1. The document provides instructions to illustrate 6 genetic crossing diagrams involving blood types, Rhesus factor, sex determination, and inheritance of blood clotting and color blindness. 2. It also provides a genetics problem involving reported switched babies and determining the probability of offspring having color blindness from parents where the father has the trait and the mother is a carrier. 3. Key concepts covered are the alleles that determine blood types, inheritance of blood types from parents with different types, issues that can arise from mismatches in Rhesus factor between mother and fetus, and sex determination in humans being controlled by X and Y chromosomes.

1. EXERCISE : BIOLOGY FORM 5 (Answer all the questions)
1. Illustrate schematic diagram, genetic crossing between parents of blood group A (heterozygous) and
blood group B (homozygous dominant )
2. Illustrate schematic diagram, genetic crossing between parents of blood group AB (heterozygous) and
blood group O (homozygous recessive)
3. Illustrate schematic diagram, genetic crossing between Rhesus positive (heterozygous) genetic cross
with Rhesus negative (homozygous recessive )
4. Draw a schematic diagram sex determination in humans
5. Illustrate schematic diagram for male normal blood clotting, genetic cross with female normal blood
clotting (carrier)
6. Illustrate schematic diagram for male color blind cross genetic with female normal color blind
(carrier )
Understanding Key Ideas
1. The type of blood group is controlled by the allele A,B, AB and O
2. The blood group O is caused by a pair of recessive alleles O
3. A family with the parents with the blood group AB and O respectively will
not have any child with a blood group AB
4. Problems will arise during pregnancy if the mother is Rh positive and the
foetus is Rh negative
5. In human, sex is determined by the X and Y chromosome
STRUCTURE QUESTION
1 Couple X and Couple Y both had their newborn babies on the same day, in the same
. hospital. The blood group of the parents and the babies are shown in Table 2. One day later,
couple X made a report to the hospital claiming that baby X was not their baby.
Blood Group Husband X Wife X Baby X
AB B O
Blood Group Husband Y Wife Y Baby Y
A O B
a. With the help of a genetic diagram, explain whether the babies were accidentally exchanged
b Color blindness is a genetic disease caused by sex-linked recessive allele.
. Complete the genetic Diagram below.
Parents : Father X Mother
Phenotypes : Color blind Normal but carrier
Genotype :
Gamete :
Offspring :
Genotype :
Phenotype :
c. What is the probability of the children having color blindness ?