Wrong

Question 1

Explain why a mammal born with a hole between two ventricles becomes tired with lack of enegry 3m

Answer 1

• less oxygen available for aerobic respiration

• deoxygenated blood mixed with oxygenated blood

• reduces concentration of oxygen in vlood

Question 2

Explain how a diet of a person could affect development of CVD 3m

Answer 2

• damage to endothelium

• Hugh LDLs link to plaque forming

• high intake of cholesterol= high LDL

Question 3

Explain how athersclorisis can cause damage to heart muscle 3m

Answer 3

• narrowing of lumen
• reduces blood flow
• reduces aerobic respiration

Question 4

Describe the role of thrombin in blood clotting 3m

Answer 4

• thrombin is an enzyme
•which catalysed the conversion of fibrinogen into fibrin
•a mesh of fibrin traps platelets to form a blood clot

Question 5

Explain how a blood clot can form in a blood vessel 4m

Answer 5

• blood clots form when collagen is exposed if the walls of a blood vessel is damaged

• leading to release in thromboplastin
• thromboplastin catalyses the conversion of prothrombin into thrombin
• thrombin catalyses conversion of fibrinogen into fibrin
• fibrin forms a mesh of fibres + traps platelets to form a clot

Question 6

Explain how platelet inhibitors would reduce risk of heart attack 2m

Answer 6

• platelet inhibitors reduce risk of blood clotting
•so less likely for blood clot to block arteries

Question 7

Devise a procedure for measuring heart rate daphnia w caffeine

Answer 7

• daphnia immobilised on cavity slide
• acclimation time as a control in caffeine solution
• use diff concentrations
•use a method to count heart rate
•use daphnia of same sex size species as control

• repeat calc for mean

Question 8

Explain how pressure differences in headset ensure efficient pumping of blood into arteries 4bp

Answer 8

• pressure increases in ventricles
• greater pressure in ventricles than in atria
• causing atrioventricular calves to close
• causes semilunar valves to open forcing blood into arteries

Question 9

Compare and contrast the process of transcription w process of dna replication 4m

Answer 9

• both use enzyme helicase to unzip dna
• both involve formation of phosphodiested bonds
• transcription uses RNA nucleotides
•replication uses DNA polymerase

Question 10

Explain how a change of one amino acid could lead to a change in the
structure and properties of the haemoglobin protein. 4 m

Answer 10

• change in primary structure
• diff amino acids will have diff R groups
• secondary structure will change
• may not bond to haem

Question 11

Describe the role of tRNA in production of …3m

Answer 11

• trna molecules transport amino acids to the ribosome
• trna molecule has an anticodon that binds to a codon on the MRNA
• each tRNA carries a particular amino acid

Question 12

Describe how the primary structure of leptin enables it to be soluble in water ,

Answer 12

• primary structure of amino acids determines the folding of the polypeptide
• forming a globular structure
• hydrophobic R groups located in centre of protein + hydrophilic R groups located on outsides
• hydrogen bonds form with the hydrophilic R group

Question 13

Describe how a frameshift mutation could result in the production of lepton (anything) w a shorter primary structure 3m

Answer 13

•adding or removing one or two nucleotides changes the triplet code so diff codons produced

• introducing a new star/ stop codon

• coding for a shorter sequence of amino acids c

Question 14

Describe how translation leads to production of polypeptide 5m

Answer 14

• mRNA binds to ribosome
• ribosome finds start codon
• tRNA has specific anticodon, complementary to codon so they bind

• ribosome moves along to next codon
• amino acids join by condensation reactions to form polypeptides

Question 15

Compare and contrast endocyyosus and exoytosis 3m

Answer 15

• both require energy from ATP

• both involve vesicles

• exocytosis is molceucles leaving cell whereas endocytosis is molecules entering cell

Question 16

Explain some of the symptoms a person w cystic f could have 6m

Answer 16

• mucus thicker than normal
• pancreatic enzymes cannot whether intestines coz pancreatic duct blocked w mucus
• high energy diet required coz digestion less efficient

• pancreatic enzymes trapped behind mucus damage pancreatic cells such as those that produce insulin
• cysts form in pancreas

• sperm cannot leave testes coz sperm duct blocked w mucus

• gene mutation
• non functioning CFTR protein channel

• chloride ions cannot move out of epithical cells
• accumulation of sodium and chloride in cells prevent water mocing into mucus

Question 17

Definition of allele

Answer 17

• caused by a faulty allele that is only experessed in absence of normal allele

Question 18

State what is meant by term allele 2m

Answer 18

• diff version of a gene
• found at same locus on chromosome

Question 19

Describe role of TRNA in production of leptin 3m

Answer 19

• trna molecule transports amino acids to ribosome

• trna molecule has anticodon that binds to a codon on the mrna

• each trna carries a particular amino acid

Question 20

Describe how the primary structure of leptin enables it to be soluble in water 3m

Answer 20

• primary structure determines the folding of polypeptide

• forming globular structure

• hydrophobic R groups located in centre and hydrophilic outside of protein

• water forms hydrogen bonds with the hydrophilic

Question 21

Explain why diff mutations have diff effects on protein structure 4m

Answer 21

• deleting could affect every codon on MRNA whereas substitution will only affect one codon

• deletion more likely to affect position of stop or start codon

• deletion results in a diff sequence of amino acids/ substitution may not affect the sequence of amino acids

• substituoon may code for same amino acid

•
Same amino acid due to degenerate nature of genetic code

Question 22

Deduce what happens to lactate in these cells after liver cells absorb lactate in blood 2m

Answer 22

• lactate in oxidised to form pyruvate
• pyruvate conveyed to glucose

Question 23

Explain the importance of primary structure for functioning of enzyme 3m

Answer 23

• primary structure determines interaction between R groups

• primary structure determines folding and 3D shape

• thus shape of active site is affected

Question 24

Explain how a single base mutation can lead to an altered primary structure of enzyme G

Answer 24

• change in base results in a change in triplet code

• this changes codon in MRNA

• resulting in diff amino acid sequence

Question 25

Describe what happens to these proteins following the process of translation until they are released from the cell 3m

Answer 25

• proteins folded in rough w do plastic reticulum • proteins then packed into vesicles •proteins modified in in Golgi apparatus • exoytosis

Question 26

Compare and contrast molecular structures of globular and fibrous proteins 4m

Answer 26

• both are long chains of amino acids joined by peptide bonds • both contain hydrogen bonds holding tnem in shape • globular proteins have hydrophilic groups on outside whereas fibrous have hydrophobic on outside • fibrous proteins are long chains globular proteins are folded compactly

Question 27

Explain why the nucleus cannot be observed at the end of prophase in eukaryotic cell 2m

Answer 27

• because the nuclear membrane is broken down • coz dna is coiled into individual chromosomes

Question 28

Describe how polypeptide chain is processed to make AFGP 4m

Answer 28

• polypeptide chain moves through endoplasmic reticulum then the Golgi apparatus • in the RER (rough endo) the polypeptide chain in folded • in Golgi apparatus carbohydrate added • polypeptide chain then transported around cell in vesicle

Question 29

What is function of plasmodesmata 2m

Answer 29

• cytoplasmic connection between cells • allows communication

Question 30

Describe the events of fertilisation that occur after the acrosome reaction

Answer 30

• fusion of sperm cell membrane with egg cell membrane • cortical granules release contents into zona pellucida • contents of cortical granules react w zona pellucida and it thickens • fusion of sperm and egg

Question 31

Explain why offspring may be genetically different even w same dad and mum 2m

Answer 31

• difference gametes • each gamete contains diff combintuaoons of alleles

Question 32

Explain why a second sperm cell cannot fertilise the egg cell 3m

Answer 32

• cortical reaction- fusion of cortical granules with egg cell surface membrane • resulting in thickening of zona pellucida • therefore other sperm cells can’t reach egg cell surface membrane

Question 33

Explain what is meant by a sex linked disorder 2m

Answer 33

• disorder caused by a mutated gene • on x/y chromosome • so disorder more likely in one gender than igher

Question 34

Explain how vesicles are involved in the successful fertilisation of an egg cell by only one cell 2m

Answer 34

• cortical granules fuse with egg cell surface membrane • releasing enzyme that hardens the zona pellucida

Question 35

Describe how meiosis leads to genetic variation in the gametes produced 2m

Answer 35

• produces non indenfuxak gamete’s due to indepdeng asornement of chromosomes • crossing over between chromatids

Question 36

Explain why some genes show linkage and others shiw sex linkage 3m

Answer 36

• there are more genes than chromosomes • linkages relate to genes for diff characteristics located on same non sex chromosome • sex linkage relates to genes in x/y chromosome

Question 37

Explain how crossing over and independent assortment can produce gametes w new combinations of the alleles shown on the diagram of the 2 pairs of chromosomes 4m

Answer 37

Crossing over • chromatids are produced w diff combinations of alleles • eg Ab/aB Independent assortment • diff combinations of chromosomes r produced •therefore alleles for A and B could be in same gamete as C or c

Question 38

Explain how crossing over may differ in sex chromosomes 2m

Answer 38

• crossover cannot form between some sections of the x and Y chromosome • coz they are not homologous chromosomes

Question 39

Explain why dna is replicated before mitosis begins 2m

Answer 39

• to ensure diploid number of chromosomes in each daughter cell • to ensure daughter cells r genetically identical

Question 40

Explain how large numbers of cells.with the same phenotype can be produced in a tissue 2m

Answer 40

• phenotype determined by the genotype + effect of environment • mitosis produces cells with the same genotype

Question 41

Explain why the nucleus cannot be observed at the end of prophase in a eukaryotic cell 2m

Answer 41

• because nuclear membrane is broken down • coz dna is cookies into individual chromosomes

Question 42

Describe how the acrosome is involved in digestion of zona pellucida

Answer 42

• membrane of acrosome fuses with membrane of sperm • releasing enzymes from acrosome by exocytosis

Question 43

Describe the events that occur during prophase in an animal cell 3m

Answer 43

• nucleus breaks down • spindle fibres formed • centrioles migrate to opposite poles of cell

Question 44

Describe role of acrosome in fertilisation 3m

Answer 44

• acrosome fuses with the cell surface membrane of the sperm cell • digestive enzymes released • to break down zona pellucida

Question 45

Describe appearance of chromosome in the cells undergoing metaphase 3m

Answer 45

• visible • seen as pairs of chromatids held together by a centromere • joined to spindle fibres aligned in middle

Question 46

Describe how clinical trials of a vaccine would be conducted 3m

Answer 46

• small groups of healthy volunteers given drug to see side effects • healthy volunteers tested for presence of antibodies • a group of ppl at risk of contracting diseases given vaccine • n. Ppl who get disease aftwr vaccine monitored

Question 47

Describe the role that zoos play in animal conservation 3m

Answer 47

• zoos protect animals from hunters • breeding programmes in place to increasee numbers • used for research purposes or educating

Question 48

3 phases kn drug testing + what they do 3m

Answer 48

• phase 1 to test if drug to make surenot harmful • phase 2 to see if effective in treating illness • phase 3 to gather as much info from statistical tests

Question 49

Describe structure of starch 3m

Answer 49

• is a polysaccharide made from alpha glucose • monomers held by 1,4 glycosidic links • starch contains unbranched amylose chains and branched amylopectin chains • branches joined to chains by 1,6 glycosidic links

Question 50

Explain the role of the middle lamella when a plant cell completes mitosis 2m

Answer 50

• produced between adjacent new cells • because middle lamella holds cell walls together