AS papers Flashcards by I S

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

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State a method to determine whether a person is obese. (1)

waist to hip ratio

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Describe how high blood pressure can be reduced by medication and lifestyle changes. (3)

treatment w/ antihypertensive medication
reduce salt intake
increase exercise

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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

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Name the products when several a.a are joined together

polypeptide and water

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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

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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

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Explain why a snake needs a heart. (2)

to supply oxygen to body cells
by mass transport

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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

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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

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Give one structural difference between amylose and amylopectin. (1)

amylopectin is branched, amylose is not.

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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

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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

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Explain why sucralose cannot be broken down by sucrase. (2)

sucralose contains Cl
therefore shape of molecule has changed

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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

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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