CfE Higher Human
Biology
Unit 1
Human Cells
Home Study Booklet
Differentiation and Stem cells
1 . Give an account of cell differentiation under the following headings.
(i)
(ii)
(iii)
Stem cells;
Somatic cells;
Germline cells;
(4)
(4)
(2)
2.
1
3.2.
2
DNA and its replication
4. The diagram shows part of a DNA molecule. (Image taken from
http://johnbright.conwy.sch.uk/vle/mod/resource/view.php?id=362 and modified under a Creative Commons
licence).
X
Y
a. Identify molecules X and Y.
X:
Y:
b. The full molecule contains 8000 nucleotides, of which 20% contain adenine. What number of
nucleotides in the molecule contain guanine?
5.If ten percent of the bases in a molecule of DNA are adenine, what is the ratio of adenine
to guanine in the same molecule?
A 1:1
B 1:2
C 1:3
D 1:4
6. A fragment of DNA was found to consist of 72 nucleotide base pairs. What is the total
number of deoxyribose sugars in this fragment?
A 24
B 36
C 72
D 144
3
7. A DNA molecule consists of 4000 nucleotides, of which 20% contain the base adenine. How
many of the nucleotides in this DNA molecule will contain guanine?
A 800
B 1000
C 1200
D 1600
8. A fragment of DNA was found to have 120 guanine bases and 60 adenine bases. What is the
total number of sugar molecules in this fragment?
A 60
B 90
C 180
D 360
9. A DNA molecule contained 8000 nucleotides of which 20% contained adenine. How many
nucleotides would have contained guanine?
A 1600
B 2400
C 3200
D 4800
10. A section of a double stranded DNA molecule contains 80 bases. 24 of these are thymine.
The percentage of cytosine bases in the molecule is?
A 12
B 16
C 20
D 30.
4
11. The percentage of adenine bases in a double stranded DNA molecule is 30% and in a single
stranded RNA molecule it is 25%. Which line in the table below shows the number of other
bases in each molecule for which the percentage could be calculated?
12. The diagram shows part of a DNA molecule.
(a)
DNA is a large molecule made up of a large number of nucleotides. Each
nucleotide has three components.
(i)
Name the components that make the parts of the DNA molecule labelled
A and B.
A .....................................................
and
B ......................................................
(3)
(ii)
Name the type of bond found at C.
5
(1)
13.
6
14.
15.
7
16.
17. Which of the following diagrams correctly shows the structure of DNA?
18. Write short notes on:
i)
ii)
The structure of DNA
The replication of DNA
(4)
(6)
8
Gene expression
1. Give 3 differences between DNA and RNA.
DNA
RNA
2. The function of tRNA in cell metabolism is to?
A transport specific amino acids to be used in synthesis
B carry codons to the ribosomes
C synthesise proteins
D transcribe the DNA code.
3. Which of the following compounds are linked by peptide bonds to form more complex
molecules?
A Bases
B Nucleic acids
C Nucleotides
D Amino acids
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4. Table 2 shows the genetic code as triplets of bases found in mRNA.
Second base
U
C
UUU
A
UCU
G
UAU
Phe
UUC
UCC
U
UGU
Tyr
Cys
UAC
C
UGC
Ser
U
UCA
UAA
Stop
UGA
Stop
A
UUG
UCG
UAG
Stop
UGG
Trp
G
CUU
CCU
CAU
UUA
Leu
U
CGU
His
CUC
C
CCC
CAC
CUA
CCA
C
CGC
Arg
Pro
Leu
CAA
CGA
A
CGG
G
Gln
CUG
CCG
CAG
AUU
ACU
AAU
AUC
ACC
Ile
A
U
AGU
Asn
Ser
AAC
C
AGC
Thr
AUA
ACA
AAA
AUG
Met
GUU
ACG
AAG
GCU
GAU
A
AGA
Arg
Lys
AGG
G
GGU
U
Asp
GCC
GUC
G
GAC
GCA
GUA
C
GGC
Ala
Val
Gly
GAA
GGA
A
GGG
G
Glu
GCG
GUG
GAG
Table 2
(i)
What is the sequence of amino acids in the peptide coded for by the
following length of mRNA?
A
G
A
C
C
G
G
C
U
G
G
A
..........................................................................................................................
(1)
10
(ii)
What is the sequence of bases in DNA which, when transcribed, gives
the above length of mRNA?
..........................................................................................................................
5. The table shows the sequence of bases on part of the coding strand of DNA.
Base sequence on coding
strand of DNA
C
G
T
T
A
C
Base sequence of mRNA
(a)
Complete the table to show the base sequence of the mRNA transcribed from
this DNA strand.
(2)
(b)
A piece of mRNA is 660 nucleotides long but the DNA coding strand from
which it was transcribed is 870 nucleotides long.
(i)
Explain this difference in the number of nucleotides.
...........................................................................................................................
...........................................................................................................................
(1)
(ii)
What is the maximum number of amino acids in the protein translated
from this piece of mRNA? Explain your answer.
Number of amino acids
Explanation.....................................................................................................
11
(c)
Complete the table to give two differences between the structure of
mRNA and the structure of tRNA.
mRNA
tRNA
(2)
6.
The flow chart shows some steps in the production of a protein.
Specific sequence of
DNA nucleotides
in a gene
Transcription
Molecule X
Individual
amino acids
Ribosomes
Molecule Y
Process Z
Specific sequence of
amino acids
in a protein
(a)
(i)
Name the organelle in which transcription occurs.
...........................................................................................................................
(1)
(ii)
Name Process Z.
(1)
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(b) (i)
Name:
Molecule X; ......................................................................................................
Molecule Y. ......................................................................................................
(ii)
(1)
Explain the role of Molecule Y.
..........................................................................................................................
..........................................................................................................................
..........................................................................................................................
..........................................................................................................................
(2)
(c)
How many amino acids will be present in the protein produced if Molecule X
has 282 nucleotides?
.....................................................................................................................................
7.
The diagram shows a stage in protein synthesis.
Q
Z
P
Y
X
A A A
(a)
(i)
C C C
Name this stage.
......................................................................................................................(1)
(ii)
What type of molecule is Q?
......................................................................................................................(1)
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(b)
Give the base sequence on the anticodon of molecule Z.
.....................................................................................................................................
(2)
..........................................................................................................................
(3)
8.
(a)
Table 1 shows some of the events which take place in protein synthesis.
A
tRNA molecules bring specific amino acids to the mRNA molecule
B
mRNA nucleotides join with exposed DNA bases and form a molecule of
mRNA
C
The two strands of a DNA molecule separate
D
Peptide bonds form between the amino acids
E
The mRNA molecule leaves the nucleus
F
A ribosome attaches to the mRNA molecule
Table 1
(i)
Write the letters in the correct order to show the sequence of events
during protein synthesis, starting with the earliest.
...........................................................................................................................
(2)
(ii) In which part of a cell does C take place?
...........................................................................................................................
(1)
(iii) Which of A - F are involved in translation?
...........................................................................................................................
(1)
(b) Table 2 shows some mRNA codons and the amino acids for which they code.
mRNA codon
Amino acid
14
GUU
Valine
CUU
Leucine
GCC
Alanine
AUU
Isoleucine
ACC
Threonine
Table 2
(i)
A tRNA molecule has the anticodon UAA. Which amino acid does the
tRNA molecule carry?
...........................................................................................................................
(1)
(ii)
Give the DNA base sequence that codes for threonine.
...........................................................................................................................
15
(1)
9. The diagram shows a molecule of an enzyme called ribonuclease. Each amino acid
in the protein is indicated by a 3-letter symbol e.g. Arg = arginine.
Ser
Ser
Ser
Iso
100
Asp
Asp
Cys
Thr
Glu
Met
Lys
Ser
Gly
Arg
Ser
Asp
Phe
Lys
Leu
Ser
His
Thr
Thr
His
Tyr
Val
Pro
Lys
Asp
Ser
Pro
Asp
Asp
Ser
Glu
Val
Ala
Arg
Ser
Tyr
Tyr
Cys
Cys
Thr
Cys
Cys
Asp
Pro
Tyr
Lys
Ser
Glu
Lys
Lys
Asp
Lys
Pro
Arg
Asp
Asp
Glu
Lys
Thr
Val
Glu
Thr
Gly
Ser
Glu
Asp
Asp 80
Phe
Cys
Cys
Ala
Thr
Lys
Val
Ala
Glu
Phe
Ala
Ala
Val
Ala
Glu
Iso
Iso
Val
Ala
Ala
Ala
Ser
Ala
Met
Glu
Thr
Met
Ala
120
Thr
Thr
Val
Glu
Asp
Ser
Ala
60
Lys
Cys
40
Arg
Ala
Asp
Val
Glu
Ser
Thr
20
His
Val
Lys
Ser
Leu
His
Glu
X
(i)
How many nucleotides are there in the mRNA molecule that codes for
this enzyme?
...........................................................................................................................
...........................................................................................................................
16
(1)
10. (a) The diagram below shows one stage in the synthesis of a protein at a
ribosome.
(i) Name this stage in protein synthesis.
................................................................................................................................(1)
(ii) Name bond X.
...............................................................................................................................
(
(1)
11.
(i)
Where does translation occur in a cell?
...........................................................................................................................
(1)
(ii)
Describe what happens during translation.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
17
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(7)
(e) Describe two ways in which the polypeptide structure can be modified following
translation
....................................................................................................................................
................................................................................................................................
(2)
Genes and Proteins in Health and Disease
1. Structure of proteins
As you know! The structure of a protein is dependent on the sequence of amino acids in the
polypeptide chain which is based on the order of bases in the DNA sequence. Your mission is to
find an example of a structural protein, an enzyme, and a hormone. Write notes for each one
using the following criteria:
(i)
(ii)
The function of the protein (3)
How is its structure suited to its function?
Use the following keywords to guide you. You won’t need all the keywords for each
example.
a. Active site, specificity, interaction with other proteins/chemicals, overall
structure, (6)
(iii)
Give some information on how the overall structure of the protein is formed with
respect to bonding. (2)
You can use any source to find your information.
18
Mutations
1. Which of the following statements refers to a gene mutation?
A. A change in the chromosome number caused by non-disjunction.
B . A change in the number of genes on a chromosome caused by duplication.
C . A change in the structure of a chromosome caused by translocation.
D . A change in the base sequence of DNA caused by substitution.
2. The list below shows types of point mutation within genes.
1 substitution
2 insertion
3 deletion
Which of these would affect only one amino acid in the polypeptide produced?
A. 1 only
B. 2 only
C. 3 only
D. 2 and 3 only
3. Which type of gene mutation occurs when a codon for an amino acid is replaced by
a stop codon?
A. missense
B. nonsense
C. frameshift
D. splice-site
4. Individuals with Cri-du-chat syndrome have a shortened chromosome 5. No other
chromosomes are affected. Which type of mutation causes Cri-du-chat syndrome?
A.
B.
C.
D.
deletion
insertion
duplication
translocation
5. The diagram below shows a section of a chromosome and the locations of ten genes.
1 2 3 4 5 6 7 8 9 10
A mutation during cell division resulted in the following sequence of genes on the same
chromosome.
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1 2 3 4 5 6 7 8 6 7 8 9 10
The type of mutation involved in this example is
A.
B.
C.
D.
deletion
translocation
duplication
inversion.
6. Which of the following terms describes types of mutations which occur in both genes
and chromosomes.
A.
B.
C.
D.
Duplication
Insertion
Deletion
Translocation
7. The following is a list of single gene mutations
Nonsense
Missense
Frameshift
Which of these gene mutations is a result of a single nucleotide substitution?
A. 1,2 and 3
B. 1 and 2
C. 3 only
D. 1 only
8. Which type of gene mutation occurs when a codon for an amino acid is replaced
by a stop codon.
A. Nonsense
B. Missense
C. Frameshift
D. Splice-site
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9. The chromosome mutation in humans can result in the formation of the
Philadelphia chromosome.
The stages leading to the formation of a Philadelphia chromosome are shown in the
diagram.
Normal chromosome 9
mutated chromosome 9
Mutated
Normal chromosome 22
Chromosome 22
swap
Phil adelphia
chromosome
a) Name the type of chromosome mutation, shown in the diagram, which results in
the formation of a Philadelphia chromosome.
_________________________________________________ (1)
b) The presence of a Philadelphia chromosome causes a type of leukaemia through
the over-production of an enzyme.
Normal white blood cell count ranges from 5 000 to 10 000 cells per ml of
blood. The table below shows the white blood cell counts from a patient with
Leukaemia before and after treatment with Imatinib (a drug which blocks the
enzyme stopping it from working).
Treatment with Imatinib
Before treatment
After treatment
i)
Number of white blood cells
(per ml of blood)
150 000
7 500
Calculate the percentage decrease in the white blood cell number after
treatment with Imatinib.
_____%
21
(1)
ii)
Explain how the results confirm that the type of leukaemia in this patient
was a result of the presence of a Philadelphia chromosome.
_________________________________________________________
_________________________________________________________
________________________________________
(2)
10. a) Give three features which describe the frequency of mutations in nature.
_________________________________________________ (2)
b) How is the mutation rate of a gene expressed?
__________________________________________________ (1)
11. Give an account of the different types of gene mutation, explaining the
effect of the mutation. Your explanations for at least two examples
should discuss mutations which result in genetic disorders. (10).
22
Human Genomics
1.
23
1.
2.
3.
24
4.
25
5. 30 years ago, the human genome project was at the start considered
by many to be an impossible task. The genome was too huge and the
technology simply wasn’t there. Yet here we are, the genome is
completed along with that of many other species.
Write an account of:
a) How has technology improved so much that DNA sequencing can be
done so quickly?
(2)
b) Lay out the arguments for actually having this vast database of
knowledge.
(4)
c) How is all this information analysed?
(2)
6. Explain what is involved in the branch of Genomics called Personal
genomics, including the potential future use.
26
(2)
Metabolism and enzymes
27
3.
2.
28
5.
4.
29
7.
8.
9.
30
10.
31
11
32
33
12,(a) Compare the mechanism of competitive and non-competitive enzyme inhibition.
(6)
(b) Sketch two line graphs which demonstrate the effects of a non competitive or a competitive inhibitor on
enzyme activity (remember to show the control!) as the substrate concentration increases. (4).
34
Cellular Respiration
1.
pyruvate
pyruvate
35
2.
36
37
3.
pyruvate
38
pyruvate
39