Resource pack 1: Factors affecting enzyme activity in metabolic reactions

CfE Higher Biology: Assignment

How this topic links to your courseUnit- Metabolism and Survival

Key Area 1: Metabolism pathways and their control

(a) Introduction to metabolic pathways — integrated and controlled pathways of enzyme-catalysed reactions within a cell.

(i) Anabolic (energy requiring) and catabolic (energy releasing) pathways — can have reversible and irreversible steps and alternative routes.

(ii) Membranes form surfaces and compartments for metabolic pathways. The high surface area to volume ratio of small compartments allows high concentrations and reaction rates. Protein pores, pumps and enzymes embedded in phospholipid membranes.

(b) Control of metabolic pathways (presence or absence of particular enzymes and the regulation of the rate of reaction of key enzymes within the pathway).

(i) Induced fit and the role of the active site of enzymes including shape and substrate affinity and orientation of reactants. Products have a low affinity for the active site. Activation energy. The effects of substrate and end product concentration on the direction and rate of enzyme reactions. Enzymes often act in groups or as multi-enzyme complexes.

(ii) Control of metabolic pathways through competitive, non-competitive and feedback inhibition of enzymes.

Key Area 4 Metabolism in conformers and regulators

(e) Importance of regulating temperature for optimal enzyme controlled reaction rates and diffusion rates to maintain metabolism.

Key Area 5 Metabolism and adverse conditions

(c) Extremophiles. Some species have enzymes that are extremely tolerant and allow them to thrive in environments that would be lethal to almost all other species. Examples of extremophiles include thermophilic bacteria living in hot springs or seabed vents which may generate ATP by removing high energy electrons from inorganic molecules.

Research Resources: Read these for some background information on enzymes and metabolism (remember not all

may be reliable due to bias)- SQA – Assessment Criteria - Jotter notes- Summary- Essay – marking schemes - How to Pass Higher Biology book- Leckie and Leckie- Higher Biology Revision Guide- Bright Red- Higher Biology Revision Guide- http://courses.scholar.hw.ac.uk/vle/scholar/ - http://www.bbc.co.uk/education/topics/zck82hv

Data Sources: Can be used for the processing marks:1. Source: Data table from your L01 Practical Experiment- factors affecting enzyme activity

2. Source: http://www.sqa.org.uk/pastpapers/papers/papers/2012/H_Biology-Revised_All_2012.pdf Q. 14. The graph below shows the effect of substrate concentration on the rate of an enzyme-catalysed reaction.

3. Source: http://www.sqa.org.uk/pastpapers/papers/papers/2013/H_Biology-Revised_all_2013.pdf

In an investigation into the effect of lead ion concentration on respiration in yeast, two flasks were set up as described below.

The flasks were placed in a water bath at 20 °C for 10 minutes. After this time2·5cm3 of yeast suspension was added to each and oxygen sensors fitted as shownin the diagram below.

The flasks were left for a further 10 minutes and then oxygen concentration was measured in each flask every 20 seconds for 2 minutes.The results are shown in the table below.

4. Source: http://www.sqa.org.uk/pastpapers/papers/papers/2012/H_Biotechnology_All_2012.pdf

Q. 27. An experiment was carried out to determine the optimum pH for activity of lysozyme. The results are shown below.

5. Source: Source: SQA Intermediate 2 Biology Past Paper 2009 P.22

An investigation was carried out to estimate the concentration of urea in two unknown urine samples. A tablet of the enzyme urease was added to a test tube containing the urine sample. When urease reacted with urea in the sample the gas produced turned moist litmus paper blue.

The time taken for the litmus paper to turn blue was recorded in each case. The table below shows the results obtained when various urine samples of known and unknown urea concentration were tested.

6. Source: http://www.sqa.org.uk/pastpapers/papers/papers/2012/H_Human-Biology_All_2012.pdf Q.4. (a) Photographic film consists of a clear sheet of plastic coated with chemicals that give it a dark appearance. The chemicals are stuck to the plastic by the protein gelatine.An investigation was carried out using photographic film and the enzyme trypsin which digests protein.A piece of photographic film was placed in a test tube containing a solution of trypsin, as shown in Figure 1 below.The time taken for the film to turn clear was measured.The procedure was then repeated using different concentrations of trypsin solution.The results of the investigation are shown in Table 1 below.

7. Source: http://www.sqa.org.uk/pastpapers/papers/papers/2013/H_Human-Biology-Revised_all_2013.pdf

Q.1. Trypsin is an enzyme which catalyses the breakdown of proteins in the small intestine.The graphs below show how pH and temperature affect the activity of trypsin.

8. Source: SQA Higher Biology Past Paper 2010 P.26-27Q.10 Catechol oxidase is an enzyme found in apple tissue. It is involved in the reaction which produces the brown pigment that forms in cut or damaged apples.The effect of the concentration of lead ethanoate on this reaction was investigated.10 g of apple tissue was cut up, added to 10cm3 of distilled water and then liquidised and filtered. This produced an extract containing both catechol and catechol oxidase.Test tubes were set up as described in Table 1 and kept at 20 ºC in a water bath.

Every 10 minutes, the tubes were placed in a colorimeter which measured how much brown pigment was present.The more brown pigment present the higher the colorimeter reading.The results are shown in Table 2.

Assignment Guide: Instructions for candidatesThis Higher Biology Assignment is worth 20 marks out of the total of 120 marks. The Course will be graded A–D.

The assignment assesses the following skills, knowledge and understanding:

Applying knowledge of biology to new situations and analysing information

Selecting information from a variety of sources Presenting information appropriately Processing the information/data collected (using calculations and

units, where appropriate) Drawing valid conclusions and giving explanations supported by

evidence/justification Evaluating experimental/practical investigations

Communicating findings/information effectively

In this assessment, you will have to investigate a relevant topic in biology and communicate your research findings in a report. This must relate to a key area of the Higher Biology Course. Your assessor will let you know how the assignment will be carried out and any required conditions for doing it.

Your report must be completed independently. You will have to sign that you have not copied or plagiarised any other work. If you are caught you will lose your Higher Biology and potentially all other Highers that you have sat this year.

The assignment has two stages:a research stagea communication stage

Research stageYou need to choose a relevant topic in biology to investigate. Your assessor must review your chosen topic to check that it is appropriate.

Once you have chosen your relevant topic, you need to decide the specific aspect which you want to research. This will become the aim of your assignment. The aim may change during the research stage of your assignment, depending on the information you find.

Most of the work in this stage is to gather data/information. This could come from the internet, books, published articles or extracts, journals, an experiment/practical activity, or any other appropriate source.

Your information/data could include, for example: statistical, graphical, numerical or experimental data/information; notes taken from a visit or talk; notes taken from a written or audio-visual source; or extracts from publications.

Downloads directly from the internet or copying directly from books may suggest to the assessor that you have not understood the biology involved. This may be considered plagiarism unless you acknowledge the sources carefully. It is always best to put things in your own words to make sure you really understand them.

You must: Select sufficient sources of information/data that: are relevant: how useful are they for your topic?are reliable: who wrote them? Who published them? have similar/different perspectives: do they agree or disagree with each other?

Select sufficient relevant data/information from your sources. This could include raw data from an experiment/practical activity, extracted tables, graphs, diagrams and text. Record the sources you have used with enough detail to allow someone else to find them again. If one of the sources is an experiment/practical activity, then you need to record the title and the aim.

If you use an experiment/practical activity as one of the sources of information/data, your assessor will give you instructions for this. The experiment/practical activity will not be assessed and you may carry out the experiment/practical activity as part of a group.

If you are working in a group to gather data/information, you must take an active part in this and choose your own sources of data/information.

Checkpoint: inform your assessor that you have finished the research stage.

Communication stageIn this stage of your assignment you need to select, process, present and analyse information/data from the sources you have gathered, and produce your report.

This stage will be conducted under a high degree of supervision. This means that:

you will be in direct sight of the assessor during the period of the assessmentyou must not discuss your work with other candidates

In this stage of your assignment you can only use information/data that you have collected from your research. This may include, for example: statistical, graphical, numerical or experimental data; data/information from the internet; published articles or extracts; It cannot include a prepared draft report.

As a guide, your report should be 800–1500 words, excluding tables, charts and diagrams.

The table below shows how many marks are available for each aspect of your report.

Criteria Mark allocation

Aim(s) 1Applying knowledge and understanding of biology

5

Selecting information 2Processing and presenting data/information

4

Analysing data/information 2Conclusion(s) 1Evaluation 3Presentation 2

Guidance on producing your reportYour report must have an appropriate structure with an informative title and headings, where necessary and be clear and concise.

Your report must containTitleAimUnderlying BiologyExperimental procedure (if appropriate)Data/informationEvidence of processing and analysing data/informationConclusion(s)EvaluationReferences

Title: Title- not just ‘Assignment’- must relate to your topic

Aim(s)The aim must describe clearly what is to be investigated. The aim must describe clearly what is to be investigated, eg ‘to investigate the effectiveness of using stem cells to create skin grafts’.

Acceptable versions of an aim could be: ‘to investigate the effect of altitude training on athletic performance’ NOT simply: ‘to investigate altitude training’.

The aim must be stated separately from the title.

Underlying biologyHere you must explain how the underlying biology relates to your topic. This should include expanded descriptions and/or explanations.

Experimental procedure (if appropriate)This must include a description of your experimental procedure. This may include clearly labelled diagrams.

Data/informationHere you must include sufficient data/information from a minimum of two sources that is relevant to your investigation and sufficient for you to draw a conclusion that addresses some aspect(s) of the aim.

This may include, for example, statistical, graphical, numerical or experimental data; data/information from the internet; published articles or extracts.

Processing and presenting data/informationOne source of raw data/information must be processed and presented.

It must be clear where the raw or extracted data/information that you processed came from. You must present your processed data/information in one of the following formats: graph, table, chart or diagram.

Think carefully about the format you choose because it must be suitable for the information you are presenting.

Check that you have included, as appropriate:suitable scalesunitsheadingslabelsAnalysing data/informationTo analyse the data/information included in your report, you must interpret that data/information by drawing out the relevant parts and identifying any relationships that are relevant to your investigation. Analysis may include comparisons, determining patterns and trends, discussion of experimental results, describing what graphs show, etc.2 marks will only be awarded for fully analysing data/information from at least two sources.Conclusion(s)You must clearly state the conclusion(s) of your investigation. Your conclusion(s) must relate to your aim and be supported by what you have found out. Where the data is giving an indirect measure of the aim then the link must be stated somewhere in the report to access the conclusion mark. eg Aim — to investigate the effect of altitude training on athletic performance. Data included shows an increase in red blood cell production. The candidate must state that this would improve athletic performance to gain the conclusion mark.

EvaluationThis should include an evaluation of your individual sources and an evaluation of the investigation as a whole.

You may include for example:significance/interpretation of findingsvalidity of sourcesreliability of data/informationevaluation of (experimental) procedure, which could include:accuracyadequacy of repetitionadequacy of range of variablescontrol of variableslimitations of equipmentreliability of methodssources of errors, uncertainties

ReferencesAt the end of your report you must record the sources you have used, with enough detail to allow someone else to find them. For example:

Source Reference

Experiment

Title and aim

Website Full URL for the page or pagesJournal Title, author, volume and page numberBook Title, author, page number and edition or ISBN

Before submitting your report, check that you have included everything you need.