the nucleus divide during this process? 6. What are homologous chromosomes? 14 Reproduction of Organisms Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 4. Compare a diploid cell and a haploid cell. Include where each cell is located. Name Date Language Arts Support Class LESSON 1 Writing Activity: Revisions Learning the Skill Few people get everything right the first time. When you draw a picture, you probably erase and sketch it many times. A theater performance requires many rehearsals before it is ready for an audience. In a similar way, the writing process involves more than one draft. After you gather ideas, take notes, and develop an outline, you write a draft, which puts the ideas together. Then it is time to revise. Revision takes a piece of writing to the next level. During this step, you review your work to make sure your ideas will be clear to your readers. Multiple revisions are often necessary. It might help to think of revisions on four different levels: • Overall Structure—Readers can understand your writing more clearly if you combine related ideas. As you review your writing, circle each main point in a different color. Then underline each sentence that supports that point in the same color. If your paragraph contains marks of several different colors, move sentences to the paragraph they support. If you find sentences that are not circled or underlined, delete the sentence or use it in a new paragraph. • Paragraphs—Make sure the main idea in each paragraph is adequately supported. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Several types of sentences can support a main idea. Use the following list to evaluate the strength of each paragraph. If your review shows that an idea needs more support, add one of the sentence types from this list. Paragraph Number Supporting Sentences: Main Idea: Detail: Example: Fact: Quotation: • Sentences—Review your sentence patterns. Are your sentences mostly short or long? Do their beginnings vary, or do they start the same way? Some ways to add variety to your sentences include inserting a short sentence between two long ones; combining two sentences into one longer, compound sentence; changing the passive to the active tense to make the writing more vivid and concise. • Word Choice—Review your draft again, checking for repeated words or words that are too general. Highlight nouns, verbs, adjectives, and phrases you have used more than once. Then use a thesaurus to find alternate words. Highlight general words and replace them with more concise ones; for example, tree → oak; dog → beagle; red → crimson. Reproduction of Organisms 15 Name Date Language Arts Support Class LESSON 1 Writing Activity: Revisions Practicing the Skill Directions: Read the following draft. Then answer each question or respond to each statement on the lines provided. Meiosis is a special type of cell division that produces eggs and sperm for sexual reproduction. Mitosis is a different process by which cells divide. Meiosis is cell division that produces eggs or sperm from certain cells in an organism’s reproductive system. Meiosis is a process that only takes place in eukaryotes that reproduce sexually. Sexual reproduction only occurs among some organisms. 1. What is the main idea of the paragraph? 2. Which two sentences do not fit the main idea of the paragraph? What do you think the writer should do with these sentences? Explain why. Revise the sentence below to eliminate the repetition. Meiosis is cell division that produces eggs or sperm from certain cells in an organism’s reproductive system. 4. Look at the sentence you revised in question 3. Three sentences start with the words “Meiosis is.” Make an additional revision to the sentence above or another sentence to vary the sentence structure. Applying the Skill Directions: Review a piece of writing that you have worked on for this class. Evaluate it using the four levels of revisions outlined under Learning the Skill. Then use the suggested strategies to revise your draft. Exchange your revised paper with a partner to find out whether your ideas are clear. 16 Reproduction of Organisms Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 3. The phrase “cell division that produces eggs and sperm” appears twice in this paragraph. Name Date Class Math Skills LESSON 1 Use Proportions A proportion is an equation that shows that two ratios are equal. When two ratios form a proportion, the cross products are equal. In this example, the cross products are 2 × 10 and 4 × 5. 5 2 = ___ If __ , then 2 × 10 = 4 × 5. 10 4 If one of the numbers in a proportion is unknown, cross multiply to change the proportion to an equation. Then solve the equation for the unknown number. You know that 1 cell produces 2 daughter cells at the end of mitosis. How many daughter cells will be produced by 19 cells? Step 1 Use the information in the problem to write a proportion. 1 __ 2 19 = ___ n Step 2 Cross multiply to solve for the unknown number. 1 × n = 2 × 19 n = 38 Step 3 Use the solution to answer the question in the original problem situation. The 19 cells will produce 38 daughter cells. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Practice 1. If 7 cells go through mitosis, how many daughter cells will be produced? 3. The egg of a type of frog is 1.5 mm wide. If you place 12 eggs in a line, what is the length of the line from end to end? Reproduction of Organisms 2. If 47 sex cells go through meiosis, how many daughter cells will be produced? 4. For another type of frog, 3 eggs in a row measure 6 mm across. What is the length of a line of 12 eggs? 17 Name Date Class School to Home LESSON 1 Sexual Reproduction and Meiosis Directions: Use your textbook to answer each question. 1. The production of an offspring resulting from the combination of genetic materials of two different cells is called sexual reproduction. How is a zygote formed in sexual reproduction? 2. Diploid cells have pairs of chromosomes, whereas haploid cells have only one chromosome from each pair. Which cells are sex cells, diploid cells or haploid cells? 3. Meiosis and mitosis are similar processes in which an organism produces new cells. 4. Meiosis produces cells that are not genetically identical to the parent cell. What are the advantages and disadvantages of sexual reproduction? 18 Reproduction of Organisms Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. What are the differences between the processes of meiosis and mitosis? Name Date Class Key Concept Builder LESSON 1 Sexual Reproduction and Meiosis Key Concept What is sexual reproduction, and why is it beneficial? Directions: Work with a partner to answer each question or respond to each statement on the lines provided. 1. Name the type of reproduction that occurs when the genetic materials from two different cells combine to produce an offspring. 2. What are egg cells? 3. What are sperm cells? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 4. Explain the relationship between fertilization and a zygote. 5. What happens to a zygote? 6. Compare the DNA of an offspring to the DNA of its parents. 7. Why do offspring from the same parents usually have a different set of traits? Reproduction of Organisms 19 Name Date Class Key Concept Builder LESSON 1 Sexual Reproduction and Meiosis Key Concept What is the order of the phases of meiosis, and what happens in each phase? Directions: On each line, write the term from the word bank that correctly completes each sentence. Some terms may be used more than once or not at all. diploid haploid homologous chromosomes meiosis mitosis sister chromatids 1. In meiosis, one cell divides to make four cells. 2. A cell has half the chromosomes of a cell. 3. A cell has pairs of chromosomes. 4. Pairs of chromosomes that are not identical but have genes for the same trait arranged in the same order are . has one chromosome from the mother and one chromosome from the father. 6. In 7. During , the two chromosomes are always identical. , two divisions of the nucleus and the cytoplasm occur. 8. When a cell duplicates one chromosome, two are formed. 9. During interphase of mitosis and meiosis, two are formed for each chromosome. 10. A reproductive cell goes through interphase before beginning I, but not before II. 11. Prophase I and Prophase II are stages in . 20 Reproduction of Organisms Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 5. Each pair of Name Date Class Key Concept Builder LESSON 1 Sexual Reproduction and Meiosis Key Concept What is the order of the phases of meiosis, and what happens in each phase? Directions: Work with a partner. On each line, write the term or phrase that correctly completes each sentence. Meiosis I Phase Prophase I Description 1. Chromosomes that are duplicated during remain sister chromatids. 2. join and form pairs. 3. The membrane surrounding the nucleus Metaphase I apart. 4. Homologous chromosome pairs align along the of the cell. 5. Anaphase I fibers attach to each pair. 6. Pairs of duplicated and are pulled toward opposite ends of the cell. chromosomes separate 7. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Telophase I stay together. 8. A nuclear membrane forms around each group of chromosomes. The cytoplasm divides forming daughter cells. 9. remain together. Meiosis II Phase Prophase II Description 10. do not duplicate. breaks apart. Metaphase II 11. Sister chromatids along the middle of the cell. Anaphase II 12. Sister chromatids of each duplicated chromosome are and move to Telophase II . 13. A nuclear membrane forms around each set of chromatids, which are again called 14. The cytoplasm divides, and 15. Each cell has as the original cell. Reproduction of Organisms . cells form. the number of chromosomes 21 Name Date Class Key Concept Builder LESSON 1 Sexual Reproduction and Meiosis Key Concept Why is meiosis important? Directions: Answer each question on the lines provided. 1. If a male organism has 40 chromosomes in each body cell, how many chromosomes does a female of the same species have in each body cell? 2. How many homologous pairs of chromosomes does the male have? 3. How many chromosomes would be in a sperm cell and in an egg cell? 4. How many chromosomes would be in an offspring? 5. How many pairs of homologous chromosomes would be in an offspring? 6. What is the difference between a diploid cell and a haploid cell? diploid, haploid, fertilized egg, and sex cells in your answer. 22 Reproduction of Organisms Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 7. How does meiosis help maintain diploid cells in offspring? Use the terms chromosomes, Name Date Class Enrichment LESSON 1 Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Rescuing Native Plants Most North American food crops are not native. Instead, they were brought to America by European settlers. Many of these crops are not resistant to American diseases and pests—but native plants often are. That’s why native plants play an important role in growing healthy food crops. drier and hotter conditions than most other species of rice. Such traits are especially useful in areas that experience droughts, or extended periods of belowaverage rainfall. The traits might also be needed if Earth’s surface temperatures continue to rise on a global level. Breeding with Native Plants Benefits Versus Costs Scientists can breed native plants with crop plants to produce hardier plants. For example, if potatoes are threatened by disease, scientists can cross potatoes with a native plant that has traits that make it naturally disease resistant. Using the same technique, scientists can produce plants that are more resistant to pests. Improved resistance has environmental benefits as well, because farmers can use less chemical pesticide. Some native plants are better able to withstand the climatic conditions in different parts of America. For example, a wild rice plant grows on the banks of a single stream in Texas. This plant, which is in danger of becoming extinct, can survive Most scientists agree that native plants should be preserved. They point out that the health of the planet depends on a high level of species diversity. In addition, some native plants might have unknown medicinal or commercial value; if they become extinct, these benefits are lost forever. However, other experts point out that the cost of saving each native plant is very high. They argue that society must determine the potential value of each species before paying the high cost of saving that species. About 700 native plants in the United States are endangered, or at risk of becoming extinct. That’s nearly onefourth of all native plants in the country. Applying Critical-Thinking Skills Directions: Answer each question or respond to each statement. 1. Infer Why are native plants often resistant to the diseases and pests in their native land? 2. Weigh Do you think that all native plants should be preserved, or should only those plants that have value for people be preserved? Explain. Reproduction of Organisms 23 Name Challenge Date Class LESSON 1 Sequencing Meiosis The diagrams show the stages of meiosis in scrambled order. To the left of each diagram, label and sequence the stages in the correct order. To the right of each diagram, include a brief description of what happens during each stage. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 24 Reproduction of Organisms
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