IB SL Biology 2012 Practice Exam
1. Which of the following are features of prokaryotes and eukaryotes?
2. What route is used to export proteins from the cell?
A. Golgi apparatus → rough endoplasmic reticulum → plasma membrane
B. Rough endoplasmic reticulum → Golgi apparatus → plasma membrane
C. Golgi apparatus → lysosome → rough endoplasmic reticulum
D. Rough endoplasmic reticulum → lysosome → Golgi apparatus
3. Which events occur during the G1 phase and S phase of the cell cycle?
4. Which substance in prokaryotes contains sulfur?
A. DNA
B. Phospholipids
C. Proteins
D. Antibiotics
5. Which describes these molecules correctly?
6. What sequence of processes is carried out by the structure labeled X during translation?
7. A plant is exposed to increasing light intensity from very dim to bright light, while the carbon
dioxide
concentration and temperature are kept at an optimum level. What will happen to the rate of
oxygen
production?
A. It will increase exponentially.
B. It will remain constant.
C. It will decrease to a minimum level.
D. It will increase to a maximum level.
8. The diagram below shows a biochemical pathway in a yeast cell. Which of the following
correctly identifies a compound in the diagram?
A. I is fat.
B. II is pyruvate.
C. III is lactate.
D. IV is carbon dioxide.
9. In some people, hemoglobin always contains the amino acid valine in place of a glutamic acid
at one position in the protein. What is the cause of this?
A. An error in transcription of the hemoglobin gene
B. An error in translation of the mRNA
C. Lack of glutamic acid in the diet
D. A base substitution in the hemoglobin gene
10. What is a suspected heterozygous individual crossed with in a test cross?
A. Homozygous dominant
B. Homozygous recessive
C. Heterozygous dominant
D. Heterozygous recessive
11. What are homologous chromosomes?
A. Identical chromosomes
B. Non-identical chromosomes with different genes
C. Non-identical chromosomes with the same genes in the same sequence but not
necessarily the same alleles
D. Non-identical chromosomes with the same genes in a different sequence and not
necessarily the same alleles
12. Which processes involved in cloning an animal are indicated by the letters X and Y?
13. What type of inheritance is shown in this pedigree chart?
14. What is a community?
A. A group of organisms living and interacting in the same trophic level
B. A group of populations living and interacting in a food chain
C. A group of organisms of the same species living and interacting in an ecosystem
D. A group of populations living and interacting in an area
15. What is a potential consequence of the rise in global temperatures on the Arctic ecosystem?
A. Increased exposure to UV light
B. Increased rate of decomposition of detritus
C. Decreased success of pest species
D. Increase in the ice habitat available to polar bears
16. What can limit increases in population size?
I. Decrease in prey
II. Decrease in parasites
III. Increase in predators
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
17. A photomicrograph of a tissue is accompanied by a scale bar which represents 1 µm. The
scale bar is 10 mm long. What is the magnification of this photomicrograph?
A. X 10
B. X 1, 000
C. X 10, 000
D. X 1, 000, 000
18. What is facilitated diffusion?
A. The passive movement of a particle through the phospholipid bilayer of the cell membrane.
B. The passive movement of a particle across a cell membrane via a channel protein.
C. The movement of a particle down a concentration gradient helped by active pumping.
D. The movement of a particle up a concentration gradient helped by active pumping.
19. A cell has a high density of rough endoplasmic reticulum (ER) in its cytoplasm. Which other
organelle can be expected to occur in large numbers in this cell?
A. Chloroplasts
B. Microvilli
C. Golgi apparatus
D. Nuclei
20. Which labels on the diagram are parts of a nucleotide?
21.
22. What are the products of photosynthesis?
I. 2 O
II. 2 H O
III. ATP
IV. 2 CO
A. I only
B. I and II only
C. I and III only
D. I, III and IV only
23. What causes Down’s syndrome?
A. Non-disjunction in the formation of sex cells
B. Random alignment of chromosomes in the formation of sex cells
C. Gene mutation in the formation of sex cells
D. Crossing over in the formation of sex cells
24. What is a test cross used for?
A. To determine if two individuals belong to the same species.
B. To identify the presence of dominant alleles.
C. To identify the presence of recessive alleles.
D. To test the viability of offspring.
25. Which combination of parents could produce children with all of the different ABO blood
types?
A. A % B
B. B % O
C. A % AB
D. A % A
26. What feature in a family pedigree chart would suggest that a trait is sex-linked?
A. Numbers of offspring affected by the condition increased over several generations.
B. Girls only inherit the trait from their mothers.
C. Equal numbers of males and females show the trait.
D. One gender was more commonly affected than the other.
27. What conditions exist when a population is in the plateau phase of population growth?
A. immigration + emigration = natality + mortality
B. natality + immigration = emigration + mortality
C. mortality . immigration = natality - emigration
D. immigration . natality = mortality - emigration
Section 2 Short Answer and Extended Essay
1. Genetic engineering allows genes for resistance to pest organisms to be inserted into various
crop plants. Bacteria such as Bacillus thuringiensis (Bt) produce proteins that are highly toxic
to specific pests.
Stem borers are insects that cause damage to maize crops. In Kenya, a study was carried out
to see which types of Bt genes and their protein products would be most efficient against three
species of stem borer. The stem borers were allowed to feed on nine types of maize (A–I),
modified with Bt genes. The graph below shows the leaf areas damaged by the stem borers after
feeding on maize leaves for five days.
(Question 1 continued)
(a) (i) State what would be used as the control in this experiment.
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[1]
(ii) Calculate the percentage difference in leaf area damaged by Sesamia calamistis
between the control and maize type H. Show your working.
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[2]
(b) Outline the effects of the three species of stem borer on Bt maize type A.
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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ….
[2]
(c) Evaluate the efficiency of the types of Bt maize studied, in controlling the three species
of stem borers.
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[2]
(Question 1 continued)
Before the use of genetically modified maize as a food source, risk assessment must be carried
out. A 90-day study was carried out in which 3 groups of 12 adult female rats were fed
either:
• seeds from a Bt maize variety
• seeds from the original non-Bt maize variety
• commercially prepared rat food.
All the diets had similar nutritional qualities.
(d) Calculate the change in mean mass of female rats fed on Bt maize from day 14 to 42.
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[1]
(e) Describe the change in mean mass for the female rats during the 90-day experiment.
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[2]
(f) Evaluate the use of Bt maize as a food source compared to the other diets tested.
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[3]
2. (a) Glucose and galactose are examples of monosaccharides. State one other example of a
monosaccharide.
__________________________________________________________________________ [1]
(b) The equation below shows the production of glucose and galactose from lactose.
(i) There are several different types of carbohydrate. State which type of carbohydrate
lactose is.
________________________________________________________________________
____________________________________________________________________ [1]
(ii) State the type of chemical reaction that occurs when lactose is digested into glucose
and galactose.
___________________________________________________________________[1]
(c) Lactase is widely used in food processing. Explain three reasons for converting lactose
to glucose and galactose during food processing.
[3]
1.____________________________________________________________________________
_____________________________________________________________________________
2. ____________________________________________________________________________
_____________________________________________________________________________
3. ___________________________________________________________________________
_____________________________________________________________________________
(d) Simple laboratory experiments show that when the enzyme lactase is mixed with lactose,
the initial rate of reaction is highest at 48 °C. In food processing, lactase is used at a
much lower temperature, often at 5 °C. Suggest reasons for using lactase at relatively low
temperatures.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
__________________________________________________________________________ [2]
3. (a) Gene transfer to bacteria often involves small circles of DNA into which genes can be
inserted. State the name of a small circle of DNA, used for DNA transfer, in bacteria.
________________________________________________________________________[1]
(b) The diagram below shows a cut circle of DNA into which a gene is being inserted. Before
it can be transferred into a bacterium, the ring must be altered, using an enzyme.
Outline what must be done next to complete the process of gene insertion into the
DNA circle, including the name of the enzyme that is used.
______________________________________________________________________________
______________________________________________________________________________
__________________________________________________________________________ [2]
(c) Discuss the potential benefit and possible harm of one named example of gene transfer
between species.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
__________________________________________________________________________ [3]
Extended Essay
1. (a) Draw a labelled diagram showing the main features of the ultra structure of an animal [4]
(b) Explain the process of passive transport across the cell membrane. [8]
(c) Outline the ethical issues of cloning humans. [6]
Answer Key
1.A
!5. B
2.B
16.B
3.D
17.C
4.C
18.B
5.D
19.C
6.D
20.D
7.D
21.A
8.B
22.C
9.D
23.A
10.B
24.C
11.C
25.A
12.A
26.D
13.C
27.B
14.D
Section 2
1. (a) (i) maize not modified/transformed with Bt (genes) / maize that did not have Bt
gene added / not genetically modified / untreated maize [1]
(ii) ; Accept 50-12 = 38 (mm2) or 12-50= -38(mm2)
38/50 x 100= (+/-) 76%
[2]
(b) there was a decrease in damage by all three types of stem borers compared to control;
there was almost no change in damage by Eldana compared to control;
there was almost no damage/little effect (to Bt maize type A) by Sesamia (and Eldana);
Busseola caused the most damage (to Bt maize type A); [2 max]
(c) very efficient at controlling Sesamia;
type B is the most effective against the three stem borers collectively;
no type of Bt maize controlled Busseola well / vice versa i.e. Busseola not well controlled by any
types of Bt maize;
all types of Bt maize decreased Sesamia damage (significantly) / Bt maize type E not damaged by
Sesamia / vice versa;
Bt maize types C/H/I had more damage caused by Busseola (than was caused in the control) / vice
versa;
(f) all three foods result in the same pattern of growth/mass gain / highest rate of growth at start of
study / tapering off later in the study;
Bt maize causes same amount of growth as non-Bt maize / appears to be as good a food source as
non-Bt maize / there is no significant difference between Bt and non-Bt maize (in terms of mass
gain);
corn (both types) appears to cause less growth/mass gain than rat food / vice versa;
genetic modification does not affect growth/mass gain;
no evidence to support risk of Bt maize to growth/mass gain;
study does not investigate other possible risks of Bt maize to rats;
sample size is small / only 12 rats (in each group) so this may not be enough to give trends;
only female rats tested, no males; [3 max]
2. a. fructose/ribose/deoxyribose/ other monosaccharides apart from glucose and galactose [1]
b. disaccharide [1] ii- hydrolysis
c. it allows people who are lactose intolerant/ have difficulty digesting lactose to consume milk
products;
galactose and glucose taste sweeter than lactose reducing need for additional sweetner;
galactose and glucose are more soluble than lactose/ give a smoother texture/ reduces crystals in
icecream;
(bacteria) ferment glucose and galactose more rapidly than lactose shortening production time of
(yogurt/cottage cheese)
[3 max]
d. less denaturation/enzymes last longer at lower temperatures;
lower energy costs/less energy to achieve 5 degrees C compared to 48 degrees C;
reduces bacterial growth/reduces milk spoilage;
to form products more slowly/to control rate of reaction;
3. a. plasmid [1]
b. DNA ligase involved; (DNA required)
seals gaps/nicks in DNA;
makes sugar-phospahate bonds; [2 max]
[2 max]
C. named example of DNA source and organism to which it is transferred;
Benefit of the example of gene transfer;
Possible harm from the example
Example:
Gene transfer details [1 max]
e.g. BT gene transferred from bacterium to maize
specific benefits [1 max]
e.g. corn borer/ insect killed by Bt toxin increasing crop yield
e.g. less pesticides/fertilizers/ chemicals needed so better for environment;
specific harmful effects [1 max]
eg. Non-target insects may be killed;
risk of cross-pollination may introduce gene to unintended species [3 max]
Extended Response:
(a) Award [1] for every two of the following structures, accurately drawn and
correctly labelled.
ribosomes (attached or free);
rough ER;
smooth ER;
lysosome;
Golgi apparatus/body;
mitochondrion;
nucleus;
plasma membrane/cell (surface) membrane;
nucleolus;
nuclear membrane/envelope;
centriole(s);
peroxisome;
vesicles;
cytoskeleton; [4 max]
Award only [3 max] if any plant structures are included.
(b) passive transport involves diffusion / movement of molecule down a
concentration gradient / from high to low concentration;
osmosis is a form of passive transport;
osmosis is diffusion of water across a semi-permeable membrane;
ATP not required for this process;
energy for diffusion comes from the kinetic energy / Brownian movement of the
diffusing molecules;
some molecules diffuse through the phospholipids bilayer;
examples of molecules which diffuse across membrane are gases / water / lipids /
steroids / hydrocarbons;
larger molecules / hydrophilic molecules diffuse through membrane
proteins/channels;
diffusion through membrane proteins/channels is facilitated diffusion;
facilitated diffusion is faster than normal diffusion;
facilitated diffusion is limited by the number/density of pores; [8 max]
(c) clones are genetically identical individuals / cell lines / tissues;
risks to society:
cloning mammals is expensive/allocation of resources;
cloning could lead to copying selected individuals / equity concerns;
could lead to uncontrolled / unethical eugenics;
risks to individuals:
many cloned animals die soon after birth / die from complications / premature
aging of clones;
cloned humans could experience identity crises/problems in psychological
development;
reduction of human dignity;
cloned tissues will still possess genetic diseases;
risk for unknown consequences is too great;
belief systems:
artificial cloning in humans is opposed by some as being unnatural/against their
religion;
cloning occurs naturally when identical twins form;
benefits:
cloning humans may help to provide tissues/organs for transplantation;
research in cellular mechanisms/developmental biology/possible medical
breakthroughs; [6 max]
(Plus up to [2] for quality)