paper 2 past exam questions

• Which of the statements, A to D, is not a role of membranes in cells?

  • provides support for cell
• Which of the statements, A to D, about amylopectin is correct?

  it contains 1-4 and 1-6 glycosidic bonds between α-glucose monomers
• Which of the following processes occur during DNA replication?

  • breakage and reformation of hydrogen bonds
  • alignment of free nucleotides with their complementary bases
• Which of the following statements about a pioneer community are correct?

  • species produce large numbers of wind carried seeds or spores
  • biomass is low
  • many species are lichens and mosses
• Which of the options, A to D, is a primary defence against pathogens?

  • inflammation
• Which of these processes is important in determining the body plan of an organism?

  • apoptosis
  • mitosis
• Which of the methods of pathogen transmission does not apply to plants?

  • direct contact
  • vectors
• Suggest why it was not appropriate to estimate the number of jaguars using the capture-recapture technique.

  • estimate will be inaccurate
  • dangerous
• Other evidence used to estimate the jaguar population includes footprints and reports of sightings by local humans. Suggest one disadvantage of each of these methods for estimating the size of the jaguar population.

  human sightings = seeing the same individual twice

  footprints = misidentification
• Conservationists have been working with: • local people to promote sustainable use of these resources; and • government agencies to maintain the quality of the national park. Explain why the Madidi National Park is an example of conservation rather than preservation.

  • there are local people there
  • sustainable use
• A ratio that is different from the expected 9 : 3 : 3 : 1, in a cross such as this, can be the result of epistasis. Suggest and explain one reason, other than epistasis, why the phenotype ratio might not be 9 : 3 : 3 : 1.

  • autosomal linkage
  • no independent assortment
  • alleles occur on same chromosome
• With reference to the proteins coded for by the seed colour gene, explain why the y allele is recessive.

  • enzyme will still be synthesised even if you only have one Y allele
• Potatoes are susceptible to infection by a pathogen called Phytophthora infestans, which causes a disease known as potato late blight. The most visible sign of the disease is a brown discolouration of the leaves. Some varieties of potato are resistant to infection by P. infestans. State two ways in which an individual S.tuberosum plant could respond to infection by P.infestans

  • leaf drop
  • necrosis
• Suggest why it is important to use clones in an investigation such as this

  • no genetic variation
  • control more variables
• The base sequences of homeobox genes in humans and chimpanzees are almost identical. What conclusions about the evolutionary relationship between humans and chimpanzees can be drawn from this piece of evidence?

  • humans and chimpanzees belong to the same kingdom
• State two other structural similarities between lactose and maltose.

  • two hexoses
  • rings contain one oxygen atom

  
• lactose

  • contains beta glucose
  • B-glycosidic bond
  • sugars flipped
  • one glucose monomer and one galactose monomer

  Maltose

  • both monomers are glucose
  • alpha glucose
  • a-glycosidic bond
  • both monomers in same direction
• Explain how the structure of galactose allows it to be used as a respiratory substrate.

  • bonds contain energy
  • bonds can be broken by respiratory enzymes
  • soluble, so can move within cell
• Suggest and explain why lactose is unable to cross membranes

  • too big
  • need to use carrier protein
• In order for lactose to enter the cytoplasm of Ecoli a protein is required. The Ecoli living in the digestive system of young mammals are more likely to contain this protein than Ecoli living in the digestive system of old mammals. Suggest an explanation for this observation.

  • mammal diet high in milk, high lactose concentration
  • protein is lactose permease
• Some people are concerned about genetic modification. State one valid concern that people have about the genetic modification of bacteria.

  • increase in antibiotic resistance