Questions and Answers of Cambridge International AS And A Level Biology

An investigation is carried out into the effect of temperature on the activity of lipase. Separate tubes of substrate solution and enzyme solution are left in temperature-controlled water baths for
An investigation is carried out into the effect of substrate concentration on the activity of catalase. What could be the dependent variable?A. The concentration of catalaseB. The pH of the enzyme
The table below shows the blood cell counts for four young female patients at a hospital. Each patient has a different medical condition.Use the data in the table above and Table 11.1 on page 231 to
a. Rearrange the following statements to produce a flow diagram to show how monoclonal antibodies are produced.1. Hybridoma cells cultured2. Mouse injected with antigen3. Mouse plasma cells fused
The diagram shows an antibody molecule.a. Describe briefly how antibody molecules are produced and secreted.b. Name:i. The regions X and Yii. The bond labelled Z.c. Explain how the structure of an
Measles is a common viral infection. Babies gain passive immunity to measles. a Explain:i. The term passive immunityii. How babies gain passive immunity.A vaccine for measles has been available
Phagocytes and lymphocytes are both present in samples of blood.a. Describe how the structure of a phagocyte differs from the structure of a lymphocyte.T-lymphocytes are involved in immune responses
Tetanus is a bacterial disease that may be acquired during accidents in which a wound is exposed to the soil.B-lymphocytes originate from stem cells, mature and circulate around the body. Following
What describes the cells producing monoclonal antibodies?A. A clone of B-lymphocytes, all of which secrete diff erent antibodiesB. A clone of hybridoma cells, all of which secrete identical
Which type of immunity is provided by vaccination?A. Artificial activeB. Artificial passiveC. Natural activeD. Natural passive
Which of the following explains why antibody molecules have quaternary structure?A. Antibodies have a variable regionB. Antibodies have complex 3D shapesC. Antibodies have four polypeptidesD.
The following occur during the response to infection.1. Attachment of bacteria to cell surface membrane of phagocyte2. Movement of phagocyte to site of infection by bacteria3. Formation of a
A student made drawings of four blood cells as shown in the figure.The correct identification of the cells is: granular cytoplasm 2 nucleus nucleus nucleus 3.
a. i. Name the causative organism of TB.ii. Explain how TB is transmitted.b. i. State the regions of the world with the highest number of cases of TB.ii. Suggest reasons for the high number of cases
a. Describe how cholera is transmitted.The table shows the number of cases of cholera and deaths from the disease for the five countries with the greatest outbreaks as reported to the WHO in 2010.b.
a. Describe how malaria is transmitted.The figure shows the global distribution of malaria in 2010 (data from UNAIDS).b. Describe and explain the global distribution of malaria.c. Outline the
a. State three ways in which HIV is transmitted.The table shows statistics published by UNAIDS for four regions of the world and the global totals for HIV/AIDS in 2010.b. Suggest three sources of
Rearrange the order of the following statements to give a flow diagram showing the evolution of resistance to the antibiotic streptomycin by the bacterium Escherichia coli.1. Most of the population
Which of the following diseases is transmitted by an insect vector?A. CholeraB. HIV/AIDSC. MalariaD. TB
An antibiotic sensitivity test was carried out on bacteria isolated from a patient with a blood disease. Four antibiotics were tested, A, B, C and D. The results are shown in the figure.Which
Non-infectious diseases are best defined as:A. Diseases caused by malnutritionB. All diseases of old ageC. All diseases that are not caused by a pathogenD. All diseases that can be transmitted from
Cholera, malaria, measles and tuberculosis (TB) are infectious diseases. Which row shows the type of organism that causes each of these diseases? Cholera Malaria Measles Tuberculosis bacterium virus
The figure shows photomicrographs of alveoli from 1 a non-smoker (× 200) and 2 a smoker (× 50).a. Use the photomicrographs to describe how the lungs of this smoker diff er from the lungs of the
Cigarette smoke contains tar, nicotine and carbon monoxide. Tar contains carcinogens.a. Describe the effect of tar on the lining of the bronchi in the lungs.b. Describe the effects of nicotine and
The graph below shows the relationship between rate of transpiration and rate of water uptake for a particular plant.a. Define the term transpiration.b. State the two environmental factors which are
The composition of alveolar air remains fairly constant even though gases are exchanged with the blood in the capillaries that surround the alveoli.a. Describe the process of gas exchange between
a. Copy and complete the table to compare the trachea with a respiratory bronchiole. Use a tick (✓) to indicate that the structure is present and a cross (✗) to indicate that it is not.b.
The diagram below shows two cells from the lining of the trachea.a. Name:i. Cells P and Rii. Structures S, T, U and W.b. Explain:i. Why cell P contains many of the structures labelled Tii. The role
The diagram below shows an alveolus.a. Name:i. Cells A, B and Cii. The fluid at D.b. Calculate the actual distance indicated by X–Y. Show your working.c. Explain how alveoli are adapted for the
Which substance in tobacco smoke decreases the oxygen-carrying capacity of haemoglobin?A. Carbon dioxideB. Carbon monoxideC. NicotineD. Tar
Which of the following substances in tobacco smoke damage the gas exchange system?A. Carbon monoxide and carcinogensB. Carbon monoxide and nicotineC. Carcinogens and tarD. Nicotine and tar
Which of the following best describes the process of gas exchange in the lungs?A. Air moves in and out of the alveoli during breathing.B. Carbon dioxide diff uses from deoxygenated blood in
Which of the following is not a role of elastic fibres in the gas exchange system?A. Contract to decrease the volume of the alveoli during expirationB. Recoil to force air out of the alveoli during
Cartilage is found in which structure?A. AlveolusB. BronchioleC. CapillaryD. Trachea
The following structures are found in the walls of the gas exchange system.1. Capillaries2. Cilia3. Elastic fibres4. Goblet cells5. Smooth muscle cellsWhich would be found in the lining of an
The diagram below shows a cross-section of the heart at the level of the valves.a. i. Copy and complete the following flow chart to show the pathway of blood through the heart.ii. Explain how the
Figure 8.28, page 176, shows the pressure changes in the left atrium, left ventricle and aorta throughout two cardiac cycles. Make a copy of this diagram.Figure 8.28a. i. How long does one heart beat
Mammals have a closed, double circulation.a. State what is meant by the term double circulation.b. Explain why the wall of the artery is thicker than the wall of the vein.c. Suggest one role for the
Carbon dioxide is transported in the blood in various forms.a. Describe how carbon dioxide molecules reach red blood cells from respiring cells.The diagram below shows part of a capillary network and
The following statements were all made by candidates in examination answers. Explain what is wrong with each statement.a. Oxyhaemoglobin gradually releases its oxygen as it passes from the lungs to a
Explain how the structure of haemoglobin enables it to carry out its functions.
Construct a table comparing blood plasma, tissue fluid and lymph.
Construct a table comparing the structure of arteries, veins and capillaries. Include both similarities and differences, and give reasons for the differences which you describe.
What causes the bicuspid valve to close during ventricular systole?A. A greater blood pressure in the left atrium than in the left ventricleB. A greater blood pressure in the left ventricle than in
Where is the mammalian heart beat initiated?A. Atrioventricular nodeB. Left atriumC. Purkyne tissueD. Sinoatrial node
The micrograph shows an artery and a vein.Which row correctly identifies and describes the artery and the vein? X Y
The diagram shows the changes in blood pressure as blood flows through the blood vessels in the human systemic circulatory system. Which correctly identifies the vessels labelled P to S? 20- 15- 10-
Translocation of organic solutes takes place between sources and sinks. a. Briefly explain under what circumstances:i. A seed could be a sinkii. A seed could be a sourceiii. A leaf could be a
Figure 7.31d on page 148 shows a sieve element with red-stained ‘triangles’ of callose at each end. These triangles indicate the positions of the sieve plates.a. Assuming the magnification of the
Explain how active loading of sucrose into sieve elements accounts for the following observations:a. The phloem sap has a relatively high pH of about pH 8.b. The inside of sieve element/companion
The graph below shows the results of two experiments, A and B. In both cases the uptake of potassium ions into the roots of young plants was measured. Roots were thoroughly washed in pure water
An instrument called a dendrogram can be used to measure small changes in the diameter of a tree trunk. Typically, the instrument reveals daily changes, with the diameter at its lowest during
Figure a shows changes in the relative humidity of the atmosphere during the daylight hours of one day. Figure b shows changes in the tension in the xylem of a tree during the same period.a. Describe
Arrange the following in order of water potential. Use the symbol > to mean ‘greater than’. dry atmospheric air; mesophyll cell; root hair cell; soil solution; xylem vessel contents
a. Name three cell types found in:i. Xylemii. Phloem.b. State the functions of the cell types you have named.
Explain how water moves from:a. The soil into a root hair cellb. One root cortex cell to anotherc. A xylem vessel into a leaf mesophyll cell.
The diagram shows the effect of light intensity on the rate of transpiration from the upper and lower epidermis of a leaf. Other environmental factors were kept constant. What could explain the
Which of the following rows correctly describes the hydrostatic pressure of the two types of elements? Hydrostatic pressure Xylem vessel element A negative B negative C positive D positive Phloem
If sucrose is actively loaded into a sieve tube, which combination of changes takes place in the sieve tube? Solute potential decreases (becomes more negative) decreases (becomes more negative)
In the 1940s, Chargaff and his co-workers analysed the base composition of the DNA of various organisms. The relative numbers of the bases adenine (A), cytosine (C), guanine (G) and thymine (T) of
The drawing shows a polyribosome.a. Name X, Y and Z.b. In which direction are the ribosomes moving? Explain how you were able to decide on their direction of movement. Y X O0口
Copy and complete the following table to distinguish between the processes of transcription and translation. Transcription Translation Site in cell where process occurs Molecule used as a template in
Suggest why:a. A mutation in which one nucleotide of a triplet code is altered often makes no difference to the protein molecule coded by the DNA [2]b. The addition or deletion of three nucleotides
In most people, the first six amino acids in their β-globin polypeptide chains are:The DNA triplet coding for the sixth amino acid (Glu) in most people is CTT. In some people this DNA triplet is
The table shows all the messenger RNA (mRNA) codons for the amino acid leucine. Copy the table and write in, for each codon, the transfer RNA (tRNA) anticodon that would bind with it and the DNA
Use Appendix 2 (page 513) to find the sequence of amino acids that is coded by the following length of messenger RNA (mRNA):AUGUUUCUUGAUUAA
Copy the drawing and annotate it to explain the replication of DNA.
Distinguish between a nucleotide and a nucleic acid.
Look at the structures of nucleotides in Figure 6.2. Draw a nucleotide that could be found:a. In either DNA or RNAb. Only in DNAc. Only in RNA.Figure 6.2 adenine thymine sugar sugar P guanine
How many different arrangements of four bases into triplets can be made?A. 3 + 4B. 3 × 4C. 34D. 43
Which statement about base pairing in nucleic acids is not correct?A. Adenine can pair with either thymine or uracil.B. Guanine only pairs with cytosine.C. Thymine can pair with either adenine or
What can be found in both DNA and messenger RNA (mRNA)?A. Double helix structureB. Sugar–phosphate chainC. RiboseD. Thymine
Which of the following statements are true and which are false?A. Centrosomes are replicated before M phase of the cell cycle begins.B. Sister chromatids contain identical DNA.C. The microtubules
If a 10 cm long piece of string was packed into a 5 cm long tube, the packing ratio would be 2 (2 cm of string per cm of tube). The packing ratio is a useful measure of the degree of compactness
In Chapter 1 it was noted that microtubules are tiny tubes made of protein subunits which join together and the protein is called tubulin. Colchicine is a natural chemical which binds to tubulin
a. Diagram 1 below shows a plant cell dividing by mitosis. Only two of the many chromosomes are shown for simplicity.i. What stage of mitosis is shown?ii. Draw prophase for the same cell assuming the
The diagram shows three cells (labelled A, B and C) from a root tip which have been stained to show chromosomes.a. Identify the stage of mitosis shown by each cell.b. Describe what is happening at
Distinguish between the following terms: centrosome, centriole and centromere.
A cell with four chromosomes undergoes a cell cycle including mitosis. Which diagram correctly shows the changes in chromatid number during interphase? 2 chromatids 4 chromatids 4 chromatids 8
Growth of cells and their division are balanced during the cell cycle. Which column shows the consequences that would follow from the two errors shown in the table? Consequence Error A B C D speeding
During prophase of mitosis, chromosomes consist of two chromatids. At which stage of the cell cycle is the second chromatid made?A. CytokinesisB. G1C. G2D. S
The diagram shows the concentration in mmol dm–3 of two different ions inside a human red blood cell and in the plasma outside the cell.a. Explain why these concentrations could not have occurred
When a cell gains or loses water, its volume changes. The graphs show changes in the water potential (ψ), pressure potential (ψp) and solute potential (ψs) of a plant cell as its volume changes as
The rate of movement of molecules or ions across a cell surface membrane is affected by the relative concentrations of the molecules or ions on either side of the membrane. The graphs below show the
A cell with a water potential of –300 kPa was placed in pure water at time zero. The rate of entry of water into the cell was measured as the change in water potential with time. The graph shows
Copy and complete the table below to compare cell walls with cell membranes. Feature Cell wall Cell membrane is the thickness normally measured in nm or um? location chemical composition permeability
Copy the table below and place a tick or cross in each box as appropriate. Uses energy in the form of ATP Process Uses proteins Specific Controllable by cell diffusion osmosis facilitated diffusion
The diagram shows part of a membrane containing a channel protein. Part of the protein molecule is shaded.a. Identify the parts labelled A, B and C.b. For each of the following, state whether the
a. Describe fully what will occur if a plant cell is placed in a solution that has a higher water potential than the cell. Use the following terms in your answer.cell wall, freely permeable,
Prepare a table to summarise briefly the major functions of phospholipids, cholesterol, glycolipids, glycoproteins and proteins in cell surface membranes.
The cells of the myelin sheath are wrapped in layers around nerve cell axons. Freeze-fractured preparations of the myelin sheath cell surface membranes show very few particles. This indicates that
Where are the carbohydrate portions of glycolipids and glycoproteins located in cell surface membranes?A. The inside and outside surfaces of the membraneB. The inside surface of the membraneC. The
What are the most abundant molecules in the cell surface membranes of plant cells?A. CholesterolB. GlycolipidsC. PhospholipidsD. Proteins
Two inhibitors of the same enzyme, inhibitor A and inhibitor B, were investigated to discover if they were competitive or non-competitive. In order to do this, the rate of reaction of the enzyme was
The activity of the enzyme amylase can be measured at a particular temperature by placing a sample into a Petri dish containing starch-agar (‘a starch-agar plate’). Starch-agar is a jelly
You are provided with three solutions: A, B and C. One solution contains the enzyme amylase, one contains starch and one contains glucose. Starch is the substrate of the enzyme. The product is the
The reaction below occurs during aerobic respiration. The reaction is catalysed by the enzyme succinate dehydrogenase.a. Name the substrate in this reaction.b. The molecule malonic acid, which is
The graph below shows the eff ect of temperature on the rate of reaction of an enzyme.a. What is indicated by X?b. What temperature would X be for a mammalian enzyme?c. Explain what is happening in
The graph shows the eff ect of changes in pH on the activity of the enzyme lysozyme.a. Describe the effect of pH on this enzyme.b. Explain why pH affects the activity of the enzyme. 4 6. 7 8. 10 pH
Copy the graph in question 3 and draw a line from which the initial rate of reaction could be calculated. Time Amount of product formed

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