BIOLOGY MOCK 2022 A LEVEL QUESTIONS

• Describe the structure and function of nucleus:

  • nuclear envelope and pores
  • chromosomes
  • nucleolus
  • produces mRNA, tRNA, mRNA
  • stores genetic info for polypeptide production
• name the main polymer that forms plant and fungal Cell wall:

  • plant = cellulose
  • fungal = chitin
• Explain how the use of antibiotics has lead to antibiotic resistant strains of bacteria becoming a common cause of infection in hospital:

  • some bacteria have alleles for resistance
  • non resistant bacteria die
  • more antibiotics used in hospitals
• Name the disaccharide formed from 2 glucose molecules

  • maltose
• Give 2 features of all prokaryotic cells that are not in eukaryotic cells :

  • circular dna
  • dna Not associated with proteins/histones
• What type of bond maintains the helical structure of the polypeptide

  • hydrogen
• Suggest how the properties of AP allow them to become positioned across the membrane and make a channel which ions can pass :

  • hydrophobic side next to fatty acids
  • hydrophilic side forms a channel
• why the AP don’t damage the eukaryotic cell of the organism that produces them:

  • cholesterol stabilises the membrane
  • AP Can’t enger eukaryotic membrane
• Observation of APs on prokaryotes when stained with gold monoclonal antibodys with a microscope:

  • antibody binds to AP
  • antibody complimentary to AP
  • gold interacts with electrons in TEM
  • TEM used as high resolution
• Describe viral replication:

  • attachment proteins attach to receptors
  • viral nucleic acid enters cell and replicated
  • cell produces viral proteins
  • virus released from cell by exocytosis
• Define the quarternary structure of protein:

  • more than 1 polypeptide
• Explain how 2 enzymes with diff amino acid sequences can catalyse the same reaction:

  • both active sites have similar tertiary structure
  • so ES complexes are formed
• Describe an experiment that you could do to investigate whether the mangrove root cells have a lower water potential than seawater:

  • record mass before and after
  • place in sea water for equal time
  • tissue to remove surface water
  • increace mass = water absorbed by osmosis
• 3 differences in DNA to TRNA:

  • TRNA- ribose , uracil, clover shape
  • DNA- deoxyribose, thymine , linear
• How scientists would remove large organelles from cell mix :

  • centrifuge at high speeds
  • dense organelle removed first
• Transport of carbs in plants:

  • sucrose actively transported into phloem
  • by companion cells
  • lowers water potential in phloem and water enters from xylem by osmosis
  • makes higher hydrostatic pressure
  • carbs unloaded from phloem by active transport
• Structure of starch vs cellulose :

  • both polysacchrides, contrails glycosidic bonds between monomers, have C H O
  • differences. Starch has alpha glucose,coiled,branched,microfibrils
  • cellulose has beta glucose,straight,not branched, no fibrils
• Digestion of starch by mammal:

  • hydrolysis
  • of glycosidic bonds
  • starch to maltose by amylase
  • maltose to glucose by maltase