1. The document provides a task for students to investigate dihybrid inheritance through two experiments - examining mitosis in garlic root tip cells under a microscope and analyzing patterns of inheritance using monohybrid and dihybrid corn. 2. To pass the assignment, students must identify the stages of meiosis and mitosis and carry out an investigation into dihybrid inheritance patterns. 3. To merit, students must explain how chromosome behavior during meiosis leads to variation and apply classical genetics principles to account for observed dihybrid inheritance patterns. 4. To distinguish, students must explain how mutations lead to evolutionary change and analyze the correlation between observed and expected dihybrid inheritance patterns.

1. P1/M1/D1 Dihybrid inheritance
Unit 18: Genetics and Genetic Engineering Assessed by Teresa Greer
Start date: February 16th Hand in date: March 9th
Purpose
Mendelian laws of genetics have shaped all of our current understanding of inheritance.
This unit provides students with the opportunity to study the pattern of inheritance of char-
acteristics and link it to the ways in which our cells divide and gametes are formed.
Scenario
As part of the Darwin 200 celebrations you are investigating subjects that are related to
DNA, genetics and inheritance to support a documentary that you will be making a little
later in the year. Before you get to the documentary you need to research the areas that
surround the issues that you will cover. Here you will look at the origins of our under-
standing of inheritance and the mathematical evidence for these patterns.
Task A This provides evidence for P1/M1/D1
For this task you will be undertaking two investigations.
1. Garlic root tip squash
In this investigation you will look under the microscope at the stages of mitosis in
dividing garlic root tips. You will use a stain specifically targeted to the DNA inside the
cell. Once stained you will examine cells under the microscope to see if you can see the
distinct phases of mitosis.
You will create a table that includes each of the five stages of mitosis and collabora-
tively with the rest of the class count the number of cells in each stage and create a run-
ning tally.
With these results you will write a formal practical report that includes a statistical
Chi Squared analysis of the frequencies of each stage to see if this follows expected values.
2. Dihybrid inheritance in Maize Corn
For this task you will be looking at patterns of inheritance and methods of repre-
senting them. You will first examine some monohybrid inheritance patterns and perform
Chi Squared tests to see if expected frequencies match observed frequencies.
You will then calculate the expected ratio of dihybrid characteristics (purple, col-
ourless, smooth, wrinkled) for maize corn cobs then investigate a single cob of corn to see
if the observed match the expected frequencies using the Chi squared test.
Hand in date March 9th
BTEC National Diploma Applied Science Dihybrid inheritance

2. Dihybrid Inheritance
To achieve a pass grade To achieve a merit To achieve a distinction
the evidence must grade the evidence grade the evidence
show that the learner is must show that the must show that the
able to: learner is able to: learner is able to:
P1 Identify the stages of M1 Explain how the D1 Explain how muta-
meiosis and mitosis and behaviour of chromo- tions lead to evolution-
carry out a practical in- somes during meiosis ary change and analyse
vestigation into patterns leads to variation and the correlation between
of dihybrid inheritance correctly apply princi- observed pattern of di-
ples of classical genet- hybrid inheritance and
ics to account for the the pattern expected
pattern of dihybrid in-
heritance shown in the
practical investigation
Assessed by: Teresa Greer
Internally verified by:
Hand in date: March 9th
BTEC National Diploma Applied Science Dihybrid inheritance