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Two dogs, heterozygous for the colour white, were crossed. (White hair colour is dominant to black.) What would be the phenotypic ratio of the F1 generation regarding hair colour?
One quarter black and three quarters white.
All white.
One third white and two thirds black.
One half black and the other half white.
Question 1
A person carries the gene pairs A and A, B and b, and C and c on different chromosome pairs. One of his/her gametes would contain ...
A B c
A B Cc
Question 2
a b c
Aa Bb Cc
An inherited characteristic, which is shown only when the genes which are known to determine it occur in the homozygous condition, is referred to as ...
Question 3
recessive.
dominant.
linked.
heterozygous.
In a test-cross an organism, of unknown genotype for a characteristic, is mated with one that is ...
Question 4
homozygous recessive.
heterozygous recessive.
homozygous dominant.
heterozygous dominant.
A pair of chromosomes carry the gene combination Cd and cD respectively before meiosis. How can a CD-gamete be explained?
Question 5
Crossing over
Independent assortment
Segregation of alleles
Chromosome mutation
How many heterozygous offspring would you expect if two parents, who were heterozygous for a trait, produced an F1 generation of 80 individuals?
Question 6
40
10
15
20
Which cross will produce a 9 : 3 : 3 : 1 ratio of phenotypes?
Question 7
BbCc x BbCc
bbcc x BbCc
BbCc x BbCC
bbCC x Bbcc
A child with Down’s Syndrome has 22 pairs of normal chromosomes in the somatic cells and three chromosomes in place of the 21st pair. This abnormality is the result of ...
Question 8
failure of homologous chromosomes to separate during meiosis.
incomplete dominance.
crossing over.
gene mutation.
Mr. Smith is blood type B and Mrs. Smith is blood type O. They have three children of their own and one adopted child. John is blood type AB, Anne O, Susan B and Paul B. Which child is adopted?
Question 9
John
Anne
Susan
Paul
A couple with blood types O and AB can produce children that are blood type ...
Question 10
A and B
AB and O
AB
A, B and O
A father with a sex-linked dominant characteristic on the X chromosome will pass it on to ...
Question 11
all of his daughters.
half of his daughters.
all of his sons.
all of his offspring.
A homozygous red-flowered snapdragon is crossed with a homozygous yellow-flowered snapdragon. The F1 generation, which produces orange flowers only, is inbred and 20 of the F2 offspring have yellow flowers. What will be the number and phenotype of the remainder of the F2 generation?
Question 12
20 plants with red flowers and 40 with orange flowers.
20 plants with red flowers and 20 with orange flowers.
10 plants with orange flowers.
10 plants with red flowers.
Parent 1’s genotype is ...
Question 13
heterozygous.
homozygous recessive.
homozygous dominant.
lacking the mutant gene.
The genotypes of persons 1, 2 and 3, in the correct sequence, in this family tree are...
Question 14
HH ; Hh ; hh
HH ; HH ; hh
Hh ; HH ; Hh
Hh ; Hh ; hh
Human genetic condition resulting from having an extra chromosome 21 is known as …
Question 15
Trisomy 21
Independent assortment
gene mutation
haemophilia
Questions 13 and 14 refer to the following …..
For questions 33 and 34, refer to the following information about hyperdactyly, a genetically inherited condition.
In humans the condition of hyperdactyly (the possession of twelve fingers) is determined by the dominant allele (H) and the normal condition by the recessive allele (h). The following diagram shows a family tree in which some members of the family are hyperdactylous.
