BIOLOGY MOCK AS 1 2022 QUESTIONS

• Describe the mechanism for the absorption of amino acids in ileum;

  • facilitated diffusion of amino acids into cell by co transport
  • sodium ions actively transported out from cell into blood
  • creating sodium ion conc gradient
  • facilitated diffusion Of amino acids into blood
• 2 types of molecule which a ribosome is made :

  • RNA
  • protein
• Figure 2 is a diff image of this bacteria using TEM. explain one difference between these images:

  • 3D with TEM
  • Electrons bounce off specimen using SEM
• The resolution of an image obtained using an electron microscope is higher than the resolution of an image obtained by an optical. explain why:

  • shorter wavelength between electrons
• 2 structure found in all bacteria and Not found in plant cells:

  • circular dna
  • murein cell wall
• 2 features of hiv particles that are Not found in bacteria:

  • capsid
  • reverse transcriptase
• What can you conclude about the uptake of oxygen over the entire body of the lungworm:

  • enters by diffusion down a conc gradient
  • mostly across part of body with gills
  • gills increase SA:V
• Describe how scientists would use info from colorimeter and callibration curve to determine PO2 in a sample of lungworm:

  • measure light absorption
  • draw line to curve then to PO2
• Describe how monomers join to form primary structure of protein:

  • condensation reaction between amino acids
  • forming peptide bond
  • creating specific sequence of amino acids
• Describe one similarity and one difference between the induced fit model of enzyme and lock and key model:

  • similarly = ES complex formed
  • diff = active site changes shape but not in lock and key
• Explain how iron ions carry out role in RBC:

  • iron ions are polar
  • so bonds with oxygen
• Explain why iron ion conc is higher in the plasma of people with haemochromatosis:

  • no ferrportin hydrolysis
  • so more in the cell surface membrane
  • so more iron transport from Cytoplasm
• Tumor :

  • abnormal cell growth by uncontrolled cell division
• Describe how you would determine a reliable MI from tissue observed with optical microscope:

  • count cells in mitosis
  • divide by total cells in view
  • repeat 5x
• Describe how the composition of blood in the pulmonary artery of a fetus is different from the mother:

  • fetal blood has more oxygen
  • because gas exchange occurs in placenta
• How a Fetus is protected against pathogens that infect mother during pregnancy:

  • antibodies from mother bind specifically to pathogens
  • giving passive immunity to fetus