Oct/Nov 2012

The diagram is a drawing based on an electron micrograph of a cell. Which structure shows that this is a secretory cell?

Cells as the basic units of living organisms

Which two monosaccharides combine to form sucrose?

Carbohydrates and lipids

Which of the following statements about triglycerides is correct?

Carbohydrates and lipids

Which molecules possess $\text{C}=\text{O}$ bonds? 1 amino acids 2 fatty acids 3 glycerol

Carbohydrates and lipids

Which of these statements about polysaccharides applies to both amylose and glycogen? 1 has $1,4$ glycosidic bonds 2 has $1,6$ glycosidic bonds 3 is a polymer made of $\alpha$-glucose

Carbohydrates and lipids

What effect does an enzyme have in an enzyme-catalysed reaction?

Mode of action of enzymes

The diagram shows the fluid mosaic model of membrane structure. Which two components help to make the membrane fluid?

Fluid mosaic membranes

The graph illustrates how the rate at which glucose enters a cell varies as the glucose concentration outside the cell changes. What causes the plateau at X?

Movement into and out of cells

A molecule may move into a cell by two different passive processes. Which of these processes would make the molecule enter the cells more quickly?

Movement into and out of cells

Which statement is not correct for mitotic cell division?

Chromosome behaviour in mitosis

The diagram illustrates the chromosomes in a single cell that has been flattened during mitosis. Which mitotic stage is depicted, and what is the haploid chromosome number for this species?

Chromosome behaviour in mitosis

Four students were each asked to propose a set of four labels for a plan diagram showing a transverse section of a dicotyledonous leaf. Which student, A, B, C or D, proposed the correct set of labels?

Structure of transport tissues

What is required for translation?

Proteins

Which characteristics of DNA allow it to satisfy these requirements as a molecule of inheritance?

Structure of nucleic acids and replication of DNA

Which diagram shows the bond that connects the individual units of a nucleic acid?

The microscope in cell studies

Which row correctly recognises xylem vessel elements and sieve tube elements?

Structure of transport tissues

The diagram presents a model that can be used to illustrate mass flow. X and Y are each filled with sucrose solutions of different concentrations, so water moves into or out of X and Y by osmosis or because of hydrostatic pressure. Sucrose solution then passes through tube T connecting X and Y. Which description is correct?

Movement into and out of cells

Which of the following statements explain why a stem is cut and attached to a potometer while submerged in water?

Movement into and out of cells

What takes place during ventricular systole in a mammalian heart?

The heart

Which two of the following statements concerning the Bohr effect are correct?

Proteins

The diagram illustrates the heart and some of its blood vessels. Which combination of numbers correctly identifies the blood vessels that deliver blood to the heart and carry blood away from the heart?

The circulatory system

The diagram illustrates pressure changes on the left side of the heart during the cardiac cycle. What occurs at X?

The heart

Which of the following can be found in both eukaryotic and prokaryotic cells?

Cells as the basic units of living organisms

The photograph depicts a kind of blood cell. Which of these statements about the cells is correct?

Transport of oxygen and carbon dioxide

Which symptom is characteristic of emphysema?

The microscope in cell studies

Haemoglobin is able to bind to carbon dioxide, carbon monoxide and oxygen. Which of these gases bind at the same site?

Proteins

Some research indicates that smoking raises the chance of developing lung cancer. The graphs illustrate the percentage of smokers and the number of deaths from lung cancer in men in two age groups between 1950 and 1998. Which statement is not supported by the data in the graphs?

The gas exchange system

Which row accurately pairs a function with B-lymphocytes and T-lymphocytes?

The immune system

What occurs when dead bacteria are injected into people?

Antibodies and vaccination

Some children are born with Severe Combined Immune Deficiency (SCID). These children usually have no T-lymphocytes and are affected by many diseases. How may these children be cured?

The immune system

Which of the following increase the risk of catching TB?

Infectious diseases

Which box contains a community?

Cells as the basic units of living organisms

The diagram illustrates a simplified nitrogen cycle. Which arrow indicates the action of nitrogen-fixing bacteria?

Cells as the basic units of living organisms

Which row gives the correct set of locations of ribosomes in a eukaryotic cell?

Protein synthesis

The diagram presents some values for gross primary productivity (GPP) and energy flow in an ecosystem, measured in $\text{kJ m}^{-2}\text{ y}^{-1}$. What percentage of GPP in the producers can be passed on to the tertiary consumers?

The microscope in cell studies

Which statement about the light microscope is correct?

The microscope in cell studies

The diagram illustrates the ultrastructure of a cell taken from a dicotyledonous leaf. What is the magnification?

The microscope in cell studies

Four students, 1, 2, 3 and 4, each performed the reducing sugar test and the non-reducing sugar test on a sucrose solution. Which observations show that they had carried out the correct tests?

Testing for biological molecules

Which row is correct for every one of the molecules?

Testing for biological molecules

As the temperature of an enzyme is increased, which bond will break last?

Factors that affect enzyme action

Which combination of eyepiece and objective lens in a light microscope allows the largest number of cells to be seen within the field of view?

The microscope in cell studies

Haemoglobin is made up of two $\alpha$ chains and two $\beta$ chains. In about $5\%$ of all humans, one amino acid in the $\beta$ chain differs from the normal form. Which level(s) of protein structure may be altered in these humans?

Proteins

Which statement about polysaccharides can be used to describe both glycogen and amylopectin?

Carbohydrates and lipids

Which row identifies the kinds of bond present at the different levels of protein structure?

Proteins

What role do enzymes play in metabolism?

Mode of action of enzymes

Two enzyme investigations were performed. In the first one, experiment X, the temperature was $37^\circ\text{C}$. In the second investigation, the temperature was raised to $80^\circ\text{C}$. Every other condition stayed unchanged. Which graph represents the results?

Factors that affect enzyme action

Which function of the cell surface membrane does not arise from the properties of the phospholipids?

Fluid mosaic membranes

An increase in which component would cause the cell surface membrane to become more fluid?

Fluid mosaic membranes

Which of the processes that move substances across cell surface membranes requires energy?

Movement into and out of cells

Diagrams 1 and 2 illustrate how the transverse section of a leaf alters when it is transferred from solution W to another solution Y. How has the water potential changed in diagram 2?

Movement into and out of cells

Immediately after which stage of mitosis in an animal cell does the cytoplasm begin to divide?

Replication and division of nuclei and cells

What features does a prokaryotic cell have?

Cells as the basic units of living organisms

The diagram shows a cell from an organism produced by reduction division. What is the diploid number of this organism?

Chromosome behaviour in mitosis

Which of the following is not a description of a gene?

Replication and division of nuclei and cells

Which row in the table correctly indicates situations where both DNA and RNA are involved?

Proteins

The diagram outlines the steps involved in synthesising a polypeptide. DNA nucleotide sequence (template strand): TACGACAATCGC mRNA sequence: AUGCUGUUAGCG amino acid sequence: met leu leu ala Which characteristic of the triplet code is shown by the information provided?

Proteins

Which statement about the uptake and movement of water in plants is correct?

Movement into and out of cells

Which set of conditions causes the transpiration rate in plants to increase?

Transport mechanisms

Which statement gives the reason that sucrose, instead of glucose, is carried in phloem?

Carbohydrates and lipids

The diagrams display transverse sections of parts of a plant (leaf, stem and root). In the transverse sections, what do 1, 2, 3, 4, 5 and 6 represent?

Structure of transport tissues

The diagram illustrates how three different concentrations of carbon dioxide affect the dissociation curve of human haemoglobin. X = partial pressure of carbon dioxide: $3.0\,\text{kPa}$, Y = partial pressure of carbon dioxide: $5.0\,\text{kPa}$, Z = partial pressure of carbon dioxide: $7.0\,\text{kPa}$. What effect does carbon dioxide have on haemoglobin?

Proteins

Why does the red blood cell count in a human rise after spending several weeks at high altitude?

Replication and division of nuclei and cells

Each item below is a feature of eukaryotic cells. 1 chloroplast 2 Golgi apparatus 3 lysosome 4 mitochondrion 5 nucleus Which one of these is enclosed by a single membrane?

Cells as the basic units of living organisms

The graph illustrates how pressure varies in the left atrium, left ventricle and aorta throughout one cardiac cycle. Referring to the semilunar valve and atrioventricular valve, what is occurring at points 1, 2, 3 and 4?

The heart

The normal venous pressure in the feet is $3.3\,\text{kPa}$. If a person stands very still, venous blood pressure in the feet increases to $5.0\,\text{kPa}$. What causes this high pressure?

The circulatory system

Some individuals have difficulty expelling large amounts of air from their lungs. Their breathing is noisy and fast. Which disease are they most likely to have?

The gas exchange system

Which of the following may lead to heart failure?

The heart

A mature human body contains about $5\,\text{dm}^3$ of blood, and this blood makes one complete circulation roughly every minute. Each $100\,\text{cm}^3$ of arterial blood contains $19\,\text{cm}^3$ of oxygen. Each $100\,\text{cm}^3$ of venous blood contains $12.5\,\text{cm}^3$ of oxygen. What is the approximate volume in $\text{cm}^3$ of oxygen absorbed per minute in the lungs?

Transport of oxygen and carbon dioxide

Which of the following makes contracting measles more likely?

Infectious diseases

To stop a disease, dead bacteria can be injected into the body. Which type of immune response is generated?

Antibodies and vaccination

The graph illustrates the primary and secondary immune system responses to antigens. What are responses X and Y?

Antibodies and vaccination

A primary consumer, X, is eliminated from a community because of a fatal viral infection. Some time later, the population sizes of some organisms in the food web have altered. Which population of organisms increased?

Infectious diseases

The diagram illustrates a simplified nitrogen cycle. At which stage does nitrification occur?

Transport mechanisms

Plant cells are fixed, stained and observed using a light microscope. What would be plainly visible at $\times 400$ magnification?

The microscope in cell studies

The overall rate at which producers manufacture organic material is known as gross primary productivity (GPP). The rate at which producers keep organic material as fresh tissue is known as net primary productivity (NPP). What illustrates the connection between GPP and NPP?

Transport mechanisms

Which size range would cover most prokaryotic cells?

Cells as the basic units of living organisms

The photomicrograph displays some plant tissues, and the magnification is $\times 200$. What is the diameter of the cell labelled Z?

The microscope in cell studies

Which solution, when heated, breaks glycosidic bonds?

Testing for biological molecules

The diagram shows four molecules. Which pair of molecules join by condensation to make sucrose?

Carbohydrates and lipids

Which molecules have a structural formula containing $\text{C}=\text{O}$ bonds?

Carbohydrates and lipids

Which structure occurs in both prokaryotic and plant cells?

Cells as the basic units of living organisms

Five biochemical tests were performed on four unidentified substances, A, B, C and D. After the tests, it became possible to establish whether each biochemical was present or absent in each substance. Which substance contains glucose, fat and protein?

Testing for biological molecules

Which term is used for a globular protein that is insoluble in water?

Proteins

Polymers of molecule X or polymers of molecule Y may be formed by glycosidic bonds. Which statement is correct?

Carbohydrates and lipids

The diagrams illustrate the point at which an inhibitor binds to an enzyme and whether the binding is permanent or temporary. Which diagrams show a non-competitive inhibitor?

Mode of action of enzymes

The diagrams display two molecules present in cell surface membranes. Which part influences the membrane’s fluidity?

Fluid mosaic membranes

The graph illustrates how the rate at which glucose enters a cell varies as the glucose concentration outside the cell changes. What is the cause of the plateau at X?

Movement into and out of cells

All of the processes listed below are ways substances may move into cells. Which of them require ATP?

Movement into and out of cells

Which diagram shows a cell in metaphase during mitosis?

Chromosome behaviour in mitosis

Colchicine is a substance that prevents the formation of spindle fibres. At which stage does the cell cycle stop?

Chromosome behaviour in mitosis

In a gene, the DNA nucleotide sequence that directs protein synthesis is arranged as triplets, with each triplet specifying particular amino acids. The table gives three examples of these triplet codes. Which option shows the correct codon and anticodon?

Proteins

Which substance exits the nucleus via the pores in the nuclear envelope?

Protein synthesis

Enzymes are ......1...... proteins that consist of polypeptides. A gene is a run of ......2......, and these are sections of a ......3...... molecule that codes for a polypeptide. Which words correctly fill gaps 1, 2 and 3 in the sentences?

Proteins

During the formation of messenger RNA, which process does not take place?

Proteins

Which option correctly pairs the structure with the function of sieve tube elements?

Structure of transport tissues

How can single-celled organisms survive without having a specialised transport system?

Movement into and out of cells

The photomicrograph presents a transverse section through a leaf. Which cell has the water potential that is least negative?

Movement into and out of cells

What happens during the movement of water through the apoplast pathway?

Movement into and out of cells

What causes the red blood cell count in humans to rise when they stay at high altitudes?

Replication and division of nuclei and cells

Which row correctly lists every blood vessel that has the features shown in the table below?

The circulatory system

The graph illustrates oxygen dissociation from haemoglobin at two different pHs. Which curve corresponds to the lower pH, and in what tissue could these data have been collected?

Proteins

The diagram illustrates how pressure changes in the left side of the heart during the cardiac cycle. Which statement about the heart valves is correct?

The microscope in cell studies

A student examined the same plant cells with both an electron microscope and a light microscope. The electron microscope had a magnification of $\times 1000$. The light microscope was fitted with a $\times 10$ eyepiece lens and a $\times 100$ objective lens. The student decided that the image of the plant cell produced by the electron microscope was clearer and showed more detail than the image produced by the light microscope. Which explanation supports this conclusion?

The microscope in cell studies

When a person has an asthma attack, the tubes in the gas exchange system become narrower and more mucus is produced. Which of these changes happen during an asthma attack?

The microscope in cell studies

What symptoms might be observed in a person with chronic obstructive pulmonary disease (COPD)?

Movement into and out of cells

Which row indicates the effects of chronic bronchitis?

The gas exchange system

An oxygen molecule moves by diffusion straight from the air in an alveolus to haemoglobin in a red blood cell. What is the smallest number of cell surface membranes that this molecule has to cross?

Movement into and out of cells

For certain diseases, tracing individuals who have had contact with infected people is one of the most effective ways to prevent and control them. Which disease would benefit from tracing the contacts of infected people for its prevention and control?

Infectious diseases

A child receives a vaccine for a viral disease. Several weeks afterwards, she comes into contact with the same virus. What response would be expected following this exposure?

Proteins

Why has it been hard to develop an effective vaccine against malaria?

Antibodies and vaccination

Which statement identifies the role of lymphocytes in the immune response?

The immune system

The diagram illustrates several of the processes involved in the nitrogen cycle in an ecosystem. What type of bacterium is present at X?

Infectious diseases

The diagram illustrates the route of energy through a food chain. What percentage of the energy do the green plants use for photosynthesis?

Carbohydrates and lipids

The diagram depicts an organelle shown at a magnification of $\times 20\,000$. What is the greatest length of the organelle?

The microscope in cell studies

A tree performs photosynthesis and supplies organic compounds to other organisms in the forest. It absorbs carbon dioxide from the atmosphere and releases oxygen back into it. Water is absorbed from the soil by its roots, and water is lost from its leaves to the atmosphere. Many other organisms live on or in the tree. Which term is used to describe the tree?

The microscope in cell studies

In a plan diagram of a transverse section of a dicotyledonous leaf, which feature must be left out?

The microscope in cell studies

What is starch’s general formula?

Carbohydrates and lipids

When an enzyme is heated, which bonds are broken last?

Factors that affect enzyme action

Which molecules have structural formulae that include $\text{C}=\text{O}$ bonds?

The microscope in cell studies

Which statement about polysaccharides applies to both starch and cellulose?

Carbohydrates and lipids