BTEC Level 3 National Applied Science, Student Book
This is Btec Applied Science Unit 11 Assignment C (Human inheritance and predicting genetic traits) which was awarded a distinction and contains all the practical results. This is an example of a Distinction level assignment, and you may use it as a guide to help you achieve a distinction and finis...
Unit 11: Genetics and Genetic engineering
B: Explore how the process of cell division in eukaryotic cells contributes to genetic variation
Assignment title: Human inheritance and predicting genetic traits
Investigations to collect valid and reliable data for one monohybrid and one dihybrid phenotypic
ratio.
Aim: In this experiment we will use a website cgslab.com to carry out an experiment to see patterns of
monohybrid and dihybrid inheritance.
Genetic cross: A genetic cross is when two people intentionally mate, combining their genetic makeup in
the offspring. Crosses can be carried out in a variety of model systems, such as plants, yeast, flies, and
mice, and they can be used to analyse genetic processes or develop new features in species. For
example, if the two parents of a child are homozygous for a certain trait, the child has a 100% chance if
inheriting that trait. Genetic crosses are used in agriculture to produce crops with better yields and
livestock with desired features. This can be achieved by selecting the best individuals for a particular
trait, and crossing them with each other, to increase the chances that the resulting child generation will
have that same trait.
Monohybrid cross: A monohybrid cross is made up of two homozygous individuals and results in the
phenotype for that particular genetic trait being opposite. A monohybrid cross consists of the traits (TT
and tt) of two monohybrids. One gene is transmitted by the monohybrid cross. The use of a Punnett
Square makes demonstration easy. Monohybrid crossings are used by geneticists to examine the
expression of heterozygous genes that are transferred from parents to homozygous offspring.
Dihybrid cross: A dihybrid cross occurs when two organisms are bred together and are identical hybrids
for two traits. So two organisms that are heterozygous for two different traits are combined to form a
dihybrid cross. The homozygous carriers of this particular trait are the individuals who display it. These
traits are under the control of genes, which are bits of DNA. In a dihybrid cross, each set of parents has a
unique pair of alleles for each trait. The homozygous dominant allele is present in one parent, whereas
the homozygous recessive allele is present in the other parent. After the crosses, every child of the F1
generation is heterozygous for certain traits.
Requirement: Cgslab.com, wild population set up by teacher, login details.
Method: First we will open the website cgslab.com. Then you will launch the website. After this you will
be given the option to log into your account. When you press the option to log into your account you will
be asked if you are a new student or a returning student. When you click the option of new student your
teacher will provide you with the information to log in. Once you log in with information given to you by
your teacher you will be provided with a personalised code which u can use to log into your account
again. After this you will be given the option to either undertake a monohybrid cross or dihybrid cross.
For each one of these you will be provided with a wild population and you will perform 3 crosses for each
monohybrid and dihybrid. You will cross a male and a female with certain traits. When you complete the
3 crosses for any one them, you will select the stats option on the top of the page. In the stats page you
will complete the chi-squared test for one of the trait. The expected ratio for monohybrid will be 3:1 and
for dihybrid the expected ratio will be 9:3:3:1. Once you get the result for your chi-squared test you will
compare the value obtained to the table given below. If the value on the table is lower than the value
, obtained from the chi-squared test you will accept the hypothesis and if the value on the table is greater
than the value obtained from the chi-squared test you will reject the hypothesis. You will take
pictures/screenshots for each one of these results.
Results
Monohybrid
Figure 1 shows the result for the first monohybrid crossing vial 1 between Figure 2 shows the result for the second monohybrid crossing vial 2
male (wild) (truncated)(aa) and female(wild) (truncated) (aa) between male (truncated)(aa) and female (truncated) (aa)
Figure 3 shows the result for the third monohybrid crossing vial 3 between Figure 4 shows the chi-squared test and its result for the
male (wild) (truncated) (aa) and female(wild) (truncated) (aa) monohybrid crosses including chi squared value, degrees of freedom
and p value. The chi-squared test shows the result for 1 trait (tarsi)
and 2 variables (truncated, wild type).
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