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Flashcards in Unit 1 Deck (100):

what is the intermolecular force that explains many of the important properties of water is (1 mark)

hydrogen bonds


suggest why glucose is soluble in water (2 marks)

- glucose is a polar molecule
- forms hydrogen bonds with water


suggest how triglycerides are transported in water (2 marks)

- triglycerides are insoluble in water (non polar/hydrophobic)
- transported as lipoproteins (HDL and LDL)
- formed in vesicles/micelles


the role of thrombin in the blood clotting process is to (1 mark)

catalyse the conversion of fibrinogen to fibrin


the ion required in the conversion of prothrombin to thrombin is (1 mark)



blood clots form only when required because the clotting factors used are (1 mark)

present in an inactive form in the blood


describe how the human lung is adapted for rapid gas exchange (5 marks)

- folded into large number of alveoli
- providing a high SA
- walls of alveoli/capillary are thin
- the walls are made from a single layer of flattened cells
- the thin wall decrease diffusion distance
- extensive network of capillaries
- maintains concentration gradient


suggest why blood clots, formed in the pulmonary thrombosis, reduce gas exchange in the lungs (2 marks)

- reduced blood flow to the lungs via the arteries
- decrease in concentration gradient
- decrease in diffusion rate


suggest reasons for the different death rates in different countries (3 marks)

- genetic differences
- ethnic differences
- healthcare differences
- lifestyle differences (stress/smoking/alcohol consumption)
- dietary differences
- different age profiles


explain why statins reduce the risk of CVD (2 marks)

- inhibits cholesterol synthesis/ production of cholesterol in the liver
- reducing total blood cholesterol levels
- raises HDL : LDL ratio
- lowers LDL levels


state the risks of using statins to treat CVD (2 marks)

- muscle inflammation/pain
- joint inflammation/pain
- kidney damage/ failure
- liver damage/failure
- depression
- nausea
- constipation
- cataracts
- diabetes
- allergies
- skin inflammation (skin rash)
- respiratory problems


in phospholipids, the fatty acid tails are (1 mark)

- non-polar
- hydrophobic


in phospholipids, the fatty acid tails are formed from (1 mark)

carbon and hydrogen only


in phospholipids, each fatty acid is joined to glycerol by (1 mark)

ester bond


suggest how cholesterol affects membrane fluidity (3 marks)

- combines with the fatty acid tails
- holds/pulls the fatty acid chains together
- reducing the movement of the phospholipid/ fatty acid tails


red blood cells swell and burst if placed in water, explain why this happens (3 marks)

- water diffuses into the cell
- by osmosis
- from a region of high water potential/concentration (outside the cell) to a region of low water potential/concentration (inside the cell)
- stress on membrane components increases
- overcomes the adhesion between molecules


recessive allele (1 mark)

- it is only expressed in the homozygous condition
- it is only expressed in the absence of the dominant allele


gene mutation (1 mark)

- alteration of the DNA
- change in the base sequence
'a change in the base sequence of DNA'


explain how a mutation can result in a change in activity of an enzyme (5 marks)

- change in the DNA triplet/codon
- results in different amino acids/amino acid sequence/ primary structure
- different R groups/ different position of R groups
- this may change the bonding
- change in folding
- therefore changing the shape/structure of the active site
- enzyme is unable to combine with the substrate


name a test that could be used to find out if an unborn baby has a disease (1 mark)

- chronic villus sampling
- amniocentesis


suggest why testing for a disease on an unknown baby is not offered to all pregnant women (1 mark)

- rare condition
- there may be no family history of this condition
- cost availability for testing


give the disadvantages of carrying out genetic tests on unborn children (1 mark)

- risk of harming the baby
- risk of miscarriage
- risk of abortion
- risk of inaccurate results (false negative/ false positive)
- difficulty in getting insurance


explain why animals need a heart and circulation (4 marks)

- small SA to vol. ration
- overcome limitations of diffusion
- heart is needed to pump blood around the body
- transport of oxygen and glucose
- removal of carbon dioxide/ waste products
- high metabolic rate
- high energy demand


describe the structure of the aorta and how it relates to its function (4 marks)

- thick wall (contains collagen)
- able to withstand pressure
- wall of aorta contains elastic fibers/ elastic tissue
- allowing the wall of the aorta to stretch and recoil
- recoil helps maintain high pressure/ rapid flow
- semilunar valves present at the start of the aorta that prevents back flow of the blood during diastole


describe how the vitamin C content of broccoli could be measured (4 marks)

- extracting juice from the broccoli
- use DCPIP
- titration of juice
- color change (blue to colorless) when juice is added to DCPIP
- record the volume added
- calibration curve


suggest why the vitamin C content of broccoli changes when its boiled ( 3 marks)

- boiling damages the cell membrane
- boiling increases membrane permeability
- vitamin C moves out of the cell
- by diffusion


suggest what is meant by relative risk (1 mark)

- the chance/ probability of an event
- in one group/ person compared to another


suggests why questionnaires are useful for collecting data (1 mark)

- cheap
- easy
- efficient
- quick
- fewer staff are needed
- large sample size
- people are more likely to give an honest answer


describe the process of facilitated diffusion (2 marks)

- movement down a concentration gradient
- that requires a membrane/ channel/ carrier protein
- does not require ATP/ is a passive process


name the bond between glucose molecules in glycogen (1 mark)

glycosidic link


name the type of reaction that takes place when glycogen is broken down to glucose (1 mark)



explain why glycogen is a good energy storage molecule i muscle cells (3 marks)

- branching polysaccharide
- that is rapidly hydrolyzed
- allows the storage of large quantities of glucose in a small place
- low solubility - it does not move out of the cells
- it has no osmotic effect


atherosclerosis is initiated by damage to (1 mark)

endothelial cells


atherosclerosis occurs in (1 mark)



in atherosclerosis, the blood vessels become (1 mark)

less elastic with a narrow lumen


explain why atherosclerosis is a risk factor for coronary heart disease (3 marks)

- formation of blood clot/ thickening of artery wall
- blocks/ narrows coronary arteries
- reduces blood flow
- depriving heart muscles of oxygen and nutrients


explain why the human heart is divided into a left and right side (3 marks)

- keeps oxygenated and deoxygenated blood separate
- concentration/diffusion gradient is steep
- results in sufficient oxygen being carried to the tissues/ cells
- allows the removal of carbon dioxide from tissues and cells
- allows a difference in pressure in each side
- right side pumps blood to the lungs, left side pumps to the rest of the body


explain one way in which the structure of a capillary is related to it's function (2 marks)

- thin walls - consists of a single layer of flattened cells allowing rapid diffusion
- gaps (pores) between cells in the wall of a capillary - to allow exchange of material - increases permiability


state two factors other than surface area, that affect the rate of gas exchange (1 mark)

- diffusion distance
- temperature
- concentration gradient
- permeability


explain why a gene mutation affects gas exchange in a person with cystic fibrosis (4 marks)

- defective CFTR protein
- chloride ions are not transported out of the cells
- sodium ions move into the cell
- water does not move out of the cell / water moves into the cell
- mucus on the cell surface is not diluted/ thick/ sticky
- reduced rate of gas diffusion/ reducing ventilation of the alveoli


name the bond that links fatty acids to glycerol (1 mark)

ester bond


distinguish between the structure of a saturated fatty acid and the structure of an unsaturated fatty acid (2 marks)

- saturated fatty acid has no carbon-carbon double bonds whereas an unsaturated fatty acid has at least one carbon-carbon double bond
- saturated fatty acid chain are straight, unsaturated fatty acids chains are not straight
- ratio of H:C is higher in saturated fatty acids than in unsaturated fatty acids


explain why a buffer solution should be used - in experiments involving enzymes (4 marks)

- controlling pH
- changes in pH in experiments involving enzymes would lead to a change in shape of the active site
- changes in pH change ionic bonding with enzyme
- changes in pH change the rate of reaction


describe the structure of the cell membrane (5 marks)

- phospholipid bilayer
- orientation of phospholipid
- phospholipids have hydrophilic phosphate head (polar)
- phospholipids have hydrophobic fatty acid tail (non-polar)
- proteins on the membrane
- 2 different locations of proteins - intrinsic and extrinsic
- glycoprotein
- glycolipid
- lipoprotein
- cholesterol


define genotype (1 mark)

the combination of/pair of alleles present in an organism


define phenotype (1 mark)

the observable feature


describe how the primary structure results in a protein with a three dimensional structure (3 marks)

- primary structure is the sequence of amino acids
- the amino acids each have different R groups bonds between R groups
- bonding determines the folding of the polypeptide


the sugar in a mononucleotide of RNA is ... (1 mark)



in a DNA double helix, the two strands are held together by ... (1 mark)

hydrogen bonds between bases


the base present in RNA but not present in DNA is ... (1 mark)



the mononucleotides in a molecule of mRNA are joined together by ... (1 mark)

phosphodiester bonds


the complementary base that pairs with guanine is ... (1 mark)



explain the meaning of the term semiconservative replication (2 marks)

- new DNA is synthesized
- new DNA contains original strand and new strand


ribosomes are involved in ... (1 mark)



DNA acts as a template in ... (1 mark)



tRNA is involved in ... (1 mark)



peptide bonds are made in ... (1 mark)



mRNA is made in ... (1 mark)



name the bond that joins two alpha glucose molecules together (1 mark)

glycosidic bond


describe the structure of starch and explain why the structure makes it a suitable molecule for storing energy (4 marks)

- amylose
- amylopectin
- amylose has a straight chain, spiraled, 1-4 glycosidic link
- amylopectin is branched, 1-4 and 1-6 glycosidic link
- its easily hydrolyzed
- compact structure leading to more glucose in a smaller space in a cell
- insoluble/ large
- does not diffuse out of the cell/ no osmotic effect


explain why the phospholipid molecules form a bilayer (3 marks)

- fatty acid tales are non polar/ hydrophobic
- therefore they orientate themselves away from water and polar environments
- phosphate heads are hydrophilic/polar
- hence are able to interact with water and polar environments
- cytoplasm and tissue fluid (example of polar environments)


there was some red coloration in the tube containing only water. suggest an explanation for this (2 marks)

- cell/membrane damaged by cutting up of pieces
- as a result pigment could leak out of vacuoles/cells


describe what the students should have done to reduce the red coloration in the tube containing only water (1 mark)

rinse pieces thoroughly/ dab pieces dry


suggest the effect of ethanol on the permeability of beetroot (3 marks)

- disruption of membrane
- ethanol is non polar/ organic solvent
- lipid dissolve in alcohol
- increase in ethanol causes solution to be less polar
- orientation of phospholipids depend on water around it


explain how the structure of an artery relates to its function (3 marks)

- wide wall to withstand blood under high pressure
- narrow lumen to maintain high pressure
- elastic fibers to allow vessels to stretch
- recoil maintains pressure/ squeezes blood
- smooth muscle contracts to squeeze blood along
- smooth lining to reduce friction
- folded lining to allow artery to stretch


give two differences between the structure of a vein and the structure of a capillary (2 marks)

- walls of veins are more than one layer thick whilst capillaries are composed of a single layer of flattened cells
- wall of veins contain connective tissue/ smooth muscle/ collagen/ elastic tissue whilst capillaries do not
- veins have valves capillaries do not
- veins do not have pores, capillaries do
- veins have a wide lumen, capillaries have a narrow lumen


suggest the way in which statins work (2 marks)

- lower cholesterol/LDL levels will decrease
- inhibit cholesterol synthesis
- result in more LDL receptors on liver cells
- more LDL will be cleared up from the blood


state the risks of using statins (2 marks)

- gastrointestinal problems
- bowl and constipation complaints
- joint and muscle problems (cramps/ pains/ myopathy)
- liver problems
- kidney problems
- mental health problems (depression)
- reduced vitamin uptake
- respiratory cancer


explain the meaning of the term correlation (1 mark)

when one variable changes there is also a change in an accompanying variable


two additional pieces of information that would increase validity of any conclusion (3 marks)

- number of people in survey
- where the survey was carried out
- information about their occupation
- their family medical history
- information about their lifestyle


describe how somatic gene therapy may have been carried out (3 marks)

- use of normal alleles/genes
- coding for enzyme
- introduction of allele/DNA/gene into target cells
- into DNA/chromosomes/nucleus
- use of vector to introduce gene into cells
- named vectors - i.e. virus, liposomes
- delivery of vector - i.e. nebulizer, spray, injection


suggest treatment control group could receive for investigation involving gene therapy (1 mark)

- water
- saline
- virus only
- empty liposome
- vector
- use of placebo


triglycerides are composed of ... (1 mark)

1 glycerol molecule and 3 fatty acid molecules


the bond between a glycerol molecule and a fatty acid molecule is ... (1 mark)

ester bond


ester bond is formed by ... (1 mark)



unsaturated lipids have ... (1 mark)

have double bonds between carbon atoms and between carbon and oxygen atoms


name an enzyme involved in DNA replication (1 mark)

- DNA polymerase
- DNA helicase
- DNA ligase


how can amniocentesis can be used to detect mutations (3 marks)

- amniotic fluid removed from amniotic sac of mother
- fetal/ embryonic cells present in amniotic fluid/ embryonic cells needed
- DNA can be analysed
- to detect defective genes in sample


how can chorionic villus sampling be used to detect mutations (3 marks)

- placental tissue removed from womb of mother
- fetal cells present in placenta/ placental tissue/ chorionic tissue/ fatal cells are needed
- DNA can be analyzed
- to detect defective genes in sample


describe the benefit to a pregnant woman of prenatal testing (2 marks)

- gives information about abnormalities in fetus
- opportunity for choice
- consider termination
- time for preparation
- time to prepare for treatment
- peace of mind


describe the risk to a pregnant woman of prenatal testing

- possibility of miscarriage due to procedure
- potentially a healthy baby would be lost
- risk to mother
- false negative result
- false positive result
- damage/harm to fetus
- subsequent health issue (miscarriage)


discuss the ethical and social issues relating to the use of prenatal testing (3 marks)

- fetus is living - abortion is wrong
- who has the right to decide if tests should be preformed
- implications of medical costs
- implications pf disagreement over the next step
- issues relating to confidentiality of parents/child
- some other abnormality may be found
- paternal DNA does not match
- other family members have the right to know the results
- some other abnormality may be found
- possible problems with future employment/ insurance/ what consists a serious condition
- not fully understanding the possible risk of parental testing
- possibility of miscarriage/harm to child
- who has the right to make the decision for the fetus/ fetus has decision rights if the test is positive
- denying them the opportunity to live
- fetus should be allowed to live
- fetus has a right to love


during atrial systole are the atria contracted or relaxed ... (1 mark)



during atrial systole are the ventricles contracted or relaxed ... (1 mark)



during ventricular systole are the atria relaxed or contracted ... (1 mark)



during ventricular systole are the ventricles contracted or relaxed ... (1 mark)



during diastole are the atria contracted or relaxed ... (1 mark)



during diastole are the ventricles relaxed or contracted ... (1 mark)



describe the role of the atrioventricular (bicuspid and tricuspid) valves during the cardiac cycle (4 marks)

- valves separate atria from ventricles
- open during atrial systole/contraction
- so that blood can pass through the ventricles
- closed during ventricular systole/ contraction
- to prevent blood being forced back/ back flow up into atria/ to maintain pressure in ventricles
- open during diastole
- so that ventricles can start to fill up (as the atria are filling)


suggest reasons for the difference between this pressure and the maximum pressure in the left ventricle (3 marks)

- pressure differences - left has a higher pressure
- left ventricle pumps blood around the body (to the rest of the body)
- right ventricle pumps blood to lungs/pulmonary systems
- if blood us under high pressure there would be damage to the lungs/ capillaries
- lots of muscle contracting in the left ventricle/ thick wall of left ventricle


define causation (1 mark)

when a change in one variable is responsible for a change in another variable


define correlation (1 marks)

relationship between two variables such that a change in one variable is reflected by change in the other variable


suggest why the number of death in coronary heart disease changes (typical graph question) ... (3 marks)

- people more aware of the danger
- better education
- more exercise
- better screening
- better treatments
- change in diet
- less obesity
- less alcohol intake
- change in population genetics
- decrease in smoking


describe how atherosclerosis develops (4 marks)

- damage to endothelial cells/ cells lining artery walls
- inflammatory response
- accumulation of white blood cells in damaged area
- build up cholesterol in damaged area
- build up of calcium salts/ fibrous tissue/ fibrin/ platelets
- formation of atheroma/ plaque
- loss of elasticity of artery/ narrowing of lumen
- process is self perpetuating


state what is meant by the term template for the synthesis of messenger RNA (1 mark)

- the RNA nucleotide/base attach to this strand
- nucleotide/base sequence that directs the synthesis of complementary sequence/mRNA


DNA and mRNA both have ... (1 mark)

a sugar phosphate chain


one advantage of DNA having two complimentary strands is that ... (1 mark)

semi conservative replication is possible


differences between replication and transcription (3 marks)

- REPLICATION uses DNA nucleotides
- TRANSCRIPTION uses RNA nucleotides
- REPLICATION uses DNA polymerase
- TRANSCRIPTION does not use DNA polymerase/ it uses RNA polymerase
- REPLICATION includes semi conservative replication
- TRANSCRIPTION does not include semi conservative replication
- REPLICATION copies both DNA strands
- TRANSCRIPTION copies only one strand/template/gene
- REPLICATION makes DNA double helix
- TRANSCRIPTION makes single strand mRNA
- REPLICATION - deoxyribose
- REPLICATION - thymine/ t
- TRANSCRIPTION - uracil/ u
- REPLICATION - whole DNA molecule is unzipped for replication
- TRANSCRIPTION only part of the DNA molecule is unzipped in transcription
- TRANSCRIPTION - no ligase


explain the meaning of recessive allele (3 marks)

- both alleles need to be present inorder for the recessive phenotype to be expressed
- not expressed in the presence of a dominant allele
- different form of a gene
- same locus/ position
- different base sequence


reasons why daphnia is a suitable organism for investigating the effect of chemicals on heart rate (2 marks)

- you can see the heart/ internal organs - transparent
- daphnia are simple organisms/ have less developed nervous system/ cant feel pain
- fewer ethical concerns because it is an invertebrate
- they are abundant/ used as fish food/ reality available
- can absorbs chemical from the surround quickly - they are small have a large SA to VOL ratio therefore the chemicals can affect them quickly