May/June 2011

The diameter of a cell organelle is $4 \times 10^{-1}\,\text{mm}$. What is the diameter in $\mu\text{m}$?

The microscope in cell studies

Which rows indicate the chemical groups found in the biological molecules listed?

The microscope in cell studies

Which option correctly pairs the functional and structural characteristics of cellulose, collagen, glycogen or triglyceride?

Carbohydrates and lipids

The enzyme catalase catalyses the decomposition of hydrogen peroxide into water and oxygen. In an investigation of how pH affects the reaction rate of catalase, potato cubes were placed in hydrogen peroxide. Which dependent variable should be measured?

Factors that affect enzyme action

Which protein-structure levels can determine an enzyme’s specificity?

Proteins

Certain inhibitors of enzyme reactions attach to the enzyme / substrate complex. Which of the following statements about this form of inhibition are correct?

Factors that affect enzyme action

Which statement is accurate for the cell surface membrane and the membranes inside cells?

Fluid mosaic membranes

What evidence supports the idea that a membrane protein is involved in active transport?

Movement into and out of cells

Segments of plant tissue were placed into sucrose solutions spanning different concentrations. Their lengths were measured both before they were placed in the solutions and after 30 minutes. The graph shows the ratio of initial length to final length. What is a correct description of how the cells alter and of their water potential as the sucrose concentration increases?

Movement into and out of cells

Which statement is always correct about cytokinesis?

Replication and division of nuclei and cells

What process takes place in prophase of the mitotic cell cycle in an animal cell?

Chromosome behaviour in mitosis

In the table below, which option gives the correct comparison of light microscopes and electron microscopes?

The microscope in cell studies

The diagram illustrates how genetically identical frogs may be produced from unfertilised frog eggs. The diploid number $(2n)$ in frogs is $26$. Which set of numbers correctly shows the number of chromosomes in each type of cell in the diagram?

Replication and division of nuclei and cells

The mode of action for four drugs that block DNA replication is given here. Aphidicholine blocks DNA polymerase. Cytarabine is changed into a molecule that can replace a DNA nucleotide and it also blocks DNA repair mechanisms. Epirubicin blocks an enzyme needed for DNA unwinding and strand separation. Hydroxycarbamide blocks an enzyme involved in making deoxyribonucleotides. Which row pairs a drug with the correct explanation of its mechanism of action?

Replication and division of nuclei and cells

The events below happen during transcription. Before the mRNA leaves the nucleus, which events will have taken place twice?

Proteins

What type of sugar and what kinds of bonds are present in a DNA molecule?

Carbohydrates and lipids

In an animal cell, which process depends on cell surface area, and which process depends on cell volume?

Movement into and out of cells

Which xerophytic adaptations lower the water potential gradient?

Movement into and out of cells

During transpiration, where in the leaves does evaporation of water occur?

Movement into and out of cells

The photomicrograph shows a vascular bundle. Which statement describes the relationship between the water potential of the labelled cells?

Movement into and out of cells

The diagram shows how water moves through a plant. Which row correctly identifies the processes involved at the stages of water movement illustrated?

Movement into and out of cells

Which statement about tissue fluid is correct?

Movement into and out of cells

Which structures can be found in a typical plant cell?

Cells as the basic units of living organisms

What occurs during ventricular diastole?

The heart

Which row gives the correct description of the events that occur during the cardiac cycle?

The heart

Which row correctly states the structure of an artery in comparison with a vein when viewed in transverse section with a light microscope?

The microscope in cell studies

Within the lungs, oxygen and carbon dioxide move across cell membranes by diffusion. Which row is correct?

Movement into and out of cells

A student was asked to state the differences seen on four microscope slides of sections from different regions of the gas exchange system. slide 1: cartilage and glands absent; few goblet cells, ciliated epithelial cells and smooth muscle present slide 2: incomplete cartilage rings, glands, goblet cells, ciliated epithelial cells and smooth muscle present slide 3: cartilage, glands, goblet cells and smooth muscle absent; squamous epithelial cells present slide 4: plates of cartilage, glands, goblet cells, ciliated epithelial cells and smooth muscle present Which option correctly identifies the parts of the gas exchange system?

The microscope in cell studies

A person with mild emphysema has given up smoking cigarettes. Why would this person’s health get better?

Movement into and out of cells

Which disease is not likely to be transmitted directly from parent to child?

Infectious diseases

The diagram illustrates one method for investigating the effect of an antibiotic on bacteria. The table presents the results from tests on five different types of bacteria. Zones of less than 13 mm indicate the presence of resistant bacteria. Which statement is supported by these data?

Fluid mosaic membranes

Smallpox has been eliminated, yet malaria and cholera have not. Which statements give the correct reasons for this?

Infectious diseases

Each year, around 1 047 000 kJ of solar light energy falls on 1 square metre of grassland. The table indicates how this energy is transferred. How much energy is taken up by the grass for photosynthesis?

Carbohydrates and lipids

Plant cells are stained and then examined with a light microscope. Which structures would be clearly visible at a magnification of $\times 400$?

The microscope in cell studies

Which process does not make nitrogen available for plants to use?

Transport mechanisms

Which type of cell will have the greatest proportion of structures enclosed by a single membrane?

Cells as the basic units of living organisms

Four distinct fruit juices, A, B, C and D, were examined using Benedict’s solution. A second portion of each juice was hydrolysed and then tested with Benedict’s solution. The table shows the masses of precipitates produced. Which juice has the largest mass of non-reducing sugar?

Testing for biological molecules

During hydrolysis, which molecular bonds are broken when a molecule of glycogen is converted into glucose?

Carbohydrates and lipids

Which group of statements accurately describes haemoglobin?

Proteins

Certain foods include ‘hydrogenated vegetable oils’. These are unsaturated fats that have been changed into saturated fats. Which property of the fats would be different?

Carbohydrates and lipids

With a stage micrometer scale, one division of an eyepiece graticule was found to equal $0.005\ \text{mm}$. A spongy mesophyll cell measured $3.5$ divisions on the eyepiece graticule. What is the estimated diameter of the cell?

The microscope in cell studies

The diagram illustrates the structure of the amino acid cysteine. When two of these amino acids combine, what bond(s) are formed?

Proteins

Which row gives the description of a triglyceride?

Carbohydrates and lipids

The graph illustrates the activation energy for an enzyme-catalysed reaction and for the same reaction when no catalyst is present. Which of the following indicates the activation energy of the reaction without a catalyst?

Mode of action of enzymes

Which of the following statements are true for every enzyme?

Mode of action of enzymes

The graphs illustrate how temperature and pH affect enzyme activity. Which statement explains the enzyme activity at the point shown?

Factors that affect enzyme action

The diagram depicts a section of a cell surface membrane. Which molecules contain both hydrophobic and hydrophilic regions?

Fluid mosaic membranes

Raising the number of which type of bond increases the fluidity of the cell surface membrane?

Fluid mosaic membranes

Potato tissue cylinders placed in a $0.35\,\text{mol dm}^{-3}$ sucrose solution showed no change in mass. What will happen if the cylinders are placed in a $0.1\,\text{mol dm}^{-3}$ sucrose solution?

Movement into and out of cells

The graph shows how the amount of DNA in one nucleus varies at different points in the life cycle of a mammal. At which stage does $X$ occur?

Replication and division of nuclei and cells

During which stage of mitosis do these events take place? centromeres divide spiralisation and condensation of DNA

Chromosome behaviour in mitosis

The endoplasmic reticulum in cells forms membranous sacs that contain products of metabolism. In what part of the cell are these products used?

Cells as the basic units of living organisms

In which process does only mitosis take place?

Replication and division of nuclei and cells

The table gives the tRNA anticodons for four amino acids. A cell produces a polypeptide with this amino acid sequence: glutamic acid - asparagine - threonine - proline What sequence of bases was present in the DNA that produced this?

Proteins

What is synthesised by the enzyme RNA polymerase?

Mode of action of enzymes

The diagram illustrates a section of a DNA molecule. How many hydrogen bonds take part in keeping these DNA strands joined together?

The microscope in cell studies

Which characteristics allow the aorta to withstand the high pressure during ventricular systole?

The circulatory system

At high altitude, the partial pressure of oxygen is lower than it is at sea level. Which row gives the correct description and explanation of the body's response to high altitude?

Movement into and out of cells

Which events take place during contraction of the left ventricle?

The heart

Blood, tissue fluid and lymph do not all share the same composition. Which row gives the composition of lymph?

Movement into and out of cells

Which processes take part in transport in both phloem and xylem?

Transport mechanisms

Which characteristics of xerophytes are adaptations that reduce water loss via transpiration?

Movement into and out of cells

Visking tubing is an artificial partially permeable membrane that is used to show diffusion. Glucose molecules can move through the pores in the membrane, which are approximately $2.4\ \text{nm}$ in diameter. Which of the following could pass through the pores?

Movement into and out of cells

The graph presents the findings from measuring the concentration of sucrose in the xylem, phloem and leaves of a plant over 24 hours. Which conclusion can be drawn from these findings?

Movement into and out of cells

Water that is inside a root hair cell may leave the cell and enter the xylem. By which route must the water move?

Movement into and out of cells

State the approximate diameters of a trachea, an alveolus, a bronchiole and a bronchus.

The microscope in cell studies

What effect could result from breathing in the nicotine present in tobacco smoke?

The circulatory system

What effects does emphysema cause?

The gas exchange system

Which of the diseases shown in the table can be treated only with antibiotics?

The microscope in cell studies

The diagram illustrates the characteristics of diseases. Which part of the diagram represents the characteristics shared by both cholera and tuberculosis?

Infectious diseases

The disease smallpox has been eradicated through a global vaccination programme. Which group of reasons correctly identifies the difficulties involved in planning vaccination programmes to eradicate other diseases?

Antibodies and vaccination

Anaerobic bacteria occur in large numbers in waterlogged soils. What impact does this have on soil fertility, and what is the reason for this?

Transport mechanisms

What term is used for all the organisms in an area and the ways they interact with their environment?

Cells as the basic units of living organisms

Which of the following structures occur in photosynthetic prokaryotes?

Cells as the basic units of living organisms

What role do nitrifying bacteria play in the soil?

Transport mechanisms

The lumen of a human aorta is $2\ \text{cm}$ wide. A human red blood cell has a diameter of $7\ \mu\text{m}$. If red blood cells were placed in a line end to end, how many would span the diameter of the aorta lumen?

The microscope in cell studies

Which polysaccharides are branched, and which are unbranched?

Carbohydrates and lipids

Three carbohydrate molecules are illustrated. Which two molecules join together to make one molecule of sucrose?

Carbohydrates and lipids

At which levels of protein structure are ionic bonds present?

Proteins

Myoglobin is a protein that carries out a role similar to haemoglobin. Yet myoglobin has no quaternary structure. Why is there no quaternary structure in myoglobin?

Proteins

The diagram shows water moving through a plant. Which row correctly identifies the processes taking place during the stages of water movement shown?

Movement into and out of cells

Plant cells are stained before being examined with a light microscope. Which structures would be visible clearly at a magnification of $\times 400$?

The microscope in cell studies

In the table below, which comparison between light and electron microscopes is correct?

The microscope in cell studies

What evidence indicates that a membrane protein takes part in active transport?

Movement into and out of cells

Which statement is correct about the cell surface membrane and the membranes inside cells?

Fluid mosaic membranes

Pieces of plant tissue were placed into sucrose solutions at a variety of concentrations. Their lengths were recorded before being placed in the solutions and again after 30 minutes. The graph shows the ratio of the starting length to the final length. What is a correct description of how the cells change and how their water potential changes as the sucrose concentration increases?

Movement into and out of cells

Which kind of cell would contain the largest proportion of single membrane-bound structures?

Cells as the basic units of living organisms

A person with mild emphysema gave up smoking cigarettes. Why would this person’s health get better?

The microscope in cell studies

A student had to compare four microscope slides showing sections from different regions of the gas exchange system. Slide 1: missing - cartilage, glands; seen - few goblet cells, ciliated epithelial cells, smooth muscle. Slide 2: seen - incomplete cartilage rings, glands, goblet cells, ciliated epithelial cells, smooth muscle. Slide 3: missing - cartilage, glands, goblet cells, smooth muscle; seen - squamous epithelial cells. Slide 4: seen - plates of cartilage, glands, goblet cells, ciliated epithelial cells, smooth muscle. Which option correctly identifies the parts of the gas exchange system?

The microscope in cell studies

In the lungs, oxygen and carbon dioxide move through cell membranes by diffusion. Which row is correct?

Movement into and out of cells

Which process does not involve supplying nitrogen to plants?

Transport mechanisms

Which xerophytic adaptations lower the water potential gradient?

Movement into and out of cells

Each year, one square metre of grassland gets about $1\,047\,000\ \text{kJ}$ of solar light energy. The table indicates how this energy is transferred. How much energy is taken in by the grass for photosynthesis?

Carbohydrates and lipids

In transpiration, where in the leaves does water evaporate from?

Movement into and out of cells

Some inhibitors of enzyme reactions attach to the enzyme/substrate complex. Which statements about this type of inhibition are correct?

Mode of action of enzymes

Which protein-structure levels are able to determine an enzyme’s specificity?

Mode of action of enzymes

The enzyme catalase catalyses the decomposition of hydrogen peroxide into water and oxygen. In an investigation of how pH affects the rate of reaction of catalase, potato cubes were placed into hydrogen peroxide. Which dependent variable should be measured and recorded?

Factors that affect enzyme action

What type of sugar and what kinds of bonds are present in a DNA molecule?

Carbohydrates and lipids

During prophase of the mitotic cell cycle in an animal cell, which process takes place?

Chromosome behaviour in mitosis

Which statement is always true during cytokinesis?

Replication and division of nuclei and cells

The diagram illustrates how genetically identical frogs may be produced from unfertilised frog eggs. In frogs, the diploid number (2n) is 26. Which set of numbers correctly shows the chromosome number in each type of cell in the diagram?

Replication and division of nuclei and cells

These events take place during transcription. By the time the mRNA leaves the nucleus, which of these events will have happened twice?

Proteins

The photomicrograph shows a vascular bundle. Which statement describes how the water potential of the labelled cells is related?

Movement into and out of cells

The mechanism of action of four drugs that inhibit DNA replication is shown below. Which row correctly pairs a drug with an explanation of the mechanism of action?

Replication and division of nuclei and cells

Benedict’s solution was used to test four different fruit juices, A, B, C and D. A separate sample from each juice was then hydrolysed and tested again with Benedict’s solution. Which juice has the largest mass of non-reducing sugar?

Testing for biological molecules

Which rows indicate the chemical groups found in the biological molecules listed?

Proteins

Certain foods include ‘hydrogenated vegetable oils’. These are unsaturated fats that have been changed into saturated fats. Which characteristic of the fats will have altered?

Carbohydrates and lipids

Which molecular bonds are broken during hydrolysis when a glycogen molecule is converted into glucose?

Carbohydrates and lipids

Which option correctly links the functional and structural characteristics of cellulose, collagen, glycogen or triglyceride?

Carbohydrates and lipids

Which group of statements gives the correct description of haemoglobin?

Proteins

Smallpox has been eradicated, whereas malaria and cholera have not. Which statements give correct reasons for this?

Infectious diseases

Which disease is least likely to be transmitted directly from parent to child?

The microscope in cell studies

The diagram illustrates one method used to test the effect of an antibiotic on bacteria. The table gives the results from testing five different types of bacteria. Zones smaller than $13\ \text{mm}$ indicate that resistant bacteria are present. Which statement can be supported by these data?

Antibiotics

Which row correctly shows how the structure of an artery differs from that of a vein when viewed in transverse section under a light microscope?

Structure of transport tissues

For an animal cell, which process relies on cell surface area, and which process relies on cell volume?

Movement into and out of cells

Which line accurately describes the events that occur during the cardiac cycle?

The heart

What occurs during ventricular diastole?

The heart

Which statement about tissue fluid is correct?

Movement into and out of cells

What structures can be found in a typical plant cell?

Cells as the basic units of living organisms

An organelle inside a cell has a diameter of $4 \times 10^{-1}$ mm. What diameter does this represent in $\mu\text{m}$?

The microscope in cell studies