Investigating Inherited Traits


Heredity is the passing on of characteristics from parent to offspring. The hereditary makeup the anindividual is recognized as that genotype. The physical attributes of one individual, whichare the an outcome of the genotype and its environment, are recognized as that phenotype. Part alleles room expressed only when the genotype is homozygous. These alleles aresaid to develop recessive phenotypes. Alleles that room expressed whether the genotype ishomozygous or heterozygous create dominant phenotypes. An allele the codes because that adominant properties is stood for by a funding letter, if an allele that codes because that a recessivetrait is stood for by a small letter letter. Occasionally when the genotype is heterozygous,neither the dominant nor the recessive phenotype occurs. In this situation, calledincomplete dominance, an intermediary phenotype is produced. In humans, the sex the an individual is identified by the particular mix oftwo chromosomes called the sex chromosomes. People who have actually two Xchromosomes (XX) room females, whereas those who have actually an X and also a Y chromosome (XY)are males. In this investigation, you will observe how the results of different allelecombinations produce particular traits.

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How are traits inherited?

Pre-Lab Discussion

Read the entire investigation. Then, work-related with a companion to answerthe following questions.1. What walk a solitary side that a double-sided coin or disc represent?

2. What is the probability, in percent, that a single coin toss will an outcome in heads? In tails? The probability the a solitary coin toss will an outcome in either heads or tails is 50 percent.

Name______________________________ day __

Explain to the students the the actual mix of gene is much morecomplicated 보다 is shown by this investigation. Few of the traits result frommultiple alleles. In order to simplify the investigation, assume that all of the traitsused are the an outcome of the mix of two alleles, or one allele pair.

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Each solitary side that a coin or disc represents among two possible alleles.

There is a 50/50 probability

3. Why is a coin toss a great way to represent allele combine that occur in nature? The mix of alleles in nature wake up by chance, together does the an outcome of a coin toss.

4. because that the traits discover in this lab, perform all heterozygous pairs of alleles create an intermediate phenotype? No; for several of the properties listed, heterozygous pairs create only the leading phenotype.

5. can you accurately identify an organism’s genotype through observing that is phenotype? explain your answer. Although understanding an organism’s genotype would permit one come predict its phenotype, some phenotypic characteristics can

Materials (per group)

3 textbooks

2 coins


1. location the textbooks on the laboratory table so that they type a triangle well.2. determine which companion will toss for the female and which will certainly toss for the male. Remember that there room two gene per trait.3. have the companion who is representing the masculine flip a coin right into the well to determine the sex of the offspring. If the coin lands top up, the offspring is a female. If the coin floor tails up, the offspring is a male. Record the sex the the offspring in the empty at the top of web page 111.4. For every the coin tosses you will now make, top will represent the dominant allele and also tails will stand for the recessive allele.5. You and your partner have to now flip your coins right into the fine at the same time to identify the phenotype that the very first trait, the shape of the face. Note: The coins should it is in flipped only when for each trait.6. proceed to flip the coins for each trait listed in the table in number 1. After each flip, document the characteristics of her offspring by place a check in the proper box in the table. (Note: Some information in figure 1 has been simplified. Some listed traits room actually created by two or more genes.)7. making use of the recorded traits, draw the facial attributes for your offspring in the space on web page 111.

108 Biology Laboratory hand-operated A/Chapter 11

A coin toss is a great way to represnt the allele combinations becasue flipping acoin is no predictable.

No, for several of the properties listed, heterozygous pairs create only the dominantphenotype.

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knowing an organism"s genotype would permit one to predict that is phenotype, somephenotypic traits deserve to be the an outcome of one of two people homozygous or heterozygouscombinations the alleles.

110 Biology Laboratory manual A/Chapter 11

long LL

Dominant(both heads)

long Ll

Hybrid(one head, one tail)

short ll

bushy BB

bushy Bb

fine bb

not associated NN

not associated Nn

connected nn

large LL

large LL

medium Ll

small ll

large LL

medium Ll

small ll

present FF

Length that eyelashes


Shape the eyebrows

Position of eyebrows

Size the nose

Size that ears

Size the mouth

Freckles current Ff

absent ff

present DD

Dimples existing Dd

absent dd

Recessive(both tails)

medium Ll

small ll

medium Tt

thin tt

Shape of lips thick TT

Figure 1 continued

5Data Table for her BabyBaby’s Name

Trait Dad’s gene

Mom’s gene


Baby’s phenotype

Sex X1. Confront shape2. Slot chin3. Hair type4. Widow’s peak5. Eye spacing6. Eye shape7. Eye position8. Eye size9. Size of eyelashes10. Eyebrow shape11. Eyebrow position12. Dimension of nose13. Form of lips14. Dimension of ears15. Size of mouth16. Freckles17. Dimples

Baby’s full genotype : __