1. 3.2: Cells Comments: Required Practicals:
External Assessments:
AS – Paper 1 and Paper 2
A-level – Paper 1 and Paper 3
Required Practicals:
2. Preparation of stained squashes of cells from plant root tips; set-up and use of an optical microscope to identify the stages of mitosis in these stained squashes and calculation of mitotic index.
3. Production of a dilution series of a solute to produce a calibration curve with which to identify the water potential of plant tissue.
4. Investigation into the effect of a named variable on the permeability of cell-surface membranes.
Internal Assessments:
1. Cell Structure (due: )
2. Methods of studying cells (due: )
3. All cells arise from other cells (due: )
4. Transport across cell membranes (due: )
5. Cell recognition and the immune system (due: )
6. End of topic test
Comments:

2. 3.2.1.1: Structure of eukaryotic cells
Key Questions
What are the structures of eukaryotic cell organelles?
Key words:
Cell-surface membrane, nucleus, mitochondria, chloroplasts, golgi apparatus, golgi vesicles, lysosomes, rough and smooth endoplasmic reticulum, cell wall, cell vacuole, organelle, eukaryotic.
To start:
What does the term eukaryotic mean?
Write a brief description of the structure of the labelled organelles:

3. 3.2.1.1: Structure of eukaryotic cells
Key Questions
What does the structure of eukaryotic cell organelles tell us about their function?
Key words:
Cell-surface membrane, nucleus, mitochondria, chloroplasts, golgi apparatus, golgi vesicles, lysosomes, rough and smooth endoplasmic reticulum, cell wall, cell vacuole, organelle, eukaryotic
Organelle
Function
Nucleus
Mitochondria
Golgi apparatus
(and vesicles)
Lysosomes
Ribosomes
RER
SER
What are the organelles found only in plant/algal cells?
What are their structures and functions?
What is the function of the cytoplasm?
What is the function of the cell surface membrane?

4. 3.2.1.1: Structure of eukaryotic cells
Key Questions
What is the level of organisation within multicellular organisms?
How do features of specialised eukaryotic cells relate to their function?
Key words:
eukaryotic, specialisation, tissue, organ, organ-system, organism
Describe how large multicellular organisms are organised, from cell to whole organism?
How are leaf palisade cells adapted for their function?
How are muscle fibre cells adapted for their function?
How are sperm cells adapted for their function?

5. 3.2.1.2: Structure of prokaryotic cells and of viruses
Key Questions
What is the structure of prokaryotic cells?
How do they differ from eukaryotic cells?
Key words:
Cytoplasm, ribosomes, cell wall, murein, plasmid, bacterial chromosome, capsule, flagella, prokaryotic
To start:
What does the term prokaryotic mean?
Label the structures of a bacterial cell and describe their role:
Complete the table to show if the feature is present, not present or sometimes present:
Feature
Prokaryotic cell
Eukaryotic cell
Nuclear envelope
Cell wall
Flagellum
Ribosomes
Plasmid
Cell-surface membrane
Mitochondria
How does a prokaryotic cell wall differ from a plant cell wall?
What is the role of the capsule that sometimes surrounds prokaryotic cells?

6. 3.2.1.2: Structure of prokaryotic cells and of viruses
Key Questions
What are viruses?
What is the structure of viruses?
Are they considered alive or dead?
Key words:
Acellular, non-living, DNA, RNA, capsid, attachment protein
Complete the diagram by adding the function of the structures:

7. Cell Structure Exam Questions (due: )
1. a) An amoeba is a single-celled, eukaryotic organism. Scientists used a transmission electron microscope to study an amoeba. The diagram shows its structure.
2, a)     The diagram shows a bacterial cell.
(i)   Name the parts labelled D and E. D
E (2)
(ii)     Give one function of the cell wall.
(1)
i)      Name organelle Y.
(1)
(ii)     Name two other structures in the diagram which show that the amoeba is a eukaryotic cell.
(2)
b)     What is the function of organelle Z?

8. Cell Structure Exam Questions (due: )
2. c) Several small pieces of a saprophytic fungus were placed on a starch agar plate. After 48 hours the iodine solution was poured over the starch agar. The result is shown in the diagram below
4. The diagram shows the structure of a chloroplast
a)     Label the diagram with an X to show where the light-dependent reactions take place and with a Y to show where the light-independent reactions take place.
(1)
(i) Explain why there is a clear area around most of the pieces of fungus.
(2).
(2)(ii)     Suggest why one piece of fungus has no clear area round it.
(1)

9. 3.2.1.3: Methods of studying cells
Key Questions:
How do electron microscopes work?
What are the differences between a transmission electron microscope and a scanning electron microscope?
Key words:
electron microscope; light (optical) microscope; photomicrograph; scanning electron microscope (SEM); transmission electron microscope (TEM)
The transmission electron microscope:
How it works:
What are its limitations:
The scanning electron microscope :
How it works:
What additional information can you get from a scanning electron microscope?

10. 3.2.1.3:Methods of studying cells
Key Questions:
What is magnification and resolution?
What is fractionation?
Key words:
cell fractionation; homogenation; magnification; resolution; ultracentrifugation
Fill in the formula triangle for magnification
Label the diagram to summarise cell fractionation
What is magnification?
What is resolution?

11. Methods of studying cells Exam Questions (due: )
1. Mitochondria were isolated from the liver tissue using differential centrifugation. The tissue was chopped in cold, isotonic buffer solution. A buffer solution maintains a constant pH. The first stages in the procedure are shown in the diagram.
Tissue chopped               Homogenised                                      Centrifuged
 in solid isotonic                                                                          at low speed
  butter solution                                                                        for 10 minutes
 Stage 1                          Stage 2                                              Stage 3
1. ii)      Why is the liver tissue homogenised?
(1)
(iii)     Describe what should be done after Stage 3 to obtain a sample containing only mitochondria.
(2)
2, a)     Small samples of plant tissue were placed in a cold, isotonic solution and then treated to break open the cells to release the organelles. The different organelles were then separated. Describe a technique that could be used to
(i)      break open the cells;
(ii)     separate the organelles.
(2)
i)      The tissue was chopped in cold, isotonic buffer solution. Explain the reason for using
a cold solution;
an isotonic solution;
a buffer solution.
(3)

12. Methods of studying cells Exam Questions (due: )
2 b)     One group of organelles was placed in a hypotonic solution. The diagram shows one of these organelles seen under an electron microscope before and after it was placed in the hypotonic solution.
(i)      Name the organelle.
(1)
(ii)     Describe and explain the effect on the organelle of placing it in the hypotonic solution.
(4)

13. Methods of studying cells Exam Questions (due: )
3. The drawing shows an electron micrograph of parts of epithelial cells from the small intestine.
(a)     (i)      Name the structures labelled A.
(1)
(ii)     Explain how these structures help in the absorption of substances from the small intestine.
(b)     (i)      The scale bar on this drawing represents a length of 0.1μm. Calculate the magnification of the drawing. Show your working.
Magnification
(2)
(ii)     Explain why an electron microscope shows more detail of cell structure than a light microscope.
(c)     The length of mitochondria can vary from 1.5 μm to 10 μm but their width never exceeds 1μm. Explain the advantage of the width of mitochondria being no more than 1μm.

14. 3.2.2: All cells arise from other cells – Cell Cycle
Key Questions:
What are the three stages of the cell cycle?
What happens during interphase?
How is mitosis controlled?
Key words:
Cell cycle, DNA replication, Interphase, mitosis, cytokenesis
Describe the three stages of the cell cycle a) b) c)
Label the diagram above with the three stages of the cell cycle.

15. 3.2.2: All cells arise from other cells – Mitosis
Key Questions
What is mitosis?
When does DNA replication take place?
What is the importance of mitosis?
Key words:
mitosis; prophase; metaphase; anaphase; telophase; growth; differentiation; repair, cytokinesis, spindle fibres, centromeres, chromatids
Describe the processes that take place during the different stages of mitosis:
Why is mitosis important?

16. 3.2.2: All cells arise from other cells – Cell Cycle and Cancer
Key Questions:
How does cancer and its treatment relate to the cell cycle?
Key words:
Benign, malignant, nuclear division; cell division, mitosis
To Start:
What is cancer?
What are the two main ways that current cancer treatments work? Can you find some examples? 1. 2.
Where are the common sites of cancer in the body? Why?
What increases the chance of cancerous cells developing? Why?

17. 3.2.2: All cells arise from other cells – Prokaryotic cells and viruses
Key Questions:
How do prokaryotic cells replicate?
How do viruses replicate?
Key words:
Binary fission, daughter cells, circular DNA, plasmids, nucleic acid, host cell
Describe the process of binary fission by prokaryotes:
How does the nucleic acid of the virus contribute to its process of replication? 1. 2. 3. 4.

18. All Cells arise from other cells Exam Questions (due: )
1. (a)     Mitosis is important in the life of an organism. Give two reasons why.
(2)
b)     (i)      Explain why the biologist chose to examine 200 cells.
(1)
(ii)     Name Stage A and Stage B. Give the evidence from the photograph that you used to identify the stage.
Name of Stage A
Evidence
Name of Stage B
(4)
(c)     In this tissue one complete cell cycle took 20 hours. Using information from the table, calculate the mean time for these cells to complete mitosis. Show your working.
                                                  Answer
(2)
A biologist used a microscope to investigate plant tissue where some of the cells were dividing by mitosis. She examined 200 cells and counted the number of cells in interphase and in each stage of mitosis.
The table shows some of the cells she saw, and the percentage of cells in interphase and in two stages of mitosis, A and B.
                                               
Stage of cell cycle
Percentage of cells
Interphase 90
Stage A 3
Stage B 1

19. All Cells arise from other cells Exam Questions (due: )
1. A student investigated mitosis in the tissue from an onion root tip.
(a)     The student prepared a temporary mount of the onion tissue on a glass slide. She covered the tissue with a cover slip. She was then given the following instruction.
“Push down hard on the cover slip, but do not push the cover slip sideways.”
Explain why she was given this instruction.
(2)
The image below shows one cell the student saw in the onion tissue.
© Ed Reschke/ Oxford Scientific/Getty Images
(b)     The student concluded that the cell in the image above was in the anaphase stage of mitosis. Was she correct? Give two reasons for your answer.
(2)
(c)     The student counted the number of cells she observed in each stage of mitosis. Of the 200 cells she counted, only six were in anaphase.
One cell cycle of onion root tissue takes 16 hours. Calculate how many minutes these cells spend in anaphase.
Show your working.
Answer = minutes

20. All Cells arise from other cells Exam Questions (due: )
  1. (a)     Some tumours are benign and some are malignant.
(i)      Give one way in which a benign tumour differs from a malignant tumour.
(1)
(ii)     Describe two ways in which both types of tumour may cause harm to the body.
(2)
(b)     (i)      Explain the link between sunbathing and skin cancer.
ii)     Suggest why fair-skinned people are at a greater risk of skin cancer than dark-skinned people when sunbathing.
(1)
(iii)     Suggest why people with a family history of cancer are at a greater risk of cancer than those with no family history of cancer.

21. Unit 1: Transport Across Cell Membranes
The Cell Membrane Components
Describe the arrangement of phospholipids, proteins, glycoproteins and glycolipids.
Key words:
extrinsic protein; fluid-mosaic; intrinsic protein; phospholipid; plasma membrane;
Draw and describe the structure of:
Phospholipids
Cholesterol
Glycolipids
Protein
Glycoproteins

22. Unit 1: Transport Across Cell Membranes
Fluid Mosaic Model
The fluid mosaic model of cell membranes, including the arrangement of phospholipids, proteins, glycoproteins and glycolipids.
The role of cholesterol.
Key words:
extrinsic protein; fluid-mosaic; intrinsic protein; phospholipid; plasma membrane;
Label the diagram to show the structure of the cell surface membrane and the function of its components:

23. Unit 1: Transport Across Cell Membranes
Osmosis
The movement of water across partially permeable membranes by osmosis.
The concepts of water potential and hypotonic, hypertonic and isotonic solutions.
Key words:
Water potential gradient, osmosis, semi permeable membrane, hypertonic, hypotonic, isotonic, flaccid, turgid, plasmolyse, crenation
What is water potential and in what units is it measured?
Draw a diagram to explain osmosis, include information on the effect of water potential:
Define the terms:
Hypotonic:
Hypertonic:
Isotonic:

24. Unit 1: Transport Across Cell Membranes
Simple Diffusion and Facilitated Diffusion
What is diffusion and how does it occur?
What affects the rate of diffusion?
How does facilitated diffusion differ for diffusion?
Key words:
concentration gradient; diffusion pathway; facilitated diffusion; surface area; carrier proteins, soluble, charged
Draw a diagram to show what diffusion is and how it occurs:
What affects the rate of diffusion?
Draw a diagram to show what facilitated diffusion is and how it occurs:

25. Unit 1: Transport Across Cell Membranes
Active transport
Movement of molecules and ions against concentration gradients by simple diffusion or facilitated diffusion.
Key words:
ATP; co-transport; sodium-potassium pump
Label the diagram to explain active transport and how it is different to facilitated diffusion:
The role of ATP is missing, add it to the diagram
Write a definition for active transport:
How is active transport different to passive transport?
What is co-transport?

26. Unit 1: Transport Across Cell Membranes
Adaptations of Cells for Transport
The adaptations of specialised cells maximising the rate of transport
How surface area, number of channel or carrier proteins and differences in gradients of concentration or water potential affect the rate of movement
Key words:
ATP, surface area to volume ratio, concentration gradient, carrier proteins, mitochondria, ATP
Draw a diagram of an epithelial cell of the small intestine. Include labels and a short description as to how it is adapted to maximise transport across the membrane.
What do carrier proteins allow to pass through the cell membrane?
How does increasing the number of carrier proteins within a membrane affect the permeability?
What is the function of mitochondria?

27. Unit 1: Transport Across Cell Membranes
Co transport
Movement of molecules and ions against concentration gradients by co-transport.
Key words:
lumen; microvilli; villi
How does the structure of the villi and microvilli help the absorption of molecules in the gut?
What are the roles of diffusion, active transport and co-transport in the absorption of the products of carbohydrate digestion? Use diagrams to aid your explanation.

28. Unit 1: Transport Across Cell Membranes – Exam Questions
(2 marks)
1 (b) Give one function of the molecule labelled Y.
……………………………………………………………………………………………………………………………………………………………... ……………………………………
(1 mark)
1 (c) The part labelled Z is involved in facilitated diffusion of substances across the membrane.
(i) Give one similarity in the way in which active transport and facilitated diffusion transport across the membrane (1 mark)
……………………………………………………………………………………………………………………………………… ……………………
1 (c) (ii) Give one way in which active transport differs from facilitated diffusion. ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………
(1 mark)

29. Unit 1: Transport Across Cell Membranes – Exam Questions
1c (ii)
2. Explain how three features of a plasma membrane adapt it for its functions …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………
(6 marks)
(2 marks)

30. Unit 1: Transport Across Cell Membranes – Exam Questions
3 Many different substances enter and leave a cell by crossing its cell surface membrane.
Describe how substances can cross a cell surface membrane.
(5 marks)
4 The epithelial cells that line the small intestine are adapted for the absorption of glucose. Explain how.
(6 marks)

31. Unit 1: Cell recognition and the immune system
Antigens and Phagocytosis:
explain what is meant by an antigen, and the types of molecules which can act as antigens and identify cells which the immune system would launch an immune response against
Describe the role of lysosomes in phagocytosis.
Key words:
antigens; antigen-presenting cell; B lymphocytes; cell-mediated; T lymphocytes, phagocytes; phagocytosis; lysosome; pathogen
What are antigens?
Label the diagram to explain phagocytosis
What kinds of cells can produce antigens that would initiate an immune response?

32. Unit 1: Cell recognition and the immune system
Antibodies:
What is the structure of an antibody?
How do antibodies function?
Explain how antibodies lead to the destruction of pathogens.
Key words:
antigen-antibody complex; constant region; monoclonal; polyclonal; variable region;
Draw and label an antibody
What is antigenic variability?
Draw and label a diagram to show how the binding of antibodies leads to the destruction of a pathogen?
Agglutination
Phagocytosis

33. Unit 1: Cell recognition and the immune system
B cells and humoral immunity:
explain the humoral (antibody-mediated) immune response 
explain what is meant by a monoclonal antibody 
explain the roles of plasma cells in producing a primary response and memory cells in producing a secondary response.
Key words:
antibodies; antigenic variability; humoral immunity; memory cells; mitosis; plasma cells;
Label the diagram and label the steps of humoral immunity: 1) 2) 3) 4) 5) 6) 7)
Memory cells –
Plasma cells –
What is clonal selection?

34. Unit 1: Cell recognition and the immune system
T cells and cell-mediated immunity
explain what is meant by the specific immune response
explain the cell-mediated (cellular) immune response
explain the roles played by helper T cells.
Key words:
antigens; antigen-presenting cell; B lymphocytes; cell-mediated; T lymphocytes;
In your own words, write definitions of the following terms:
Specific immune response
Cell mediated immune response
Label the diagram and explain the 5 steps of cell mediated immunity: 1) 2) 3) 4) 5)
What is the role of the TH (T-helper) cells?
What is the role of the cytotoxic Tc (T-killer) cells?

35. Unit 1: Cell recognition and the immune system
Vaccination
What is a vaccine?
What are the features of an effective vaccination programme?
Why does vaccination rarely eliminate a disease?
What ethical issues are associated with vaccination programmes?
Key words:
active immunity; passive immunity, herd immunity, antigen, ethics, eliminate, population, epidemic, pandemic
What is passive immunity?
What is meant by herd immunity?
Why is herd immunity important?
What is active immunity?
Why does vaccination rarely eliminate a disease?
What is a vaccine?

36. Unit 1: Cell recognition and the immune system
RESEARCH: MMR Case Study
What did Andrew Wakefield claim about the MMR vaccine?
What data did Wakefield have to back up his claim?
Evaluate the scientific methods and experimental design of Andrew Wakefield.
What did Hideo Honda claim about the MMR vaccine?
What data did Honda have to back up his claim?

37. Unit 1: Cell recognition and the immune system
HIV
Structure of the human immunodeficiency virus (HIV) and its replication in helper T cells. 
How HIV causes the symptoms of AIDS.  
Why antibiotics are ineffective against viruses.
Key words:
Lipid envelope, attachment proteins, capsid, RNA, enzymes, reverse transcriptase, retroviruses
How does HIV replicate?
How does HIV cause symptoms of AIDS?
What is the ELISA test and how can it be used in the detection of HIV?
Why are antibiotics ineffective against viral diseases like AIDS?

38. Unit 1: Cell recognition and the immune system
Monoclonal Antibodies
Explain how monoclonal antibodies can be used to deliver therapeutic drugs to specific cells
Explain how monoclonal antibodies can be used in medical diagnosis
Explain how monoclonal antibodies can be used in pregnancy testing

39. Unit 1: Cell recognition and the immune system Monoclonal Antibodies
Ethics: Summarise the main advantages and ethical issues
Vaccinations
Monoclonal Antibodies
Advantages
Ethical Issues
Advantages and Uses
Ethical Issues

40. Unit 1: Cell recognition and the immune system - Exam Questions
When a pathogen causes an infection, plasma cells secrete antibodies which destroy this pathogen. Explain why these antibodies are only effective against a specific pathogen.
(2 marks)
Other scientists have been working with mice. These scientists have suggested that chlamydia may cause heart disease in a different way. They have found a protein on the surface of chlamydia cells which is similar to a protein in the heart muscle of mice. After an infection with chlamydia, cells of the immune system of the mice may attack their heart muscle cells and cause heart disease.
After an infection with chlamydia, cells of the immune system of the mice may attack the heart muscle cells. Explain why.
(2 marks)
Explain what is meant by an antigen.
(2 marks)
Some white blood cells are phagocytic. Describe how these phagocytic white blood cells destroy bacteria.
(4 marks)

41. Unit 1: Cell recognition and the immune system - Exam Questions
(4 marks)
Suggest which component of an intact red blood cell is most likely to act as an antigen during a blood transfusion. Explain your answer.
Component
Explanation
(2 marks)
(2 marks)