Questions and Answers of Cambridge International AS And A Level Biology

A student noticed that the leaves on a plant growing close to a wall had two sorts of leaves. The leaves next to the wall were in the shade and looked different from the leaves on the side away from
The table shows the numbers of two species, F and G, found in in eight randomly placed 10 × 10 m quadrats.a. Draw a scatter graph of these results.b. Describe the relationship that is suggested by
A student measured the length of 8 randomly selected bean pods and the total mass of the seeds inside them. The table shows her results.a. Draw a scatter graph of these results.b. Describe the
The scatter graphs show values for x plotted against values for y.State the letter of any graph or graphs that:a. Indicate there could be a positive correlationb. Indicate that there is probably no
The standard deviations for the data in Table P2.4 have been calculated for you. Do these calculations for yourself, showing your working fully.Table P2.4 1 Calculate x x y for each set of values.
Using the data on page 497, carry out a t-test to determine whether the difference between petal lengths in woodland and in a garden is significant.Data on page 497A student measured the length of 21
a. Calculate the standard deviation, s, for the fruit mass data on page 495. Use the formula:Show each step in your working.b. Calculate the standard error, SM, for this set of data. Use the
The figure shows the CFTR (cystic fibrosis transmembrane conductance regulator) protein in a cell surface membrane.a. i. Describe the normal function of the CFTR protein.ii. Use the letter E to
a. Draw a genetic diagram to show how two heterozygous parents may produce a child with cystic fibrosis. Use the symbols A/a in your diagram.b. State the probability of one of the children of these
a. Explain what is meant by:i. Gene therapyii. Genetic screening.b. Explain why it is easier to devise a gene therapy for a condition caused by a recessive allele than for one caused by a dominant
a. Genetic fingerprinting reveals the differences in variable number tandem repeats (VNTRs) in the DNA of different individuals. Explain what is meant by a VNTR.b. Examine the figure, which shows
Rearrange the statements below to produce a flow diagram showing the steps involved in producing bacteria capable of synthesising a human protein such as human growth hormone (hGH).1. Insert the
The table shows enzymes that are used in gene technology. Copy and complete the table to show the role of each enzyme.EnzymeRoleDNA ligaseDNA polymeraseRestriction enzymesReverse transcriptase
Which statement correctly describes the electrophoresis of DNA fragments?A. Larger fragments of DNA move more rapidly to the anode than smaller fragments.B. Positively charged fragments of DNA move
What describes a promoter?A. A length of DNA that controls the expression of a geneB. A piece of RNA that binds to DNA to switch off a geneC. A polypeptide that binds to DNA to switch on a geneD. A
Different enzymes are used in the various steps involved in the production of bacteria capable of synthesising a human protein. Which step is catalysed by a restriction enzyme?A. Cloning DNAB.
a. There are many seed banks in different parts of the world. Explain the reasons for depositing samples of seeds in cold storage.b Explain what is meant by the term frozen zoo.c. Przewalski’s
Sharks are an important part of the biodiversity of marine ecosystems. Many species are endangered as a result of overfishing. In 2004, the great white shark, Carcharodon carcharias, was added to
Researchers investigated aspects of the anatomy of the Melina tree, Gmelina arborea, which has been introduced into wet and dry forests in Costa Rica. The researchers wanted to know if the diameter
Stoneflies, Plecoptera spp., lay eggs in freshwater streams and rivers. The eggs hatch into nymphs which live in the water for several years before changing to adults. Stonefly nymphs are known as
Woodlice are small terrestrial crustaceans that feed on organic matter in leaf litter and in the soil. While carrying out an ecological survey in woodland, a student noticed that there seemed to be
Light is an important abiotic factor that determines the distribution and abundance of plants. Some plants are adapted to grow in areas of low light intensity. They are known as shade plants. Some
A sample of 39 ground beetles was captured from an area of waste ground measuring 100 × 25 metres. Each animal was marked and then released. A second sample of 35 was caught on the following day. Of
Five 0.25 m2 quadrats were placed randomly in an area of grassland in the UK. The percentage of each quadrat occupied by each species of plant was estimated to the nearest 5% and recorded in the
Some students investigated what size of quadrat they should use to assess the abundance of plant species in an old field ecosystem. They used quadrats of side 10, 25, 50, 75 and 100 cm and recorded
The numbers of elephants in Hwange National Park in Zimbabwe were counted each year between 1980 and 2001. In the 1980s, some of the elephants were culled. This practice stopped in 1986. The graph
Which of the statements about Protoctista are correct?1. A eukaryote that is not a fungus, plant or animal is a protoctist.2. An organism with cellulose cell walls and chloroplasts may be a
Which of the following is the definition of the term niche?A. All the environmental factors that determine where an organism livesB. All the food webs in an ecosystemC. The place where an organism
Biodiversity includes:A. Ecosystem and habitat diversityB. Species diversity and ecosystem diversityC. Species diversity, genetic diversity and ecosystem diversityD. Species diversity only
The heliconid butterflies of South America have brightly coloured patterns on their wings. A hybrid between two species, Heliconius cydno and H. melpomene, has wing patterns that are different from
The snail Cepaea nemoralis may have a yellow, pink or brown shell. Each colour shell may have up to five dark bands, or have no bands. Both shell colour and number of bands are genetically
Pale and dark peppered moths were collected and placed on pale and dark areas of bark on trees in a park in Liverpool, England (Figure 17.13). Some of the moths were predated by birds. The results of
Copy and complete the table to compare artificial selection with natural selection.Natural selectionArtificial selectionThe selective agent is the total environment of the organismAdaptations to the
Hybrids produced by crossing two different inbred (homozygous) varieties are often more vigorous in their growth than either of their parents. Copy and complete the flow diagram to show how breeders
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
The wings of butterflies are covered with microscopic scales that give them their colour and also provide waterproofing. The wings of some species have large transparent areas through which the
There are three genotypes of the gene for the β-globin polypeptide: HbAHbA, HbAHbS and HbSHbS. Copy and complete the table to show which genotypes have a selective advantage or disadvantage in
Which eff ect of natural selection is likely to lead to speciation?A. Differences between populations are increased.B. The range of genetic variation is reduced.C. The range of phenotypic variation
A species of finch living on an isolated island shows variation in beak size. Birds with larger beaks can eat larger seeds.After a period of drought on the island, large seeds were more plentiful
Which of the following gives rise to genetic variation in a population?1. Crossing over and independent assortment in meiosis2. Different environmental conditions3. Random mating and fertilisation4.
a. The fruit fly, Drosophila melanogaster, feeds on sugars found in damaged fruits. A fly with normal features is called a wild type. It has a grey striped body and its wings are longer than its
In sweet-pea plants, the gene A/a controls flower colour. The dominant allele gives purple flowers and the recessive allele red flowers.A second gene, B/b, controls the shape of the pollen grains.
Distinguish between the following pairs of terms.a. Genotype and phenotypeb. Homozygous and heterozygous
There is no crossing over during meiosis in male Drosophila. Assuming that no mutation occurs, the only source of genetic variation is independent assortment. Given that the diploid (2n) chromosome
Diagram 1 shows chromosomes in the nucleus of a diploid cell.a. Draw the nucleus of a gamete produced from this cell.b. What type of nuclear division would be used in the production of the gamete?c.
a. Describe the essential diff erence between meiosis I and meiosis II.b. State the similarity between meiosis II and mitosis.
Copy and complete the table to compare meiosis with mitosis. Mitosis Meiosis maintains the chromosome number does not involve crossing over or independent assortment gives daughter nuclei that are
The diploid (2n) chromosome number of Drosophila is 8. Copy and complete the table to show the different outcomes of mitotic and meiotic division of a Drosophila cell. Mitosis Meiosis number of
A man has haemophilia. Which statement correctly describes the inheritance of the gene causing his condition?A. He inherited the recessive allele from his mother.B. He inherited the dominant allele
All the off spring of a cross between pure-bred red-flowered and pure-bred white-flowered snapdragons were pink. Two of these pink-flowered plants were interbred. What proportion of the off spring
The figure shows one type of potometer used by a student to investigate transpiration.a. i. Suggest a hypothesis the student could test about the transpiration of a mesophyte (a plant adapted to a
A cell in the process of meiosis was seen to have a spindle with sister chromatids being drawn towards opposite poles of the cell. In what stage of meiosis was the cell?A. Anaphase IB. Anaphase IIC.
a. Describe a reflex arc and explain why such reflex arcs are important.b. Describe the structure of a myelin sheath and explain its role in the speed of transmission of a nerve impulse.
a. Explain how a nerve impulse is transmitted along a motor neurone.b. Describe how an impulse crosses a synapse.
Gibberellin is a plant growth regulator.a. Outline the role of gibberellin in the germination of seeds such as those of wheat and barley. In an investigation of the effects of gibberellin,
The Pacinian corpuscle is a type of receptor found in the dermis of the skin. Pacinian corpuscles contain an ending of a sensory neurone, surrounded by several layers of connective tissue called a
Copy and complete the table to show, for each hormone, the precise site of its secretion, and its effects on the ovary or on the endometrium of the uterus. Effect(s) of hormone Hormone Site of
A biopsy was taken from a leg muscle of a healthy racehorse. The muscle fibres were teased apart and cross-sections were taken from one of the muscle fibres. These cross-sections were examined with a
The diagrams show a sarcomere in different states of contraction.a. Name the parts labelled P, Q and R.b. Explain why there are no actin–myosin cross-bridges visible in diagram A.c. Muscle fibres
The electron micrograph shows parts of some myofibrils in a striated muscle that is in a relaxed state.a. i. Name the parts labelled K, L and M.ii. How many myofibrils are visible in the electron
The figure shows the changes in potential difference across the membrane of a neurone over a period of time. The membrane was stimulated at time A and time B with stimuli of different intensities.a.
Which statements about the concentrations of hormones in the human menstrual cycle are correct?1. Shortly before ovulation, the concentration of oestrogen is high and concentration of progesterone
Which of the following correctly identifies the effects of the three plant hormones, abscisic acid (ABA), auxin and gibberellin? Abscisic acid Auxin Gibberellin elongation growth of roots and shoots
Which of the following is responsible for saltatory conduction in myelinated neurones?A. Axon membranesB. Nodes of RanvierC. Schwann cellsD. Voltage-gated channel proteins
Which statement describes the biological action of the oestrogen/progesterone contraceptive pill?A. Increased concentrations of the hormones increase the thickness of the endometrium of the uterus.B.
Which of the following is an incorrect statement about the endocrine system?A. All hormones bind to receptors on the cell surface of their target cells.B. Endocrine glands are ductless.C. Endocrine
a. Describe the structure of a kidney, including its associated blood vessels.b. Describe the mechanisms involved in reabsorption in the proximal convoluted tubule and describe how the epithelial
Abscisic acid (ABA) is a weak acid. Its structure can be represented as ABA-H. It dissociates into positively charged H+ ions (protons) and negatively charged ABA− ions as shown:The following
a. Explain what is meant by a biosensor.b. Copy and complete the following passage describing the action of a biosensor.Many people with diabetes use a biosensor to measure the concentration of
An investigation was carried out to determine the response of pancreatic cells to an increase in the glucose concentration of the blood. A person who had been told not to eat or drink anything other
The control of the water content of the blood is an example of homeostasis.a. Name the part of the body that monitors the water potential of the blood.In an investigation of the factors that
a. Explain the meaning of the term excretion.b. The figure is a photomicrograph of part of the kidney.i. Name A, B, C and D.ii. Identify the region of the kidney shown in the figure and give a reason
Rearrange the following statements to make a flow diagram of the mechanism of opening a stoma.1. Volume of guard cell increases2. H+ transported out of guard cells3. Water enters guard cells by
In response to dehydration, ADH is secreted by the posterior pituitary gland. One of its effects is to stimulate:A. A reduction in the glomerular filtration rateB. An increase in the number of
Which of the following occurs in the body in response to the secretion of glucagon?A. Conversion of glucose to glycogen in liver cellsB. Decrease in the blood glucose concentrationC. Increased uptake
Glucose is small enough to be filtered from the blood in glomeruli in the kidney, but is not normally found in the urine. This is because glucose is:A. Reabsorbed in distal convoluted tubulesB.
Which of the following is an incorrect statement about the homeostatic control of the concentration of glucose in the blood?A. Negative feedback is involved in the control of blood glucose.B. The
a. Distinguish between an absorption spectrum and an action spectrum.b. Pondweed was exposed to each of three different wavelengths of light for the same length of time. For each wavelength, the
a. Copy and complete the table to show the differences between mesophyll and bundle sheath cells in C4 plants. Insert a tick (✓) when an item is present in the cell and a cross (✗) when it is
a. Explain what is meant by a limiting factor.b. List four factors that may be rate-limiting in photosynthesis.c. At low light intensities, increasing the temperature has little effect on the rate of
a. Draw a simple flow diagram of the Calvin cycle to show the relative positions in the cycle of the following molecules:CO2 (1C)GP/PGA (3C)triose phosphate (3C)RuBP (5C).b. Show the point in the
Distinguish between:a. Cyclic and non-cyclic photophosphorylationb. Photophosphorylation and oxidative phosphorylationc. The roles of NAD and NADP in a plant.
a. When isolated chloroplasts are placed in buffer solution with a blue dye such as DCPIP or methylene blue and illuminated, the blue colour disappears. Explain this observation.b. Name the compound,
a. Explain how the inner membrane system of a chloroplast makes it well adapted for photosynthesis.b. Copy the table below and insert ticks or crosses to show which structural features are shared by
In separate experiments, an actively photosynthesising plant was supplied with one of two labelled reactants:water containing the 18O isotope of oxygencarbon dioxide containing the 17O isotope of
Where in the chloroplast are the products of photophosphorylation used?A. EnvelopeB. GranumC. StromaD. Thylakoid
What are the products of the light dependent reactions of photosynthesis?A. ATP, RuBP and reduced NADB. ATP, oxygen and reduced NADPC. GP, oxygen and reduced NADD. GP, reduced NADP and RuBP
In aerobic respiration, the Krebs cycle is regarded as a series of small steps. One of these steps is the conversion of succinate to fumarate by an enzyme, succinate dehydrogenase.a. State the role
Copy and complete the following passage describing the adaptations of rice for growing with its roots submerged in water.The stems and leaves of rice plants have very large ............. in tissue
a. Explain why the energy value of lipid is more than twice that of carbohydrate.b. Explain what is meant by respiratory quotient (RQ).c. Copy and complete the table to show the respiratory
Copy and complete the table to show how much ATP is used and produced for each molecule of glucose respired in the various stages of respiration. ATP used ATP produced Net gain in ATP glycolysis link
State the roles in respiration of:a. NADb. Coenzyme Ac. Oxygen.
Distinguish between:a. An energy currency molecule and an energy storage moleculeb. Decarboxylation and dehydrogenation.
The diagram summarises how glucose can be used to produce ATP, without the use of oxygen.Which compounds are represented by the letters X, Y and Z ? glucose →X- Y in mammals Z in yeast
Where does each stage of aerobic respiration occur in a eukaryotic cell? Krebs cycle mitochondrial matrix cytoplasm mitochondrial cristae mitochondrial matrix Oxidative phosphorylation mitochondrial
What does not occur in the conversion of glucose to two molecules of pyruvate?A. Hydrolysis of ATPB. Phosphorylation of ATPC. Phosphorylation of triose (3C) sugarD. Reduction of NAD
A student investigated the time taken for the complete digestion of starch by amylase found in the saliva of 25 individuals of a species of mammal.A sample of saliva was collected from each
A student decided to investigate the effect of temperature on the activity of enzymes in yeast. The student measured the activity of the enzymes by counting the number of bubbles of carbon dioxide
For this question you need two sheets of graph paper. The light micrographs below are a a cross section of a young root, and b a representative part of a young stem of Ranunculus (buttercup).a.
Copy and complete the table. Independent Dependent variable Two important control variables Investigation variable The effect of sucrose concentration on plasmolysis of onion cells The effect of pH

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