This document provides information about Gregor Mendel and his experiments with pea plants that formed the basis of genetics. It discusses key terms like genotype, phenotype, dominant and recessive traits. It explains how Mendel used controlled breeding experiments and statistical analysis to discover that traits are passed from parents to offspring through discrete units (now known as genes) that segregate and assort independently. It also explains how his findings differed from and eventually replaced the earlier blending hypothesis of heredity.

1. Chapter 10 Concept Checks Centro Escolar Solalto 9 th Grade Biology

2. Concept Check 10.1

3. Academic Vocabulary Trait Genetics Cross-fertilization variation of a particular inherited character study of heredity process by which sperm from one flower's pollen fertilizes the eggs in a flower of a different plant

4. Academic Vocabulary Hybrid Monohybrid cross Allele Homozygous Heterozygous Dominant offspring of two different true-breeding varieties mating of two organisms that differ in only one character alternative form of a gene having identical alleles for a gene having different alleles for a gene descriptive of an allele in a heterozygous individual that appears to be the only one affecting a trait

5. Academic Vocabulary Recessive Punnett square Phenotype Genotype Testcross Dihybrid cross descriptive of an allele in a heterozygous individual that does not appear to affect a trait diagram showing the probabilities of the possible outcomes of a genetic cross observable traits of an organism genetic makeup of an organism; an organism's combination of alleles mating of an individual of unknown genotype but dominant phenotype with a homozygous recessive individual mating of two organisms that differ in two characters

6. Reading Questions & Answers What was the name of the Austrian monk who discovered the basic rules underlying inheritance patterns? Gregor Mendel Figure No. 1

7. Reading Questions & Answers Give an example of the blending hypothesis of inheritance. According to the blending hypothesis , if a red-flowered plant were crossed with a yellow-flowered plant of the same species, the red and yellow hereditary material in the offspring would blend to produce orange-flowered plants.

8. Reading Questions & Answers Why was the blending hypothesis discarded? The blending hypothesis was eventually discarded because it could not explain how traits that disappear in one generation can reappear in later ones.

9. Reading Questions & Answers In the 19th century most biologists worked by observing and describing nature. What new approach of obtaining new biological information did Gregor Mendel use? He was one of the first biologists to apply an experimental approach to the study of biological inheritance.

10. Reading Questions & Answers Describe Gregor Mendel’s hypothesis of inheritance? Mendel’s hypothesis states that parents pass on to their offspring separate and distinct factors (today called genes) that are responsible for inherited traits. Mendel stressed that these heritable factors retain their identity generation after generation .

11. Concept Check 10.1 Explain how Mendel's particulate hypothesis is different from the blending hypothesis of inheritance. The particulate hypothesis states that parents pass on to their offspring distinct factors that retain their identities, while the blending hypothesis states that parents’ hereditary material blends in the offspring.

12. Concept Check 10.1 What is the difference between self-fertilization and cross-fertilization? In self-fertilization , sperm-containing pollen fertilizes an egg of the same plant. In cross-fertilization , sperm-containing pollen from one flower fertilizes an egg of a different plant.

13. Male and Female Reproductive Structures of a Flower

14. Fertilization Process in Flowers

15. Concept Check 10.1 Describe a pattern of inheritance that the blending hypothesis fails to explain. For example, red-flower plants can produce yellow-flowered offspring.

16. The Different Stages of Mendel’s Experiment

17. Reading Questions & Answers How might two brown rabbits have white offspring? One of the brown rabbits passed on to its offspring genes that are responsible for the inherited trait of white hair color. This heritable factor retained its identity from previous generations.

18. Reading Questions & Answers What is an F 1 generation? What does the F stand for? The F 1 generation is the first hybrid offspring of two different true-breeding varieties. The F stands for filial , the Latin word for “ son ”.

19. Reading Questions & Answers Give an example of a monohybrid cross? In one experiment, Mendel crossed purple-flowered pea plants with white-flowered pea plants. This is a pairing in which the parent plants differ in only one (mono) character .

20. Mendel’s Monohybrid Cross Figure No. 2 Figure No. 3

21. Reading Questions & Answers What Mendel called factors are now called _____________. genes

22. Reading Questions & Answers What are Punnett squares used for? To show all possible outcomes of a genetic cross. You can use a Punnet square to predict probabilities of particular outcomes if you know the genetic makeup of both parents.

23. Punnet Squares Figure No. 4

24. Reading Questions & Answers What is the difference between a genotype and a phenotype? Genotype: It is the genetic makeup or combination of alleles, such as PP. Phenotype: It is an observable trait, such as the purple color of a flower.

25. Phenotype and Genotype Figure No. 5

26. Reading Questions & Answers Explain Mendel’s principle of independent assortment. The principle of independent assortment states that during gamete formation in an F 2 cross, a particular allele for one character can be paired with either allele of another character. For instance in the following example, R can end up with either Y or y , and r can end up with either Y or y .

27. Mendel’s Dihybrid Crossing

28. Punnet Square for Mendel’s Dihybrid Crossing

29. Concept Check 10.2 What are the two possible gametes produced by a plant that has the genotype Aa ? Give the probability of each type of gamete. The A or a . One half ( ½).

30. Concept Check 10.2 Use a Punnett square to predict the genotypes produced if the plant in Question 1 is self-fertilized. Calculate the probability of each outcome. Outcome probability: AA ¼, Aa ½, aa ¼

31. Concept Check 10.2 List all the possible genotypes of a pea plant with purple flowers and round seeds. PPRR, PpRr, PPRr, PpRR

32. Concept Check 10.2 List the four possible allele combinations in the gametes of a plant with genotype PpWw. PW, Pw, pW, pw

33. Reading Questions & Answers Why did Mendel select pea plants to study inheritance patterns? Because his choice increased the chance that he might be able to determine the basic rules behind inheritance patterns. This is due to the fact that pea plants have a short life cycle and this may it possible for Mendel to experiment and observe several generations.

34. Reading Questions & Answers In Mendel’s pea crosses, why did the F 1 offspring always looked like the homozygous parent? This is because one dominant allele was enough to produce the dominant phenotype.

35. Mendel’s Pea Crosses: F 1 Offspring

36. Reading Questions & Answers Does the environment have any effect on an individual’s phenotype? If yes, give an example. Yes, it does. An example of this is that although a tree’s genotype does not change throughout its lifetime, the tree’s leaves vary in size, shape, and color ( phenotype ) from year to year depending on exposure to wind and sunlight.

37. Growth of a Pea Plant

38. Growth of a Pea Plant

39. Thank you for your attention !