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STEM-8- Worksheet Activity 1- Inheritance Lawas Jeremiah
Civil Engineering (BSCE 01)
Ateneo de Davao University
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STEM 8 Worksheet.
General Biology 2
Science, Technology, Engineering, and Mathematics
NAME: Jeremiah M. Lawas SECTION: G12 SH
Activity 1
Inheritance Across Generations
Let’s Review
In this unit, you have learned about the concept of inheritance and how traits are passed on from parents to offspring. Furthermore, you have learned about the concept of Mendelian inheritance which
follows three main principles.
The three main principles of inheritance are the following:
● The law of dominance: This states that in a heterozygous pair of alleles, the phenotype expressed will be that of the dominant allele.
● The law of independent assortment: This states that alleles of different genes are independently sorted into gametes.
● The law of segregation: This states that allele pairs segregate during the formation of gametes and later unite during the process of fertilization.
The chances of which traits are inherited can also be predicted. For Mendelian inheritance, this can be done through the use of Punnett squares. In a Punnett square, the alleles of both parents are crossed with each other to come up with a prediction for the combinations of alleles that the offspring may have.
Summary crosses for Mendelian genetics.
Dominance TT x tt (Tall x Short) 100% Tt (Tall)
Segregation Tt x Tt (Tall x Tall) 75% Tall and 25% Short
Independent Assortment
RrGg x RrGg (Round-Green x Round-Green) 9/16 Round-Green 3/16 Round-Yellow 3/16 Wrinkled-Green 1/16 Wrinkled-Yellow
Objectives
At the end of this laboratory activity, the students should be able to do the following: ●
Explain how traits are inherited from parent to offspring.
● Determine the chances of the inheritance of certain combinations of traits.
Material
● device connected to the Internet
Procedure
- Find a partner to do this activity with.
- You are given the following scenario to work with:
You are studying the inheritance patterns of a species of fish. You noticed that this fish species has two distinct variants in two different traits. Their scales may either be black or white, and their tails may either be long and short. Both the black scales and long tails are dominant. You want to see how these traits are passed onto offspring across different generations.
You start with a population of three fish, and you randomly select the two of them for mating.
P-Generation
Randomly choose two of the fish below for your P-generation. Write this down in Table
Repeat Step 7 until you have the traits for 10 individual offspring.
Record the genotype and phenotype of each of the ten offspring in the F 1 generation in Table 1..
Draw each of the offspring in the F 1 generation in the space provided.
Choose two random individuals from the F 1 generation to begin the F 2 generation. Write these down in Table 1.
Calculate the probabilities for the F 2 generation offspring from the two random F 1 individuals and assign random numbers the same way you did in the previous generation. Write these down Figure 1. and Table 1.
Reminder
Make sure that you record all probabilities, genotypes, phenotypes, and offspring information. You are dealing with large amounts of data so make sure that you keep track of each.
F 2 Generation 14. Repeat Steps 7 to 10 to generate 10 random offspring for the F 2 generation. Write these down in Table 1. 15. Answer the guide questions afterward.
Data and Results
Table 1. P-generation information for parents
Fish #1 Heterozygous black scales (Ss), Heterozygous Long Tail (Tt) Fish #2 Homozygous White Scales (ss), Homozygous Short tail (tt)
Figure 1. Punnett square for the offspring of the P-generation
ST St sT st
st SsTt Sstt ssTt sstt
st SsTt Sstt ssTt sstt
st SsTt Sstt ssTt sstt
st SsTt Sstt ssTt sstt
Table 1. P-generation offspring combination
Scale Tail Probability Combinatio n
- Fish 1 (SsTt)
Heterozygou s black scale
Heterozygous Long Tail
25% 1-
- Fish 2 (Sstt)
Heterozygou s Black Scale
Heterozygous Long Tail
25% 2501-
- Fish 3 (ssTt)
Homozygous White Scale
Heterozygous Short Tail
25% 5001-
- Fish 4 (sstt)
Homozygous White Scale
Heterozygous Short Tail
25% 7501-
F1 Generation
Table 1. F1 Generation Information for individually- generated offspring
Genotype Phenotype
SsTt 4/16 = 25% 8/16 -50%= Black Scales & Longtail
Sstt 4/16 = 25% 8/16 -50% = White Scales & Short Tail
ssTt 4/16 = 25% Total Ratio = 1:1:1:
sstt 4/16 = 25%
Table 1. F1-generation information to parents
Fish Genotype 1 Heterozygous Black Scales, Homogenous Short Tail SsTt 2 Homogenous White Scalse, Heterogenous Long Tail ssTt
Figure 1 Punnett square for the offspring of the F1- Generation
ST St sT st
sT SsTT SsTs ssTT ssTt
st SsTt Sstt ssTt sstt
sT SsTT SsTt ssTT ssTt
st SsTt Sstt ssTt sstt
Figure 1 generation offspring combination
Scale Tail Probability Combinatio n
- Fish 1 Heterozygou s black scale
Heterozygous Long Tail
37% 1-
- Fish 2 Heterozygou s Black Scale
Homozygous Short tail
12% 2501-
- Fish 3 Homozygous White Scale
Heterozygous longtail
37% 5001-
- Fish 4 Homozygous White Scale
Homozygous Short Tail
12 7501-
Table 1. generation offspring combination
Phenotype Genotype Random Number
1 Heterozygous Black scales Heterozygous Longtail
SsTt 6296
2 Heterozygous Black Scales Homozygous Short Tail
Sstt 6886
3 Homozygous White scale Heterozygous Long Tail
ssTt 8056
4 Homozygous White scale Homozygous Short Tail
sstt 730
5 Heterozygous Black scales Heterozygous Long Tail
SsTt 6251
6 Homozygous White scale Homozygous Short Tail
sstt 1878
7 Homozygous White scale Heterozygous Long Tail
ssTt 3123
8 Heterozygous Black scales Homozygous Short Tail
Sstt 1885
9 Homozygous White scale Heterozygous Long Tail
ssTt 7379
10 Homozygous White scale Homozygous Short Tail
sstt 1958
Conclusion
In summary, Mendelian genetics inherits both traits from parents with a 50-50 chance of probability through offspring. In the F-2 generation, there is a 25% probability that the combination of offspring
from the F-1 generation will produce offspring from the 1st parent of the F-1 generation
Reference
Russell, Peter J. Biology: The Dynamic Science. Student Ed. Belmont, CA: Thomson/Brooks/Cole, 2008.
Starr, Cecie, Ralph Taggart, Christine A. Evers, and Lisa Starr. Biology: the Unity and Diversity of Life. Boston, MA: Cengage, 2019.
STEM-8- Worksheet Activity 1- Inheritance Lawas Jeremiah
Course: Civil Engineering (BSCE 01)
University: Ateneo de Davao University
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