WorksheetsTopic 3 Genetics
Total questions: 76
Worksheet time: 3hrs 35mins
Which statements are characteristics of alleles?
I. Alleles differ significantly in number of base pairs.
II. Alleles are specific forms of a gene.
III. New alleles are formed by mutation.
I and II only
I and III only
II and III only
I, II and III
The system of sex determination in chimpanzees (Pan troglodytes) is the same as in other mammals. A chimpanzee has 48 chromosomes in the nuclei of its body cells.
What can be deduced from this information?
The sex of the chimpanzee
The number of genes in each chromosome
Whether non-disjunction has occurred
The number of autosomes in a diploid cell
Which statement correctly describes genome and proteome?
Only the genome but not the proteome can be analysed using gel electrophoresis.
The genome and the proteome are the same in all tissues in an organism.
In cells of different tissues, the genome is the same while the proteome varies.
Only mutations in the proteome but not in the genome cause any variability.
Some yeast genes can be replaced by human genes that then continue to produce the same human proteins in the yeast cells. Which statement helps to explain this evidence?
The DNA of yeast and humans is identical.
Yeast and humans have the same number of chromosomes.
The genetic code is universal.
Yeast and humans are both eukaryotes.
What determines the genomic size of a species?
The total amount of DNA
The total number of genes
The total number of alleles
The total number of chromosomes
What distinguishes an allele from a gene?
An allele is made of RNA.
An allele is shorter.
An allele is a variety of a gene.
An allele cannot be transferred during genetic modification.
What is the effect of dominant alleles?
I. They mask the effect of recessive alleles.
II. They become more frequent than recessive alleles in a population.
III. They have a joint effect with recessive alleles when characteristics are co-dominant.
I only
I and II only
I and III only
I, II and III
A pregnant woman had fetal cells removed by chorionic villus sampling and tested. The following karyogram was produced.
What does this show?
The child is female with Down syndrome.
The child is female without Down syndrome.
The child is male with Down syndrome.
The child is male without Down syndrome.
The image shows chromosomes from an insect (2 n = 8).
Which pair of chromosomes are the sex chromosomes of this insect species?
c and e
a and h
f and h
a and e
What is the same in all parts of homologous chromosomes?
Base pair sequence
Alleles
Sequence of genes
Deletions
For what purpose is a karyogram used?
To identify gene loci in a species
To identify linked genes in the chromosomes of an individual
To identify the genome size of a species
To identify abnormal chromosomes in an individual
The image shows a karyogram.
What information can be determined from this karyogram?
The sex is female.
The haploid number is 54.
Disjunction occurred during meiosis.
The species is not human.
Which is a characteristic of the pairs of sister chromatids that are visible during meiosis?
They result from the replication of DNA before meiosis.
They are only present in meiosis I.
They split apart during metaphase I in meiosis.
They are only present in meiosis II.
Which is a characteristic of the haploid number of eukaryotic chromosomes?
It doubles in mitosis.
It is fixed for each species.
It is an even number for all species.
It is positively correlated with an animal’s mass.
The diploid number of chromosomes in humans (Homo sapiens) is 46 and the diploid number of chromosomes in rice (Oryza sativa) is 24. What does this indicate about diploid chromosome numbers?
Plant species have a lower diploid number of chromosomes than animals.
Members of a species have the same diploid number of chromosomes.
The evolutionary progress of species is determined by the diploid number of chromosomes.
The complexity of the organisms is correlated to the diploid number of chromosomes.
What is characteristic of homologous chromosomes?
They have an identical DNA sequence.
They are of the same length in karyograms.
They form pairs in prokaryotes.
They carry the same alleles.
What is a possible source of the chromosomes used for prenatal karyotype diagnosis?
The mother’s lymphocytes
The mother’s cheek cells
The cells from chorionic villi
The fetal hair root cells
What causes the presence of three chromosomes 21 in Down syndrome?
Crossing over
Allele change
Non-disjunction
Gene mutation
What is a characteristic of the human Y chromosome?
It is made of DNA and histones covered by phospholipids.
It contains some genes that are not present on the X chromosome.
It is the largest chromosome in the human karyotype.
It has a condensed length of approximately 100 µm.
At which stage of meiosis are bivalents formed?
Interphase
Prophase I
Prophase II
Metaphase II
The graph shows the incidence of trisomy resulting from non-disjunction in pregnancies at different maternal ages.
What can be inferred from the graph?
The incidence of three copies of a chromosome increases directly in proportion with the age of the mother.
The incidence of three sets of chromosomes increases from age 20.
The incidence of three copies of a chromosome increases the most from age 35.
The incidence of three sets of chromosomes increases the most from age 30.
What helps make the genome of each human unique?
A
B
C
D
What happens during meiosis I and meiosis II?
A
B
C
D
What forms when two different chromatids of the same homologous pair cross over?
Daughter centromere
Chiasma
Chromosome mutation
Telomere
Which process could cause non-disjunction if it occurred during meiosis?
Sister chromatids do not align in metaphase I.
Homologous chromosomes do not separate in anaphase I.
Sister chromatids do not align in metaphase II.
Homologous chromosomes do not separate in anaphase II.
The micrographs show four different phases from meiosis II. What is the correct order?
3-4-2-1
2-3-4-1
4-3-2-1
4-2-3-1
During which phase of the first division of meiosis can non-disjunction take place and what structure is affected by the non-disjunction?
A
B
C
D
What description is matched with the correct phase in meiosis I?
A
B
C
D
What event occurs only in meiosis?
Fusion of gametes to promote genetic variation
Random separation of chromatids
Random separation of homologous chromosomes
Replication of chromosomes
What is the chromosome number in a human gamete with non-disjunction?
46
45
24
23
A variety of Pelargonium has yellow leaves. When plants of this variety are crossed, the resulting seeds produce green, yellow and white seedlings in the ratio 1 : 2 : 1. If plants with yellow leaves are crossed with plants with green leaves, what would the expected ratio of phenotypes in the offspring be?
A
B
C
D
A pair of alleles controls the secretion of antigens corresponding to blood group in saliva. Examine the pedigree chart.
Based on this pedigree chart, which best describes the allele conferring antigen secretion in saliva?
Dominant
Recessive
Sex-linked
Co-dominant
The pedigree chart shows the inheritance of hemophilia in some of the descendants of Queen Victoria. Which letter points to a family member certain to be heterozygous?
A
B
C
D
Creeper in chickens is a condition in which the chickens are born with very short legs. The creeper allele (C) is dominant over the normal allele (c). Embryos which are homozygous for the dominant allele fail to develop into viable chickens and die before they hatch. What phenotypic ratio would you expect in the live offspring of a cross between two creeper chickens?
All creeper
1 creeper; 2 normal
2 creeper; 1 normal
3 creeper; 1 normal
Which pedigree chart is consistent with the inheritance of red-green colour blindness?
A
B
C
D
The pedigree chart shows a family affected by cystic fibrosis.
What is the genotype of the affected boy’s father?
AA only
Either AA or Aa
Aa only
aa only
The children in a family have blood groups A, B and O. What are the genotypes of their parents?
IAIA and IBi
IAi and IBi
IAIB and ii
IAIB and IBi
The image shows the chromosomes in four cells of an insect at the end of meiosis.
What is the diploid number of this insect?
16
8
4
2
A human gene has two alleles. One allele, P, is dominant over the recessive allele p. Embryos that are homozygous for the dominant allele die in the uterus. What is the expected ratio of genotypes for the live offspring of a heterozygous man and a heterozygous woman?
1 : 1
2 : 1
3 : 1
4 : 0
In cats, black coat colour is dominant over gray. A female black cat, whose mother is gray, mates with a gray male. What is the predicted ratio of phenotypes in the offspring?
100 % black
50 % black to 50 % gray
75 % black to 25 % gray
100 % gray
What explains the presence in living humans of DNA sections which are identical to DNA found in Neanderthals who lived 40 000 years ago?
Genetic mutation
Inheritance
Adaptation
Speciation
What is the percentage risk of a child inheriting Huntington’s disease if only one parent has the disease?
0 %
25 %
50 %
100 %
What contributes to the total DNA content of a zygote?
A
B
C
D
Nail patella syndrome is a rare disease that causes abnormalities of the nails and some bones. Its alleles are linked to the blood group alleles on the same chromosome. The pedigree chart shows the inheritance of these two characteristics over three generations.
Generation III has 1 individual
Generation III has 4 individuals
Generation II has 5 individuals
Generation II has 13 individuals
An allele for lactase persistence allows humans to digest milk as adults. People who lack this allele are lactose intolerant in adulthood.
What is the pattern of inheritance?
Lactase persistence is sex-linked recessive.
Lactase persistence is autosomal recessive.
Lactase persistence is sex-linked dominant.
Lactase persistence is autosomal dominant.
A dominant autosomal allele for lactase persistence allows humans to digest milk as adults. People who lack this allele are lactose intolerant in adulthood.
If J and K have a child L, what is the probability that L will be lactase persistent?
25 %
50 %
75 %
100 %
A child has blood group A. The father of the child has blood group B. What are the possible genotypes of the mother?
I. IAIA
II. IAIB
III. IAi
I only
I and II only
II and III only
I, II and III
Some breeds of dogs are characterized by the presence of a melanistic mask, which is a darkening of the fur near the nose, as shown by the arrow in this photograph.
Which outcome is matched with a valid conclusion if dogs that were pure breeding for melanistic masks were crossed with dogs without melanistic masks?
If 0 % of the puppies have a mask, the character is recessive.
If 25 % of the puppies have a mask, the character is dominant.
If 75 % of the puppies have a mask, the character is dominant.
If 100 % of the puppies have a mask, the character is recessive.
The diagram shows a pedigree of cystic fibrosis, in which the black colour indicates the presence of cystic fibrosis.
What is the probability that the individual labelled X is a carrier of cystic fibrosis?
1.00
0.50
0.25
0.00
What proves that the inheritance of the condition shown in this pedigree chart is autosomal recessive and not autosomal dominant?
There is no affected person in generation I.
Both males and females are affected.
Two unaffected parents have a child that is affected.
Not everybody in generation III is affected.
What is the major health issue resulting from the Chernobyl nuclear accident in 1986?
Coronary thrombosis
Cholera
Sex-linked diseases
Thyroid cancer
It is possible for two parents to have children with each of the four ABO blood groups. What blood groups would the parents have?
A
B
C
D
In a person who is heterozygous for sickle-cell anemia, where is the mutation found?
In every gamete produced
Only in gametes carrying an X chromosome
In all brain cells
In blood plasma
In a human with type A blood, what determines the blood group?
Sex chromosomes
One or two alleles
Multiple alleles
Codominant alleles
In a person who is heterozygous for sickle-cell anemia, where is the mutation found?
In every gamete produced
Only in gametes carrying an X chromosome
In all brain cells
In blood plasma
In a human with type A blood, what determines the blood group?
Sex chromosomes
One or two alleles
Multiple alleles
Codominant alleles
Which individuals are colour blind in this Punnett grid?
XB Y
XB XB
Xb Y
XB Xb
What maximum number of different genotypes and phenotypes are possible among the children of a mother with blood group A and a father with blood group B?
A
B
C
D
What is PCR used for?
Separate fragments of DNA by size
Amplify small amounts of DNA
Compare DNA samples
Genetically modify organisms’ DNA
Genetically modified maize, called Bt maize, is thought to be affecting the monarch butterfly (Danaus plexippus) in the USA. What is the reason for this?
The monarch butterfly feeds on maize nectar, which contains Bt toxin.
The monarch caterpillar feeds on maize leaves, which contain Bt toxin.
Bt toxin kills the plants that the monarch caterpillar usually eats.
Bt toxin is in maize pollen, which blows on to plants that the monarch caterpillar eats.
Two restriction endonucleases (EcoRI and BamHI) were used to cut a DNA sample into smaller fragments. These were then subjected to gel electrophoresis and the results are shown. The lengths of the DNA fragments are measured in kilobases (kb). One kilobase is 1000 DNA bases.
Which statement is supported by the data?
The DNA sample is approximately 16 kb in size.
Each endonuclease produces a 2 kb fragment.
Both endonucleases produce the same number of fragments.
The fragments produced using both endonucleases are all different from those produced by the individual endonucleases.
Ampicillin (Amp) is an antibiotic. A plasmid carrying a gene for Amp resistance was used to transform bacteria in a tube of broth. A control tube without plasmid was also produced. The results were plated as shown. Which plate has only colonies of transformed bacteria?
A
B
C
D
Sanger developed a method for determining DNA base sequences using terminating nucleotides called dideoxyribonucleotides. After an incubation period, the DNA samples are run on an electrophoresis gel. Results are shown in the diagram.
What is the base sequence of the original DNA template strand?
A C G C C C G A G T A G C C C A G A T T
U G C G G G C U C A U C G G G U C U A A
A C G C C C G A G U A G C C C A G A U U
T G C G G G C T C A T C G G G T C T A A
Which technique is used to amplify very small samples of DNA?
Cloning
Gel electrophoresis
PCR
DNA profiling
HindIII is an endonuclease that recognizes the sequence A A G C T T, cutting between the two adenines.
Into how many DNA fragments would the strand shown be cut by HindIII?
2
3
4
5
Which is a possible risk associated with a genetic modification of crops?
Crop plants will become weaker with time.
It can increase mutations in the organisms that consume them.
Starch obtained from genetically modified plants will be more difficult to digest.
Resistance to herbicide genes can be transferred to weeds.
What is produced by somatic-cell nuclear transfer?
Adult sheep
Cloned embryos
Rooted stem-cuttings
Genetically modified food
Which technique separates proteins according to size?
Treatment with restriction endonucleases
PCR
Gel electrophoresis
DNA profiling
Which sequence of DNA would be suitable in DNA profiling?
---ATTCGTGAATCAGCC--
---ATTCGTGAATTTGCC--
---ATTCGTGATTGCAGC--
---ATTCGTGATTCGTGA--
Laboratory analysis of DNA from a 40 000 year old woolly mammoth used the polymerase chain reaction (PCR). What role did the PCR have in the analysis?
DNA denaturation
DNA comparison
DNA separation
DNA amplification
How are enzymes used during gene transfer involving plasmids?
A
B
C
D
What was an aim of genetic modification of organisms?
To provide stem cells from embryos for medical use
To make crop plants resistant to herbicides
To provide sperm cells for in vitro fertilization (IVF)
To produce genetically identical sheep
What is a definition of a clone?
A group of cells derived from a single parent cell
Differentiated cells that retain the capacity to divide
A fetus developed specifically for medical use
A group of cells that have lost the ability to differentiate
What was an aim of genetic modification of organisms?
To provide stem cells from embryos for medical use
To make crop plants resistant to herbicides
To provide sperm cells for in vitro fertilization (IVF)
To produce genetically identical sheep
A colour blind man and a woman carrier for colour blindness have a son. What is the probability that their son will be colour blind?
25%
50%
75%
100%
A DNA profile was made of one individual in a paternity suit. Locus B was used to distinguish between this individual and other individuals. The individual had two alleles of the gene at locus B which are shown below. Gel electrophoresis was used to separate and visualize the alleles B3 and B5. The gel, with two bands of DNA, is shown below. What DNA is in bands 1 and 2?
Band 1 is a mix of B3+B5; Band 2 is B3 only
Band 1 is a mix of B3+B5; Band 2 is B5 only
Band 1 is B5 only; Band 2 is B3 only
Band 1 is B3 only; Band 2 is B5 only
