Microsoft Word - blank.doc

NEL The Basis of Heredity 611

Section18.4

A Mystery of Blood Types

Humans have four blood types; A, B, AB, and O. The alleles for

blood types A and B are codominant but dominant to O

(Table 2). We also each have one of two forms of rhesus

factor—the positive form (Rh) or the negative form (Rh).

The allele for the Rhform is dominant to the Rhallele.

Blood types can identify individuals and family members.

Case StudyCase Study

Table 2 Human Blood Types

Phenotypes Genotypes

Type A IAIA, IAi

Type B IBIB, IBi

Type AB IAIB

Type O ii

Lord Hooke Lady Hooke

Tom Jane Ann Ida Helen Roule

Beth Tina Henry

Figure 6

The family tree of the members of Lord Hooke’s family who

were in the castle

Evidence

In Black Mourning Castle, a scream echoed from the den of

Lord Hooke. When the maid peered through the door, a

freckled arm reached for herneck. She bolted and telephoned

the police. Inspector Holmes arrived to find the dead body of

Lord Hooke. Apparently, the lord had been strangled. The

inspector noted blood on a letteropener, even though Lord

Hooke did not have any cuts. This blood was type O, Rh.

Inspector Holmes took blood samples from the family members

shown in Figure 6.

The inspector gathered the information shown in Table 3.

The gene for freckles is dominant to the gene for no freckles.

Some family members were wearing long-sleeved shirts, so

the inspector could not determine whether freckles were

present.

The inspector then announced, “Lady Hooke had been

unfaithful to her husband. One ofthe heirs to the fortune was

not Lord Hooke’s child. The murder was committed to preserve

a share of the fortune!”

Case Study Questions

1. Who was the murderer? What was the murderer's
   probable blood type?
   2.Describe how you obtained your answer.
   3.How did the inspector eliminate the other family
   members?

Table 3 Traits of the Hooke Family

Family Blood type Rh factor Freckles

Lord Hooke AB + no

Lady Hooke A + no

Helen A + no

Roule O + no

Henry refused blood test?

Ida A –?

Ann B +?

Tom O – no

Jane A +?

Beth O –?

Tina A + yes

Purpose Design Analysis

Problem Materials Evaluation

Hypothesis Procedure Synthesis

Prediction Evidence

To perform this investigation, turn to page 620.

How Do Environmental Factors Affect

Gene Expression?

Design and carry out an investigation of the effect of an
environmental factor on the phenotype of genetically identical
plants.

INVESTIGATION 18.1Introduction Report Checklist