AQA A Level Biology Paper One Revision 2023 100% guaranteed, Exams of Biology

Download AQA A Level Biology Paper One Revision 2023 100% guaranteed and more Exams Biology in PDF only on Docsity! AQA A Level Biology Paper One Revision 2023 100% guaranteed What's the type of bond between glycerol and a fatty acid in a phospholipid? Ester bonds How would a fatty acid be unsaturated? If it contained a double bond between adjacent carbon atoms in the hydrocarbon chain. Suggest one advantage of the different percentage of cholesterol in red blood cells compared with cells lining the ileum. Red blood cells would be free in blood, and not supported by other cells which ensures that cholesterol will maintain its shape. E. coli has no cholesterol in its cell-surface membrane. Despite this, the cell maintains a constant shape. Explain why. - Cells are unable to change shape due to the cell having a cell wall. - This makes the cell rigid since it is made of murein. Explain the difference between starch molecules and cellulose molecules - Starch formed w a glucose, Cellulose w b glucose - Position of hydrogen and hydroxyl groups on carbon atom 1 are inverted. How is starch adapted for its role? - Insoluble, meaning that it doesn't affect water potential. How is cellulose adapted for it's function in plant cells? - Long and straight chains -Become linked together with hydrogen bonds which form fibrils - Provides strength for cell wall. How is mRNA produced in the nucleus of a cell? DNA helicase breaks down hydrogen bonds - One DNA strands acts as a tempalte - RNA nucleotides exposed to bases - Attraction linked to the base pairing rule - RNA Polymerase joins RNA nucleotides together - Pre-mRNA spliced to remove introns. Describe the structure of proteins - Polymer of amino acids; - Joined by peptide bonds; - Formed by condensation; Describe how proteins are digested in the human gut? hydrolysis of peptide bonds occur so: endo - break polypeptides to smaller peptide chains exo - remove terminal amino acids di - hydrolyze dipeptides to amino acids What reducing sugar, or sugars, would you expect to be produced during chewing? Give a reason for your answer. Maltose, since amylase is produced during chewing. how is starch similar to cellulose? - both are polymers - both contain glucose - have 1,4 links What organ produces amylase and maltose? pancreas Why is maltose only hydrolyzed by maltase? Active site of enzyme has complementary shape to substrate maltose Only maltose can bind, forming an enzyme substrate complex. How do you identify is DNA is single stranded? If it does not have the same amount of A and T or G and C DNA Polymerase joins nucleotides to form new strand DNA Prokaryotic Cell differences to Eukaryotic Cells - Circular - No introns Why are Humans and X genetically similar, but different They have different genes triplets are in different places so different amino acids code for different proteins Cutting x thin for optical microscope to see what has successfully reacted successful reactions will glow How to use an optical microscope add drop of water to slide obtain thin section of tissue and place on slide stain with iodine in potassium iodide lower cover slip using mounted needle What is the chloroplast's function? photosynthesis Advantage of transmission electron microscope High resoloution Can see internal structures of organelles how phospholipids are arranged in the lipid bilayer bilayer hydrophobic tails to inside phosphate heads to the outside How is the RER involved in the production of enzymes has ribosomes to make proteins (which is what an enzyme is) How is golgi apparatus involved in secretion of enzymes Golgi apparatus modifies proteins. Why should you not push the cover slip sideways in a glass slide Pushing hard would spread the issue, but pushing sideways would break chromosomes protein synthesis Ribosomes what organelle modifies protein Golgi apparatus what organelle site of aerobic respiration mitochondria Describe and explain how centrifuging the culture allowed the scientists to obtain a cell-free liquid Large dense cells, spinning allows pellets to move to the bottom of the centrifuge. Liquid can be removed. Lysosomes break down food and worn out cell parts one advantage of different percentage of cholesterol in RBC compared with cells lining ileum RBC are free in blood which means that cholesterol can maintain shape high blood pressure leads to an accumulation of tissue fluid how tissuse fluid is formed 2 ways pathogens cause disease releases toxins that kills cells how does the monoclonal antibody prevent the regulatory protein from working tertiary structure complimentary to regulatory protein binds to form complex regulatory protein is not complementary to receptor the advantage of closing stomata water is lost through stomata, closure prevents water loss, this maintains the water content of cells how does the uptake of co2 increase when stomata closes? through the upper surface of the leaf (waxy cuticle) how would the mutation of a tumor suppressant gene result in tumor formation? tumor suppressor would not be able to control cell division meaning that rate of cell division would be too fast. why would there be a % decrease in people vaccinated fewer cases would be reported + fear of side effects why is a virus described as inactive no more cells are infected, virus is not replicating advantage of cell death prevents cell replication limitations of a TEM to investigating cell structure cell must be dead image produced is not 3D specimen must be thin principles of a TEM microscope electrons pass through thin specimen denser parts absorb more electrons dense parts are darker electrons have short wavelength so there is a high resoloution interphase + mitosis = two genetically identical cells. how? - dna is replicated via complementary base pairing - two identical chromatids produced - each chromatid moves to opposite ends of the cell. two structures in a eukaryotic cell which is not visible in optical microscope ribosomes cell surface membrane how tissue fluid formed outward pressure forces small molecules out of capilary why hydrostatic pressure falls from the arteriole end of the capilary to the venule end of the capilary friction against capillary lining. mechanism that causes forced expiration (4) contraction of intercostal muscles decrease in volume of chest air pushed down a pressure gradient how oxygen in the air reaches capillaries surround alveoli in lungs trachea, bronchi + bronchioles down pressure gradient down diffusion gradient across alveolar epithelium across capillary endothelium In vitro cloning gene copies are made outside of living organism using the polymerase chain reaction (EG PCR) in vivo cloning gene copies are made within a living organism as it grows and divides. (so bacteria) EG - INSULIN IS MADE FROM PUTTING INSULIN GENE INTO BACTERIA, BACTERIA REPLICATES THE GENE. DNA ligase linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3' end of a new DNA fragment to the 5' end of a growing chain. seals phosphodiester backbone in vivo cloning insertion vector DNA isolated. cut open using same restriction endonuclease that isolated the DNA fragment with targeted gene. sticky ends of vector of DNA are complementary to stick ends of DNA fragment lowers WP of sieve cell increase in pressure causes mass movement sugars used conversed in roots (stored as starch) for respiration for storage common difference between two amino acids different R group deletion of the sixth base in DNA would = change in nature of protein but substitution would not. why? all code for same amino acid deletion would cause frame shift. how mutation would = production of a protein with a missing amino acid loss of triplet stop codon formed production of protein with 1 amino acid missing could = genetic disorder. how/why? change in active site - so the protein is non functional. (or fewer E-S complexes formed) how could monoclonal antibodies stop the growth of a tumor? antibody has specific tertiary structure. complementary shape to the receptor protein. this prevents the growth factor from binding to the receptor. two ways meiosis produces genetic variation independent segregation crossing over two reasons why population may have little genetic diversity inbreeding population may have been very small how courtship behaviour would lead to an increase in mating recognition of the opposite sex + same species, stimulates the production of gamestes. hierarchy groups within groups independent segregation in meiosis allows combination of maternal + paternal chromosomes. mutations and how it can lead to the production of a non-functional enzyme change in base change in amino acid sequence change in hydrogen bonds change in tertiary structure and active site substrate no longer complimentary genetic diversity The number of different alleles of genes in a species or population. heirarchy groups within groups what is a species groups of organisms with similar features independent segregation to provide genetic variation allows different combination of maternal and paternal chromosomes. Phylogenetic group grouped according to evolutionary links how is carbon dioxide converted to other substances in the light independent stage of photosynthesis? carbon dioxide combines with RuBp produces 2 glycerate 3-phosphate GP converted to triose phosphate using reduced NADP and energy from ATP, triose phosphate converts to glucose. Primary, Secondary and Quaternary Structure of Amino Acids - Primary structure is order of amino acids; - Secondary structure is folding of polypeptide chain due to hydrogen bonding. - Quaternary Structure is two or more polypeptide chains. reverse transcriptase An enzyme encoded by some certain viruses (retroviruses) that uses RNA as a template for DNA synthesis. RNA polymerase Enzyme similar to DNA polymerase that binds to DNA and separates the DNA strands during transcription Lymphocytes A type of white blood cell that make antibodies to fight off infections mass transport in plants The transport of water and solutes in the xylem and phloem xylem carries water source cell - facilitated diffusion of glucose into companion cell, active transport into phloem - through sieve cells (negatively charged at the top) glucose travels down phloem which travels to companion cells and then sink cells by active transport . + charged. Capsid Outer protein coat of a virus Helper T cells help the immune system by increasing the activity of killer cells and stimulating the suppressor T cells