1 Because water and oil don’t mix, water is not very effective at washing away oily dirt. The ability of soap to mix with both water and oily dirt allows dirt to be washed away.

Which statement provides the most logical chemical explanation for this phenomenon?

A Soap molecules carry no charge. As a result, soap can form an effective bridge between charged water molecules and neutral oil molecules.B Soap molecules have charged regions and neutral regions. The neutral regions are attracted to water molecules; the charged regions are attracted to oils.C Soap molecules have both positively and negatively charged regions. The

negatively charged regions are attracted to water; the positively charged regions are attracted to oil.D Soap molecules have charged regions and neutral regions; the charged regions are

attracted to water molecules; the neutral regions are attracted to oils.

2 The diagram below shows which areas on the surface of a protein are composed of hydrophobic amino acids and which areas of hydrophilic amino acids.

Where in a cell would the protein be located?

A In a nuclear pore B In the space between the inner and outer mitochondrial membranesC In the matrix of a mitochondrionD In a phospholipid bilayer

3 In some diseases like cystic fibrosis, a cell membrane receptor fails to function. In the majority of cases, the problem comes from a change in the receptor so that it cannot reach the cell surface. The site in the cell where membrane proteins are synthesized and

1

Class Reg Number

Candidate Name .......................................................................

Biology H2 9747Tutor TuteeRevision Exercise 3: MCQ

assembled builds up with the abnormal protein. This site would likely be the:

A nucleusB rough endoplasmic recticulumC smooth endoplasmic recticulumD lysosome

4 If you isolate mitochondria and place them in buffer with a low pH they begin to manufacture ATP. Why?

A Low pH increases the concentration of base causing mitochondria to pump out H+ to the inter membrane space leading to ATP production.

B The high external acid concentration causes an increase in H+ in the inter membrane space leading to increased ATP production by ATP synthase. 

C Low pH increases the acid concentration in the mitochondrial matrix, a condition that normally causes ATP production.

D Low pH increases the OH- concentration in the matrix resulting in ATP production by ATP synthase.

5 In the first step of glycolysis, the enzyme hexokinase uses ATP to transfer a phosphate to glucose to form glucose-6-phosphate. The product continues to be oxidized forming pyryvate in glycolysis and is a precursor to acetyl-CoA for the citric acid cycle.

Suppose that a cell has only glucose available for energy and that the activity of hexokinase is suddenly stopped in this cell. Which of the following conditions will occur?

A The cell will continue to produce energy from mitochondrial electron transport.B The cell will continue to produce ATP using the citric acid cycle.C The cell will ultimately be unable to produce ATP.D The cell will be forced to switch to fermentation to produce ATP.

6 Calvin and colleagues determined the pathway of carbohydrate synthesis in plants by studying the incorporation of radioactive carbon dioxide into biological compounds. Suppose that photosynthesis is proceeding at a steady pace in a typical experiment with the lights on, and carbon dioxide is being combined with ribulose-bisphosphate (RuBP) to produce 3-phosphoglycerate (3PG). Then suddenly the source of carbon dioxide is eliminated.

What changes in the concentrations of 3PG and RuBP would occur?

A 3PG levels rise, RuBP levels fall.B 3PG levels fall, RuBP levels rise.C 3PG levels rise, RuBP levels rise.D 3PG levels fall, RuBP levels fall

7 What is the advantage of having a small volume inside the thylakoids of the chloroplast?

A A high proton concentration is rapidly developed.B A high electron concentration is rapidly developed.C Photosynthetic pigments are highly concentrated.D Enzymes of the Calvin cycle are highly concentrated.

8 In a nerve impulse, what happens at the site following the highest point of the action potential?

2

A Voltage-gated sodium ion channels open and Na+ is pumped in.B Voltage-gated sodium ion channels open and Na+ diffuses out.C Voltage-gated potassium ion channels open and K+ is pumped out.D Voltage-gated potassium ion channels open and K+ diffuses out.

9 What is a possible consequence of two base substitution mutations occurring in the same gene?

A Two amino acids coded for by the gene are changed.B Amino acids in two polypeptides coded for by the gene are changed.C All of the codons between the two mutations are changed.D All of the codons from the first mutation onward are changed.

10 Which statement is not true of double stranded DNA molecules?

A Adenine pairs with thymine and guanine pairs with cytosine.B The nitrogenous bases hold both strands by a single hydrogen bond.C During DNA replication, a new strand is synthesised from 5' to 3' direction.D The sugar phosphate backbone of the polynucleotide is on the outside of the helix.

11 Red-green color blindness is X-linked in humans. If a male is red-green color blind, and both parents have normal color vision, which of the male's grandparents is most likely to be red-green color blind?

A maternal grandmotherB paternal grandfatherC paternal grandmotherD paternal grandfather

12 A human geneticist determined the pedigree shown in the diagram with filled symbols showing the affected individuals. How is this pattern of inheritance described?

A autosomal dominantB autosomal recessiveC sex-linked dominantD sex-linked recessive

13 What does Mendel’s law of independent assortment relate to?

A The independent separation of alleles of a geneB The independent separation of a pair of homologous chromosomesC The independent separation of alleles of different genesD The formation of new combinations of chromosomes

14 The sputum (fluid coughed up from the lungs) of many smokers contain cells with mutations (errors) in the genes for p53. The smoking induced mutations appear to be an

3

early signal showing that cancer of the lungs will follow. What is the likely relationship between early p53 mutation and the development of lung cancer?

A p53 with a mutation directly stimulates the growth of cancer cellsB mutations in p53 would prevent abnormal cells from dying by apoptosisC mutant p53 triggers the M phase of the cell cycle leading to abnormal cell divisionD p53 causes a cell to enter G0, blocking cell division

15 Of all the flower colours that appear in zinnias, we will consider three: red, yellow, and orange. The following crosses were performed to investigate inheritance of flower color in these plants. In each case, F1 progeny were intercrossed to form the F2 generation.

Determine the likely mode of inheritance for flower colour in zinnias.

A Codominance R is dominant over O and Y and that O is dominant over Y but recessive to R.

B Codominance R is dominant over O and Y and Y is dominant over O but recessive to R

C Gene interaction 2 genes interact with each other to determine flower colour

D Codominance The orange flower colour produced is an intermediate phenotype of red and yellow.

16 The following statements are parts of the theory of evolution by natural selection.

I. Only the best adapted individuals survive and pass on their genes.II. More offspring are produced than the environment can support.III. As one generation follows another, the characteristics of the species gradually change.IV. There is a struggle for survival in which some individuals are more successful than others.

What is the correct sequence of statements?

A I, II, III, IVB II, IV, I, IIIC III, I, IV, IID IV, III, II, I

17 What is a centimorgan?

A The distance between two loci that will give an average of 100 crossovers per gamete.B The distance between two loci that will give an average of one crossover in 100 gametes.

4

C The number of gametes that will give an average of 100 crossovers between two loci.D The number of gametes that will give an average of one crossover between 100 loci.

18

19 A cell replicates its DNA and then starts to divide by meiosis. What is the expected arrangement of chromosomes if crossing over has taken place between the two genes shown?

20 In the lac operon model for lactose metabolism in prokaryotes, what is active when the operon is turned off?

A Lac I geneB RNA polymeraseC Promoter regionD Lac Z gene

21 Why do histones bind tightly to DNA?

5

A Histones are positively charged, and DNA is negatively charged.B Histones are negatively charged, and DNA is positively charged.C Histones are covalently linked to the DNA.D Both histones and DNA are strongly hydrophobic.

22 Which one of the following statements concerning bacteriophages is false?

A The phage genome can sometimes be inserted into the host cell chromosome.B Phage infection never improves the growth of the bacterial host.C Phage reproduction typically involves the takeover of host cell enzymes.D Environmental cues regulate whether a phage infection will lead to lysis or lysogeny.

23 The percentage of bacteria showing antibiotic resistance in Neisseria gonorrhoeae and other species of disease-causing bacteria has risen considerably since antibiotics were introduced.

What has caused this increase?

A When a bacterium detects an antibiotic, it changes its metabolism so that it becomes resistant.B When people do not complete courses of antibiotic, bacteria that were partly resistant become more resistant.C When a bacterium is treated with an antibiotic, it increases its resistance to the antibiotic and passes on increased resistance to its offspring.D When an antibiotic is used, only bacteria that are resistant to it survive and these bacteria pass on resistance to their offspring.

24 Parus major is a species of bird which is widely distributed throughout Europe and Asia. If a population of this species migrated to a small, isolated island and over many generations became a different species, what would be a suitable name?

A Parus majoretteB Imparus majorC Imparus minorD Parus major insulae

25 Scientists often deduce the evolutionary history of the different members of a gene family by

A comparing the sequences of the genes.B determining which of the genes are mutated in human diseases.C overexpressing each of the genes in a cell and determining which has the most destructive effect.D examining the relative stability of the mRNAs produced from the genes.

26 Proto-oncogenes

A are viral genes that can be a cause for cancer.B are genes that normally slow down cell growth and division.C are genes that stimulate normal cell growth and cell division.D are mutated genes that cause cancer.

6

27 Photoreceptors in the retina have special channels that are open to Na+ in the dark. When light hits photoreceptors, these special channels close. What can you conclude from this?

A Photoreceptors depolarize to light. B Photoreceptors hyperpolarize to light. C Photoreceptor voltage does not change in the presence of light. D None of the above

28 Weaver mice have difficulty maintaining posture and moving normally. This defect has been attributed to a defect in some potassium channels that allows Na+ as well as K+ to pass through the channel. What effect does increasing the Na+ permeability have on the membrane potential of the neuron?

A The membrane potential will become more negative. B The membrane potential will become less negative. C There will be no change in membrane potential. D There is not enough information to answer this question.

29 Errors sometimes occur in the base sequence of a strand of DNA, yet some errors do not result in the incorporation of an incorrect amino acid during translation. How is this possible?

A The cell accounts for errors by changing the code used during protein synthesis.B The error is corrected by repair of the mRNA.C The genetic code is redundant with different codes specifying the same amino acid.D Protein synthesis is also error-prone, so the two errors can cancel.

30 Biologists have sequenced the genomes of many organisms. The number of genes found in organisms varies greatly. Some examples are listed in the table below.

From this data it can be concluded that

A larger organisms have larger genomes.

7

B puffer fish show greater genetic variety than E. coli.C a nematode and flowering mustard plant have the same number of chromosomes.D the larger the genome of an organism, the greater the number of proteins it produces.

31 Since the introduction of the poisonous cane toad to Australia in 1935, there has been an increase in the ratio of body length to head size in two species of snakes, the Red-bellied Black Snake and the Green Tree Snake. A smaller headed snake cannot consume a large prey item, and so cannot swallow a large cane toad that has sufficient toxin to kill the snake.

The rapid evolution of body dimensions in the Red-bellied Black Snake and the Green Tree Snake most likely came about because

A cane toad toxin reduced the head size of the snakes. (selection pressure)B even small cane toads contain enough toxin to kill a long-bodied snake.C smaller headed snakes are better at catching cane toads than large headed snakes.D larger headed snakes were killed by the levels of toxin ingested when they ate a large cane toad.

32 Members of a barley plant species show varying levels of partial resistance to the leaf rust, Puccinia hordei. The graph below shows the distribution of a population of barley plants with regard to this characteristic.

With respect to rust resistance, these plants show

A high mutation rates.B polygenic inheritance.C discontinuous variation.

8

D inheritance due to a single pair of alleles.

33 In sheep, white wool (B) is dominant to black wool (b). In 2005, a farmer with a flock of sheep containing a few black sheep decided to prevent all black sheep from breeding in the future. White sheep in the flock continued to reproduce in that year and the years that followed.

As a result of the farmer’s action it is reasonable to predict that

A no black lambs were born in 2006 and beyond.B black lambs were born in 2006 but none in the following years.C the proportion of black lambs born in 2006 was the same as in previous years.D the proportion of black lambs born would decline gradually in the years following 2005.

34 The genome of a small virus is depicted below, showing the positions of cutting sites (P and Q) for two restriction enzymes.

The length of DNA fragments obtained when using these restriction enzymes is shown in the table below.

If both EcoR1 and BamH1 are used together on this viral DNA, the length of fragments obtained would be

A 3, 8, 5, 2B 7, 2, 1C 3, 5, 2D 3, 7, 8, 2

35 A suspect is accused of two crimes, one in Great Britain and the other in the United States.Forensic investigators in each country match the suspect’s profile to samples found at the local crime scene, and circumstantial evidence links him to both crimes. However, when scientists compare the profiles from the two crime scenes, they do not match. What is the best explanation for this discrepancy?

9

A The suspect must have an identical twin.B The suspect must have had an accomplice at one of the crimes.C The scientists were probably analyzing different hypervariable regions.D One of the scientists must have engaged in forensic fraud.

36 There are many different views on the ethics of reproductive cloning in humans. Which is a valid argument against cloning in humans?

A It involves the use of donor sperm which is unethical.B It happens naturally when identical twins are conceived.C Only females can be cloned.D The life expectancy of children produced by cloning might be lower than normal.

37 Police scientists, investigating the scene of a murder, found a drop of blood. The sample was analysed to produce a DNA profile. It was compared with the profiles of the victim and three suspects on an electrophoresis gel.

Which person does the blood sample match?

A The victimB Suspect 1C Suspect 2D Suspect 3

38 RFLP analysis can be used to distinguish between alleles based on differences in

A the amount of DNA amplified from the alleles during PCR.B the ability of nucleic acid probes to hybridize to the alleles.C restriction enzyme recognition sites between the alleles.D the ability of the alleles to be replicated in bacterial cells.

39 Agrobacterium is a “natural genetic engineer” and works byA lysing the host cell after transcribing its genome in the host cell.B taking over the host’s transcriptional machinery to produce virus particles.

10

C inserting retrotransposons into the plant’s genome.D inserting part of its DNA into a plant cell’s genome causing a tumor.

40 Retroviruses can be used to treat brain tumors because

A They only replicate in rapidly dividing tumor cells, not brain cellsB They replicate only in non-dividing cellsC They can carry more than 50 kb of foreign DNAD They make GFP

End of Paper

11