New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
Chapter 27 p.1/26
Suggested answers to Exercise and Reading to learn (Note: The overseas examination boards bear no responsibility for the suggested answers contained in this publication. Answers for HKCEE and HKALE questions are not available due to copyright restrictions.
Chapter 27 Basic genetics Exercise Multiple-choice questions (p. -45) 27
1
D
2
C
3
C
4
D
5
A
6
D
7
A
8
B
9
C
10
A
Short questions (p. -47) 27
11
a
b c
1)
(or other correct places)
1m
i
B
1m
ii
A
1m
i
To determine the sequence of amino acids. / A specific protein is produced. / Formation of mRNA 1m
ii iii
They are held together by hydrogen bonds. 1m To provide stability. / The bases are protected. / This allows replication. (any 1m
Oxford University Press 2010
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
12
Chapter 27 p.2/26
(a) nucleus
1m
(b) bases
1m
(c) amino acids
1m
(d) protein
1m
13
HKCEE Biology 2005 I Q2
14
a Maize plant A D
d
D
DD
Dd
d
Dd
dd
Maize plant B
0.5m x 4 b
Circle around dd
1m
c Colour of corn
Number of whole corn
Dark
36
Light
18
1m x 2 d
2:1
1m
e
Any one from: Only part of the cob is counted. / Only a small sample area is involved.
1m
Independent assortment of chromosomes at meiosis / gamete production. Fertilization is a random process. 15
a Pheonotype of parent
Genotype of parent
Genotype(s) of gamete(s)
Smooth green pod
TtGg
TG, Tg, tG, tg
Constricted yellow pod
ttgg
tg
0.5m x 4 b
i
28
ii
Any two from: Fertilization / fusion of gametes is a random event. Not enough offspring are examined. / Sample size is too small. The genes are sex-linked. Mutation occurs.
16
HKALE Biology 2006 I Q6a
Oxford University Press 2010
1m 1m x 2
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
17
Chapter 27 p.3/26
a
Continuous variation
1m
b
i
It is the DNA that passes from the parent to the offspring.
1m
ii
Plentiful / healthy / balanced diet / named mineral
1m
can lead to more growth / increased height.
1m
c
Discontinuous variation There are only rollers and non-rollers / no intermediates.
1m 1m
Structured questions (p. -49) 27
18
a
i
Palisade
1m
ii
1m b
Any two from: There are two strands. It is coiled / a double helix.
1m x 2
There are base pairs (A-T and G-C). It is made up of nucleotides. The two strands are complementary. There is pentose sugar. It has phosphate. Complementary bases are joined by hydrogen bonds. c
to
A description that includes four from: A base pairs with T.
1m x 4
G base pairs with C. Percentage of A is very similar to percentage of T. / Percentage of C is very similar percentage of G. There is not exact ratio / figure because the technology was not good enough. The situation for C and G in ox spleen is unusual. Effective communication
Oxford University Press 2010
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
19
HKALE Biology 2005 II Q2
20
HKCEE Biology 2007 I Q5
21
a
Chapter 27 p.4/26
Any three from: The allele is carried on the sex / X chromosome.
1m x 3
The allele is expressed only if both chromosomes carry the allele. The allele is always expressed in the male (since Y is not homologous). Allele is the different form of the same gene. b
XNXn
1m
N
X Y
1m
N
1m
X Y c
4m
Essay (p. -51) 27
22
HKALE Biology 2002 II Q8
Reading to learn (p. -52) 27
1
Any two from: The pea plant was easy to cultivate.
2m x 2
Its life cycle was short. The anthers could be removed easily without damaging the female part of the flower. The plant was self-pollinating. 2
Yes.
1m
Mendel made observations,
1m
proposed hypothesis,
1m
Oxford University Press 2010
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
3
Chapter 27 p.5/26
did experiments
1m
and made conclusions in his study of pea plants.
1m
To make sure the results are reliable / valid / representative.
1m
Oxford University Press 2010
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
Chapter 27 p.6/26
Suggested answers to Exercise and Reading to learn (Note: The overseas examination boards bear no responsibility for the suggested answers contained in this publication. Answers for HKCEE and HKALE questions are not available due to copyright restrictions.)
Chapter 28 Molecular genetics Exercise Multiple-choice questions (p. -21) 28
1
D
2
A
3
A
5
C
6
A
7
C
4
A
Short questions (p. -22) 28
8
HKALE Biology 2006 II Q2a
9
a Base sequence on coding strand of DNA
C
G
T
T
A
C
Base sequence of mRNA
G
C
A
A
U
G
(1m only if T instead of U) b
Any two rows from: mRNA
10
2m 1m x 2 tRNA
No base pairing / linear
Has base pairing / cloverleaf shape
No binding site for amino acids
Has a binding site for a specific amino acid
Different for each gene / many kinds
Only few / 20 / 64 kinds
Longer / more nucleotides
Shorter / less nucleotides
P — mRNA Q — tRNA
1m 1m
R — amino acid
1m
S — anticodon
1m
Oxford University Press 2010
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
11
Chapter 27 p.7/26
a AGC
UUC
TCG
AAG
2m b
tRNA has an anticodon complementary to the codon on the mRNA.
1m
Specific amino acid
0.5m
is carried / transferred to the ribosome.
0.5m
It helps produce a polypeptide of correct sequence of amino acids.
1m
c Met
Phe
Gln
Gln
Lys
Gln
Phe
(1m for three, four or five correct answers)
2m
12
HKALE Biology 2001 I Q4
13
a
It is a change in the base / nucleotide.
1m
b
The base sequence of the mRNA is changed.
1m
c
Different tRNA molecules pair with the mRNA.
0.5m
The primary structure (sequence of amino acids) of the protein is changed.
0.5m
The tertiary structure of the protein is changed.
0.5m
The shape of the active site is changed.
0.5m
i ii
There will be no accumulation of phenylalanine. Phenylalanine is needed to form proteins or named protein. / It is impossible to get a diet with no phenylalanine present. / It is an essential
1m
amino 14
a b
acid. 1m i
Natural radioactivity in air
1m
ii
12%
1m
i
Oxford University Press 2010
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
ii
Chapter 27 p.8/26
Correct y-axis
1m
Correct line
1m
As the dosage of X-rays increases, the number / percentage of chromosome mutations increases. 1m
Structured questions (p. -24) 28
15
HKALE Biology 1998 II Q3
16
a
Ring drawn around one phosphate, one sugar and one base lined together and label with the letter M. 1m
it b
c
Part of the DNA molecule unwinds. DNA strands separate / unzip. / Hydrogen bonds break.
0.5m 0.5m
Nucleotides line up against their complementary bases
0.5m
against one strand.
0.5m
RNA synthesis is catalysed by the RNA polymerase.
1m
Individual nucleotides join up by phosphodiester bonds.
1m
mRNA strand separates from DNA molecule.
0.5m
mRNA migrates into cytoplasm.
0.5m
i
Ribosomes / rough endoplasmic reticulum
1m
ii
Ring drawn around U C G and label it with the letter C.
1m
Oxford University Press 2010
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
17
Chapter 27 p.9/26
a DNA molecule
RNA molecule
DNA has deoxyribose.
RNA has ribose.
DNA has thymine.
RNA has uracil.
DNA is double-stranded.
RNA is single-stranded.
1m x 3 b
c
i
For attachment of amino acid
1m
ii
Allow binding / joining / attaching to
1m
codon / complementary base sequence on mRNA
1m
i ii
Each base is part of only one codon. / tRNA ‘reads’ three bases, then the next three. 1m Some amino acids are coded for by more than one codon / base sequence. 1m
Oxford University Press 2010
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
18
a
i
Ribosome
1m
ii
Anticodon
1m
iii
Messenger RNA, transfer RNA and ribosomal RNA / mRNA, tRNA and (1m for 2 correct) 2m
i
Translation
1m
ii
Each type of tRNA has a specific linkage with one type of amino acid. tRNA joins to mRNA.
1m 1m
Codon joins / base pairs with anticodon on tRNA.
1m
rRNA b
c chain
Chapter 27 p.10/26
B moves into the vacant space to the right of A and adds B’s amino acid to the (removes the chain from A to B).
1m
A is now free to move off and combine with another identical amino acid molecule. 1m strand
19
B occupies position A. / The ribosome moves one codon to the right. / mRNA moves one codon to the left.
1m
d
The protein will only perform its function if the structure is correctly reproduced. / Give an example: The active site of an enzyme is altered or destroyed if its amino acid sequence is changed. 1m
a
i
b
ii
It catalyses the joining of ribonucleotides together by phosphodiester bonds to form a RNA strand. 1m Ribosome / Rough endoplasmic reticulum 1m
i
CGTTACCAA
1m
ii
CGU UAC CAA
1m
c
Substitution
1m
d
i
Alanine
1m
ii
Mutation 1: The sequence of amino acids is not changed 1m because both the codons before and after the mutation code for the same amino acid alanine. / the code is degenerate. 1m Mutation 2: The sequence of amino acids is changed: valine is replaced by alanine. 1m The folding / shape / tertiary structure / position of bonds of the protein may change. 1m
Oxford University Press 2010
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
20
Chapter 27 p.11/26
a
Any one from: 1m High energy radiation / ionizing radiation / X-rays / cosmic rays / ultraviolet light / UV light / named carcinogen (e.g. mustard gas or tar)
b
i ii
(primary
The removal of one or more bases / nucleotides
1m
shifts the reading frame (frameshift) from the point of mutation.
1m
The sequence of bases in mRNA would change. 1m This would lead to an enzyme with a different sequence of amino acids structure). 1m The tertiary structure / active site of that enzyme would be changed.
1m
White pigment would not bind to the enzyme. 0.5m Thus, lilac pigment would not be produced / white pigment would remain unchanged. 0.5m 21
HKALE Biology 2004 II Q3
Essays (p. -27) 28
22
Any ten from: The code for the formation of a protein is on one strand of nuclear DNA.
1m x 10
Free ribonucleotides base pair with the relevant section of DNA. The mRNA produced carrying the code goes out of the nucleus / to ribosome. Ribosome is made of rRNA and proteins. Ribosome encloses the mRNA. Each triplet of mRNA is a codon. Ribosome passes along mRNA, exposing space for two codons. Protein synthesis requires linking of amino acids in a correct order. Each amino acid is coded by a codon. Each amino acid is brought to the ribosome by tRNA molecules. tRNA molecules have an attachment site for one amino acid (with a labelled diagram). At the other end of the tRNA molecules is an anticodon. Each anticodon specifies one amino acid. At ribosome, the mRNA codon base pairs with the appropriate tRNA anticodon. A second tRNA molecule brings its amino acid to the adjacent ribosome site and a peptide bond forms between the amino acids. Ribosome moves one codon along. Repetition of the process results in a growing peptide chain. Effective communication
Oxford University Press 2010
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
23
Chapter 27 p.12/26
In transcription, the hydrogen bonds break and the DNA unzips. The sequence of bases on one DNA strand acts as a template.
1m 1m
Ribonucleotides line up along the template.
1m
Under the catalysis of RNA polymerase, mRNA forms.
1m
The mRNA leaves via the nuclear pores and enters the cytoplasm.
1m
In translation, the mRNA attaches to a ribosome.
1m
The ribosome moves along the mRNA and two codons / two triplets / six bases are exposed. tRNA presents a specific amino acid to the mRNA by anticodon-codon binding / complementary base pairing.
24
1m 1m
A peptide bond is formed between two amino acids.
1m
Effective communication
1m
HKALE Biology 1999 II Q5
Reading to learn (p. -28) 28
1 /
Mutagens can be natural or man-made. 1m Natural mutagens: cosmic rays / radiations from outer space / radon gas / ultraviolet light other correct examples 1m Man-made mutagens: radiations from nuclear fallout / X-rays / other correct examples 1m
2
3
A mutation may cause changes in a gene that prevents cells from dividing endlessly. 1m A mutation may result in a gene that encourages cells to keep dividing.
1m
In either case, uncontrolled cell division leads to formation of tumours.
1m
They have more active-dividing cells.
1m
Active-dividing cells are more sensitive to mutagens.
1m
Oxford University Press 2010
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
Chapter 27 p.13/26
Suggested answers to Exercise and Reading to learn (Note: The overseas examination boards bear no responsibility for the suggested answers contained in this publication. Answers for HKCEE and HKALE questions are not available due to copyright restrictions.)
Chapter 29 Applied genetics Exercise Multiple-choice questions (p. -22) 29
1
B
2
A
3
B
5
C
6
B
7
D
4
C
Short questions (p. -23) 29
8
a
i ii
H
DNA from two sources joins together. 1m Cut DNA containing the gene of interest and plasmid using a specific enzyme. 1m Join the gene of interest and the plasmid together.
b
Any two from:
1m 1m x 2
Better understanding of genetics Improved diagnoses and treatment of diseases Better understanding of evolution 9
a
b
Plasmid with insulin gene inserted
1m
Plasmid inside bacterium
1m
i
Insulin gene is cut from DNA.
1m
Plasmid is cut open.
1m
Extraction / Purification of insulin
1m
ii
Oxford University Press 2010
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
Chapter 27 p.14/26
10
1m x 2
a
Any two from: DNA does not change. DNA is unique to each individual. The test is reliable.
11
12
b
Tissue It contains intact DNA.
1m 1m
c
Obtain DNA sample from dead body. Match it with DNA samples from the same family.
1m 1m
Example of source of comparison (e.g. hairbrush, toothbrush).
1m
(i) DNA (ii) enzymes
1m 1m
(iii) bands
1m
b
DNA is unique to each individual.
1m
c
James The bands / stripes match.
1m 1m
a
Any two from:
a
1m x 2
To map human chromosomes. / To find where each gene is located on the human chromosomes. To determine the base sequence. It is an international project about human genes. b
i
Any two from:
1m x 2
To warn people at risk to take precautions / make lifestyle changes. To plan medical provision for the individual. To warn people there is a risk: if they have children they may have genetic disorders. To make it easier to develop ways of treating genetic deficiencies / gene therapy. ii
Any three from:
1m x 3
People are put under pressure to have abortions / not to have children. It may lead to discrimination over jobs / insurance premiums. It may lead to other ethically questionable developments such as ‘designer babies’ / eugenics / immigration. After knowing something might happen may cause psychological stress even if it never happens in your life-time. People may not believe the test is reliable. People may not want to know. Civil rights / personal freedom: who should decide who should have genetic tests?
Oxford University Press 2010
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
Chapter 27 p.15/26
Data protection issues: who will have access to genetic information about individuals?
13
a
No males can be excluded.
b c
Males 1 and 2 can be excluded as they have no matching DNA fragments. 1m The probability of having the same genetic fingerprints is much much lower than of having the same blood groups. 2m
that
1m
DNA fingerprinting is more accurate. 14
1m
HKALE Biology 2004 I Q9
Structured questions (p. -25) 29
15
a
A plasmid that is cut open and then joins with a foreign gene.
1m 1m
b
Number of gene copies produced: 248 = 281 474 976 710 656
3m
c
Oxford University Press 2010
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
16
a b
Chapter 27 p.16/26
Plants can photosynthesize / make their own food / glucose. 1m Moving / changing / modifying / altering the gene(s) / DNA / genetic material / genotype 1m of a cell / an organism
1m
c
The plant has genes from bacteria. / Bacterial genes are now in the plant. The bacterial genes code for proteins.
1m 1m
d
Any two from: 1m x 2 Plants / oilseed rape can now make nitrates / nitrogen-containing compounds / ammonium compounds. Plants can produce more proteins / amino acids. Growth / yield of plants is increased. Less fertilizer is needed. / Plants can grow in nitrogen poor soils. Cost is reduced. There is less pollution.
Oxford University Press 2010
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
17
a
i ii
b
Reason for:
Chapter 27 p.17/26
DNA 1m They are developed from the same zygote and have the same chromosomes / genes / DNA. 1m
Identify people for crimes. / Identify compatible organ donors.
1m
Reason against: Rights argument. / Cost of setting up / managing DNA bank. c
1m
i
1m x 2 ii
18
Luke 1m Luke has many / most bands identical to the child. / George and Joe have no bands in common. 1m
a
All the genetic material / DNA in a cell / an organism.
b
At least three areas: Find link between gene(s) and disease(s) Genes influence development Reliable gene tests / DNA tests Tests for / diagnosis of a specific disease (e.g. breast cancer) Antenatal tests / screening unborn children Therapeutic abortions (e.g. thalassaemia) Post-natal screening for diseases Targeting preventive measures
Oxford University Press 2010
1m 1m x 8
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
Chapter 27 p.18/26
Targeting treatment DNA produces proteins Drugs / medication Gene therapy Results from gene tests are not always clear cut Effect of knowing about harmful allele on psychological health Discrimination by employers Discrimination by insurance companies Copyright / ownership problems (who owns genetic information) Reluctance of people to be tested Confidentiality / privacy Effective communication
Essays (p. -27) 29
19
Gene must be identified using DNA probes / nucleotide / amino acid sequence. Gene is cut out / isolated using restriction enzymes.
2m 1m
Suitable vector, e.g. plasmid, is used.
1m
Vector DNA is cut using the same enzyme, results in sticky ends.
1m
Gene and vector DNA join together using an enzyme, forming recombinant DNA.
2m
Recombinant DNA is inserted into a bacterial cell.
1m
Bacteria are grown on an industrial scale to produce metabolic products, e.g. insulin. 1m Protein is finally purified.
Oxford University Press 2010
1m
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
20
Chapter 27 p.19/26
Benefits: (any 3) 1m x 3 Better understanding of genetics. / Allow scientists to understand how genes control biological activities.
Improved diagnoses and treatment of diseases. / Discover the relationship between certain diseases, e.g. Alzheimer’s disease / breast cancer and the genes. Better understanding of evolution. / Comparing the genomes of different organisms helps build up their evolutionary relationships. Limitations: (any 3)
1m x 3
Ethical issue Ownership of personal genetic information is in doubt. Legal issue It is hard to avoid illegal use of the information. Social issue It causes anxiety to the patients carrying the faulty genes. It affects the public perception of people with certain genes. Make judgement based on the benefits and limitations discussed.
1m
Reading to learn (p. -28) 29
1
The living relative of the royal family
1m
2
No Only hair with hair roots contains cells from which
1m 1m
DNA can be extracted.
1m
DNA fingerprinting is an accurate method of identification. The remains need not be intact.
1m 1m
3
Oxford University Press 2010
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
Chapter 27 p.20/26
Suggested answers to Exercise and Reading to learn (Note: The overseas examination boards bear no responsibility for the suggested answers contained in this publication. Answers for HKCEE and HKALE questions are not available due to copyright restrictions.)
Chapter 30 Evolution I Exercise Multiple-choice questions (p. -13) 30
1
D
2
C
3
A
5
D
6
B
7
B
4
C
Short questions (p. -14) 30
8
a
Fish B is probably more primitive than fish A.
1m
b
Changing environment on earth leads to the extinction of fish B.
1m
c
The fossil record provides information about
d
the time of existence of organisms and
1m
the structures of organisms for comparison.
1m
Soft-bodied organisms cannot be fossilized. / The bodies of dead organisms may be eaten by other organisms or decay before fossilization occurs. / Most fossils are incomplete and may be damaged. / Some fossils are located in inaccessible areas. (any 1)
1m
9
Soft parts decay before fossilization occurs. / Bones and teeth are too hard to decay. / Bones and teeth take a long time to decay. 1m
10
HKALE Biology 2006 I Q8
11
a
Bones scattered by animals / buried / washed away by rain or water / damaged by (earth movement) / eaten by animals 1m
b
i ii
Same number of teeth
1m
Same type of teeth
1m
Jaw of Australopithecus is narrower / Teeth of Australopithecus are slightly rounder (any 1) 1m
Oxford University Press 2010
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
12
Chapter 27 p.21/26
HKALE Biology 2007 II Q2
Structured questions (p. -15) 30
13
a
3m b c more
The higher the % of similarities of the base sequence of DNA, the closer the evolutionary relationship with humans.
2m
Mutation leads to changes of the base sequence of DNA. 1m Organisms with closer evolutionary relationship would have fewer mutations or similar base sequence. 1m
Essay (p. -15) 30
14
There are many ways of forming fossils. Remains of organisms may be preserved by sedimentary rocks, amber, ice, etc. 1m Fossil formation in sedimentary rocks: Skeletons of organisms are buried by mud and sand in the seabed.
1m
After millions of years, the mud and sand become rock due to great pressure from the upper layers of sediment. Meanwhile, mineral salts deposit in the skeletons and harden them into stone. 1m Earth movement raises the rock over water.
1m
Further earth movement and weathering expose the fossils.
1m
How scientists make use of fossils: The lowest layer of rock contains the earliest fossils while the uppermost layer of rock contains the most recent fossils. 1m A fossil record is formed. 1m By comparing the structures of organisms shown in the fossil record, the evolutionary history of a particular group of organisms can be traced. 1m Using radioisotope dating, the age of fossils can be estimated. Thus information about the time of existence of organisms is also obtained. 1m Effective communication
Oxford University Press 2010
max 3m
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
Chapter 27 p.22/26
Reading to learn (p. -16) 30
1
The skull of Piltdown Man looked like that of modern humans,
1m
while the jaw looked liked that of apes.
1m
2
No experiments can be done to confirm the findings.
1m
3
Scientific knowledge is tentative and subject to change. Science is affected by the technology and equipment available at the time.
1m 1m
Observations are theory laden.
1m
Oxford University Press 2010
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
Chapter 27 p.23/26
Suggested answers to Exercise and Reading to learn (Note: The overseas examination boards bear no responsibility for the suggested answers contained in this publication. Answers for HKCEE and HKALE questions are not available due to copyright restrictions.)
Chapter 31 Evolution II Exercise Multiple-choice questions (p. -17) 31
1
D
2
D
3
D
4
C
5
A
6
B
7
B
8
C
Short questions (p. -18) 31
9
a
Competition
1m
b
Genetic mutation / meiosis
1m
c
Best suited / adapted
1m
d
Any two from: Favourable genes passed on
10 a the
max 2m 1m
Favourable adaptations are selected
1m
Population becomes better adapted
1m
In the rabbit population, there is variation among individuals in their resistance to virus. Few are resistant to the virus. 1m In the presence of the virus, the resistant rabbits have a higher chance of surviving. 1m They are able to produce more offspring.
1m
The proportion of virus resistant rabbits increases in subsequent generations.
1m
Variations cause some individuals to be better adapted to the environment.
1m
This reduces the chances of extinction of the entire species.
1m
a
Unable to reproduce / interbreed with each other to produce fertile offspring.
1m 1m
b
Populations geographically separated
1m
Populations cannot interbreed
1m
Different mutations in each population
1m
b
11
Oxford University Press 2010
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
Chapter 27 p.24/26
Environmental conditions differ
1m
Leads to difference in physical characteristics / behaviour / appearance
1m max 4m
12
a
Geographical / ecological / reproductive
b
i
1 2
1m
Mutations are different in each sub-population / Mutations are in one sub-population but not the other one.
1m
Survival of the fittest / Organisms with favourable characteristics are selected.
1m
Favourable characteristics passed on to offspring / Organisms with favourable characteristics survive and pass them on. ii
They cannot interbreed to produce fertile offspring.
1m 1m
Structured questions (p. -19) 31
13
HKCEE Biology 2005 I Q10b
14
a b
Breed together
1m
If their offspring are fertile, then they belong to the same species.
1m
Isolation of two populations Variations already present due to mutations
1m 1m
Different environmental conditions
1m
Selection of different features and hence different alleles
1m
Separate gene pools / no interbreeding
1m max 4m
c
Selection of mate dependent on colour pattern Prevent interbreeding / keep gene pools separate
1m 1m
Essays (p. -19) 31
15
a
Isolating mechanisms: (1) A species is a group of organisms interbreeding to produce fertile offspring 1m (2) Common gene pool
1m
(3) A species / a population separated into two by an isolating mechanism (e.g geographical, ecological, reproductive) 1m (4) Prevents gene exchange / gene flow / interbreeding between populations / groups 1m b
Effects of mutations and natural selection: (1) Mutation occurs in each population
Oxford University Press 2010
max 6m 1m
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
16
Chapter 27 p.25/26
(2) Mutation gives variation
1m
(3) Different environments
1m
(4) Selection is different for each population
1m
(5) Best adapted survived / survival of the fittest
1m
(6) Best adapted pass on favourable characteristics to offspring
1m
(7) Many generations / long period of time
1m
(8) New species formed when populations can no longer interbreed
1m
Should include all four areas:
max 3m x 4
(1) Gene mutation: Addition
1m
Deletion
1m
Substitution
1m
Effect on alleles
1m
Effect on polypeptide / protein
1m
(2) Sexual reproduction: Crossing over
1m
Independent assortment
1m
Random fusion
1m
Chromosome mutation
1m
(3) Environmental: Nutrients
1m
Disease
1m
Light
1m
Temperature
1m
(4) Biological importance: Enables adaptation
1m
Natural selection
1m
Speciation
1m
Evolution
1m
Reading to learn (p. -20) 31
1
Darwin recorded his observations in notes and pictures.
2
People believed that all life on earth was created by God. After creation organisms stay the same. The theory was also against the observable data, as no evolution could be observed directly.
Oxford University Press 2010
1m
1m
1m
New Senior Secondary Mastering Biology Suggested answers to Exercise and Reading to learn
3
Chapter 27 p.26/26
A group of ancestral finches reached the Galapagos Islands from the mainland, but there was not enough food for all the birds. 1m Finches with slightly different beaks (variation) were able to eat other types of food. These finches were allowed to survive and reproduce. 1m They passed on the adaptive features to the next generation. 1m The geographical isolation of different groups of finches on different islands results in the formation of different species. 1m
4
Darwin’s work was scientific though he did not carry out any experiments. Science is about collecting and interpreting data in a systematic and logical manner. 1m It does not necessarily involve any experiments. There is not a single so-called scientific method. 1m
Oxford University Press 2010
