Albinism is an inherited condition in which pigment does not develop in the skin, hair and eyes. The allele for albinism is recessive.
What are the chances of albino parents having an albino child?
A 0%
B 25%
C 50%
D 100%
Owners of successful race horses hope that the horses’ offspring will be like their parents.
How does a young race horse inherit its characteristics?
A equally from its mother and father
B mainly from its father
C mainly from its mother
D passed across the placenta
In pea plants the allele for tall, T, is dominant to the allele for dwarf, t.
Which cross would produce plants in the proportion of 1 tall : 1 dwarf?
A TT × Tt
B Tt × Tt
C Tt × tt
D tt × tt
Which substance is coded for by a length of DNA?
A fat
B fatty acid
C glycerol
D lipase
What are alleles?
A a pair of chromosomes
B different versions of the same gene
C the total number of genes on one chromosome
D two genes side by side on the same chromosome
Which statement about the human sex chromosomes is correct?
A All boys have two Y chromosomes.
B Everybody has at least one X chromosome.
C Girls have a Y chromosome and an X chromosome.
D Nobody has two X chromosomes.
What will be the genotypes of the offspring resulting from a genetic cross between two individuals, one of which is homozygous dominant, (TT), and the other heterozygous?
A all Tt
B 50% TT, 50% tt
C 50% TT, 50%Tt
D 25%TT, 75% Tt
Which of these cells is haploid?
A liver cell
B red blood cell
C sperm cell
D zygote
A genetic cross between two organisms may be shown as Gg × Gg.
What does g represent?
A a dominant allele
B a dominant chromosome
C a recessive allele
D a recessive chromosome
Some fruit flies have orange eyes and others have red eyes. If two orange-eyed fruit flies are crossed, their offspring always have orange eyes. If two red-eyed fruit flies are crossed, their offspring sometimes include both orange-eyed and red-eyed flies.
What can be concluded from these observations?
A Crossing an orange-eyed fly with a red-eyed fly will produce a 1 : 1 ratio in the offspring.
B The allele for orange eyes is dominant.
C The allele for red eyes is dominant.
D We could determine which allele is dominant only by doing a cross that produces a 3 : 1 ratio.
A man has three sons.
What is the chance of his next child being a son?
The diagram shows a cross between heterozygous tall pea plants.
Which statement is NOT correct?
A Offspring E and H are both homozygous.
B Offspring F and G are both heterozygous.
C The phenotypes of offspring E, F and G are the same.
D The ratio of different phenotypes in the offspring is 1 : 1.
The top diagram shows the chromosomes in the nucleus of a cell that divides by mitosis. Which diagram (A, B, C or D) shows the chromosomes in the nucleus of one of the daughter cells produced?
A
B
C
D
The diagram shows the fusion of gametes to produce a son and a daughter.
A plant has two different alleles of a gene resulting in it having a green seed.
Which row describes the phenotype and genotype of the seeds of this plant?
In pea plants, the allele for tall stems is dominant to the allele for short stems. A heterozygous tall plant is crossed with a short plant, and 100 offspring are produced.
How many of the offspring are likely to be tall?
A 25
B 50
C 75
D 100
The nucleus in a body cell of a fly contains 12 chromosomes.
How many chromosomes are there in the nucleus of a sperm from this fly?
A 3
B 6
C 12
D 24
In a species of plant, the allele for red flowers (R) is dominant over the allele for white flowers (r). Two red–flowered plants were crossed.
What are the genotypes of the parents?
A RR and rr
B RR and Rr
C Rr and Rr
D Rr and rr
The diagram shows a potato tuber that developed from the stem of a parent potato plant. Three shoots are starting to grow from the tuber.
How do the genotypes of the shoots compare with the genotypes of the tuber and of the parent?
A They are all different
B They are all identical.
C The shoots are identical to each other, but are different from the tuber and the parent.
D The shoots are identical to the tuber, but are different from the parent.
The colour of a mouse’s fur is controlled by a single pair of alleles. A mouse with black fur was crossed with a mouse with white fur. All the offspring had black fur.
What would be the most likely ratio in several litters of offspring if two of these black offspring were crossed?
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