2024 AQA AS BIOLOGY CELL STRUCTURE EXAM QUESTIONS WITH CORRECT ANSWERS, Exams of Advanced Education

Download 2024 AQA AS BIOLOGY CELL STRUCTURE EXAM QUESTIONS WITH CORRECT ANSWERS and more Exams Advanced Education in PDF only on Docsity! 2024 AQA AS BIOLOGY CELL STRUCTURE EXAM QUESTIONS WITH CORRECT ANSWERS    Give one advantage of using a SEM rather than a TEM - CORRECT- ANSWERSCan produce 3D images Thin sections do not need to be prepared Give one advantage of using a TEM rather than an SEM - CORRECT- ANSWERSTEM has a higher resolution Name 2 structures in an epithelial cell from the small intestine that are not present in a cholera bacterium - CORRECT-ANSWERSNucleus Mitochondria State in which process ribosomes are important. - CORRECT- ANSWERSProtein synthesis List three carbohydrates that are absorbed by an epithelial cell of the small intestine. - CORRECT-ANSWERSGlucose, fructose, galactose State the organelle that possesses cristae - CORRECT-ANSWERSMitochondria State the organelle that contains chromatin. - CORRECT-ANSWERSNucleus State the organelle that synthesises glycoproteins. - CORRECT- ANSWERSGolgi apparatus State the organelle that digests worn out organelles. - CORRECT- ANSWERSLysosome Suggest 2 organelles that might be numerous and/or well developed in a sperm cell. - CORRECT-ANSWERSMitochondria, nucleus Suggest 2 organelles that might be numerous and/or well developed in one type of white blood cell that engulfs and digests foreign material. - CORRECT- ANSWERSGolgi apparatus, lysosomes Suggest 2 organelles that might be numerous and/or well developed in liver cells that manufacture proteins and lipids at a rapid rate. - CORRECT- ANSWERSRough ER, ribosomes, mitochondria, smooth ER Explain what is meant by a tissue. - CORRECT-ANSWERSA collection of similar cells aggregated together to perform a specific function. Explain why an artery is describes as an organ whereas a blood capillary is not. - CORRECT-ANSWERSAn artery is made up of more than one tissue whereas a blood capillary is made up of only one tissue. It would be possible to kill more cancer cells if the same dose of the drug was given more frequently. Suggest why the drug was not given more frequently. - CORRECT-ANSWERSIf the frequency was increased the healthy body cells would not have time to increase their numbers to near normal again between treatments. Their numbers would decline rapidly after a few treatments and possibly kill the patient. It would be possible to kill more cancer cells if a larger dose of the drug was used each time. Suggest why the dose of the drug was not increased. - CORRECT- ANSWERSThe increased dose would kill even more healthy cells each time and again their numbers would decline rapidly after a few treatments. List the three main stages of the cell cycle. - CORRECT-ANSWERSInterphase, nuclear division, cell division Suggest an advantage and a disadvantage of having offspring that are genetically identical to their parents. - CORRECT-ANSWERSAdvantage- The genetic makeup of the parent has enabled it to survive and reproduce, so offspring will be able to too. Disadvantage- Genetic variety is limited- may fail to adapt to new conditions and become extinct. What is a plant cell wall made of? What is a fungal cell wall made of? - CORRECT-ANSWERSCellulose Chitin What are the functions of a plant cell vacuole? - CORRECT-ANSWERSHelps maintain pressure inside the cell Keeps cell rigid Isolates unwanted chemicals inside the cell -Image contains artefacts- hard to see what are artefacts and what is real. -Only 2D images produced Describe how a Scanning Electron Microscope works. - CORRECT-ANSWERS- Beam of electrons directed onto surface of specimen from above -Beam passed back and forth in a regular pattern -Electrons scattered across -3D image produced -Lower resolving power Describe how cell fractionation and ultracentrifugation can be used to isolate mitochondria from a suspension of animal cells. - CORRECT- ANSWERSFRACTIONATION 1. Cell homogenisation (blender) to break open cells 2. Filter to remove debris 3. Use isotonic (same water potential) solution to prevent damage to organelles 4. Keep cold to prevent damage by enzymes and use buffer to prevent enzyme denaturation CENTRIFUGATION 5. Centrifuge at lower speed to separate nuclei 6. Re-spin supernatant at higher speed to get mitochondria in pellet Name 2 structures in plant cells that are not present in animal cells - CORRECT-ANSWERSCell wall Chloroplasts Some fresh water organisms use starch as a carbohydrate store. Suggest an advantage of this. - CORRECT-ANSWERS-Starch is insoluble -Doesn't affect water potential Single-celled underwater organisms have adaptations that help them to maintain a high rate of photosynthesis. Explain what these adaptations are. - CORRECT-ANSWERS-Light sensitive eyespot to detect light -Flagellum enables movement towards light -Chloroplast/chlorophyll absorbs light for photosynthesis Describe what happens in metaphase. - CORRECT-ANSWERS-Chromosomes attach to spindle fibres -Chromosomes line up in the middle of nucleus Describe what happens in anaphase. - CORRECT-ANSWERS-Spindle fibres pull chromatids apart -to opposite poles of nucleus Cells lining the human intestine complete the cell cycle in a short time. Explain the advantage of these cells completing the cell cycle in a short time. - CORRECT-ANSWERSNew cells can be replicated rapidly to replace old cells. How many cell cycles have to occur to produce 8 cells? - CORRECT- ANSWERS3 Mikanolide is a drug that inhibits the enzyme DNA polymerase. Explain why this drug may be effective against some types of cancer. - CORRECT- ANSWERS-Prevents DNA replication -Prevents mitosis; -New strand not formed When investigating mitosis in plants, why is it necessary to take cells from the root tip? - CORRECT-ANSWERSRegion where mitosis/cell division occurs; When investigating mitosis in plants, why is it necessary to firmly squash the root tip ready for the microscope? - CORRECT-ANSWERSTo allow light through / make tissue layer thin; Describe how you could make a temporary mount of a piece of plant tissue to observe the position of starch grains when using an optical microscope. - CORRECT-ANSWERS1. Add drop of water to glass slide 2. Obtain thin section of plant tissue and float on water 3. Stain with iodine in potassium iodide 4. Lower cover slip using mounted needle. A transmission electron microscope was used to produce an image of a plant cell. Explain why. - CORRECT-ANSWERSHigh resolution See internal structure of organelles List the structures found in a bacterium cell. - CORRECT-ANSWERSCell Wall Capsule Cell-surface membrane Circular DNA Plasmid RNA Enzyme molecules List the structures found in a HIV cell. - CORRECT-ANSWERSRNA Enzyme molecules Capsid What can be evidence that a scanning electron microscope was used to take a photograph? - CORRECT-ANSWERSImage in 3D Suggest why the development of a monopolar mitotic spindle would prevent successful mitosis. - CORRECT-ANSWERS1. No separation of chromatids/chromosomes/centromeres; 2. Chromatids/chromosomes all go to one pole/end/sides of cell/not pulled to opposite poles; 3. Doubles chromosome number in cell/one daughter cell gets no chromosomes or chromatids; Chloroplasts have a greater mass than mitochondria but a smaller mass than nuclei. Starting with a sample of plant cells, describe how you would obtain a sample rich in chloroplasts. - CORRECT-ANSWERS-Keep the plant cells in a cold, buffered, isotonic solution -Break up the cells using a homogeniser -Filter the homogenate to remove cell debris -Centrifuge the homogenate at 1000 times gravity and remove the supernatant liquid -Centrifuge the supernatant liquid at 2000-3000 times gravity -Sediment produced will be rich in chloroplasts. Explain how the electron microscope is able to resolve objects better than the light microscope. - CORRECT-ANSWERSThe electron microscope uses a beam of electrons that has a much smaller wavelength than the light microscope. Explain why specimens have to be kept in a near-vacuum in order to be viewed effectively using an electron microscope. - CORRECT- ANSWERSElectrons are absorbed by the molecules in air which would prevent the electrons reaching the specimen In practise, the theoretical resolving power of an electron microscope cannot always be achieved. Explain why not. - CORRECT-ANSWERSThe preparation of the specimens may not be good enough