AS AQA Biology (New Spec) Flashcards


Flashcards containing exam style questions based off the new AS biology specification, specifically AQA, but with overlap with the other courses
Lucy Frances
Flashcards by Lucy Frances, updated more than 1 year ago
Lucy Frances
Created by Lucy Frances over 7 years ago

Resource summary

Question Answer
High blood pressure can lead to an accumulation of tissue fluid. Explain how High blood pressure=high hydrostatic pressure Increased outward pressure from arteriole end of capillary Decreased inward pressure from venule end more tissue fluid formed/less reabsorbed
Describe how bacteria are destroyed by pathogens Phagocyte engulfs bacteria to form phagosome Lysosomes in phagocyte release lysozymes Lysozymes hydrolyse the bacterium in the phagosome
Describe and explain the mechanism that causes forced expiration Contraction of internal intercostal muscles Relaxation of diaphragm/external intercostal muscles Decrease in volume of thorax External pressure lower than internal pressure Air pushed down pressure gradient
Describe the appearance and behaviour of chromosomes during mitosis Prophase - Shortening and thickening - Attach to spindle fibres Metaphase - Line up along the equator of the cell Anaphase - Spindle fibres contract - Splitting of the centromere - Chromosomes split in half - Half go to each pole
Compare and contrast the processes by which water and inorganic ions enter cells Both move down concentration gradients Both move through (protein) channels in the membrane Ions can move against a concentration gradient by active transport
Give two properties of water that are important in the cytoplasm of cells Polar - Solvent Solvent - Speeds up metabolic reactions Reactive - Hydrolysis/condensation reactions
Cells lining the ileum of mammals absorb the monosaccharide glucose by co-transport with sodium ions. Explain how Sodium is actively transported out the epithelial cells Sodium-potassium pump Lower concentration of sodium ions inside epithelial cells Sodium enters from lumen Enters via sodium-glucose co-transport channel Must be in association with glucose to enter Glucose enters blood capillaries via facilitated diffusion
Homologous chromosomes carry the same genes but are not genetically identical. Explain why (Homologous chromosomes) carry different alleles
Explain why meiosis is important in sexual reproduction Produces gametes that are genetically different Chromosome number halved (haploid) When fertilisation occurs the embryo has the correct number of chromosomes (diploid)
Explain the advantage of peptidases being secreted in an inactive form Cell membranes contain protein Active peptidases may digest these proteins
Amylase is not secreted in an inactive form. Explain why this is not a disadvantage Amylase digests starch Starch is not present in animal cells
Describe the reaction catalysed by a peptidase enzyme Hydrolysis reaction Water is added (to a large soluble molecule) Breaking the peptide bond
Explain how water enters a bacterial cell Water potential lower/more negative in cell Water enters by osmosis
Explain -(i) The shape of the curve at 55C after 20 minutes -(ii) Why the curves for 27C and 37C level off that the same value (i) Causes detnaturation H+/ionic bonds break Shape of active site changed Substrate can no longer bind (ii) All substrates changed into product Same amount of product formed Same initial substrate concentration
Describe how the Golgi apparatus is involved in the secretion of enzymes Modifies protein Put into Golgi vesicles Transport to cell surface/vacuole
Describe how two amino acids differ from one another Different R groups
Give structural differences between mRNA and tRNA tRNA - Folded shape mRNA - No hydrogen bonds
Describe how phospholipids are arranged in a plasma membrane Bilayer Hydrophobic (lipid) (tails) to inside Hydrophillic (polar) (phosphate) (heads) to outside
Describe and explain the processes that occur during meiosis that increase genetic variation Crossing over - Bivalents overlap - Break off at chiasmata - Recombination - Different alleles Independent assortment/segregation - Homologous chromosomes are independent of each other
When a vaccine is given to a person it leads to the production of antibodies against a disease causing organism. Describe how Vaccine contains antigen from pathogen Macrophage presents antigen on its surface T cell with complementary receptor protein binds to antigen T cell stimulates B cell with complementary antibody B cell secretes large amount of the antibody B cell divides by mitosis Memory cell formed producing the same antobody
How do mutations lead to non-functional proteins? Base deletion/substitution Frame shift - changes codons after that point - Base deletion Different amino acids coded for Change in hydrogen/ionic/disulfide bonds Change in tertiary structure Can no longer bind to substrate as it is no longer complementary
Describe the difference between passive and active immunity Active - Memory cells - Production of antibody by plasma/memory cells - Long term - antibody production - Takes time to develop Passive - Antibody introduced into body from outside source - Short term - Antibody given is eventually broken down
Explain how the structures of the walls of arteries and arterioles are related to their function Elastic fibres - Stretch under pressure/during systole - Recoil during diastole - Maintain constant blood pressure Muscle - Contracts -Reduces diameter of lumen/vasoconstriction - changes pressure to maintain a constant Epithelium - smooth - Reduces friction/blood clots/resistance
Compare and contrast the structure of starch and cellulose Both - Polysaccarides - Contain glucose - Contain hydrogen bonds within the structure Starch - Contains alpha glucose - Helical structure - No hydrogen bonds between molecules Cellulose - Contains beta glucose - Straight molecule
When comparing variation it is often considered more useful to compare standard deviations rather than ranges. Explain why Range influenced by a single outlier (anomaly) Standard deviation shows dispersion around the mean Range only shows extremes Standard deviation allows statistical use
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