VCE Biology flashcards
VCE Biology · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Prokaryote
- A cell lacking a membrane-bound nucleus and organelles; its circular DNA lies free in the cytoplasm and it usually has a cell wall and plasmids.
- Eukaryote
- A cell with a membrane-bound nucleus and organelles such as mitochondria and endoplasmic reticulum; includes protists, fungi, plants and animals.
- Endosymbiotic theory
- The proposal that mitochondria and chloroplasts originated from bacteria engulfed by a host cell, supported by their double membranes, circular DNA and 70S ribosomes.
- Surface area to volume ratio
- The ratio of a cell's outer surface to its internal volume; it falls as cells grow, limiting the rate of exchange and constraining cell size.
- Fluid mosaic model
- The description of membranes as a dynamic phospholipid bilayer with embedded proteins, cholesterol and glycoproteins, giving selective permeability and flexibility.
- Facilitated diffusion
- Passive movement of substances down their concentration gradient through specific membrane channel or carrier proteins, requiring no energy input.
- Active transport
- Movement of substances against their concentration gradient using carrier proteins and energy from ATP hydrolysis, as in the sodium-potassium pump.
- Osmosis
- Net movement of water across a semipermeable membrane from a region of lower solute concentration to a region of higher solute concentration.
- Meiosis
- A reduction division producing four haploid cells from one diploid cell, with crossing over and independent assortment generating genetic variation.
- Homologous chromosomes
- A pair of chromosomes, one inherited from each parent, carrying the same genes at the same loci but possibly different alleles.
- Genotype and phenotype
- Genotype is the combination of alleles an organism carries; phenotype is the observable trait produced by that genotype interacting with the environment.
- Monohybrid cross
- A genetic cross tracking one gene; a cross of two heterozygotes gives a 1:2:1 genotype ratio and a 3:1 phenotype ratio for complete dominance.
- Negative feedback
- A homeostatic mechanism in which a response counteracts the original stimulus, returning a variable such as body temperature toward its set point.
- Insulin and glucagon
- Antagonistic hormones regulating blood glucose; insulin lowers glucose by promoting uptake and glycogen storage, while glucagon raises it by releasing glucose.
- Signal transduction
- The process by which a signal molecule binds a receptor and triggers an intracellular cascade, converting the signal into a specific cellular response.
- Enzyme active site
- The specific region of an enzyme where substrate binds; its complementary shape lowers activation energy and determines substrate specificity.
- Competitive inhibition
- An inhibitor that binds the enzyme active site and competes with substrate; its effect can be reduced by increasing substrate concentration.
- Non-competitive inhibition
- An inhibitor that binds a site other than the active site, changing enzyme shape so substrate cannot bind; adding more substrate does not overcome it.
- Light-dependent reactions
- Stages of photosynthesis in the thylakoid membranes where light energy splits water, producing oxygen and generating ATP and NADPH.
- Calvin cycle
- Light-independent reactions in the stroma where ATP and NADPH are used to fix carbon dioxide into carbohydrate via enzyme-catalysed steps.
- Glycolysis
- The first stage of cellular respiration, occurring in the cytosol, where glucose is split into pyruvate with net production of ATP and NADH.
- Anaerobic respiration
- ATP production without oxygen; in animals pyruvate is converted to lactate, and in yeast to ethanol and carbon dioxide, regenerating NAD+ for glycolysis.
- Antibody structure
- A Y-shaped protein with two variable antigen-binding sites and a constant region; antibodies agglutinate pathogens and mark them for immune destruction.
- Clonal selection
- The process by which an antigen activates specific lymphocytes, causing them to proliferate and differentiate into effector and memory cells.
- Natural selection
- Differential survival and reproduction of individuals with heritable traits suited to the environment, changing allele frequencies in a population over generations.
- Genetic drift
- Random change in allele frequencies between generations due to chance, with strongest effects in small populations such as after a bottleneck.
- Allopatric speciation
- Formation of new species when a geographic barrier separates populations, preventing gene flow and allowing independent selection and mutation to diverge them.
- Hardy-Weinberg equilibrium
- A model where allele and genotype frequencies stay constant without mutation, gene flow, selection or drift in a large randomly mating population.
- Frameshift mutation
- Insertion or deletion of nucleotides not in multiples of three, shifting the reading frame and usually altering all downstream amino acids.
- CRISPR-Cas9
- A gene-editing tool in which a guide RNA directs the Cas9 nuclease to cut a target DNA sequence, enabling gene disruption or insertion.
- Gel electrophoresis
- A technique separating DNA fragments by size using an electric field; smaller negatively charged fragments move further through the gel toward the positive electrode.
- Polymerase chain reaction
- A method amplifying DNA through repeated cycles of denaturation, primer annealing and extension by a heat-stable DNA polymerase.