How to Use This Presentation To View the presentation as a slideshow with effects select “View” on the menu bar and click on “Slide Show”, or simply press F5 on the top row of your keyboard. To advance to the next slide click the left mouse button once. From the Chapter screen you can click on any section to go directly to that section’s presentation. Blank or “missing” areas of a slide will remain hidden until the left mouse button is clicked. You may exit the slide show at any time by pressing the Esc key. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu

Chapter Presentation Transparencies Image and Math Focus Bank Bellringers Standardized Test Prep Visual Concepts Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter menu Resources

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Table of Contents Section 1 Mendel and His Peas Section 2 Traits and Inheritance Section 3 Meiosis Chapter 19 Heredity

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Mendel and His Peas Bellringer You have probably noticed that different people have different characteristics, such as eye color, hair color, and ear lobes that do or do not attach directly to their head. Where do you think people get these different traits? How do you think they are passed from one generation to the next? Record your answers in your science journal. Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Mendel and His Peas Objectives Explain the relationship between traits and heredity. Describe the experiments of Gregor Mendel. Explain the difference between dominant and recessive traits. Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Mendel and His Peas Who Was Gregor Mendel? Gregor Mendel was born in 1822 in Heinzendorf, Austria. At age 21, Mendel entered a monastery. He performed many scientific experiments in the monastery garden. Mendel discovered the principles of heredity, the passing of traits from parents to offspring. Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Unraveling the Mystery Mendel used garden pea plants for his experiments. Self-Pollinating Peas have both male and female reproductive structures. So, pollen from one flower can fertilize the ovule of the same flower. When a true-breeding plant self pollinates, all of the offspring will have the same trait as the parent. Section 1 Mendel and His Peas Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Unraveling the Mystery, continued Pea plants can also cross-pollinate. Pollen from one plant fertilizes the ovule of a flower on a different plant. The image below shows cross-pollination and self- pollination. Section 1 Mendel and His Peas Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Unraveling the Mystery, continued Characteristics and Traits of Pea Plants Mendel studied only one pea characteristic at a time. A characteristic is a feature that has different forms in a population. Different forms of a characteristic are called traits. Section 1 Mendel and His Peas Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Unraveling the Mystery, continued Mix and Match Mendel was careful to use plants that were true breeding for each of the traits he was studying. By doing so, he would know what to expect if his plants were to self-pollinate. Section 1 Mendel and His Peas Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Mendel’s First Experiments Mendel crossed pea plants to study seven different characteristics. Mendel got similar results for each cross. One trait was always present in the first generation, and the other trait seemed to disappear. Mendel called the trait that appeared the dominant trait. The trait that seemed to fade into the background was called the recessive trait. Section 1 Mendel and His Peas Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Mendel’s Second Experiments To find out more about recessive traits, Mendel allowed the first- generation plants to self- pollinate. In each case some of the second-generation plats had the recessive trait. Section 1 Mendel and His Peas Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Mendel’s Second Experiments, continued Ratios in Mendel’s Experiments The recessive trait did not show up as often as the dominant trait. Mendel decided to figure out the ratio of dominant traits to recessive traits. Section 1 Mendel and His Peas Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Mendel’s Second Experiments, continued In all cases the ratio was about 3:1 dominant : recessive. Section 1 Mendel and His Peas Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Mendel’s Second Experiments, continued Gregor Mendel – Gone But Not Forgotten Mendel realized that his results could be explained only if each plant had two sets of instructions for each characteristic. Mendel’s work opened the door to modern genetics. Section 1 Mendel and His Peas Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Bellringer If you flip a coin, what are the chances that it will land on heads? tails? Suppose that you flipped the coin and got heads. What are the chances that you will get heads again? What are the chances you will get heads two times in a row? five times? Record your answers in your science journal. Section 2 Traits and Inheritance Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Objectives Explain how genes and alleles are related to genotype and phenotype. Describe how the information in a Punnett square predicts possible genotypes. Explain how probability can be used to predict possible genotypes. Section 2 Traits and Inheritance Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Objectives, continued Describe how interactions between genes can allow for a variety of traits in offspring. Describe how the environment can influence traits. Section 2 Traits and Inheritance Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu A Great Idea Mendel knew that there must be two sets of instructions for each characteristic. The instructions for an inherited trait are called genes. The different forms (often dominant and recessive) of a gene are alleles. Section 2 Traits and Inheritance Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu A Great Idea, continued Dominance occurs when certain alleles mask the expression of other alleles. A recessive trait or allele is expressed only when two recessive alleles for the same characteristic are inherited. Phenotype An organism’s appearance is known as its phenotype. Genes affect the phenotype. Section 2 Traits and Inheritance Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Genotype The combination of inherited alleles together form an organism’s genotype. A plant with two dominant or two recessive alleles is said to be homozygous. A plant that has the genotype Pp is said to be heterozygous. Section 2 Traits and Inheritance Chapter 19 A Great Idea, continued

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Punnett Squares are used to organize all the possible genotype combinations of offspring from particular parents. Section 2 Traits and Inheritance Chapter 19 A Great Idea, continued

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Traits and Inheritance Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu What Are the Chances? Probability is the mathematical chance that something will happen. Probability is most often written as a fraction of percentage. Section 2 Traits and Inheritance Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Calculating Probability Section 2 Traits and Inheritance Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Genotype Probability To have white flowers, a pea plant must receive a p allele from each parent. Each offspring of a Pp Pp cross has a 50% chance of receiving either allele from either parent. So, the probability of inheriting two p alleles is 1/2  1/2, which equals 1/4, or 25%. Section 2 Traits and Inheritance Chapter 19 What Are the Chances?, continued

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Gene Interactions and Variations Incomplete Dominance Researchers have found that sometimes one trait is not completely dominant over another. One Gene, Many Traits Sometimes one gene influences more than one trait. Many Genes, One Trait Some traits, such as the color of your skin, hair, and eyes, are the result of several genes acting together. Section 2 Traits and Inheritance Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Importance of Environment Genes aren’t the only influences on traits. A combination of things determine an individual’s characteristics. Your environment also influences how you grow. Lifestyle choices can also affect a person’s traits. Section 2 Traits and Inheritance Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Meiosis Bellringer Write a sentence to describe each of the following terms: heredity, genotype, and phenotype. Note how genotype and phenotype are related, and how they are different. Is heredity necessarily a factor in both genotype and phenotype? Why or why not? Record your answers in your science journal. Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Meiosis Objectives Describe the patterns and advantages of asexual reproduction in animals and plants. Describe the patterns and advantages of sexual reproduction in animals and plants. Differentiate between mitosis and meiosis. Explain how the process of meiosis relates to the passing of traits from parent to offspring. Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu In asexual reproduction, only one parent cell is needed. The structures inside the cell are copied, and then the parent cell divides, making two exact copies. This type of cell reproduction is called mitosis. Most of the cells in your body and most single-celled organisms reproduce this way. Section 3 Meiosis Chapter 19 Asexual Reproduction

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Mitosis Section 3 Meiosis Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Advantages of Asexual Reproduction One advantage of asexual reproduction is that organisms can produce many offspring in a relatively short amount of time. An advantage for animals that reproduce asexually is that they do not have to use energy to find a mate. Section 3 Meiosis Chapter 19 Asexual Reproduction, continued

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Sexual Reproduction In sexual reproduction, two parent cells (sex cells) join together to form offspring that are different from both parents. Chromosomes that carry the same sets of genes are called homologous chromosomes. Each sex cell has only one of the chromosomes from the homologous pair. Section 3 Meiosis Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Sexual Reproduction, continued Advantages of Sexual Reproduction The combination of genetic information during sexual reproduction allows for variation among a population. The variation of genes allows a population to adapt to changes in the environment over time. Section 3 Meiosis Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Sexual Reproduction, continued Meiosis Sex cells are made during meiosis. Meiosis is a copying process that produces cells with half the usual number of chromosomes. Section 3 Meiosis Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Meiosis Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Section 3 Meiosis Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Genes and Chromosomes Walter Sutton studied meiosis in sperm cells in grasshoppers. Using his observations and his knowledge of Mendel’s work, Sutton proposed that: Genes are located on chromosomes. Section 3 Meiosis Chapter 19 Sexual Reproduction, continued

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Steps of Meiosis During meiosis, chromosomes are copied once, and then the nucleus divides twice. The resulting sex cells (sperm and eggs) have half the number of chromosomes of a normal body cell. Section 3 Meiosis Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Meiosis Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Meiosis Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Meiosis and Fertilization The next slide shows what happens to a pair of homologous chromosomes during meiosis and fertilization. The cross shown is between a plant that is homozygous for round seeds (dominant trait) and a plant that is homozygous for wrinkled seeds (recessive trait). Section 3 Meiosis Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Meiosis Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Meiosis and Fertilization, continued Sex Chromosomes carry genes that determine sex. Human females have two X chromosomes. Human males have one X chromosome and one Y chromosome. Section 3 Meiosis Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Meiosis and Fertilization, continued Sex-Linked Disorders The genes for certain disorders, such as colorblindness, are carried on the X chromosome. Genetic Counseling Genetic counselors use pedigrees to trace traits through generations of a family. These diagrams can often predict if a person is a carrier of a hereditary disease. Selective Breeding In selective breeding, organisms with desirable characteristics are mated. Section 3 Meiosis Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Concept Mapping Use the terms below to complete the concept map on the next slide. meiosis eggs cell division sperm X chromosome mitosis Y chromosome sex cells Heredity Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Heredity Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Heredity Chapter 19

End of Chapter 19 Show Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu FCAT For the following questions, write your answers on a separate sheet of paper. Chapter 19 Standardized Test Preparation

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 1. A peach tree has been bred to produce more peaches. While the peach crop from the tree has been considerably larger, the tree has also become susceptible to a disease that will eventually kill it. If this tree is self-pollinating, what is the chance that seedlings from this tree will also be susceptible to the disease? A.25% B.50% C.75% D.100% Chapter 19 Standardized Test Preparation

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 1. A peach tree has been bred to produce more peaches. While the peach crop from the tree has been considerably larger, the tree has also become susceptible to a disease that will eventually kill it. If this tree is self-pollinating, what is the chance that seedlings from this tree will also be susceptible to the disease? A.25% B.50% C.75% D.100% Chapter 19 Standardized Test Preparation

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 2. Caroline has two lilies in her garden. She wants to see if she can produce offspring that will have traits of both lilies. Which of the following structures will Caroline have to remove from the plant she is pollinating to ensure that cross- pollination occurs? F.the anthers G.the ovule H.the petals I.the stigma Chapter 19 Standardized Test Preparation

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 2. Caroline has two lilies in her garden. She wants to see if she can produce offspring that will have traits of both lilies. Which of the following structures will Caroline have to remove from the plant she is pollinating to ensure that cross- pollination occurs? F.the anthers G.the ovule H.the petals I.the stigma Chapter 19 Standardized Test Preparation

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 3. Juanita visited a friend’s farm. At the farm she noticed a calf with a mixture of brown and white fur. The calf’s father had brown fur and the calf’s mother had white fur. What principle of heredity can explain why the calf had a mixture of brown and white fur? A.cross-pollination B.selective breeding C.incomplete dominance D.environmental influence Chapter 19 Standardized Test Preparation

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 3. Juanita visited a friend’s farm. At the farm she noticed a calf with a mixture of brown and white fur. The calf’s father had brown fur and the calf’s mother had white fur. What principle of heredity can explain why the calf had a mixture of brown and white fur? A.cross-pollination B.selective breeding C.incomplete dominance D.environmental influence Chapter 19 Standardized Test Preparation

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 4. Organisms reproduce either asexually or sexually. In asexual reproduction, there is only one parent and the offspring are genetically identical to the parent. In sexual reproduction, there are two parents and the offspring inherit traits from both parents. How is the process of cell division in asexual reproduction different than the process of cell division in sexual reproduction? Chapter 19 Standardized Test Preparation

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Question 4, continued Full credit answers should include the following points: Students should explain that asexual reproduction is referred to as mitosis and that sexual reproduction is referred to as meiosis. Students should explain that the main difference between the two processes is the number of times the cell divides and the resulting - number of chromosomes in each final cell. In mitosis the cell divides one time and both of these cells have the same number of chromosomes as the parent cell. In meiosis the cell divides two times and each of the four resulting cells has half the number of chromosomes as the parent cell. Chapter 19 Standardized Test Preparation

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 5. Chad created the pedigree diagram shown below to show the occurrence of sickle cell anemia in his family. Sickle cell anemia is a recessive disease (ss) that affects the ability of red blood cells to carry oxygen. Those who do not carry the gene are noted as (SS). According to the diagram, Chad is one of five children. Both a brother and a sister do not carry the gene for the disease. One of his sisters has the disease. Continued on the slide Chapter 19 Standardized Test Preparation

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Question 5, continued 5. Which of the following are the genotypes of Chad’s parents? F.Ss and SS G.Ss and Ss H.ss and ss I.ss and SS Chapter 19 Standardized Test Preparation

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Question 5, continued 5. Which of the following are the genotypes of Chad’s parents? F.Ss and SS G.Ss and Ss H.ss and ss I.ss and SS Chapter 19 Standardized Test Preparation

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 6. Traits vary from person to person. Two traits include straight hair and curly hair. Curly hair is the dominant trait (WW), while straight hair is the recessive trait (ww). If a man with straight hair (WW) and a woman with curly hair (ww) have children, what percentage of their children will have straight hair? Complete the Punnett square below to show the possible genotypes for the children. Chapter 19 Standardized Test Preparation

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 6. Complete the Punnett square below to show the possible genotypes for the children. Chapter 19 Standardized Test Preparation ww WWw W

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Mendel and His Peas Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Mendel and His Peas Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Mendel and His Peas Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Mendel and His Peas Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Mendel and His Peas Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Traits and Inheritance Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Mitosis Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Mitosis Chapter 19

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 19 Standardized Test Preparation

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 19 Standardized Test Preparation