Cambridge IAL Biology flashcards
Cambridge IAL 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.
- Magnification formula
- Magnification equals the size of the image divided by the actual size of the object. Rearrange to find actual size by dividing image size by magnification, converting units first.
- Resolution definition
- The smallest distance between two points at which they can still be seen as separate. It depends on the wavelength of the radiation used and the quality of the lens.
- Water potential equation
- Water potential equals solute potential plus pressure potential. Pure water at standard atmospheric pressure has a water potential of zero, and adding solute makes it negative.
- Fick's law
- The rate of diffusion is proportional to surface area and to the concentration gradient, and inversely proportional to the thickness of the diffusion pathway.
- Countercurrent gas exchange
- Blood in the gill lamellae flows in the opposite direction to the water. This maintains a concentration gradient along the whole gill, so more oxygen is absorbed.
- Competitive inhibition effect
- The inhibitor binds to the active site, so a higher substrate concentration is needed to reach a given rate. Maximum rate stays the same because substrate can outcompete the inhibitor.
- Non-competitive inhibition effect
- The inhibitor binds away from the active site and changes its shape. The maximum rate falls because some enzyme molecules are effectively removed from the reaction.
- Photolysis in photosystem II
- Light energy splits water into protons, electrons and oxygen. The electrons replace those lost by photosystem II, and the protons contribute to the gradient used for ATP synthesis.
- Transpiration pull mechanism
- Water evaporates from the leaf mesophyll, creating tension in the xylem. Cohesion between water molecules and adhesion to xylem walls pull water up as a continuous column.
- Tissue fluid formation
- High hydrostatic pressure at the arteriole end forces plasma out of the capillary. At the venule end, lower pressure and higher solute potential draw most fluid back in.
- Cell cycle stages
- Interphase includes growth and DNA replication; mitosis separates chromosomes into two identical nuclei; cytokinesis divides the cytoplasm. Mitosis produces genetically identical diploid cells.
- Monoclonal antibody use
- Identical antibodies from a single clone of plasma cells bind to one specific antigen. They are used in pregnancy tests, disease diagnosis and targeted cancer treatment.
- Biodiversity definition
- The variety of living organisms in an area, including species richness, species evenness and genetic variation within species. It can be measured by sampling and compared statistically.
- Random sampling technique
- Choose positions using random numbers or a grid, then place quadrats. This avoids bias and makes the sample representative, allowing valid estimates of population size.
- Chi-squared formula
- Chi-squared equals the sum of observed minus expected, squared, divided by expected, across all categories. Degrees of freedom equal the number of categories minus one.
- Spearman's rank formula
- The coefficient equals one minus six times the sum of squared rank differences, divided by n times n squared minus one. It measures correlation between two ranked variables.
- Hardy-Weinberg assumptions
- The model assumes no natural selection, no mutation, no migration, no genetic drift and random mating. Under these conditions, allele and genotype frequencies stay constant between generations.
- Test cross purpose
- Crossing an organism showing a dominant phenotype with a homozygous recessive organism. The ratio of phenotypes in the offspring reveals whether the parent was homozygous or heterozygous.
- Sex-linked recessive inheritance
- A recessive allele on the X chromosome affects more males because they have only one X chromosome. An affected father passes the allele to all daughters but to no sons.
- Allopatric speciation
- A geographical barrier separates populations, which then experience different selection pressures. Over many generations, allele frequencies diverge until the populations can no longer interbreed.
- Genetic drift
- Random changes in allele frequency caused by chance, especially in small populations. It can fix or remove alleles regardless of whether they are advantageous.
- Calvin cycle inputs
- Carbon dioxide, ATP and reduced NADP. Rubisco carboxylates RuBP, forming two molecules of glycerate phosphate, which are reduced to triose phosphate for regeneration and synthesis.
- Glycolysis products
- One glucose is split into two pyruvate molecules in the cytoplasm. Net gain is two ATP and two reduced NAD, and no oxygen is required.
- Oxidative phosphorylation
- Electrons from reduced NAD and reduced FAD pass along the inner mitochondrial membrane, pumping protons. Protons flow back through ATP synthase, generating most of the ATP in aerobic respiration.
- Krebs cycle location
- The cycle occurs in the mitochondrial matrix. It produces reduced NAD, reduced FAD, ATP and carbon dioxide, and it links to the electron transport chain.
- Resting potential maintenance
- The sodium-potassium pump moves three sodium ions out for every two potassium ions in. This creates a negative potential and a concentration gradient across the membrane.
- Action potential depolarisation
- Voltage-gated sodium channels open, and sodium ions diffuse in. The membrane potential becomes positive, triggering neighbouring regions to depolarise and propagate the impulse.
- Muscle sliding filament theory
- Calcium ions bind troponin, exposing myosin-binding sites on actin. Myosin heads attach, pivot and pull actin filaments, shortening the sarcomere when ATP is present.
- Homeostasis negative feedback
- A change in a factor is detected by receptors, and an effector response reverses the change. This keeps internal conditions within narrow limits around a set point.
- t-test selection rule
- Use it to compare two means from interval data in independent samples. It assumes approximately normal distribution and calculates a value compared with a critical table.
- Mann-Whitney U test
- A rank-based test comparing two independent groups when data are ordinal or not normally distributed. The calculated U value is compared with a critical value.
- Wilcoxon matched pairs test
- A rank-based test comparing two sets of ordinal data from the same individuals or matched pairs. It tests whether the median difference between conditions is zero.