AS papers Flashcards
Three differences between DNA replication and DNA transcription. (3)
- rep = DNA nucleotides
trans = RNA nucleotides - rep = DNA polymerase
trans = RNA polymerase - rep produces double stranded DNA
trans produces single stranded RNA
State a method to determine whether a person is obese. (1)
waist to hip ratio
Describe how high blood pressure can be reduced by medication and lifestyle changes. (3)
- treatment w/ antihypertensive medication
- reduce salt intake
- increase exercise
Explain why platelet inhibitors reduce the risk of a heart attack. (2)
- reduce risk of blood clots forming
- therefore less likely to get blocked coronary arteries
Name the products when several a.a are joined together
- polypeptide and water
State and justify a suitable method of collecting cells for prenatal testing. (3)
- chorionic villus sampling
- cells taken from placenta b/w 10-14 weeks of pregnancy
- benefit of earlier diagnosis
Compare and contrast human and snake heart/circulatory system. (4)
-both: double circulatory system
-both: 2 atria, arteries , veins , capillaries
- snake heart has 1 ventricle, human has 2
- snake heart: deoxygenated and oxygenated blood mix, they dont mix in human heart
Explain why a snake needs a heart. (2)
- to supply oxygen to body cells
- by mass transport
Explain how vein structure relates to its function. (4)
- valves prevent backflow of blood
- smooth endothelium reduces resistance to blood flow
- larger lumen also reduces resistance
- thin layer of elastic tissue to maintain blood pressure
Explain why children with CF would be given dietary supplements. (5)
- CF causes production of thicker mucus
^blocks pancreatic duct
^ prevents enzymes digesting proteins
^ therefore reduced absorption of vitamins
^ leads to slower growth rate
- dietary supplements increase growth rate
Give one structural difference between amylose and amylopectin. (1)
- amylopectin is branched, amylose is not.
Explain how the structures of amylopectin and glucose make them suitable for storing energy. (3)
- branched: rapid hydrolysis
- compact: more energy stored
- insoluble: cant effect osmosis
Explain why high sugar intake could lead to obesity. (3)
- energy intake higher than energy output
- excess sugar stored as fat
- leading to weight gain
Explain why sucralose cannot be broken down by sucrase. (2)
- sucralose contains Cl
- therefore shape of molecule has changed
Explain how changing one amino acid can change the structure of haemoglobin. (4)
- diff. primary struture
- diff. R group
- therefore, diff. secondary structure
- haemoglobin may not be able to bond to oxygen
Explain why pickling in vinegar results in pigment leaving cells. (3)
- increases permeability of cell surface membrane
- low pH denatures protein
- as vinegar affects bonds in proteins
Give one function of glycoproteins in cell surface membranes. (1)
- cell recognition
Compare and contrast the process of exocytosis and endocytosis. (3)
-both: involve vesicles
-both: involves energy from ATP
- exo: molecules leaving cells
endo: molecules entering cells
Describe how mRNA is synthesised at a template strand of DNA. (2)
- DNA nucleotides align w/ complimentary DNA bases
^ joined together by RNA polymerase
Describe the differences between DNA structure and RNA structures. (3)
- DNA: double strand , RNA is single
- DNA: deoxyribose, RNA: ribose
- DNA: thymine , RNA: uracil
Explain how a blood clot could form in a blood vessel. (4)
- damage to endothelium exposes collagen
- release of thromboplastin: converts prothrombin to thrombin
- thrombin converts: fibrinogen to fibrin
^ forms mesh of fibres & traps red blood cells to form a clot
Compare and contrast diffusion and active transport. (3)
- diffusion: along conc. gradient , AT: against
- AT requires ATP , diffusion doesn’t
- both move molecules through cell surface membrane
Explain how properties of water make it an ideal transport medium. (3)
- solvent
^ bcs water molecules surround polar molecules
- is a liquid so has ability to flow
Define: allele. (2)
- alternative form of a gene
- found at the same locus on a chromosome
Explain why the offspring have the palomino coat colour. (3)
- offspring is heterozygous
- therefore co-dominance occurs
- bcs both alleles are expressed
Name the type of genetic screening that can screen an IVF embryo before its placed in the uterus. (1)
pre-implantation genetic diagnosis
Explain one ethical issue of prenatal genetic screening. (2)
- risk of incorrect result
^ healthy foetus could be aborted
Explain how structure of blood vessels carrying blood away from heart in graph A and B are different. (3)
- aorta has thicker layer of elastic tissue
- collagen to withstand increased blood pressure
- elastic tissue to maintain blood pressure
Explain why the percentage of fluorescence inside and outside the alveolar cells changed. (4)
- fluorescence inside cell decreases
- because A.As used to synthesise proteins
- proteins packaged into vesicles
^ & leave cell by exocytosis
Explain how high salt diet effects someones CVD risk. (5)
- increases risk of CVD
- bcs higher b.p
^ damage to artery endothelium
^ inflammatory response
^ leading to risk of atheroma forming
Explain why CF produces thicker mucus. (2)
- Cl- ions cannot leave cell
- therefore water leaves mucus via osmosis
Explain the advantages of using young zebrafish for investigation. (2)
- transparent bodies
- heart more visible
Explain how human lung structure enables rapid gas exchange. (4)
- many alveoli increase s.a
- one cell thick walls = short diffusion pathway
- capillaries = short diff. path.
- high conc. gradient maintained by circulation
Describe how nucleotides join together to form DNA.
- phosphodiester bonds
- condensation reactions
Compare and contrast ATP and DNA nucleotide structures. (3)
- both: phosphate, pentose sugar & base
- DNA nuc: deoxyribose , ATP = ribose
- DNA nuc: 1 phosphate , ATP = 3
State why enzymes are described as biological catalysts. (1)
- reduce activation energy of biological reactions
Describe function of carrier proteins in c.s membrane. (4)
- involved in facilitated diffusion
^ from high to low conc.
- involved in active transport
^ needs ATP to move molecules against conc. gradient
Compare and contrast globular and fibrous protein structures. (4)
- both: A.A chains joined by peptide bonds
- both: contain H bonds
- globular: tertiary structures , fibrous = none
- globular: folded into compact shapes , fibrous: has long chains
Explain the different effects of deletion and substitution on protein structure. (4)
- del affects every codon
^ more likely to affect stop codon position
- subs may code for same A.A
^ due to degenerate nature of genetic code
