AQA As Biology Past Paper questions 7401-7402-2015 specification
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Key
ele-/e-= electron
(2)= a past paper question worth 2 marks
Tips
Use comparative words; Use 'more' and 'less', inc/dec , higher/lower; volume/concentration not amount!
In "evaluate" questions, writeno stat test, don't know its significance, can be due to chance; too little time, results
Cells
Resolution the minimum distance apart that two objects can be distinguished as separate objects in an image
Magnification=I=AM
artefacts Something artificial, a distortion that does not reflect normal anatomy or pathology
tissues grouping of cells of similar structure and function
Eukaryotic has membrane bound organelles. Has nucleus.
define chromosomes a single tightly coiled molecule of DNA;
define chratids replicate chromosomes; joined at their centromere
define clones 2 or more cells with identical genetic material; (don't say DNA cause viruses have RNA
Describe how you could make a temporary mount of a piece of plant tissue to observe the position of starch gra
Explain why its called fluid mosaic. Give one advantage to it being fluid (phospholipids can move around eachot
Distinguish between the features of channel p and carrier p and their roles in membrane Channel is 'pore' allowing
Outline the role of organelles in the production, transport and release of proteins from eukaryotic cells.(dont inclu
name 3 properties and uses of a solution used in cell fractcold- reduce enzyme activity, no digestion of organelle
SER produces and processes lipids
RER fold and processes protiens
Golgi apparatuprocesses and packages protiens and lipids.
Explain how ultracentrifugation separates a protien from other molecules.spin at high speed; molecules separate
give 2 features of all prokaryotic cells that aren't features of eukaryotic ceno histones; circular DNA;
Describe how HIV is replicated once inside T hepler cells(RNA converted into DNA by reverse transcriptase; dn
biological molecules
Isomer organic molecules that have the same chemical formula but different structural formula
,Describe 3 features of Glycogen that makes it well suited to its role as an energy store Insoluble;won't affect wat
Define unsaturated fatty acidHas double bonds; between carbons; long hydrocarbon chains; with a carboxylic a
Why aren't tryglycerides polymers?(1) Polymers contain many repeated monomers; or triglycerides contain
Draw a dipeptide with the R group shown phospholipids have hydr
Compare and contrast the structure and properties of triglycerides and phospholipids.( hydrophobic region;
Describe how lactose is formed and where in the cell it would be attached to a polypeptide to form a g
Give the two types of molecule from which a ribosome is RNA/rRNA; protien/amino acid;
Describe the structure of glycogen(2) Plymer/polysaccharide of a-glucose; branched or glycocidic bonds;
Suggest and explain two ways the cell-surface membranes of the cells lining the uterus may be adapted to allow
NHE3 actively transports 1 sodium ion into cell in exchange for 1 proton (h ion) out of the cell. How does NHE3
They calculated a P value of less than 0.05. What does t it is significant.
What is tissue fluid? water that leaks out of the capillaires an builds up in the tissue.
Why can a large salt intake lead to a build up of tissue fluitissue fluids water potential is lower; ) less water retur
Describe how bacteria dividebinary fission; replication of DNA; division of cytoplasm to produce 2 daughter cells
reaction catalysed by ATP synthase (1) ADP + Pi --> ATP + H2O
Contrast how an optical microscope and a transmission electron microscope work and contrast the limitations of
Contrast the processes fo facilitated diffusion and active transport (3) Facillitated diff requires either channel p
Cell wall component in Algae, Fungi and Prokaryotes (3) Cellulose; Chitin; Murein;
Describe the structure of the HIV (4) RNA; reverse transcriptase; capsid; lipid envelope;attachment protie
Explain 5 properties that make water important for organisms (5) metabolite in condens/photo…; solvent
Describe tests for lipid, non-reducing sugar, and amylase Lipids: ethanol then water and mix; milky white emulsi
Describe how the structure of glycogen is realted to its funciton (4) helix, compact; branched, easily hydroli
Describe how a triglyceride mol is formend(Condensation reaction and removal of 3 water mol; ester bond forms
Describe a biochemical test to show the presence of a non-reducing sugBoil the sol with an acid; heat benedicts
Describe the structure and function of the nucleus(4) nuclear envolope and pores; DNA with histones; Tran
what are ribosomes made of RNA and proteins
Explain how cellulose molecules are adapted for their function in plant cel long and straight chains; linked togethe
Suggest and explain how the viruses became able to infect other speciesMutation in DNA; altered
could viral
identify attachme
proteins/pro
Determining the genome of the viruses could allow scientists to develop a vaccine. Exp(to use in the vaccine);
Enzymes all key words: complementary; specific; E-S complex; tertiary structure changes; changes shape;
Explain the induced fit hypothesis (3) Reduces activation energy; Due to bending
explain why DNA polymerase goes in opposite directions along the strands of DNA.(4) DNA has antiparallel stra
describe the funciton of DNA helicase and DNA polymerase (2) Unzips nucleotides by breaking the hyd
Formation of an enzyme-substrate complex increases the rate of reaction. Explain how.Reduces activation energ
Explain how 2 enzymes with different amino acid seq can catalyse the same reaction(2same tertiary structure; e
DNA
State 2 differences in the structure of ATP and DNA ATP has 3 phosphates, DNA has one; DNA had deox
How can a mutation that changes an amino acid lead to thChanges the amino acid coded for; changes bonding/
Give the 2 types of molecule from which a ribosome is marRna and amino acid/protien/polypeptide;
,Describe the role of a ribosome in the production of a polypeptide. Don't inc transcription in your ans
Give 2 differences between the structure of mRNA and the structure of tRNA (2) mRNA is a straight line. t
homologoues chromosome (1(Two chromosomes that) carrgenetic variation; different combos of maternal and pa
Give two ways in which the arrangement of prokaryotic DNA is different from the arrangement of the human DN
Describe the role of two named enzymes in the process of semi-conservative replication of DNA.(2)
Define Exon(1)Seq of bases coding for a protein
In a eukaryotic cell, the base sequence of the mRNA might be different from the sequence of the pre-mRNA.Exp
Describe the structure of DNA (5) Polyer od mucleotides; double helix helix has H bonds; phosphodies
Explain how the structure of DNA is related to its functionsbackbone/ double stranded so provides strength; long
Describe viral replication(3) attachment proteins attacch to receptors; nucleic acid(RNA) enters cell; nucleic aci
3 differences between DNA and tRNA(3) double helix/linear, clover shape; deoxyribose, ribose; thymine, urac
where does crossing over occur? in prophase 1 only in meiosis. (between non-sister chromatics)
remember what the last step in transcription is(1) pre-mrna is spliced to remove introns;
in transcription, only one DNA strand acts as the template
Genetic Information, Variation & Relationships between Organisms
key words: common anccestor, more recent common ancestor.
Bionomial system rules 1) italics or underlined 2. 1st letter cap,
Explain the principles which biologists use to classify organisms into gro large groups are divided into smaller gr
what are the 5 kingdoms: animals, plants
Taxonomic groups: Domain, King Prawn Curry Or Fat Greasy Sausage: Kingdom, phlum, class
three domainsBacteria, Archaea and Eukaryota.
What
Threeisofmeant
the beebyspecies:
‘speciesPeponapis
richness’? pruinosa,the number
Andrenaofchlorogaster
(different) species in a community;
and Andrena piperi. What do these names
bee species? Explain your answer.
What are the 3 types of selection? draw a graph for each stabalising; directional; distruptive;
define biodiversity variety of living organisms
Define species diversity, and its method the number of different species and the number of different individua
Genetic diversity (1) Differences in DNA; (or number of different alleles);
Ecosystem diversity is the range of different habitats.
Species diversity formula d= N(N-1) / sum n(n-1) where N= total no of organisms of all sp, and n= no of 1 spe
Define species (2) similar organisms that can reproduce to produce fertile offspring;;
define phylogenetics The study of evolutionary relationships based on molecular similarities.
Define phylogenetic group(1)groouped according to their history;
What can these molecular differences be? amino acids; proteins; DNA;
Explain why the romoval of hedges causes a decrease in the diversity of birds on a far Fewer food sources; rem
Describe how breeding experiments could determine whether the two populations are from the same species (2
Give 2 ways in which courtship behavior increases the probability of successful mating To recognise the same s
What is DNA hybridisation? where 2 complementary DNA strands bond together to form a double stranded mo
Statistical tests
, Scientists thought that 2 species of seehourses where closely realted. Describe how comparisons
of bioligical molecules in theses two species could be used to find out if they are closely related. (6)
In a chi-squared statistical test, the calculated value was 350. The critical value at P=0.05 is 3.841. What can be
In another chi squared test, the P value calculatted was 0.03 testing their H0. What can you conclude from this r
Immunity
What is active an passive immunity? Active immunity: own immune system is responsible for protec
Describe how presentation of a virus antigen leads to the secretion of an antibody against this virus antigen.(2)
Suggest why a mixture of venoms from several snakes of the same species are used to produce anitvenom? (2
Why are animals that are injected with venom undergo observation? (1) so that the animal doesn't suffer from th
During vaccination, each animal is injected with a small dose of venom, then 2w later a large does. Explain why
Suggest why HIV controllers do not develop symptoms of AIDS? (3) HIV controllers have more Helper T cell
BrdU in DNA can be detected using an anti-BrdU antibody with an enzyme attached. Use ELISA test to suggest
Explain how HIV affects the production of antibodies when AIDS develops in a person (HIV reduces the no of T h
draw HIV
Explain how the use of antibiotics has led to antibiotic-resistant strains of bacteria becoming a common cause o
Describe how scientists use aseptic techniques to transfer liquid culture from a bottle onto and agar p
Gas exchange and mass transport
Use knowledge on gas exchange, explain why plants grown in soil with very little water grow only slowly. (2)
Looking at a oxyhaemoglobin dissociation curve for a mouse and a horse, suggest how these differences allow
Explain the advantage larger animals have for having a specialised system that facilitates oxygen upt
Key terms for oxygen dissociation curves: lower affinity to oxygen; saturation/ more 02 bind; binding causes a c
Suggest and explain when it would be an advantage to a human to have a lower affinit during exercise; more ox
Use your knowledge of surface area to volume ratio to explain the higher metabolic rate of a mouse compared t
Heart and circulatory system
Explain how an arteriole can reduce the blood flow into capillaries (2) Muscle contracts; narrows lumen;
digestion
hydrolysis of peptide bond; Endopeptidases break polypeptides into smaller peptide chains; . Exopeptidases rem
Describe the processes involved in the absorption and transport of digested lidid molecules from the ileum into l
Describe the role of micelles in the abosrption of fats into the cells lining the iliem (3) Micelles include bile salts
Describe the complete digestion of starch by a mammal(4hydrolysis;
hydrolysis of ofpeptide
glycosidic bonds;
bond; starch to maltose
Endopeptidases breaktopol
am
Describe how proteins are digested in the human gut.(4) into amino acids;
