Paper 1 Flashcards
Give THREE structural features found in ALL virus particles and describe the function of ONE of these features.
[2 marks]
- Genetic material
- Capsid
- Attachment protein - binds to receptors
Explain why bacteria are described as acellular and non-living.
[2 marks]
- Not made of cells
- Have no metabolic reactions
Give one reason why antibiotics are not effective against viruses.
[1 mark]
- Do not have a cell wall/murein
Describe THREE ways the structure of chitin is similar to the structure of cellulose.
[3 marks]
- Alternate glucoses rotated 180°
- Joined by glycosidic bonds
- Forms unbranched chains
Chitin keeps the trachea open in the tracheal system of gas exchange in an insect. Gas exchange does not occur in the trachea.
Explain the importance of ONE adaptation of the gas exchange surface in the tracheal system of an insect.
[2 marks]
- Tracheoles are highly branched
- So short diffusion pathway
Lignin is a polymer found in the walls of xylem vessels in plants. Lignin keeps the xylem vessel open as a continuous tube.
Explain the importance of the xylem vessel being kept open as a continuous tube.
[3 marks]
- Allows unbroken water column
- Cohesion from H bonds between all water molecules
- Transpiration creates tension in column
Describe TWO functions of the Golgi apparatus in a eukaryotic cell.
[2 marks]
- Transport proteins
- Transport lipids
In Africa today, most of the human population are resistant to malaria caused by P.vivax.
Use your knowledge of natural selection to explain why this resistance is so common in Africa.
[4 marks]
- Mutation produced allele
- Those with allele less likely to get malaria
- So more likely to survive and reproduce and pass on the allele
- Allele frequency increases
“” Bacterium releases toxins that cause the cells lining the ileum to lose their microvilli.
Explain why damage to the cells lining the ileum reduces absorption of the products of digestion and why this reduces absorption of water.
[3 marks]
- Reduced surface area
- Decreases water potential in ileum
- So water moves out of ileum by osmosis
To be used as passive immunity treatment, anti-toxin antibody would be injected.
If it was given by mouth, it would be digested.
Describe how the anti-toxin antibody would be digested.
[3 marks]
- Peptide bonds hydrolysed
- Endopeptidases break internal peptide bonds
- Exopeptidases break terminal peptide bonds
Describe aseptic techniques.
[3 marks]
- Wash hands with soap
- Use sterile pipette
- Flame neck of bottle
- Lift lid of agar plate at an angle
- Use sterile spreader
Define genome and proteome.
[2 marks]
- Genome: All the DNA in a cell
- Proteome: Full range of proteins that a cell can produce
Consider the accuracy and limitations of the early classification of bacteria using the arrangement of flagella.
[3 marks]
- Cannot identify species
- Optical microscope resolution too low
- Not all bacteria have flagella
Suggest why several bacteria have been renamed in recent years.
[1 mark]
- Amino acid sequencing
MiTMAB inhibits cytokinesis. MiTMAB acts as a non-competitive inhibitor of an enzyme called dynamin.
Suggest how MiTMAB can cause dynamin to become inactive.
[3 marks]
- MiTMAB binds to dynamin other than the active site
- Changes the shape of dynamin active site
- Not complementary so fewer enzyme-substrate complexes form
