1. Discuss possible exceptions to cell theory. [4]

2. Explain how the surface area to volume ratio influences cell sizes. [3]

3. Outline differentiation of cells in a multicellular organism. [4]

4. Draw a labeled diagram showing the structure of a prokaryotic cell [6]

5. Draw a labeled diagram to show the organelles which are found in the cytoplasm of plant cells. [6]

6. State one function of each of the following organelles: lysosome, Golgi apparatus, rough endoplasmic reticulum, nucleus, mitochondrion. [5]

7. Draw a labeled diagram showing the ultra-structure of an animal cell as seen in an electron micrograph. [6]

8. Distinguish between the structure of plant and animal cells. [6]

9. Using a table, compare the structures of prokaryotic and eukaryotic cells. [5]

10a. Explain the importance of the surface area to volume ratio as a factor limiting cell size. [3]

10b. State one difference between the proteins produced by free ribosomes and those produced by ribosomes attached to the endoplasmic reticulum. [1]

11. The diagram below shows the structure of a cell.

(a) State the names of I and II. [2](b) Calculate the actual length of the cell, showing your working. [2](c) State the function of the structure labeled III. [1](d) Deduce which type of cell is shown in the diagram, giving reasons for your answer. [2]

12. Discuss the functions of the cell wall. [4]

13. (a) State one function for each of the following organelles. [3]

(i) Ribosomes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .(ii) Rough endoplasmic reticulum. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .(iii) Golgi apparatus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .(c) Compare prokaryotic and eukaryotic cells in regards to three different features. [3]

14. Explain the role of vesicles in transportation of materials within cells. [8]

15. Draw the structure of a mitochondrion as seen in an electron micrograph. [5]

16. Discuss whether the light microscope or the electron microscope is more useful for studying cells, tissues and organs. [5]

17. Draw a diagram to show the structure of a cell membrane [5]

18. Explain how the structure and properties of phospholipids help to maintain the structure of cell membranes. [9]

19. Describe the process of active transport. [4]

20. Outline the ways in which substances move passively across membranes. [5]

21. Explain the reasons for cell division in living organisms. [8]

22. Outline the processes that occur in a cell during interphase, including those needed to prepare for mitosis. [4]

23. Describe the events that occur in the four phases of mitosis (prophase, metaphase, anaphase and telophase) [12]

24. State some processes that involve mitosis. [4]

25a. Differentiate between cell division and mitosis. [1]25b. Define what a tumor is. [1]25c. Define what cancer is. [1]25d. Explain how stem cells can be used for therapeutic treatment of Leukemia( cancer of the blood ) [2]

26a. Explain how mitosis produces two genetically identical nuclei. [2]26b. Draw a pie chart to show the time spent in each phase of cell division. [4]

27. Explain the role of protein pumps and ATP in active transport across membranes.[3]

28. Differentiate between diffusion and facilitated diffusion. [5]

29. Define diffusion and osmosis. [2]

30. List the functions of membrane proteins. [4]

31. Define Exocytosis and Endocytosis and state examples of both. [4]

32. List 6 ways that substances move from one side of a membrane to the other. [6]

33. Suggest why the fatty acid ‘tails’ of the phospholipid molecules always align themselves in the middle of the membrane. [1]

34. State the function of the;Pilli, Chloroplast, Capsule, Plasmid, Smooth Endoplasmic Reticulum. [5]

35. Outline 1 extracellular component and state the roles of extracellular component. [4]

36. Define what is meant by the term ‘binary fission’. [1]

37. Describe how the fluidity of the membrane allows it to change shape, break and re-form during endocytosis and exocytosis. [3]

38. Predict some of the significant features you would expect to see in a liver cell? Give a just reasoning for your answer. [6]

39. Identify how the mitochondrion is adapted to function efficiently. [4]

40a. Define the term stem cell. [1]40b. Suggest one therapeutic use of stem cells. [1]40c. Discuss the benefits and problems of stem cells. [4]

Answers1. Discuss possible exceptions to cell theory. 4 marksskeletal muscle fibers are larger/have many nuclei/are not typical cellsfungal hyphae are (sometimes) not divided up into individual cellsunicellular organisms can be considered acellularbecause they are larger than a typical cell/carry out all functions of lifesome tissues/organs contain large amounts of extracellular materiale.g. vitreous humor of eye/ mineral deposits in bone/ xylem in trees/other examplestatement of cell theory/all living things/most tissues are composed entirely of true

cells

2. Explain how the surface are to volume ratio influences cell sizes. 3 marks

small cells have larger ratio (than larger cells)/ratio decreases as size increasessurface area/membrane must be large enough to absorb

nutrients/oxygen/substances neededsurface area/membrane must be large enough to excrete/pass out waste productsneed for materials is determined by (cell) volumecell size is limited (by SA/Volume ratio)/cells divide when they reach a certain sizereference to diffusion across/through membrane/surface area

3. Outline differentiation of cells in a multicellular organism. 4 marks

differentiation is development in different/specific wayscells carry out specialized functions/become specializedexample of a differentiated cell in a multicelluar organismcells have all genes/could develop in any waysome genes are switched on/expressed but not othersposition/hormones/cell-to-cell signals/chemicals determine how a cell developsa group of differentiated cells is a tissue

4. Draw a labelled diagram showing the structure of a prokaryotic cell 6 marks

cell wall shown clearly and labelledcell surface membrane shown thinner than and adjacent to cell wall and labelledcytoplasm shown with no nucleus present and labelledribosomes shown free in the cytoplasm and labelledloop of DNA shown in the cytoplasm/nucleoid and labelled as DNAplasmid shown as a small loop and labelledslime capsule shown as a layer outside the cell wall and labelledmesosome shown as a membrane invagination and labelledflagellum shown and labelled (reject if shown with microtubules)

5. Draw a labelled diagram to show the organelles which are found in the cytoplasm of plant cells. 6 marks

Award 1 mark for each of the following structures accurately drawn and labelled

rough endoplasmic reticulumfree ribosomesGolgi apparatusmitochondrionchloroplastvacuolenucleuslysosomesmooth endoplasmic reticulum

6. State one function of each of the following organelles: lysosome, Golgi apparatus, rough endoplasmic reticulum, nucleus, mitochondrion. 5 marks

lysosome: hydrolysis/digestion/break down of materials (macromolecules)Golgi apparatus: synthesis/sorting/transporting/secretion of cell productsrough endoplasmic reticulum: site of synthesis of proteins (to be secreted)/

intracellular transport of polypeptides to Golgi apparatusnucleus: controls cells activities/mitosis/replication of DNA/transcription of DNA (to

RNA)/directs protein synthesismitochondrion: (aerobic) respiration/generates ATP

7. Draw a labelled diagram showing the ultra-structure of an animal cell as seen in an electron micrograph. 6 marks

Award 1 mrak for each of the following structure clearly drawn and labelled correctly. Award marks for labelled eukaryotic structures, then deduct 1 mark per labelled prokaryotic structure shown, e.g. mesosome, cell wall.

nuclear membrane/nucleus (with nuclear membrane shown double with pores)ribosomes (free or attached to ER)endoplasmic reticulum/ ERplasma/cell membrane (reject if shown as a double line)mitochondria (shown with inner and outer membrane)Golgi (apparatus)

lysosomes

8. Distinguish between the structure of plant and animal cells. 6 marks

Award 1 mark per difference plant cells

have cell walls, animals do nothave plastids/ chloroplasts, animals do nothave a large central vacuole, animals do notstore starch, animal cells store glycogenhave plasmodesmata, animal cells do notanimal cells

have centrioles, plant cells do nothave cholesterol in the cell membrane, plant cells do not

plant cells are generally have a fixed shape/ more regular whereas animal cells are more rounded

9. Using a table, compare the structures of prokaryotic and eukaryotic cells. 5 marks prokaryotic cells eukaryotic cells

DNA naked/loop of DNA associated with protein/histones/nucleosomes/DNA in chromosomes

location of DNA in cytoplasm/nuceloid/no nucleus within a nucleus/nuclear membranemembrane bound organelles none presentribosomes 70S 80Splasma membrane same structure within both groupscell wall peptidoglycan/not cellulose/not chitin cellusose/chitin/not peptidoglycanrespiratory structures mesosomes/no mitochondria mitochondria

10a. Explain the importance of the surface area to volume ratio as a factor limiting cell size. (3)

the rate of material / heat exchange / diffusion is proportional to surface area;the rate of metabolism is proportional to mass/volume;as a cell grows, the volume increases faster than the surface area / as a cell grows,surface area to volume ratio decreases;(without cell division) material / heat cannot be exchanged fast enough to meetthe needs of the cell;

10b. State one difference between the proteins produced by free ribosomes and those produced by ribosomes attached to the endoplasmic reticulum. (1)

free ribosomes synthesize proteins for use within the cell/cytoplasm and attachedribosomes produce proteins for export / use within lysosomes / membranes

11. The diagram below shows the structure of a cell.

(a) State the names of I and II. [2](b) Calculate the actual length of the cell, showing your working. [2](c) State the function of the structure labelled III. [1](d) Deduce which type of cell is shown in the diagram, giving reasons for your answer. [2]

11. (a) I: is the plasma membrane/cell (surface) membrane/phospholipid bilayer;II: is the mesosome; [2]

(b) size of drawing divided by magnification / figures using this equation; (units not required)Award [1] for working even if length measurement is incorrect.1.41 (! 0.02) μm; (units required) [2]Accept answers given in m, cm, mm and nm.

(i) protection / support / maintains shape / prevents bursting [1]

(d) bacterium/bacteria/prokaryote;reason: [1 max]as no nuclear membrane / no nucleus;as no mitochondria / membrane bound organelles;as mesosomes / small size / circular DNA; (Do not accept naked DNA or no histone.) [2 max]Reject reasons if cell type is incorrectly identified.

12. Discuss the functions of the cell wall. [4]

13. (a) Explain how the surface area to volume ratio influences cell sizes. [3]

(b) State one function for each of the following organelles. [3]

(i) Ribosomes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .(ii) Rough endoplasmic reticulum. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .(iii) Golgi apparatus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .(c) Compare prokaryotic and eukaryotic cells in regards to three different features. [3]

13a) small cells have larger ratio (than larger cells) / ratio decreases as size increases;surface area/membrane must be large enough to absorb nutrients/oxygen/substances needed;surface area/membrane must be large enough to excrete/pass out waste products;need for materials is determined by (cell) volume;cell size is limited (by SAvol / ratio) / cells divide when they reach a certain size;reference to diffusion across/through membrane/surface area; [3 max]

(b) Award [1 max] for each organelle. Mark first answer only.(i) translation / produces polypeptides / proteins / protein synthesis;(ii) support of ribosomes / site of protein synthesis / synthesis of proteins for secretion /folding of polypeptides;(iii) produces glycoproteins / processing of proteins / forms lysosomes / formationof vesicles (for exocytosis); [3 max](c) Award [1] for each of the following pairs. Mark first answer only in boxes 1, 2 and 3.prokaryotic cells eukaryotic cellsnucleoid / no nucleus / nuclear membrane vs. nucleus / nuclear membrane;naked DNA / no histones vs. DNA associated with protein / histone;no mitochondria vs. mitochondria present;no Golgi / no ER vs. Golgi / ER present;circular DNA vs. linear DNA;no/very few membrane-bound organelles vs. membrane-bound organelles;ribosomes smaller / 70S vs. ribosomes larger / 80S;no mitosis / meiosis vs. mitosis / meiosis;flagella lack internal microtubules vs. flagella have microtubules (9+2); [3 max]Allow [1] only for a similarity.

14. Explain the role of vesicles in transportation of materials within cells.

Marks can be achieved by means of a suitable annotated diagrams.vesicles are membrane bound packages/droplets;formed by pinching off/budding off a piece from a membrane;can carry proteins;rough ER synthesizes proteins;proteins enter/accumulate inside the ER;transported to Golgi apparatus for processing;targeted to/transported to specific cellular organelles;fuse with membrane of organelle so contents of vesicle join the organelle;transported to the plasma membrane;fuses with plasma membrane releases/secretes contents;exocytosis; [8 max]

15. Draw the structure of a mitochondrion as seen in an electron micrograph. [5]

Award [1] for each of the following structures clearly drawn and labelled correctly.outer membrane;intermembrane space / outer compartment;inner membrane;matrix;cristae;ribosome;naked / circular DNA;ATP synthase;Do not accept plasma membrane.

16. Discuss whether the light microscope or the electron microscope is more useful for studying cells, tissues and organs. [5]

(Award 1 mark for any of the below; up to a maximum of 5 marks)

Advantages of light microscopeColours of material from tissues/organ can be seen;Living material can be studied/less damage to specimen;Cell activities/movement can be studiedLarger field of view

Advantages of electron microscopeGreater resolutionSmaller structures can be seen/greater magnification;

(Award up to 2 marks for the following overall assessment)Electron microscope better for cells/small structures;But light microscope better for organs;

17. Draw a diagram to show the structure of a cell membrane 5 marks1. phospholipids labelled with hydrophillic (heads) and hydrophobic (tails)2. phospholipid bilayer clearly shown and labelled3. proteins shown in the bilayer and labelled4. transmembrane and peripheral/extrinsic proteins shown and labelled5. glycoproteins shown and labelled6. cholesterol shown and labelled7. glycolipids shown and labelled8. thickness shown as 10 nm/ + or - 2 nm

18. Explain how the structure and properties of phospholipids help to maintain the structure of cell membranes. 9 marks

phospholipid structure

1. hydrophobic tail/hydrophilic head2. head made from glycerol and phosphate3. tail made from two fatty acids4. saturated/ unsaturated fatty acid (in tail)arrangement in membrane1. phospholipids form a bilayer2. heads face outside the membrane/ tails face inside the membrane/ hydrophic

interior/ hydrophilic exterior of membraneA suitable annotated diagram may incorporate all or many of the above points. Award 5 marks maximum for a suitable diagram that is labelled correctly.

1. phospholipids held together by hydrophobic interactions2. phospholipid layers are stabilized by interaction of hydrophilic heads and surrounding

water3. phospholipids allow for membrane fluidity/ flexibility4. fluidity/ flexibility helps membranes to be (functionally) stable5. phospholipids with short fatty acids/ unsaturated fatty acids are more fluid6. fluidity is important in breaking and remaking membranes (e.g. endocytosis/

exocytosis)7. phospholipids can move about/ move horizontally/ "flip flop" to increase fluidity8. hydrophilic/ hydrophobic layers restrict entry/ exit of substances

19. Describe the process of active transport. 4 marks

1. uses/ requires energy/ ATP2. goes against concentration gradient/ lower to higher concentration3. requires a protein in the cell membrane/ pump/ carrier protein (reject channel)4. hydrolysis of ATP/ ATP --> ADP + phosphate5. involves a conformational change in the pump/ protein/ diagram to show this

20. Outline the ways in which substances move passively across membranes. 5 marks

1. diffusion (is a method of passive transport across the membrane)2. pore/ channel proteins for facilitated diffusion/ to allow hydrophilic particles across3. movement from high to low concentration/ down the concentration gradient4. membrane must be permeable to the substance diffusing5. oxygen/ other named example of a substance than can diffuse through membranes6. osmosis is movement of/ diffusion of water through a membrane7. from a region of lower to a region of higher solute concentration/ higher to lower

water potential8. membranes are (nearly) always freely permeable to water

21. Explain the reasons for cell division in living organisms. 8 marks

1. to increase the number of cells in an organism2. to allow differentiation/ cell specialization3. for greater efficiency4. to replace damaged/ lost cells5. example

1. binary fission2. asexual reproduction of unicellular organisms3. gamete/ spore formation

1. cells only arise from pre-existing cells2. refer to Virchow3. cells cannot grow beyond a certain size4. surface area to volume ratio becomes too small5. transport across the membrane too slow6. example7. nucleus cannot control the cell

control of cell division sometimes losttumor formation

22. Outline the processes that occur in a cell during interphase, including those

needed to prepare for mitosis. 4 marks

DNA replicationDNA transcriptionenzyme/ protein synthesisbiochemical reactions/ example of a biochemical reactioncell respirationgrowthorganelles replicated

23. Describe the events that occur in the four phases of mitosis (prophase, metaphase, anaphase and telophase.(12 marks )Prophase1. DNA supercoils & becomes visible under light microscope.2. Spindle microtubules grow from the poles of the cell from the microtubule organising centre (MTOC) to the chromosomes. (Spindle microtubules separate & pull chromosomes to opposite sides of cell).3. Nuclear membrane breaks down.Metaphase1. Mitotic spindle is formed completely. 2. Microtubules attach to centromeres.3. Microtubules move the chromosomes to the equator of the cell.Anaphase1. Pairs of sister chromatids separate at the centromere and 2. are pulled to opposite poles by the microtubules.3. Microtubules contractTelophase1. Nuclear membrane reforms around chromosomes at both poles. 2. DNA uncoils3. Mitotic spindle breaks down.

24. State some processes that involve mitosis. 4 marks-Embryonic development-Growth-Tissue repair-Asexual reproduction

25a. Differentiate between cell division and mitosis. 1 markCell division is the division of one cell into 2 daughter cells. Mitosis however is a stage in cell division in which the nucleus divides.

25b. Define what a tumour is. 1 markA tumour is an excess of cells which clump together.

25c. Define what cancer is. 1 markCancer is the term referring to the condition of having abnormal growths ( tumours )

25d. Explain how stem cells can be used for therapeutic treatment of Leukemia ( cancer of the blood ) 2 marks

26a. Explain how mitosis produces two genetically identical nuclei. 3 marks-During S phase, each chromosome replicates (forms an exact copy of itself). These copies are called sister chromatids. -These identical sister chromatids are separated during Anaphase, and are moved to each pole. When they are separated they are referred to as chromosomes.-The result is two nuclei, identical to each other and to the original nucleus.

26b. Draw a pie chart to show the time spent in each phase of cell division. 4 marks-Show that interphase approximately takes up 75% of the duration of the cell lifespan. ( otherwise award a maximum of 3 marks )-Show G1, S and G2 phases-Shows mitosis as taking approximately 20% of the duration of the cell lifespan-Shows and labels the 4 phases of Mitosis-Shows cytokinesis on the pie chart as approximately 5% of the duration of the cell lifespan.

27. Explain the role of protein pumps and ATP in active transport across membranes. 4 marks-Energy from ATP is required -to transport substances against the concentration gradient from a region of low concentration to a region of high concentration.-This process is termed active transport. -Active transport occurs when a molecule or ion attaches to a specific binding site on the carrier protein. -This carrier protein then changes shape after reacting with ATP, -letting the substance pass through the hydrophilic core, to the other side of the

membrane.

28. Differentiate between diffusion and facilitated diffusion 5 marks

29. Define diffusion and osmosis. 2 marks-Osmosis is simply a specific type of diffusion involving water. Osmosis is the passive movement of water particles across a partially permeable membrane from a lower solute concentration (high concentration of water) to a higher solute concentration (low concentration of water).

-Diffusion is the passive movement of particles from a region of high concentration to a region of low concentration.

-Passive simply means that no chemical energy such as ATP is required to move substances across the membrane, as apposed to active transport which does require chemical energy in the form of ATP to move substances across the membrane.

30. List the functions of membrane proteins 4 marks

hormone binding sitesenzyme binding siteselectron carriersChannels for passive transportPumps for active transportcell to cell recognitionreceptors for neurotransmitters

31. Define Exocytosis and Endocytosis and state examples of both. 4 marks -Exocytosis: vesicle membrane fuses with the plasma membrane. E.g. Hormone secretion

-Endocytosis: a vesicle is formed by the infolding of the plasma membrane. E.g. Phagocytosis, Pinocytosis.

32. List 6 ways that substances move from one side of a membrane to the other. 6 marks- Diffusion- Facilitated diffusion- Protein pumps- osmosis

- endocytosis- exocytosis

33. Suggest why the fatty acid ‘tails’ of the phospholipid molecules always align themselves in the middle of the membrane. 1 markFatty acids are hydrophobic of water and always orientate away from water.

34. State the function of the;Pilli, Chloroplast, Capsule, Plasmid, Ribosome, Rough Endoplasmic Reticulum, Golgi Apparatus Smooth Endoplasmic Reticulum, Plasma membrane and Mitochondrion. 10 marks

35. Outline 1 extracellular component and state the roles of extracellular component. 4 marksName of the component (1 mark max)

Functions (3 marks max)- strengths/ supports the cell/ plant (against gravity);- prevents the entry of pathogens;- maintains the shape of plant cells;- allows turgor pressure/high pressure to develop inside the cell;- prevents excessive entry of water to the cell;

OR

- Helps cells to stick together/adhere;- Needed to hold cells/ tissues together/ example of cells/ tissues- Holding together;- Forms basement membrane to support single layers of cells

36. Define what is meant by the term ‘binary fission’. 1 mark- The means of asexual reproduction in many prokaryotic cells in which the DNA replicates and separates into two different areas of the cytoplasm, which then divides into two.

37a. Describe how the fluidity of the membrane allows it to change shape, break and re-form during endocytosis and exocytosis. 3 marks- The phospholipid molecules can change places in the horizontal plane. This creates the so called fluid property of the membrane. - Molecule exchange in the vertical plane does not occur. This maintains the integrity of the membrane.

- Cholesterol embedded in the membrane reduces its fluidity.

37b. What are pinocytosis and phagocytosis classified under. 1 mark-Endocytosis

38. Predict some of the significant features you would expect to see in a liver cell? Give a just reasoning for your answer. 6 marks- They will have more mitochondria than the average cell- Because they have to carry out many metabolic reactions such as Detoxification and deamination of excess amino acids.- Also, they will have more rough endoplasmic reticulum than other cells.- This is because they play an important role in the production of bile salts.- The liver cell would also have many Golgi Apparatus- Because of their role in secreting many products created from the metabolic activities within the cell.- The liver cell would tend to have a lot of glycogen granules - Because the liver, along with the muscles are the main storages for glycogen in the body.

39. Identify how the mitochondrion is adapted to function efficiently. 4 marks- The function of the mitochondrion is aerobic respiration- The inner membrane is highly folded into folds called cristae- Giving a larger surface area for chemical reactions to take place- It has enzymes to synthesise the process of aerobic respiration

40a. Define the term stem cell. 1 mark- A stem cell is a cell with the unique ability to divide into a cell type apart from its own.

40b. Suggest one therapeutic use of stem cells. 1 mark- Treat Leukemia, multiple sclerosis or Alzheimer’s disease

40c. Discuss the benefits and problems of stem cells. 4 marksBenefits:- Allows some diseases to be cured.- Damaged tissues can now be replaced with new tissues.- Almost any type of cell can be made.- Tissue rejection is much less likely

Problems:- If using embryonic stem cells, an embryo must be destroyed. This results in debates of the ethics of doing so- Also, there are limited umbilical cords and discarded embryos and thus, there is more demand than supply resulting in only the rich being able to afford this sort of treatment.