‘Bridging the gap’ – moving from GCSE to A Level Biology



A Level Biology Bridging unit Name:

Combined science pupils need to do ALL of the work on this letter (Section 1 and 2).

Separate Science need to do section 2 (most of you will have followed this route).

Allow at least 15 hours to do section 1, and 15 hours for Section 2.

DUE IN FIRST BIOLOGY LESSON IN SEPTEMBER!

In addition: if you missed the Induction lesson you need to complete the extra section at the end of this booklet. 2020 everyone should complete this.

Section 1

As you will know, there are two main routes through science GCSE’s. The first is combined science where the candidate studies parts of the three sciences leading to two science GCSE qualifications. The other route is separate science which leads to an award of three GCSE qualifications, called biology, chemistry and physics.

Somebody who has completed combined science will have not covered as much content as those doing separate biology, chemistry and physics.

In our experience people who have done combined science find A Level harder than people who have done separate sciences.

Combined science students need to complete section 1 so that everyone has a similar starting point.

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.

o Use the aqa website to download a specification,



o Use the website below (and any others you find) to complete the work.



doddlelearn.co.uk (Keswick School pupils have a subscription to this site, others may not)

o You also have the option of collecting a GCSE textbook any time before the end of this term from the biology department.

Summary Questions Ensure the detail in your answer reflects the mark allocation.

Communicable diseases

1. List three safety precautions you must take when growing microorganisms in the lab. (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. What are the causes, symptoms and treatment for tobacco mosaic virus and rose black spot? (4)

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

Preventing and treating disease

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

10. Describe a hybridoma cell and explain the importance of hybridoma cells in the production of monoclonal antibodies (6)

11. Explain how monoclonal antibodies have revolutionised the diagnosis of pregnancy. (4)

The human nervous system

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

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

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

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

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

17. Compare myopia and hyperopia. (4)

18. 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

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

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

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

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

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

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

25. 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)

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

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

Plant hormones

28. Define phototropism and gravitropism. (2)

29. 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)

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

Reproduction

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

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

Variation and evolution

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

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

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

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

Organising an ecosystem

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

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

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

40. Define biomass. (1)

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

42.

|Organism |Biomass / g |

|Grass |100 000 |

|Sheep |5000 |

|Sheep ticks |30 |

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

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

Biodiversity and ecosystems

44. Discuss the advantages and disadvantages of intensive methods for rearing animals and fish. (6)

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

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

[pic]

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

Total marks: 186

Section 2

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 good results 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 B grade, 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.

Do both of these tasks (time - approx 5 hours):

1) Research cell structure (animal, plant and bacteria) and microscopes. Then answer the exam question. Persevere, and look things up!

Suggested websites:



s-cool.co.uk

mrothery.co.uk



biology-innovation.co.uk

(this is the specification we do).

Exam question: 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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(5)

(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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(5)

(Total 10 marks)

2) Biochemistry, Maths: Use the websites mentioned above to help you answer the following questions:

2a) 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)

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? (1)

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 |Product of the |

| | |produced |reaction catalysed |

| | | |by the enzyme |

|  |Amylase |  |  |

|  |Maltase |  |  |

(2) (Total 4 marks)

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

 [pic] 

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

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(1)

(ii)     Name bond Y.

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(1)

(iii)    What chemical group is at position Z?

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(1)

(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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(2)

(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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(3)

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

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(1)

(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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(1)

(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 |

|  |.......................................................... |.......................................................... |

| |.......................................................... |.......................................................... |

|  |.......................................................... |.......................................................... |

| |.......................................................... |.......................................................... |

(2)

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

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(1)

(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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(1)

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

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(2)

(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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(6)

(Total 15 marks)

TOTAL MARKS = 60

Induction lesson: YOU MUST DO THIS if you missed the Induction day:

1) Draw out and learn: structure of glucose.

2) Write notes on monosaccharides.

3) Work out how to join 2 monosaccharides using a condensation reaction.

4) Draw out the formation of sucrose

5) Write down the uses of glucose in living organisms.

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).

Phrases out for A Level: rushed, minimalist, lazy lump. In: independent, learning, curiosity

Have a lovely summer; see you in September!

The Biology Department.

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