Question 1

monohybrid cross

Accepted Answer

a genetic
cross performed to observe
the inheritance of alleles and
phenotypes for a single gene

Question 2

test cross

Accepted Answer

when an individual
expressing the dominant
phenotype but with an unknown
genotype is crossed with a
homozygous recessive individual.
The results indicate whether the
individual with the dominant
phenotype is homozygous
dominant or heterozygous

Question 3

dihybrid cross

Accepted Answer

a genetic cross
used to observe the inheritance
of alleles and phenotypes for
two genes

Question 4

unlinked genes

Accepted Answer

genes located
on different chromosomes, or far
apart on the same chromosome.
Unlinked genes have less chance
of being inherited together

Question 5

whenever you cross two heterozygous
individuals what is teh ratio

Accepted Answer

9 : 3 : 3 : 1.

Question 6

linked genes

Accepted Answer

genes that are
found close together on the same
chromosome and are likely to be
inherited together,

Question 7

what does thsi mean in terms of meiosis

Accepted Answer

means that during meiosis, because they are on the same chromosome,
they are inherited together and are not separated during independent assortment. Linked
genes, however, can occasionally be separated through crossing over

Question 8

what cant we assume about linked genes

Accepted Answer

we can’t assume two alleles on the same chromosome will
end up in the same gamete. Because of crossing over, the two alleles may occasionally
end up on different chromosomes and in different gametes

Question 9

map unit

Accepted Answer

a measure of the
distance between two genes on
the same chromatid. Genes that
are closer together are more likely
to be linked genes, one map unit=1% chanve of crossing over and the offspring containing a recombinant chromosome

Question 10

recombinant chromosome

Accepted Answer

a chromosome which is not
identical to one of the homologous
chromosomes in a diploid cel

Question 11

eg

Accepted Answer

eight map units apart= 8% chance that crossing
over will occur to create a recombinant chromosome- we can say 8 in 100
gametes will contain a recombinant chromosome= 92%  chance that
crossing over will not occur, resulting in a parental chromosome.

Question 12

parental chromosome

Accepted Answer

a chromosome which contains the
same combination of alleles as one
of the parents’ chromosomes

Question 13

how are linked genes genotype written

Accepted Answer

genotypes are written using a different convention. You write the alleles
on one chromosome first, then add a forward slash (/), then write the alleles on the second
chromosome.

Question 14

pedigree chart

Accepted Answer

a diagram showing
the expression of a trait over
multiple generations

Question 15

Important conventions of pedigree charts include:

Accepted Answer

• horizontal lines  mating between two individuals
• vertical lines represent the link between two generations
• circles are females and squares are males
• coloured shapes are affected individuals
• uncoloured shapes are unaffected individuals.

Question 16

consanguineous breeding

Accepted Answer

breeding of two individuals that
are closely related. Also known
as inbreeding

Question 17

Autosomal dominant

Accepted Answer

1 If both parents are affected, the offspring may be unaffected.
2 If neither parent is affected, the offspring must be unaffected.
3 If an offspring is affected, there must be an affected parent.
4 The trait cannot skip a generation.

Question 18

eg

Accepted Answer

Huntington’s disease,
achondroplasia (dwarfism)

Question 19

Autosomal recessive

Accepted Answer

1 If both parents are affected, the offspring must be affected.
2 If neither parent is affected, the offspring may be unaffected.
3 If an offspring is affected, there may be an affected parent.
4 The trait can skip a generation.

Question 20

eg

Accepted Answer

Cystic fibrosis, Tay-Sachs disease,
albinism, phenylketonuria (PKU)

Question 21

X-linked dominant

Accepted Answer

1 If a male is affected, his mother must be affected
2 If a male is affected, his daughters must be affected
4 If a female is unaffected, her sons must be unaffected.
5 The trait cannot skip a generation.

Question 22

eg

Accepted Answer

Rett syndrome, fragile X
syndrome

Question 23

X-linked recessive

Accepted Answer

1 If a female is affected, her father must be affected.
2 If a female is affected, her sons must be affected.
3 If a male is affected, his mother may be affected.
4 The trait can skip a generation.

Question 24

eg

Accepted Answer

Red-green colour blindness,
haemophilia

Question 25

Y-linked

Accepted Answer

1 Only males can show the trait.
2 All males in a lineage will show the same phenotype.
3 The trait cannot skip a generation.

Question 26

eg

Accepted Answer

Hypertrichosis pinnae auris, Y
chromosome infertility

Biology Chapter 8

8A, 8B, 8C

Question	Answer
monohybrid cross	a genetic cross performed to observe the inheritance of alleles and phenotypes for a single gene
test cross	when an individual expressing the dominant phenotype but with an unknown genotype is crossed with a homozygous recessive individual. The results indicate whether the individual with the dominant phenotype is homozygous dominant or heterozygous
dihybrid cross	a genetic cross used to observe the inheritance of alleles and phenotypes for two genes
unlinked genes	genes located on different chromosomes, or far apart on the same chromosome. Unlinked genes have less chance of being inherited together
whenever you cross two heterozygous individuals what is teh ratio	9 : 3 : 3 : 1.
linked genes	genes that are found close together on the same chromosome and are likely to be inherited together,
what does thsi mean in terms of meiosis	means that during meiosis, because they are on the same chromosome, they are inherited together and are not separated during independent assortment. Linked genes, however, can occasionally be separated through crossing over
what cant we assume about linked genes	we can’t assume two alleles on the same chromosome will end up in the same gamete. Because of crossing over, the two alleles may occasionally end up on different chromosomes and in different gametes
map unit	a measure of the distance between two genes on the same chromatid. Genes that are closer together are more likely to be linked genes, one map unit=1% chanve of crossing over and the offspring containing a recombinant chromosome
recombinant chromosome	a chromosome which is not identical to one of the homologous chromosomes in a diploid cel
eg	eight map units apart= 8% chance that crossing over will occur to create a recombinant chromosome- we can say 8 in 100 gametes will contain a recombinant chromosome= 92% chance that crossing over will not occur, resulting in a parental chromosome.
parental chromosome	a chromosome which contains the same combination of alleles as one of the parents’ chromosomes
how are linked genes genotype written	genotypes are written using a different convention. You write the alleles on one chromosome first, then add a forward slash (/), then write the alleles on the second chromosome.
pedigree chart	a diagram showing the expression of a trait over multiple generations
Important conventions of pedigree charts include:	• horizontal lines mating between two individuals • vertical lines represent the link between two generations • circles are females and squares are males • coloured shapes are affected individuals • uncoloured shapes are unaffected individuals.
consanguineous breeding	breeding of two individuals that are closely related. Also known as inbreeding
Autosomal dominant	1 If both parents are affected, the offspring may be unaffected. 2 If neither parent is affected, the offspring must be unaffected. 3 If an offspring is affected, there must be an affected parent. 4 The trait cannot skip a generation.
eg	Huntington’s disease, achondroplasia (dwarfism)
Autosomal recessive	1 If both parents are affected, the offspring must be affected. 2 If neither parent is affected, the offspring may be unaffected. 3 If an offspring is affected, there may be an affected parent. 4 The trait can skip a generation.
eg	Cystic fibrosis, Tay-Sachs disease, albinism, phenylketonuria (PKU)
X-linked dominant	1 If a male is affected, his mother must be affected 2 If a male is affected, his daughters must be affected 4 If a female is unaffected, her sons must be unaffected. 5 The trait cannot skip a generation.
eg	Rett syndrome, fragile X syndrome
X-linked recessive	1 If a female is affected, her father must be affected. 2 If a female is affected, her sons must be affected. 3 If a male is affected, his mother may be affected. 4 The trait can skip a generation.
eg	Red-green colour blindness, haemophilia
Y-linked	1 Only males can show the trait. 2 All males in a lineage will show the same phenotype. 3 The trait cannot skip a generation.
eg	Hypertrichosis pinnae auris, Y chromosome infertility

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