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Alevel Bio > AS papers > Flashcards

AS papers Flashcards

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Biology 101 flashcards
1
Q

Three differences between DNA replication and DNA transcription. (3)

A
  • 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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2
Q

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

A

waist to hip ratio

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3
Q

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

A
  • treatment w/ antihypertensive medication
  • reduce salt intake
  • increase exercise
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4
Q

Explain why platelet inhibitors reduce the risk of a heart attack. (2)

A
  • reduce risk of blood clots forming
  • therefore less likely to get blocked coronary arteries
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5
Q

Name the products when several a.a are joined together

A
  • polypeptide and water
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6
Q

State and justify a suitable method of collecting cells for prenatal testing. (3)

A
  • chorionic villus sampling
  • cells taken from placenta b/w 10-14 weeks of pregnancy
  • benefit of earlier diagnosis
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7
Q

Compare and contrast human and snake heart/circulatory system. (4)

A

-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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8
Q

Explain why a snake needs a heart. (2)

A
  • to supply oxygen to body cells
  • by mass transport
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9
Q

Explain how vein structure relates to its function. (4)

A
  • 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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10
Q

Explain why children with CF would be given dietary supplements. (5)

A
  • 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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11
Q

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

A
  • amylopectin is branched, amylose is not.
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12
Q

Explain how the structures of amylopectin and glucose make them suitable for storing energy. (3)

A
  • branched: rapid hydrolysis
  • compact: more energy stored
  • insoluble: cant effect osmosis
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13
Q

Explain why high sugar intake could lead to obesity. (3)

A
  • energy intake higher than energy output
  • excess sugar stored as fat
  • leading to weight gain
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14
Q

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

A
  • sucralose contains Cl
  • therefore shape of molecule has changed
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15
Q

Explain how changing one amino acid can change the structure of haemoglobin. (4)

A
  • diff. primary struture
  • diff. R group
  • therefore, diff. secondary structure
  • haemoglobin may not be able to bond to oxygen
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16
Q

Explain why pickling in vinegar results in pigment leaving cells. (3)

A
  • increases permeability of cell surface membrane
  • low pH denatures protein
  • as vinegar affects bonds in proteins
17
Q

Give one function of glycoproteins in cell surface membranes. (1)

A
  • cell recognition
18
Q

Compare and contrast the process of exocytosis and endocytosis. (3)

A

-both: involve vesicles

-both: involves energy from ATP

  • exo: molecules leaving cells
    endo: molecules entering cells
19
Q

Describe how mRNA is synthesised at a template strand of DNA. (2)

A
  • DNA nucleotides align w/ complimentary DNA bases

^ joined together by RNA polymerase

20
Q

Describe the differences between DNA structure and RNA structures. (3)

A
  • DNA: double strand , RNA is single
  • DNA: deoxyribose, RNA: ribose
  • DNA: thymine , RNA: uracil
21
Q

Explain how a blood clot could form in a blood vessel. (4)

A
  • 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

22
Q

Compare and contrast diffusion and active transport. (3)

A
  • diffusion: along conc. gradient , AT: against
  • AT requires ATP , diffusion doesn’t
  • both move molecules through cell surface membrane
23
Q

Explain how properties of water make it an ideal transport medium. (3)

A
  • solvent

^ bcs water molecules surround polar molecules

  • is a liquid so has ability to flow
24
Q

Define: allele. (2)

A
  • alternative form of a gene
  • found at the same locus on a chromosome
25
Q

Explain why the offspring have the palomino coat colour. (3)

A
  • offspring is heterozygous
  • therefore co-dominance occurs
  • bcs both alleles are expressed
26
Q

Name the type of genetic screening that can screen an IVF embryo before its placed in the uterus. (1)

A

pre-implantation genetic diagnosis

27
Q

Explain one ethical issue of prenatal genetic screening. (2)

A
  • risk of incorrect result

^ healthy foetus could be aborted

28
Q

Explain how structure of blood vessels carrying blood away from heart in graph A and B are different. (3)

A
  • aorta has thicker layer of elastic tissue
  • collagen to withstand increased blood pressure
  • elastic tissue to maintain blood pressure
29
Q

Explain why the percentage of fluorescence inside and outside the alveolar cells changed. (4)

A
  • fluorescence inside cell decreases
  • because A.As used to synthesise proteins
  • proteins packaged into vesicles

^ & leave cell by exocytosis

30
Q

Explain how high salt diet effects someones CVD risk. (5)

A
  • increases risk of CVD
  • bcs higher b.p
    ^ damage to artery endothelium
    ^ inflammatory response
    ^ leading to risk of atheroma forming
31
Q

Explain why CF produces thicker mucus. (2)

A
  • Cl- ions cannot leave cell
  • therefore water leaves mucus via osmosis
32
Q

Explain the advantages of using young zebrafish for investigation. (2)

A
  • transparent bodies
  • heart more visible
33
Q

Explain how human lung structure enables rapid gas exchange. (4)

A
  • many alveoli increase s.a
  • one cell thick walls = short diffusion pathway
  • capillaries = short diff. path.
  • high conc. gradient maintained by circulation
34
Q

Describe how nucleotides join together to form DNA.

A
  • phosphodiester bonds
  • condensation reactions
35
Q

Compare and contrast ATP and DNA nucleotide structures. (3)

A
  • both: phosphate, pentose sugar & base
  • DNA nuc: deoxyribose , ATP = ribose
  • DNA nuc: 1 phosphate , ATP = 3
36
Q

State why enzymes are described as biological catalysts. (1)

A
  • reduce activation energy of biological reactions
37
Q

Describe function of carrier proteins in c.s membrane. (4)

A
  • involved in facilitated diffusion

^ from high to low conc.

  • involved in active transport

^ needs ATP to move molecules against conc. gradient

38
Q

Compare and contrast globular and fibrous protein structures. (4)

A
  • 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
39
Q

Explain the different effects of deletion and substitution on protein structure. (4)

A
  • 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

Alevel Bio (8 decks)

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