A Level Biology Bridging unit Name:_______

You need to complete all tasks below. Tick when they are FULLY complete. READ the instructions for each task carefully. Write your answers in full sentences on paper ready to hand in. Electronic versions will not be accepted – they must be printed out if you are using a device. Acceptance on to the A Level course is conditional on you completing this work to a good standard. In plain English, this means that if you don’t do the work and submit it at the first lesson, you cannot start biology A Level in September.

TASK Time guide Tick when FULLY

complete 1. Read the introductory

information and a reminder about our expectations.

10 mins!

2. Complete the GCSE biology review questions.

10 hours

3. Complete the A-level research tasks and exam questions on

a. Cell structure b. Biochemistry c. Maths/practical skills

10-15 hours

4. Review the induction lesson from June 24th. Work through the slides again. If you missed the live lesson then go through all slides making notes from the start.

1 hour (if not attended)

5. Prepare for a test on some of task 2 and 3 topics – This will be in the first full week back (w/b Sept 6th). Read the instructions so you know exactly what to learn!

5 hours

TASK 1 – advice A Level Biology is one of the most interesting, but difficult A levels. As teachers we find that some people find making the transition to A Level standard more difficult than others. They may have cruised through school, not doing much work, but achieving GCSE grades 8 or 9 nevertheless. This kind of person may struggle to believe the amount of TIME and SELF STUDY necessary to achieve equally high grades at A Level. Others may have worked really hard to get a grade 6, and struggle with the difficulty of some of the topics we cover. Either way, we know for sure that taking an active part in making sure you understand and learn the work, as well as putting the time in, is the most effective way to get the highest grade you can. For some people this will be an E grade, which is a pass, and for others it will be an A*. We are proud of all levels of achievement, and look forward to helping you do your best. Think back to the induction day virtual lesson and its key messages about how to prepare for starting the A level biology course in September, our expectations and the skills/attitudes successful A level biologists need to develop. Think carefully about the skills that YOU will need to practise and develop. Phrases out for A Level: rushed, minimalist, lazy, passive, disorganised, expecting to be told all the answers, ‘I don’t know – so I’ll just leave it’, last minute revision/cramming. Phrases in for A Level: independent, learning, curiosity, resilience, organised, ‘I don’t know – so I’ll find out’, taking the initiative, self-motivation, review and revise regularly.

TASK 2 – GCSE Review questions All of you have face disruption to your learning in both Year 10 and Year 11 because of Covid. You are all in the same position. A level biology is hard. It is vital that you have a good working knowledge of the GCSE topics before you start the course, especially some of the topics that build the foundations of biology that you probably studied in Year 10 (cells, cell transport, biomolecules). You have also not had to revise and prepare for the usual GCSE exams on the full biology GCSE content so some of this knowledge may be a bit rusty. We have found that many students in the current Year 12 struggled in the first term because they were in a similar position last year. Also, some of you may be joining the course having studied combined science at GCSE so will not have studied the breadth of biology that students having studied separate GCSE biology will have. In our experience, people who have done combined science tend to find A Level biology harder than people who have done separate sciences. For these reasons ALL of you should complete the following GCSE review tasks that cover the essential knowledge needed from GCSE and the content that is not covered by combined science. The aim of this section is to

1. Make sure you have a good working knowledge of the GCSE content. 2. Make you practice and develop you revision and retrieval skills.

The questions are based on the AQA GCSE biology specification - found here https://www.aqa.org.uk/subjects/science/gcse/biology-8461 You should use your GCSE notes, the above specification and the websites below (plus any others you find) to complete the work.

https://www.bbc.com/education/examspecs/zpgcbk7 http://www.docbrown.info/page20/AQAscibio3.htm Youtube – freesciencelessons – search for the topics you need

Summary Questions Ensure the detail in your answer reflects the mark allocation. Use the subheadings to order your work. Don’t leave any gaps. The sections marked with a * will be in the test in the w/b 6th Sept. Cell transport*

1. What is the definition of diffusion? (1)

2. Describe how diffusion of oxygen takes place in the lungs (2)

3. Describe how diffusion of carbon dioxide takes place in the lungs (2)

4. Where would the diffusion of carbon dioxide take place in a leaf? (1)

5. Describe and explain 3 factors that can affect the rate of diffusion (6)

6. Describe 2 other examples of diffusion in nature (2)

7. Is a large or small surface area to volume ratio better for efficient cell transport? (1)

8. Describe how the small intestines are adapted for effective cell transport

9. Describe how the roots are adapted for effective cell transport

10. Describe 4 features of an effective exchange surface

11. Define osmosis (2)

12. Define active transport

13. Give 3 biological examples of where osmosis or active transport would take place

Organsiation – Animals*

1. Define a tissue

2. Define an organ

3. Define an organ system

4. Give 3 examples of an animal tissue

5. What tissues are present in the stomach?

6. Give 3 examples of an organ system and state some of the organs that would be present in

each one

7. Define an enzyme

8. Draw a labelled diagram of an enzyme

9. Use the ‘lock and key’ theory to explain how enzymes work

10. Explain how temperature affects enzymes

11. All enzymes work best at pH 7. Do you agree or disagree? Explain your answer.

12. Name 3 digestive enzymes and say where they are made

13. State what molecule each digestive enzyme breaks down and what it breaks it down into

14. Explain the role of bile in digestion (2 answers)

15. Explain what is meant by the term optimum temperature in relation to enzymes

16. What are the four main blood vessels entering and leaving the heart? Where does each

one take blood from and to?

17. Why is the heart referred to as a ‘double pump’?

18. What is the function of valve in the heart?

19. Where is the natural resting heart rate controlled?

20. What is an artificial pacemaker?

21. What are the main airways found in the lungs in order of size?

22. Name 2 main differences for arteries, veins and capillaries?

23. What are the four main components of blood and what is the function of each?

24. Describe 3 adaptations of a red blood cell for its function

Organsiation - plants

1. Give 4 examples of plant tissues

2. Which 2 transport tissues are found in plants and what do they transport?

3. Give an example of a plant organ

4. What tissues are found in a leaf?

5. Why do leaves have stomata which open and close?

6. What feature increases the surface area of the root of a plant?

7. Define transpiration

8. Describe the difference between transpiration & translocation

9. What factors affect the rate of transpiration?

10. How can you measure the rate of transpiration?

Communicable diseases

1. List three safety precautions you must take when growing microorganisms in the lab. Explain each one (3)

2. Explain the purpose of each step involved in the preparation of an uncontaminated culture of microorganisms. (3)

3. When you set up a culture of bacteria in a Petri dish you give the bacteria everything they need to grow as fast as possible. However, these ideal conditions do not last forever. Suggest what might limit the growth of bacteria in a culture on a Petri dish. (6)

4. The mean division time for a population of bacteria is 30 minutes. Calculate how many bacteria will result from each individual bacterium after 8 hours. (3)

5. A student set up a culture plate of bacteria and placed three filter paper circles containing different concentrations of antibiotic on the surface. They were labelled A, B and C. After five days the diameters of the clear areas that developed were 5.0mm, 10.2mm and 15.8mm. Calculate the surface area of agar cleared by the three discs. Calculate how much more effective the highest concentration of antibiotic was compared to the lowest. (5)

6. Describe the effect of the following on the growth of a plant: lack of nitrate ions in the soil and lack of magnesium ions in the soil. (4)

7. State three ways a plant might defend itself against pathogens. (3)

Preventing and treating disease

8. Define a clone, antibody and a monoclonal antibody (3).

9. Describe a hybridoma cell and explain the importance of hybridoma cells in the

production of monoclonal antibodies (6)

10. Explain how monoclonal antibodies have revolutionised the diagnosis of pregnancy. (4) The human nervous system

11. Explain the functions of the cerebral cortex, the cerebellum and the medulla. (6)

12. Discuss two ways in which scientists can find out about the functions of different areas of the brain. (6)

13. State three of the main components of the human eye. (3)

14. Describe the functions of the components you have listed in your answer to Q14. (6)

15. Describe how a light ray that enters the eye is translated into a visual image in the brain. (6)

16. Compare myopia and hyperopia. (4)

17. Glasses and laser eye surgery can be used to treat long and short sightedness. Compare advantages and disadvantages of the two methods. (6)

Homeostasis in action

18. State why it is important that the core body temperature does not rise above 40oC or fall below 35oC. (1)

19. Explain the role of the thermoregulatory centre in the brain and the temperature sensors in the skin. (6)

20. Describe and explain how the body of a large horse might react to maintain its core body temperature after running a race. (6)

21. Describe thee ways water is lost from the body. (3)

22. Explain how the liver is involved in the production of urea. (4)

23. State the function of the kidneys. (1)

24. Explain how ADH stimulates your kidneys to maintain the water balance of your blood on a cold day when you stayed inside and drank lots of tea. (4)

25. Explain why people with kidney failure have to control their intake of protein and salt. (3)

26. Explain how a dialysis machine works. (4)

Plant hormones

27. Define phototropism and gravitropism. (2)

28. In an experiment, a scientist covers the tips of half a batch of newly germinated wheat

shoots with foil caps. First, both covered and normal shoots are exposed to light shining from directly above. Then they are given several days in a box with light shining from one side only. Explain how you would expect the shoots to respond. (4)

29. Discuss some ways in which plant hormones can be used to increase the food available to feed the world’s growing population. (6)

Reproduction

30. State one similarity and one difference between sexual and asexual reproduction. (2)

31. Compare the use of asexual and sexual reproduction in malaria parasites and fungi. (4) Variation and evolution

32. Explain what is meant by evolution and natural selection. (6)

33. Summarise Jean-Baptiste Lamarck’s theory about evolution. (4)

34. Describe how populations can become isolated. (3)

35. Explain why this isolation can lead to the evolution of new species. (5)

Organising an ecosystem

36. State two types of organisms involved in the process of decay. (2)

37. Explain why waste in a compost bin rots down much faster in summer than in winter. (4)

38. Define seasonal and geographical environmental changes. (6)

39. Define biomass. (1)

40. Discuss the advantages and disadvantages of using wet and dry biomass in building up a pyramid of biomass for a food chain. (4)

41.

Organism Biomass / g

Grass 100 000

Sheep 5000

Sheep ticks 30

Draw a pyramid of biomass for this grassland food chain. (3)

42. Explain why sheep ticks have so much less biomass than the grass cropped by sheep. (6)

Biodiversity and ecosystems

43. Discuss the advantages and disadvantages of intensive methods for rearing animals and

fish. (6)

44. Explain why there would be more food for everyone if people only ate plants. (6)

45. Mycoprotein is an example of sustainable food production. Mycoprotein is produced in a fermenter like the one shown below:

Explain the purpose of the sterile air, temp and pH monitors, cooling water and stirrer. (5)

TASK 3 All of you should revisit and review the virtual lesson from the induction day (available on the 6th form website). This is essential knowledge so if you missed the induction day and haven’t completed the lesson yet then make sure you do. The information in this induction lesson will be in the test w/b 6th Sept. This will help you to complete task 4.

Task 4– A level topics research and questions Use the AQA website to download a specification for your A-level biology course,

http://www.aqa.org.uk/subjects/science/as-and-a-level/biology-7401-7402

Read through sections 3.1.1 on monomers and polymers, 3.1.2 on carbohydrates and 3.2.1 on cell structure. These will be the first topics you will study in September. These will be a good guide to what to research in the following tasks.

Do all 3 of these tasks

a) Research cell structure (eukaryotes - animal, plant; prokaryotes bacteria) and microscopes.

Write notes and make diagrams. Include:

- The structures you find in each - The functions of these structures - The differences between the types of cells. - How light, TEM and SEM microscopes work (keep it simple) - Pros and cons of the different types of microscope

Then answer the exam question on the next page. Persevere, and look things up!

Suggested websites to help you: biologyguide.net s-cool.co.uk mrothery.co.uk biologymad.com biology-innovation.co.uk aqa.org (this is the specification we do).

Exam question Cells and microscopes (tip: look at the number of marks. Use biological words)

1. (a) The structure of a cholera bacterium is different from the structure of an

epithelial cell from the small intestine. Describe how the structure of a cholera bacterium is

different.

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(b) Scientists use optical microscopes and transmission electron microscopes

(TEMs) to investigate cell structure. Explain the advantages and the

limitations of using a TEM to investigate cell structure.

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(Total 10 marks)

b. BBiochemistry: Use the websites mentioned above and your notes from the taster day lesson (remote version available – see task 4 for those that weren’t there) to help you answer the following questions:

2 a) Draw out the structure of glucose (alpha glucose), to include all of the carbon atoms (1) b) Learn this off by heart and draw it out again.(1) c) What is a monosaccharide? (3) d) What is a disaccharide? (1) e) What is a polysaccharide? (1) f) What is a glycosidic bond? (1) g) What happens in a condensation reaction? (1) h) What happens in a hydrolysis reaction? (1) i) What is the test for reducing sugars? (3) j) Describe the structure of cellulose. (3)

Q3.(a) Name the monosaccharides of which the following disaccharides are composed.

(i) Sucrose

monosaccharides.....................................and....................................... (1)

(ii) Lactose

monosaccharides.....................................and....................................... (1)

(b) Amylase and maltase are involved in the digestion of starch in the small intestine.

Complete the table by identifying where these enzymes are produced and the product of the reaction they catalyse.

Name of enzyme Where the enzyme is

produced

Product of the reaction catalysed

by the enzyme

Amylase

Maltase

(2) (Total 4 marks)

Q4. The diagram shows one end of a cellulose molecule.

(a) (i) Name the monomers that form a cellulose molecule.

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(ii) Name bond Y.

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(iii) What chemical group is at position Z?

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(b) (i) Complete the table to show two ways in which the structure of cellulose is different from the structure of starch.

Starch Cellulose

(2)

(ii) Explain one way in which the structure of cellulose is linked to its function.

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(Total 7 marks)

Q5.Lettuce growers investigated the best conditions for germinating lettuce seeds. They soaked lettuce seeds for 8 hours in distilled water at different temperatures. They then germinated some of the seeds at 20°C and some at 35°C. The table shows their results.

Temperature at which seeds

were soaked / ºC Percentage of seeds which

germinated

at 20°C at 35°C

20 100 89

25 100 43

30 41 1

35 21 0

(a) Use the information above to describe and explain the effect of temperature on lettuce seed germination.

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(b) Explain why the lettuce growers measured germination as a percentage.

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(Total 4 marks)

Q6. Read the following passage. PERSEVERE ON THIS ONE!

Straw consists of three main organic substances – cellulose, hemicellulose and lignin. Cellulose molecules form chains which pack together into fibres. Hemicellulose is a small molecule formed mainly from five-carbon (pentose) sugar monomers. It acts as a cement holding cellulose fibres together. Like hemicellulose, lignin is a polymer, but it is not a carbohydrate. It covers the cellulose in the cell wall and supplies additional strength. In addition to these three substances, there are small amounts of other biologically important polymers present.

The other main component of straw is water. Water content is variable but may be determined by heating a known mass of straw at between 80 and 90°C until it reaches a constant mass. The loss in mass is the water content.

Since straw is plentiful, it is possible that it could be used for the production of a range of organic substances. The first step is the conversion of cellulose to glucose. It has been suggested that an enzyme could be used for this process. There is a difficulty here, however. The lignin which covers the cellulose protects the cellulose from enzyme attack.

Use information from the passage and your own knowledge to answer the following questions.

(a) (i) Give one way in which the structure of a hemicellulose molecule is similar to the structure of a cellulose molecule.

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(ii) Complete the table to show two ways in which the structure of a hemicellulose molecule differs from the structure of a cellulose molecule.

Hemicellulose Cellulose

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(2)

(b) Name one biologically important polymer, other than those mentioned in the passage, which would be found in straw.

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(c) Explain why the following steps were necessary in finding the water content of straw:

(i) heating the straw until it reaches constant mass (line 9);

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(ii) not heating the straw above 90°C (line 9).

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(d) A covering of lignin protects cellulose from enzyme attack (line 14). Use your knowledge of the way in which enzymes work to explain why cellulose-digesting enzymes do not digest lignin.

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(e) Describe the structure of a cellulose molecule and explain how cellulose is adapted for its function in cells.

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(Total 15 marks)

c. Maths/practical skills

Download the ‘language of measurement’ list form AQA here

https://www.aqa.org.uk/resources/science/as-and-a-level/teach/subject-specific-vocabulary Use it to help you complete the activities on the following pages.

Activity 1 Scientific vocabulary: Designing an investigation

Link each term on the left to the correct definition on the right.

Activity 2 Scientific vocabulary: Making measurements

Link each term on the left to the correct definition on the right.

Activity 3 Scientific vocabulary: Errors

Link each term on the left to the correct definition on the right

Understanding and using SI units

Every measurement has a size (eg 2.7) and a unit (eg metres or kilograms). Sometimes,

there are different units available for the same type of measurement. For example,

milligram, gram, kilogram and tonne are all units used for mass.

To reduce confusion, and to help with conversion between different units, there is a

standard system of units called the SI units which are used for most scientific purposes.

These units have all been defined by experiment so that the size of, say, a metre in the

UK is the same as a metre in China.

There are seven SI base units, which are given in the table.

Physical quantity Unit Abbreviation Mass kilogram kg

Length metre m

Time second s

Electric current ampere A

Temperature kelvin K

Amount of substance mole mol

luminous intensity candela cd

All other units can be derived from the SI base units. For example, area is measured in

metres square (written as m2) and speed is measured in metres per second (written as m s–

1, this is a change from GCSE where it is written as m/s).

Using prefixes and powers of ten

Very large and very small numbers can be complicated to work with if written out in full

with their SI unit. For example, measuring the width of a hair or the distance from

Manchester to London in metres (its SI unit) would give numbers with a lot of zeros

before or after the decimal point, which would be difficult to work with.

So, we use prefixes that multiply or divide the numbers by different powers of ten to give

numbers that are easier to work with. You will be familiar with the prefixes milli

(meaning 1/1000), centi (1/100), and kilo (1 × 1000) from millimetres, centimetres, and

kilometres.

There is a wide range of prefixes. Most of the quantities in scientific contexts will be

quoted using the prefixes that are multiples of 1000. For example, we would quote a

distance of 33 000 m as

33 km.

The most common prefixes you will encounter are given in the table.

Prefix Symbol Power of 10 Multiplication factor

Tera T 1012 1 000 000 000 000

Giga G 109 1 000 000 000

Mega M 106 1 000 000

kilo k 103 1000

deci d 10-1 0.1 1/10

centi c 10-2 0.01 1/100

milli m 10-3 0.001 1/1000

micro μ 10-6 0.000 001 1/1 000 000

nano n 10-9 0.000 000 001 1/1 000 000 000

pico p 10-12 0.000 000 000 001 1/1 000 000 000 000

femto f 10–15 0.000 000 000 000 001 1/1 000 000 000 000 000

Activity 4 SI units and prefixes

What would be the most appropriate unit to use for the following measurements?

1. The time between heart beats

2. The diameter of a cheek cell

3. The distance that a migratory bird travelled each year

4. The thickness of a DNA helix

5. The mass of a rabbit

6. The mass of iron in the body

7. The diameter of a glucose molecule

Activity 5 Units

Choose the most appropriate unit and estimate the size of each of the following.

1. The mass of an earthworm

2. The volume of water in a teardrop

3. The volume of water in a garden pond

4. The time taken for a sunflower to grow

5. The temperature difference between the blood in the heart and in the ear on a cold day

6. The diameter of a human hair

7. The length that your fingernails grow each day

8. The total length of DNA in one human body cell

Activity 6 Converting data

Re-write the following.

1. 0.00224 metres in millimetres

2. 104 micrograms in grams

3. 6.2 kilometres in metres

4. 10 micrograms in nanograms

5. 70 decilitres in litres

6. 10 cm3 in litres

k) What is 15/45 as a %? (1)

l) If the number of woodlice increases from 50 to 70, what is the percentage change? (1) m) How many micrometres (μm) are there in 1 mm? (micrometres are also called microns)? (1) n) If a cell is 20 μm in diameter, what is its volume? (Assume it is spherical) (1)

TASK 5 In the w/b 6th Sept you will have a short test on the following parts of this bridging work. Make sure you learn it!

1. The GCSE sections on cell transport and organisation (animals). These have a * next to them in section 2.

2. The content of the induction lesson from task 3.

3. Cell structure – based on what you find out in task 4a.

4. Maths - unit conversions - simple % - % change (find out and learn the equation)

OPTIONAL FURTHER READING As well as teaching to the exam, we think it is important for you to develop as biologists. So you could also be broadening your mind with reading books (eg Steve Jones: Darwin’s Island, Genetics for beginners, The Language Of The Genes. The immortal life of Henrietta Lack. Ben Goldacre: Bad Science. All available in the school library), watching documentaries (eg Horizon / similar), and following up issues you hear about in the news or personally (Wikipedia is a good place to start, and is reliable for general biology). Have a lovely summer; see you in September! The Biology Department.