Page 170 - Big Ideas Year 10 sciPAD 2025

PHOTOCOPYING PROHIBITED
© Silverback Academic Media
170 SCIPAD - BIG IDEAS - BOOK 2
THE BASIS OF HEREDITY
1. State the possible alleles of:
(a) A person with attached ear lobes. 
(b) A person with free ear lobes. 
(c) A person who is purebred for free ear lobes.
2. (a) Is attached ear lobes the dominant condition? 
(b) Justify your answer to (a). 


3. (a) Complete the Punnett square to show the possible offspring produced when a
person with attached ear lobes mates with a person who is non-purebred for free
ear lobes.
Parents’ alleles and
Ear Lobe Genetics
Humans can have two basic types of ear lobes. Ear lobes can either be ‘attached’ or ‘free’. For
simplicity, assume that they are controlled by a single gene. The free ear lobe allele is dominant
over the attached ear lobe allele.
(b) What percentage of the offspring would you expect to have attached ear lobes?

(c) What percentage of the offspring would you expect to have free ear lobes?

These ear lobes are attached. Note how the ear
lobe is joined directly to the side of the head. A
person with these ears will have the alleles ff.
These ear lobes are free. Note the overhanging,
rounded ear lobe. A person with these ears will
have the alleles FF or Ff.
Please note that this is an over-simplistic representation of the genetics involved.
Unchecked Sample Pages
For Review Purposes Only - Photocopying Prohibited
www.scipad.co.nz