2023 Paper Flashcards
(10 cards)
Explain why viruses are described as acellular and non-living.
- Acellular - not made up of cells
- Non-living - cannot independently replicate
Give one reason why antibiotics are not effective against viruses.
Do not have a cell wall
Explain one adaptation of the gas exchange surface in the tracheal system of an insect.
Tracheole has a thin wall so there is a short diffusion pathway.
Explain the importance of the xylem being kept open as a continuous tube.
- allows unbroken water column
- cohesion from hydrogen bonds between water molecules
- Evaporation creates tension
Describe two functions of the golgi apparatus in a eukaryotic cell.
-modify/package/transport lipids
-modify/package/transport proteins
Describe how an antitoxin would be digested.
- peptide bonds hydrolysed
-endopeptidases break internal peptide bonds - exopeptidases break terminal peptide bonds
Describe the aseptic techniques that should be used when dealing with bacterial cultures on an agar plate.
-disinfect surfaces
use a sterile pipette to transfer bacteria
- lift the lid of the agar plate at an angle
Describe how a quaternary protein is formed from its monomers.
-amino acids joined by peptide bonds
- by condensation reactions
- Secondary structure is formed by hydrogen bonding
- Tertiary structure formed by interaction between R groups
- Quaternary structure contains more than 1 polypeptide
Describe processes that result in an increase in genetic variation within a species other than mutation.
- independent segregation of homologous chromosomes
- crossing over between homologous chromosomes
-Random fertilisation of gametes - produces new combinations of alleles.
Describe natural selection in response to a resistant gene against malaria.
-mutation produced allele
-those with resistant gene are less likely to get malaria.
- more likely to reproduce and pass on the allele
- allele frequency increases
