Adaptation and Behavior

Lesson #1: Introduction to Inheritance - Inherited Human Traits

Time Frame: 1-2 hours

Learning Standards: Science

Life Science: Plant (and Animal) Structures and Functions;1) Differentiate between observed characteristics of plants and animals that are fully

inherited (e.g., color of flower, shape of leaves, color of eyes, number of appendages) and characteristics that are affected by the climate or environment (e.g., browning of leaves due to too much sun, language spoken).

Skills of Inquiry1) Ask questions and make predictions that can be tested.2) Select and use appropriate tools and technology in order to extend observations.3) Keep accurate records while conducting simple investigations or experiments.4) Recognize simple patterns in data and use data to create a reasonable explanation

for the results of an investigation of experiment.5) Record data and communicate findings to others using graphs, charts, maps,

models, and oral and written reports.Math

Data Analysis, Statistics, and Probability 1) 5.D.2 Construct and interpret line plots, line graphs, and bar graphs. Interpret

and label circle graphs.Number Sense and Operations

1) 6.N.9 Select and use appropriate operations to solve problems involving addition, subtraction, multiplication, division, and positive integer exponents with whole numbers, and with positive fractions, mixed numbers, decimals, and percents.

Student will be able to:1) Collect, analyze, graph, and interpret data about inherited traits found in the

classroom population.2) Understand that human traits are inherited and variable.

Resources and Materials:

Item AmountScience JournalsExamples of human inherited traits 1 (in binder)Pictures of the different types of human traits 25 (in bin)Inherited traits of humans teacher chart (overhead or copy on the board)

1 (in binder)

Inherited Human Traits student handouts (student chart, data and analysis questions, and graph outline)

25 (in bin)

Chart showing Frequency of Traits in the General Population 1 (in binder)Calculators 25 (from classroom)

General Teacher Background Information:Gregor Mendel, an Augustinian monk with farming experience and mathematical and scientific knowledge, is known as the father of modern genetics. Mendel was intrigued by his observations in plant hybridization. He felt there might be some mathematical relationship among the traits observed in different generations of hybrid plants. Mendel posited that inheritance is based on pairs of particular factors and these factors occur in pairs in each parent. These factors later became known as genes. He also concluded that a pair of factors are segregated or separated during the formation of sex cells so that each cell receives only one of the pair from each parent (Law of Segregation). He also felt that since paired elements are capable of separating, then reappearing in their original form, and then pairing differently in a later union; they are not altered as passed from individual to individual.

Mendel also identified a dominant form (allele) for each gene and a recessive form (allele) for each gene. In humans, earlobes can be detached (dominant trait) or attached (recessive trait). In general, inheritance ends up being much more complicated. For example, some traits are controlled by many genes and some genes have many different alleles. Also, alleles do not always have a strict dominant/recessive relationship. Human characteristics such as eye color and skin color have complex modes of inheritance.

Focus Activity: Ask students to individually write down 10 traits (characteristics) about themselves in their science notebooks. Then move into the introduction activities.

Introduction: Ask students to work in small groups to separate these traits into 2 groups – traits that they inherited from their parents and traits affected by the environment. Give an example of each type of trait first. For example, eye color is an inherited trait and language spoken is affected by the environment. Some groups may also have a third list; traits that are BOTH inherited and affected by the environment. As a class, make a list of inherited human traits on the board (You may use the list provided to get additional ideas). Discuss the following questions as a class. How do you know these traits are inherited? Could any of these traits also be affected by the environment?

Activity: 1) Give each student a chart to record their data about human traits. Working

individually, students will complete an inventory of their traits and then compare their traits to a partner’s traits (2-3 students in a group). Students may use the pictures provided to help determine what the different traits look like.

2) After the group discussions, ask students to make predictions about which type of trait will be most common in the classroom population. Students will record their predictions on their chart.

3) Students will share their results with the class and the teacher will tabulate the classroom number (using the overhead of the chart provided). Students will add the classroom data to their chart. Instructor will lead a brief discussion of the classroom data.

4) Then, students will determine the frequency of each trait (percentage) using the formula provided and record the frequency in their chart. Allow students to use calculators to determine the correct frequencies. They should check their work with their group. If percentages are not cover in students’ math curriculum, record the frequencies as counts rather than percentages.

5) Students will make a bar graph (using the graph outline provided) representing these frequencies. Remind students to label the Y-axis of their graph. Use either the percentages or counts graph as appropriate.

6) Students will compare their results to their initial predictions and answer the data analysis questions. Provide students with the chart showing the Frequency of Traits in the General Population.

Closure: Discuss the following questions as a class. Is there a pattern in the traits present in our classroom population? Why are there so many similarities or differences in our classroom population? Did you inherit any of these traits from your parents? Did you inherit any of these traits from your grandparents? Why would a scientist care whether populations were similar or different? Are humans all the same or all different? What are the benefits of having differences among humans? What might happen if every human was identical?Note: You may choose to discuss how traits are inherited and passed on from parents to their children (genes) or wait until the next lesson.

Assessment: List of human traits in the science notebooks, completed inherited human traits chart, graph, and analysis questions, participation in class discussions

Examples of Human Inherited Traits

Gender (male or female) Right handed / left handed Cross left thumb over right / cross right thumb over left Number of limbs, fingers, toes Hair color (natural) Hair texture (natural) Eye color (natural) Height Presence of freckles Presence of dimples Thumb flexibility (straight or curved) Cleft or smooth chin Attached or unattached earlobes Pointy or straight hair line Ability to roll tongue Allergies Length of fingers Circumference of wrists Length of feet

Inherited Traits of Humans

Total Population (# of students in the class): ________

Character Number Observed in the class:

Percentage of Population with Trait

Gender Male Female

#_____ #_____

Male Female

_____% _____%

Earlobes Attached Detached

#_____ #_____

Attached Detached

_____% _____%

Tongue Can roll Can’t roll

#_____ #_____

Can roll Can’t roll

_____% _____%

Chin Cleft Flat

#_____ #_____

Cleft Flat

_____% _____%

Hairline Pointy Straight

#_____ #_____

Pointy Straight

_____% _____%

Thumb Curved Straight

#_____ #_____

Curved Straight

_____% _____%

Data Interpretation (Using Percentages)

1) Calculate the frequency (percentage of the population with the trait) for each trait. Use the following formula:

Number observed x 100 = Percentage (%) Total Population

Use a calculator to determine the frequency for each trait on your table. You may work with your partner. Check your frequencies by adding the percentages for each trait. The added percentages should equal 100.

2) Create a bar graph (using the percentages graph outline provided) to show the different frequencies for each human inherited trait.

Data Interpretation (Using Counts)

1) Create a bar graph (using the frequency graph outline provided) to show the different counts for each human inherited trait.

Analysis Questions

1) Compare your predictions with the class results. Were most of your predictions correct or incorrect? Why?

2) Compare your results to the known frequencies for the general population (chart provided). Are your classroom percentages similar or different? Explain what you observe.

3) Where did these traits come from? Did you inherit any traits from your parents? Did you inherit any traits from your grandparents? List those traits. Do you think you will pass on any of these traits to your children? Explain.

4) Are humans all the same or all different? What are the benefits of having differences among humans? What might happen if every human was identical?

Frequency of Traits in the General Population

(percentages are approximate)

Trait Frequency of Form 1

Frequency of Form 2

Gender Male – about 50% Female – about 50%

Earlobes Attached – 25% Detached – 75%

Tongue Can roll – 70% Can’t roll – 30%

Chin Cleft – more frequent

Flat – less frequent

Hairline Pointy – 75% Straight – 25%

Thumb Curved – 25% Straight – 75%