EXAM QUESTIONS

• (IMAGE) EXPLAIN WHY IT IS NOT POSSIBLE TO DETERMINE THE IDENTITY OF THE STRUCTURES LABELLED X USING AN OPTICAL MICROSCOPE

  1. Resolution is too low
  2. because wavelength of light is too long

  
• U. MARINUM CELLS INGEST BACTERIA AND DIGEST THEM IN THE CYTOPLASM.

  DESCRIBE THE ROLE OF ONE NAMED ORGANELLE IN DIGESTING THESE BACTERIA

  1. Lysosomes
  2. fuse with vesicles
  3. releasing hydrolytic enzymes

  
• GIVE TWO STRUCTURES FOUND IN ALL PROKARYOTIC CELLS AND IN ALL EUKARYOTIC CELLS

  1. cell surface membrane
  2. ribosomes
  3. cytoplasm
  4. DNA
• (IMAGE) SUGGEST ONE EXPLANATION FOR THE FASTER RATE OF PLASMID REPLICATION IN CELLS GROWING IN A CULTURE WITH A HIGH AMINO ACID CONCENTRATION

  1. Amino acids used in protein synthesis
  2. so more enzymes for DNA / plasmid replication

  OR

  1. amino acids used in respiration
  2. so more energy for DNA / plasmid replication

  
• (IMAGE) WHAT CAN YOU CONCLUDE FROM THE FIGURE ABOVE ABOUT A STRUCTURAL DIFFERENCE BETWEEN THE PLASMIDS AND THE CIRCULAR DNA? EXPLAIN YOUR ANSWER.

  1. circular dna is heavier
  2. because band is closer to the bottom of the tube

  
• DESCRIBE HOW A SAMPLE OF CHLOROPLASTS COULD BE ISOLATED FROM LEAVES

  1. grind Leaves to break cells open and filter
  2. in cold, isotonic, buffered solution
  3. centrifuge and remove cell debris / nuclei
  4. Centrifuge at a higher speed so chloroplasts settle
• (IMAGE) GIVE ONE FEATURE OF THE CHLOROPLAST THAT ALLOWS PROTEIN TO BE SYNTHESISED INSIDE THE CHLOROPLAST AND DESCRIBE ONE DIFFERENCE BETWEEN THIS FEATURE IN THE CHLOROPLAST AND SIMILAR FEATURES IN THE REST OF THE CELL

  1. DNA
  2. isn’t associated with histones but nuclear DNA is / is shorter than DNA / is circular but nuclear DNA is linear

  OR

  1. ribosomes
  2. are 70s ribosomes in chloroplast but 80s ribosomes in cytoplasm

  
• (IMAGE) CONTRAST THE STRUCTURE OF THE TWO CELLS VISIBLE IN THE ELECTRON MICROGRAPHS SHOWN IN THE FIGURE

  1. magnification shows A is bigger than B
  2. a has a nucleus, B has free DNA
  3. A has mitochondria, B doesn’t
  4. A has Golgi body / endoplasmic reticulum, B doesn’t
  5. A has no cell wall, B has a murein cell wall
  6. A has no capsule, B does
  7. A has DNA bound to histones, B isn’t associated with histones / A has linear DNA, B has circular DNA
  8. A has larger ribosomes

  
• EUKARYOTIC CELLS PRODUCE AND RELEASE PROTEINS. OUTLINE THE ROLE OF ORGANELLES IN THE PRODUCTION, TRANSPORT AND RELEASE OF PROTEINS FROM EUKARYOTIC CELLS. DO NOT INCLUDE DETAILS OF TRANSCRIPTION AND TRANSLATION.

  1. DNA in nucleus is code for protein
  2. ribosomes produce protein
  3. mitochondria produce ATP for protein synthesis
  4. Golgi apparatus package / modify
  5. vesicles transport
  6. vesicles fuse with cell membrane
• (IMAGE) SUGGEST WHY A NUCLEUS IS NOT VISIBLE IN THE IMAGE

  nucleus isn’t stained or its a only a section so Nucleus is in another part of the cell

  
• (IMAGE) NAME THE ORGANELLES LABELLED S AND T IN THE IMAGE

  S = Vacuole

  T = chloroplast

  
• GIVE ONE ADVANTAGE OF VIEWING A BIOLOGICAL SPECIMEN USING A TRANSMISSION ELECTRON MICROSCOPE COMPARED WITH USING A SCANNING ELECTRON MICROSCOPE

  higher resolution

  OR

  view internal structures
• (IMAGE) IDENTIFY STRUCTURES LABELLED D AND E

  D = granum / thylakoid

  E = starch / lipid

  
• (IMAGE) THE DETAIL SHOWN IN THE DIAGRAM WOULDNT BE SEEN USING AN OPTICAL MICROSCOPE. EXPLAIN WHY.

  1. light has a longer wavelength
  2. so lower resolution

  
• NAME AN ORGANELLE FOUND IN BOTH A CHLOROPLAST AND A PROKARYOTIC CELL

  70s ribosomes
• (IMAGE) DESCRIBE THREE PROPERTIES OF THIS SOLUTION AND EXPLAIN HOW EACH PROPERTY PREVENTED DAMAGE TO THE ORGANELLES

  1. cold to reduce enzyme activity
  2. buffered to prevent denaturing of enzyme
  3. isotonic to prevent osmosis to prevent bursting of organelle

  
• (IMAGE)

  yes, yes, no, no

  no, no, no, yes

  no, no, yes, no

  
• (IMAGE) NAME THE STRUCTURES W, X, Y, Z

  W = cell surface membrane

  X = cell wall

  Y = capsule

  Z = flagellum

  
• (IMAGE) NAME THE MAIN BIOLOGICAL MOLECULE IN:

  W = phospholipids

  X = murein

  
• NAME THE PROCESS BY WHICH PROKARYOTIC CELLS DIVIDE

  binary fission
• (IMAGE)

  B

  A

  E

  
• (IMAGE) WHAT TYPE OF MICROSCOPE WAS USED TO OBTAIN THE IMAGE? GIVE ONE PIECE OF EVIDENCE TO SUPPORT YOUR ANSWER.

  1. scanning electron microscope
  2. 3D image

  
• CONTRAST HOW AN OPTICAL MICROSCOPE AND A TRANSMISSION ELECTRON MICROSCOPE WORK AND CONTRAST THE LIMITATIONS OF THEIR USE WHEN STUDYING CELLS.

  1. TEM use electrons and optical uses light
  2. TEM allows a greater resolution
  3. so with TEM smaller organelles can be observed
  4. TEM view only dead specimens and optical view live specimens
  5. TEM doesn’t show colour and optical can
  6. TEM requires thinner specimens
  7. TEM requires a more complex prep
  8. TEM requires using magnets and optical requires glass lenses
• (IMAGE) USING THE DIAGRAM AND YOUR KNOWLEDGE, WHAT IS THE CORRECT STATEMENT ABOUT THE STRUCTURES OF THE BACTERIOPHAGE AND THE BACTERIUM

  the bacteriophage has a capsid and the bacterium has a cell-surface membrane

  
• (IMAGE) NAME THE ORGANELLE LABELLED B AND C

  B = Golgi apparatus

  C = mitochondria

  
• NAME TWO STRUCTURES PRESENT IN PLANT CELLS THAT ARE NOT PRESENT IN ANIMAL CELLS

  1. Chloroplasts
  2. cell wall
  3. cell vacuole
  4. starch grains
• (IMAGE) EXPLAIN WHY THE SOLUTION THE BIOLOGIST USED WAS ICE COLD, BUFFERED AND THE SAME WATER POTENTIAL AS THE LIVER TISSUE

  1. ICE COLD = slows enzyme activity to prevent digestion of organelles
  2. BUFFERED = maintains pH so that enzymes aren’t denatured
  3. SAME WATER POTENTIAL = prevents osmosis so no lysis of organelles

  
• (IMAGE) EXPLAIN WHY THE BIOLOGIST USED A BLENDER AND THEN FILTERED THE MIXTURE

  1. break open cells (homogenise)
  2. remove unbroken cells / larger debris

  
• (IMAGE) NAME THE ORGANELLE THAT MADE UP MOST OF THE FIRST PELLET AFTER CENTRIFUGING AT A LOW SPEED

  nuclei

  
• (IMAGE) THE SECOND CENTRIFUGE TUBE WAS SPUN AT A HIGHER SPEED TO OBTAIN THE SAMPLE OF ORGANELLES LABELLED C IN THE DIAGRAM. SUGGEST WHY.

  Organelle C is less dense than organelle in first pellet

  
• (IMAGE)

  yes, no

  no, no

  yes, no

  no, yes

  
• DNA AND RNA CAN BE FOUND IN BACTERIA. GIVE TWO WAYS IN WHICH THE NUCLEOTIDES IN DNA ARE DIFFERENT FROM THE NUCLEOTIDES IN RNA.

  1. DNA contains thymine and RNA contains uracil
  2. DNA contains deoxyribose and RNA contains ribose
• (IMAGE) THE CELL SURFACE MEMBRANE CAN BE SEEN WITH A TRANSMISSION ELECTRON MICROSCOPE BUT NOT WITH AN OPTICAL MICROSCOPE.

  electron microscope has a higher resolution than Optical microscope.

  
• (IMAGE) NO ORGANELLES ARE VISIBLE IN THE CYTOPLASM OF THIS RED BLOOD CELL. SUGGEST WHY.

  Cytoplasm of red blood cell filled with haemoglobin

  
• (IMAGE) BEFORE THE CELL WAS EXAMINED USING THE ELECTRON MICROSCOPE, IT WAS STAINED. THIS STAIN CAUSED PARTS OF THE STRUCTURE OF THE CELL-SURFACE MEMBRANE TO APPEAR AS TWO DARK LINES.

  SUGGEST AN EXPLANATION FOR THE APPEARANCE OF THE CELL-SURFACE MEMBRANE AS TWO DARK LINES.

  1. Membrane has phospholipid bilayer
  2. Stain binds to phosphate / glycerol
  3. on inside and outside of membrane

  
• (IMAGE) NAME THE PARTS OF THE CHLOROPLAST LABELLED A AND B

  A = Stroma

  B = granum

  
• NAME TWO STRUCTURES IN A EUKARYOTIC CELL THAT CANNOT BE IDENTIFIED USING AN OPTICAL MICROSCOPE

  mitochondria, ribosome, endoplasmic reticulum, lysosome, cell surface membrane
• DESCRIBE HOW YOU COULD MAKE A TEMPORARY MOUNT OF A PIECE OF PLANT TISSUE TO OBSERVE THE POSITION OF STARCH GRAINS IN THE CELLS WHEN USING AN OPTICAL MICROSCOPE.

  1. add drop of water to glass slide
  2. obtain thin section of plant tissues and place on slide
  3. stain with iodine
  4. lower cover slip using mounted needle
• (IMAGE) GIVE THE NAME AND FUNCTION OF THE STRUCTURE LABELLED W AND Z

  W - chloroplast - photosynthesis

  Z - nucleus - contains DNA, holding genetic information of the cell

  
• (IMAGE) A TRANSMISSION ELECTRON MICROSCOPE WAS USED TO PRODUCE THE IMAGE IN THE FIGURE. EXPLAIN WHY.

  1. High resolution
  2. can see internal structure of organelles