Biology

SL Assessment Outline

Assessment component Weighting

Paper 1 20%Paper 2 40%Paper 3 20%Internal Assessment 20%

HL Assessment outline

Assessment component Weighting

Paper 1 20%Paper 2 36%Paper 3 24%Internal Assessment 20%

Assessment Objectives

1. Demonstrate knowledge and understanding of:• facts, concepts and terminology• methodologies and techniques• communicating scientific information.

2. Apply:• facts, concepts and terminology• methodologies and techniques• methods of communicating scientific information.

3. Formulate, analyse and evaluate:• hypotheses, research questions and predictions• methodologies and techniques• primary and secondary data• scientific explanations.

4. Demonstrate the appropriate research, experimental, and personal skills necessary to carry out insightful and ethical investigations.

SL External Assessment details

SL Paper 1Duration: ¾ hour • 30 multiple-choice questions on core material, about 15 of which are

common with HL.• The questions on paper 1 test assessment objectives 1, 2 and 3.• The use of calculators is not permitted.

Example exam question.Biology Standard Level Paper 1. November 2015

Arginase catalyses the hydrolysis of L-arginine to form L-ornithine and urea. Arginase was purified from cowpea cotyledons ( ) and buffalo liver ( ) and its activity was measured at different pH values.

What can be concluded from these results?A. The optimum pH for buffalo liver arginase is 10.B. Cowpea arginase works better in alkaline conditions.C. Cowpea arginase works at a wider range of pH than buffalo liver

arginase.D. At a more acid pH the cowpea arginase works better than buffalo

liver arginase.

SL Paper 2Duration: 1¼ hours • Data-based question.• Short-answer and extended-response questions on core material.• One out of two extended response questions to be attempted by

candidates.• The questions on paper 2 test assessment objectives 1, 2 and 3.• The use of calculators is permitted. (See calculator section on the OCC.)

Example exam question.Biology Standard Level Paper 2. November 2015

1 Larvae of caddis flies were observed in parts of the headwater streams where organic debris from corn crops had accumulated. Laboratory experiments were performed to try to find out if these larvae could be affected by consuming debris from Bt corn.Lepidostoma liba is a caddis fly that feeds by shredding dead plant matter. The growth rate of L. liba was measured when it was fed on leaves from Bt corn and non-Bt corn.Helicopsyche borealis is a caddis fly that feeds by scraping algae surfaces. The mortality rate of H. borealis was measured when it fed on biofilms of algae containing Bt pollen or non-Bt pollen.Two concentrations of pollen were tested. One concentration (0.055 g m–2 ) was based on the maximum observed daily pollen input rate to streams. The other concentration was 50 times higher (2.75 g m–2 ).The results are shown in the bar charts. Statistically significant

differences between non-Bt pollen and Bt pollen in each bar chart are indicated by different letters on error bars.

2 Using the data in the bar charts, evaluate the effects of the Bt pollen on caddis flies. (3)

Deduce all of the organisms that belong to each of the following phyla.(3)Filicinophyta:Arthropoda:Mollusca:

SL Paper 3Duration: 1 hour• This paper will have questions on core and SL option material.• Section A: candidates answer all questions, two to three short-answer

questions based on experimental skills and techniques, analysis and evaluation, using unseen data linked to the core material.

• Section B: short-answer and extended-response questions from one option.

• The questions on paper 3 test assessment objectives 1, 2 and 3.• The use of calculators is permitted. (See calculator section on the OCC.)

Example exam question.Biology Standard Level Paper 3. November 2015

A study was undertaken to evaluate the effectiveness of cochlear implants and hearing aids at improving the understanding of 100 abstract words such as “hope” and “trust” in pre-school children. The study involved ten deaf children with cochlear implantation, ten deaf children with hearing aids and ten children with normal hearing (control). The table shows the level of understanding of the 100 words expressed as a percentage. The initial understanding of abstract words by the deaf children was minimal.

Compare and contrast the understanding of the abstract words in the three groups. (2)Describe the type of hearing problems that are treated by cochlear

implants. (2)

HL Assessment overview

HL Paper 1Duration: 1 hour• 40 multiple-choice questions on core and AHL material, about 15 of

which are common with SL.• The questions on paper 1 test assessment objectives 1, 2 and 3.• The use of calculators is not permitted.

Example exam question.Biology Higher Level Paper 1. November 2015

Question 3 and question 4 refer to the following diagram. It shows a potassium channel in anaxon membrane. The three dots in the channel represent potassium ions.

3. What is the function of this potassium channel?A. Facilitated diffusion of potassium ions into the axonB. Passage of potassium ions by active transport out of the axonC. Facilitated diffusion of potassium ions out of the axonD. Passage of potassium ions by active transport into the axon

4. What structure is labelled X?A. DNAB. Beta pleated sheetC. Alpha helixD. Prosthetic group

6. In 1828, Friedrich Wöhler artificially produced urea (organic compound) by an internal rearrangement of the atoms of ammonium cyanate (inorganic compound). What important principle did this experiment show?A. Organic compounds can be synthesized without the need of a vital force.B. Organic compounds can only be formed from pre-existing inorganic compounds.C. Inorganic compounds are essential for living organisms.D. Organic compounds are more simple substances than inorganic compounds.

20 The cladogram shows the phylogenic relationships in jawed vertebrates.

What can be deduced about Brachythoracids from this cladogram?A. They evolved from Placoderms.B. They gave rise to Gnathostomes.C. They evolved at the same time as Ptyctodonts.D. They differ from Phylollepids by only one mutation.

HL Paper 2Duration: 2¼ hours

• Data-based question.• Short-answer and extended-response questions on core and AHL

material.• Two out of three extended response questions to be attempted by

candidates.

• The questions on paper 2 test assessment objectives 1, 2 and 3.• The use of calculators is permitted. (See calculator section on the OCC.)

Example exam question.Biology Higher Level Paper 2. November 2015

1.GPR120 is a trans-membrane protein that functions as a receptor for long-chain unsaturated fatty acids. When fatty acids outside the cell bind to the receptor, the receptor changes shape and as a result a signal is passed to the interior of the cell. This causes an increase in the intracellular calcium concentration (Ca2+ ), which has a wide range of effects on cell activity.A strain of mice was developed that did not produce GPR120 protein. Groups of these GPR120 deficient mice were fed from the age of 5 weeks until they were 16 weeks old either on a high fat diet containing 60 % fat or on a normal diet containing 13 % fat. Control groups of mice that did produce GPR120 protein were fed on the same diets. The bar chart shows the mean body mass of each group when the mice were 16 weeks old.

Compare and contrast the body mass of GPR120 deficient mice and the control mice on a normal diet and a high fat diet. (3)

2. A clone of human cells that contained the wild type allele for GPR120 was geneticallymodified by inserting either another wild-type allele (WT) or one of two mutant alleles(R67C and R270H). The intracellular concentration of calcium was measured in these cells at varying levels of linolenic acid. Linolenic acid is a long-chain unsaturated fatty acid.

The graph shows the results. The scale on the x-axis is logarithmic.

Suggest advantages of genetically modifying a clone of human cells for use in thisexperiment rather than using cells from obese people naturally containing themutant alleles. (2)

3. From an early stage in human development, blood flow is needed for transport and exchange of materials.(a) Explain the exchange of materials between the mother and the

fetus in the uterus. [8]

(b) Outline how William Harvey changed the understanding of blood flow around the human body. [4]

(c) Describe how, in microscope images, blood vessels can be identified as arteries,

capillaries and veins.(3)

HL Paper 3Duration: 1¼ hours

• Section A: candidates answer all questions, two to three short-answer questions based on experimental skills and techniques, analysis and evaluation, using unseen data linked to the core and AHL material.

• Section B: short-answer and extended-response questions from one option.• The questions on paper 3 test assessment objectives 1, 2 and 3.• The use of calculators is permitted. (See calculator section on the OCC.)

Example exam question.Biology Higher Level Paper 3. November 2015Brain death is a clinical diagnosis based on the absence of neurological

function, with a known irreversible cause of coma.

Explain a named method to assess brain damage. (2)

Distinguish between a reflex arc and other responses by the nervous system. (1)

Describe the events that occur in the nervous system when something very hot is touched.(3)

Evaluate the methods used to estimate the size of commercial fish stocks. (6)

Command Terms with definitions.

Command terms for Assessment Objective 1: Demonstrate Knowledge and Understanding.

Command Term DefinitionDefine Give the precise meaning of a word, phrase, concept

or physical quantity.Draw Represent by means of a labelled, accurate diagram

or graph, using a pencil. A ruler (straight edge) should be used for straight lines. Diagrams should be drawn

to scale. Graphs should have points correctly plotted (if appropriate) and joined in a straight line or smooth curve.

Label Add labels to a diagram.List Give a sequence of brief answers with no explanation.Measure Obtain a value for a quantity.State Give a specific name, value or other brief answer

without explanation or calculation.

Command terms for Assessment Objective 2: Apply

Command Term DefinitionAnnotate Add brief notes to a diagram or graph.Calculate Obtain a numerical answer showing the relevant

stages in the working (unless instructed not to do so).Describe Give a detailed account.Distinguish Make clear the differences between two or more

concepts or items.Estimate Obtain an approximate value.Identify Provide an answer from a number of possibilities.Outline Give a brief account or summary.

Command terms for Assessment Objective 3: Formulate, analyse and evaluate:

Command Term DefinitionAnalyse Break down in order to bring out the essential

elements or structure.Comment Give a judgment based on a given statement or result

of a calculation.Compare Give an account of the similarities between two (or

more) items or situations, referring to both (all) of them throughout.

Compare and contrast

Give an account of the similarities between two (or more) items or situations, referring to both (all) of them throughout.

Deduce Reach a conclusion from the information given.Design Produce a plan, simulation or model.Determine Obtain the only possible answer.Discuss Offer a considered and balanced review that includes

a range of arguments, factors or hypotheses. Opinions or conclusions should be presented clearly and supported by appropriate evidence.

Evaluate Make an appraisal by weighing up the strengths and limitations.

Explain Give a detailed account including reasons or causes.Predict Give an expected result.Sketch Represent by means of a diagram or graph (labelled

as appropriate). The sketch should give a general idea of the required shape or relationship, and should include relevant features.

Suggest Propose a solution, hypothesis or other possible answer.