RANDOM AS - SHORT EXAM QS

    Cards (59)

    • Give the two types of molecule from which a ribosome is made?
      rRNA/ RNA
      Protein
    • 4 structural differences between DNA and mRNA?
      DNA has deoxyribose, mRNA has ribose
      DNA is double stranded/ helix, mRNA is single stranded
      DNA is long, mRNA is short
      DNA has thymine, mRNA has uracil
      DNA has hydrogen bonds, mRNA has no hydrogen bonds
      DNA has complementary base pairing, mRNA does not
    • One difference between TEM and scanning electron microscope? and why?
      3D with SEM, but 2D with TEM OR
      only surface visible with SEM but internal structures visible with TEM
      ---------------------------------------------
      because electrons are deflected (in SEM)
      OR
      electrons transmitted/pass through (using TEM)
    • The resolution of an image obtained using an electron microscope is higher than the resolution of an image obtained using an optical microscope. EXPLAIN WHY?
      shorter wavelengths between electrons
      OR
      longer wavelengths between light
    • A student determined the size of a cell structure from a photograph obtained using a microscope. He used a ruler and a calculator and answered μm. Describe how the student determined the size of the structure (2)?
      Measure the length of the structure
      divide by magnification
      correct conversion from measured length to micrometers.
    • Name two structures found in all bacteria that are not found in plant cells?
      Circular DNA
      Murein cell wall/ peptidoglycan cell wall/ glycoprotein cell wall
    • Name two features of HIV particles that are not found in bacteria. (2)?
      Envelope proteins
      Reverse transcriptase
      Caspid
      RNA genome
    • Describe how the scientist will use information from the colorimeter and her calibration curve to determine the pO2 in a sample of lugworm blood.?
      Measure light (absorption/transmission)
      interpolate/ draw line to curve line then to pO2
      or read off pO2 figure against absorbance/transmission value obtained
    • Describe how monomers join to form the primary structure of a protein?
      Condensation reaction between amino acids
      forming peptide bonds
      creating specific sequence/ order of amino acids
    • Describe one similarity and one difference between the induced-fit model of enzyme action and the lock and key model of enzyme action.?
      Similarity:
      • substrate fits/binds to active site
      • OR enzyme substrate complex formed
      Difference:
      • Active site changes shape, but does not change in lock and key
    • State how enzymes help reactions to proceed quickly at lower temperatures?
      Reduce activation energy
    • Explain a property of iron ions that enables these ions to carry out their role in red blood cells.?
      Is charged/ polar - so is part of haem
      SO binds/associated/loads oxygen
      OR forms oxyhaemoglobin
      OR transports oxygen
    • What is a tumour?

      Mass abnormal cells/ tissue
      produced from uncontrolled mitosis/ cell division
    • Describe how you would determine a reliable mitotic index (MI) from tissue observed with an optical microscope.?
      Count cells in mitosis in field of view
      Divide this by the total number of cells in field of view
      Repeat many times (min 5 times)
      OR
      select field of view at random
    • The student used a sterilised pipette to transfer E. coli into each culture. Suggest why the number of E. coli cells per mm3 in each culture after 24 hours might have been lower if the student had not used a sterilised pipette. Explain your answer?
      Unknown/ new microorganisms/bacteria/pathogens introduced
      These bacteria use food or space
      and produce toxins
    • Describe how the composition of blood in the pulmonary artery of a fetus is different from the composition of blood in the pulmonary artery of its mother.?
      Fetal blood has more oxygen + less CO2
      because gas exchange occurs in placenta
      BUT does not occur in fetal lungs
    • Explain how a fetus is protected against the pathogens that infect its mother during pregnancy (lines 5–6)?
      Antibodies from mother are complementary/ bind specifically
      To pathogens crossing the placenta
      Giving passive immunity in fetus
      OR
      giving immediate protection in fetus
    • Explain how a fetus is protected against the pathogens that infect its mother during pregnancy (lines 5–6)?
      production of more memory cells
      so higher concentration of antibodies in blood
      so more rapid production of antibodies (on further infection)
    • What is a gene?

      A sequence of DNA bases that codes for a polypeptide
    • Describe how the production of messenger RNA (mRNA) in a eukaryote cell is different from the production of mRNA in a prokaryote cell?
      Pre-mRNA produced in eukaryote cell
      Splicing only occurs in eukaryote cell
      Introns removed in eukaryote
      INTRONS not present in prokaryote
    • Scientists produced a short, single-stranded, artificial nucleic acid, called PNA. The PNA binds to a small section of DNA. The scientists introduced PNA into cells and discovered that these cells produced less mRNA than cells that did not contain PNA. Suggest how PNA affected the transcription of the section of DNA (2)?
      PNA is complementary to DNA/ forms base pairs with DNA
      Prevents RNA polymerase activity/binding
      OR reduces transcription
    • Describe the role of ATP in the process of translation in protein synthesis?
      Provides energy
      So peptide bonds form between amino acids
      OR amino acids join to tRNA
    • What term is used to describe the different structures of α-glucose and β-glucose?
      Isomers
    • A student investigated the difference in the reducing sugar content of two fruit juices. He performed a biochemical test on each fruit juice using Benedict’s solution. He then used a colorimeter with each test result. Describe how the results from the colorimeter can identify the fruit juice containing the higher sugar content?
      Higher absorbance has more sugar
      OR lower transmission has more sugar
    • The student controlled variables in the test using Benedict’s solution. Give two variables the student controlled.?
      Benedicts solution - VOLUME
      Benedicts solution - CONC
      Fruit juice - VOL
      Water bath - Temperature
    • Iodine solution stains fresh apple tissue black. When iodine solution is added to apples stored for a week, the stain is less black. The water potential of apple juice decreases when apples are stored. Suggest why the water potential of apple juice decreases when apples are stored?
      Starch has hydrolysed
      Maltose is soluble - so has reduced water potential
      OR STARCH IS INSOLUBLE
    • Describe and explain two ways that structures shown in Figure 1 increase the rate of absorption by this cell?
      Microvilli increase surface area for DIFFUSION or FOR more channel/carrier proteins
      AND many mitochondria release ATP for active transport
    • The protein ZO-1 is found on the surface of ileum cells. A scientist used an anti-ZO-1 monoclonal antibody to identify ileum cells in a sample of intestine observed using an optical microscope. Suggest how the monoclonal antibody helped the scientist to identify ileum cells in the sample of intestine.?
      ZO-1 located in cell surface membrane
      Antibody is complementary to ZO-1
      so it binds to THE ZO-1 protein
      CELLS identified with stain/dye or fluroscent marker linked to antibody
    • Describe how organisms are grouped in a phylogenetic classification system?
      Hierarchy of groups with no overlaps // SMALLER GROUPS WITHIN LARGER GROUPS WITH NO OVERLAPS
      Grouped according to evolutionary origins
    • give three control measures the student must use to reduce the risks associated with carrying and using a scalpel?
      Carry with blade protected
      Cut away from body
      Cut on hard surface
      Disinfect/ dispose of used scalpel (as instructed)
    • Name the type of selection the scientist investigated in this fish tank. Explain why this selection affected the frequency of alleles in the population of guppies in this fish tank?
      Directional
      Fish with more spots more likely to be predated
      Alleles for more spots not passed on
      so frequency of more spots alleles decreases
    • Suggest: • a further investigation the scientist could do to confirm that the brightly coloured stones had affected guppy behaviour • a null hypothesis for the new investigation.?

      Investigation: repeat without stones/ or with uniformly coloured stones Null hypothesis: Brightly colored stones have no effect on guppy behavior.
    • Suggest one type of guppy behaviour that could be affected by the presence of brightly coloured stones.?
      Mating/ courtship/ sexual behaviour
    • Other than a change in temperature, give one change the scientist could make to the environmental conditions to increase the cut flowers’ shelf life?
      Reduce light intensity
      Stomata close
      So decreased rate of transpiration/evaporation
      ----------------------------------------------
      Increase humidity
      Reduces water potential gradient
      Decreased rate of transpiration/evaporation
    • Name the type of bond between: complementary base pairs?
      Hydrogen bonds
    • Name the type of bond between: adjacent nucleotides in a DNA strand?
      phosphodiester bond
    • Describe two differences between the structure of a tRNA molecule and the structure of an mRNA molecule.?
      tRNA has clover leaf shape, mRNA is linear
      tRNA has hydrogen bonding, mRNA does not
      tRNA has an amino acid binding site, mRNA does not
      tRNA has anticodon, mRNA has codon
    • In a eukaryotic cell, the structure of the mRNA used in translation is different from the structure of the pre-mRNA produced by transcription. Describe and explain a difference in the structure of these mRNA molecules?
      mRNA has no introns - only exons (less nucleotides)
      OR
      pre-mRNA has exons and introns (more nucleotides)
      because of splicing
    • Explain why it is not possible to determine the identity of the structures labelled X using an optical microscope.?
      resolution is too low
      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.?
      Lysosomes
      fuse with vesicles
      release hydrolytic enzymes
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