ETOSUCCESS ACADEMY

SCIENCE

Date: ______________

Preparing ___________________________ to be a Sensational Scientist. (Name)

Topic: GeneticsPre-assessment

1. Thomas drew a picture of a one-celled organism. He then labeled his drawing as shown in the illustration below.

Which of the following labeled cell parts best identifies the location of genes?A DNAB flagellumC cytoplasmD cell membrane

2. Assume you cross a pure plant that has the genotype GG with a pure pea plant that has the genotype gg. What are all of the possible genotypes of the offspring?

A GG, gg, and GgB only GgC only GGD GG and gg

Student Exploration: Mouse Genetics (One Trait)

Vocabulary: allele, DNA, dominant allele, gene, genotype, heterozygous, homozygous, hybrid, inheritance, phenotype, Punnett square, recessive allele, trait

Prior Knowledge Questions (Do these BEFORE using the Gizmo.)

The image shows a single litter of kittens. How are they

similar to one another? _________________________

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How do they differ from one another? ______________

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What do you think their parents looked like? ______________________________________

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Gizmo Warm-upThe rules of inheritance were discovered in the 19th century by Gregor Mendel. With the Mouse Genetics (One Trait) Gizmo™, you will study how one trait, or feature, is inherited.

Drag two black mice into the Parent 1 and Parent 2 boxes. Click Breed several times. What do the offspring look like?

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The appearance of each mouse is also called its phenotype.

Click Clear, and drag two white mice into the parent boxes. Click Breed several times.

What is the phenotype of the offspring now?

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Do you think mouse offspring will always look like their parents? ______________________

Explain: __________________________________________________________________

Activity A: Patterns of inheritance

Get the Gizmo ready:

· Click Clear.· Drag a black mouse and a white mouse into the

parent boxes, but don’t click Breed yet.

Question: What patterns are shown by offspring traits?

Predict : What do you think the offspring of a black mouse and a white mouse will look like?

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Observe : Click Breed several times. What do you see? _____________________________

Observe : Drag two offspring into the Holding Cages. These mice are called hybrids because their parents had different traits. Click Clear, and then breed the two hybrids.

What do you see now? ______________________________________________________

Experiment : Turn on Show statistics. Click Breed until there are 100 offspring.

How many offspring were black? ________ How many were white? ________

Explore : Try other combinations of mouse parents. Write the results of each experiment in your notes. When you have finished, answer the following questions. (Note: You can refer to the parents as “pure black,” “pure white,” or “hybrid.”)

1. Which parent combination(s) yield only white offspring? _______________________

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2. Which parent combination(s) yield only black offspring? _______________________

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3. Which parent combination(s) yield a mixture of black and white offspring? ________

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Challenge : Based on experiments similar to these, Gregor Mendel devised a theory of inheritance. Use your own observations to come up with your own explanation of how a trait such as fur color is passed down from parents to offspring.

Write your explanation down on an extra sheet of paper and attach it to this worksheet. If possible, discuss your theory with your classmates and teacher.

Activity B: Genetics basics

Get the Gizmo ready:

· Click Clear.· Drag a black mouse and a white mouse into the

parent boxes.

Introduction: Inherited traits are encoded on a molecule called DNA (deoxyribonucleic acid). Genes are segments of DNA that control a particular trait. Most genes have several different versions, or alleles. The genotype is the allele combination an organism has.

Question: How do alleles determine fur color?

1. Observe : Turn on Show genotype. Move your cursor over a mouse to see its genotype.

A. What is the genotype of the black parent? _______ White parent? _______

These mice are homozygous for fur color, meaning both alleles are the same.

B. Click Breed. What is the genotype of the offspring mice? _______

These mice are heterozygous for fur color, meaning the alleles are different.

2. Analyze : Dominant alleles are always expressed when present. Recessive alleles are not expressed when the dominant allele is also present. Look at the two alleles for fur color.

A. Which allele is dominant, and which fur color does it produce? _________________

B. Which allele is recessive, and which fur color does it produce? _________________

3. Predict : Place two of the Ff offspring into the Holding Cages. Click Clear, and then place them into the parent boxes.

A. Which allele(s) could the offspring inherit from parent 1? ______________________

B. Which allele(s) could the offspring inherit from parent 2? ______________________

C. What are the possible genotypes of the offspring? ___________________________

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4. Experiment : Click Breed several times, and look at the genotypes of the offspring. Did you find all the predicted genotypes? Explain.

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Activity C: Modeling inheritance

Get the Gizmo ready:

· Click Clear.· Drag a black mouse and a white mouse into the

parent boxes.

Question: How do scientists predict the genotypes of offspring?

1. Model : Scientists use a Punnett square to model the different possible offspring genotypes from a parent pair. The parent genotypes are written across the top and side of the square, as shown. The four possible offspring genotypes are then filled in.

The first square is filled in for you. Fill in the remaining squares.

A. What are the genotypes of the offspring? __________________________________

B. What percentage of the offspring will have black fur? _________________________

C. What percentage of the offspring will have white fur? _________________________

2. Experiment : Click Breed several times. Were your predictions correct? ________________

3. Model : Use the Punnett squares below to model each parent combination. After filling in each Punnett square, predict the percentages of black and white offspring.

Parent 1: Heterozygous black (Ff)Parent 2: Heterozygous black (Ff)

Predicted % black offspring: ______

Predicted % white offspring: ______Parent 1: Heterozygous black (Ff)Parent 2: Homozygous white (ff)

Predicted % black offspring: ______

Predicted % white offspring: _____

4. Experiment : Turn on Show statistics and Show as approximate percentage. For each combination, breed approximately 500 offspring. Record the results in the table below.

(Hint: To obtain an Ff mouse, breed an FF mouse to an ff mouse. Place two Ff offspring into the holding cages, click Clear, and then drag the Ff mice into the parent boxes.)

Parent 1 Genotype Parent 2 Genotype % Black offspring % White offspringFf Ff

Ff ff

5. Draw conclusions : How well did the Punnett squares predict the offspring percentages for each parent

pair? ___________________________________________________________

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6. Summarize : In your own words, explain how traits are passed from parents to their offspring.

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7. Think and discuss : Do you think most traits are inherited the way mouse fur color is? _____

Why do you think this is? _____________________________________________________

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Post-Assessment1. Every organism requires a set of instructions that specifies its traits. This information is carried within the cells of the organism. Which set of statements best describes hereditary information in eukaryotic cells?A Genes are made up of chromosomes. Chromosomes and genes are found in the cell’s cytoplasm.B Chromosomes are made up of genes. Chromosomes and genes are found in the cell’s cytoplasm.C Genes are made up of chromosomes. Chromosomes and genes are found in the cell’s nucleus.D Chromosomes are made up of genes. Chromosomes and genes are found in the cell’s nucleus.

2. The illustration below shows that sexual reproduction involving two parent pea plants resulted in the production of four offspring.

Which of the following statements best describes heredity in organisms that reproduce sexually?

A All four offspring received all of their genetic information only from Parent 1 and are therefore identical to that parent.B All four offspring received all of their genetic information only from Parent 2 and are therefore identical to that parent.C Each of the offspring is genetically unique and received some of its genetic information from each parent, so each has some traits in common with each parent.D All four offspring are genetically unique and did not receive any of their genetic information from either parent.

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3. The Punnett square below shows the results of a genetic cross. The mother is heterozygous for the trait shown. The father is homozygous recessive for the trait.

What can you conclude from the results of the Punnett square?

A All the offspring will have the same genotype as the mother.B All the offspring will have the same phenotype as the father.C Half the offspring will have the same phenotype and genotype as the father.D None of the offspring will have a genotype that is the same as the mother or the father.

4. For a particular trait, the allele C is dominant over the allele c. The Punnett square below shows the genetic cross of two parents, each with genotype Cc.

What percentage of the offspring will show the phenotypes of the dominant allele and the recessive allele?A 50% will show the phenotype of the dominant allele and 50% will show the phenotype of the recessive alleleB 75% will show the phenotype of the recessive allele and 25% will show the phenotype of the dominant alleleC 75% will show the phenotype of the dominant allele and 25% will show the phenotype of the recessive alleleD 100% will show the phenotype of the dominant allele and 0% will show the phenotype of the recessive allele

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