topic 2 ppqs Flashcards

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1
Q

explain why it is not possible to determine the identity of the structures labelled X using an optical microscope [2]

A
  • resolution is too low
  • because wavelength of light it too long
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2
Q

describe the role of one named organelle in digesting (these) bacteria [3]

A
  • lysosomes
  • fuse with vesicle
  • to release hydrolytic enzymes
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3
Q

describe how a sample of chloroplasts could be isolated from leaves [4]

A
  • break open cells and filter
  • in ice cold isotonic buffer solution
  • centrifuge to remove nuclei
  • centrifuge at higher speed so nuclei settle out
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4
Q

outline the role of organelles in the production, transport and release of proteins from eukaryotic cells [4]

A
  • DNA in the nucleus is code for protein
  • ribosomes / rough endoplasmic reticulum produce protein
  • mitochondria produce ATP for protein synthesis
  • golgi apparatus packages and modifies
  • vesicles transport
  • vesicles fuse with cell-surface membrane
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5
Q

explain how the body responds to a cold and suggest why you can get a cold again [5]

A
  • you will complete the primary immune response after first exposure to cold virus
  • producing specific memory T/B lymphocytes
  • secondary immune response is only possible if re-exposed to same strain with same virus
  • there are multiple strains of cold virus
  • these strains all have different antigens
  • more likely to encounter strain with different antigen, requiring new primary immune response
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6
Q

2 changes to the structure of the cell-surface membrane that would increase the rate at which glucose is transported into the cell

A
  1. increase SA with microvilli
  2. more proteins with pores that span the PLB
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7
Q

explain why glucose does not easily pass through the PLB [2]

A
  • only lipid-soluble substances diffuse across the PLB easily
  • water-soluble substances (like glucose) diffuse only very slowly
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8
Q

explain why reabsorption of glucose into the blood in the kidneys occurs by active transport rather than by diffusion [2]

A
  • diffusion, at best, can only reabsorb 50% of the glucose lost from the blood
    > the other 50% will be lost from the body
  • active transport can absorb all of the glucose, leaving none to be lost from the body
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9
Q

how can rate of movement across membranes be increased? [3]

A
  • increase SA
  • increase concentration gradient
  • increase density of protein channels
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10
Q

why does the body’s immune system take a number of days to control the pathogen after it has entered? [1]

A

lymphocytes that will finally control the pathogen need to build up their numbers and this takes time

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11
Q

why would it be inaccurate to say that the body takes days to ‘respond’ to the pathogen? [1]

A

the body ‘responds’ to the pathogen immediately; the delay is in building up the numbers of lymphocytes and therefore controlling the pathogen

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12
Q

suggest why lysozymes are also found in tears [3]

A
  • the protective covering of the eye, especially the tear ducts, are potential entry points for pathogens
  • the eyes are vulnerable to infection because the coverings are thin to allow light through
  • lysozymes will break down the cell walls of any bacterial pathogens and so destroy them before they can cause harm
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13
Q

suggest why antibodies made of proteins, rather than carbohydrates or fats, are more likely to be effective against a wider range of diseases [2]

A
  • there must be a massive variety of antibodies as each responds to a different antigen, of which there are millions
  • only proteins have the diversity of molecular structure to produce millions of different types
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