Cambridge International A Level Biology Revision Guide

Chapter 16: Inherited change
Phenotype female, striped body, normal antennae male, ebony body, aristopedia antennae
Genotype (EA)(ea) (ea)(ea)
homologous
chromosomes
E
A
E
A
e
a
e
a
e
a
e
a
e
a
e
a
in most cells
in some cells one chiasma
between two loci
E
E
e
e
E
E
e
e
e
e
e
e
A
A
a
a
A
A
a
a
a
a
a
a
most gametes
(EA) or (ea)
some gametes
(Ea) or (eA)
all gametes
(ea)
E
e
E
e
e
e
385
A
a
a
A
a
a
Parental phenotypes female male
striped body ebony body
normal antennae aristopedia
antennae
Parental genotypes (EA)(ea) (ea)(ea)
Gametes large numbers of EA and ea
small numbers of Ea and eA
Figure 16.21 Crossing over in female Drosophila.
ea
Offspring genotypes and phenotypes:
Gametes from male parent
ea
Gametes
from
female
parent
large
numbers
small
numbers
EA
ea
Ea
eA
(EA)(ea)
striped body,
normal antennae
(ea)(ea)
ebony body,
aristopedia antennae
(Ea)(ea)
striped body,
aristopedia antennae
(eA)(ea)
ebony body,
normal antennae