MTEL Biology flashcards
MTEL 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.
- Cell theory
- All organisms are composed of one or more cells, cells are the basic unit of structure and function, and all cells arise from pre-existing cells by division.
- Prokaryotic cell
- A cell lacking a membrane-bound nucleus and organelles, typically having a single circular chromosome, ribosomes, and a cell wall, as seen in bacteria and archaea.
- Endosymbiotic theory
- The hypothesis that mitochondria and chloroplasts originated from free-living bacteria engulfed by ancestral eukaryotic cells, supported by their own DNA and double membranes.
- Osmosis
- The diffusion of water across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration until equilibrium is reached.
- Active transport
- Movement of substances against their concentration gradient using energy, typically ATP, as with the sodium-potassium pump that maintains ion gradients in nerve cells.
- Enzyme active site
- The region of an enzyme where substrate binds and catalysis occurs; its shape is specific to the substrate and can be altered by heat or pH changes.
- Light reactions
- The thylakoid-membrane stage of photosynthesis in which light energy drives electron transport, producing ATP and NADPH and releasing oxygen from split water molecules.
- Calvin cycle
- The light-independent stage of photosynthesis in the stroma in which rubisco fixes carbon dioxide into organic molecules using ATP and NADPH from the light reactions.
- Glycolysis
- The first stage of cellular respiration in the cytoplasm, splitting one glucose into two pyruvate molecules and netting two ATP and two NADH.
- Transcription
- The process in which RNA polymerase builds a messenger RNA strand complementary to a DNA template, occurring in the nucleus of eukaryotic cells.
- Translation
- The process at ribosomes in which transfer RNA molecules match anticodons to messenger RNA codons, delivering amino acids to build a polypeptide chain.
- Mitosis
- Cell division producing two genetically identical diploid daughter cells, used for growth, repair, and asexual reproduction in eukaryotic organisms.
- Meiosis
- Two successive divisions producing four haploid gametes, with crossing over in prophase I and independent assortment creating genetic variation among offspring.
- Mendelian monohybrid ratio
- A cross between two heterozygotes for one gene yields a 3:1 phenotypic ratio and a 1:2:1 genotypic ratio in the offspring.
- Testcross
- A cross between an individual of unknown genotype and a homozygous recessive individual, used to determine whether the unknown carries a dominant or recessive allele.
- Incomplete dominance
- A pattern in which the heterozygote shows an intermediate phenotype between the two homozygotes, such as pink flowers from red and white parents.
- Sex-linked trait
- A trait controlled by a gene on a sex chromosome, most often the X chromosome; recessive X-linked traits appear more frequently in males.
- Hardy-Weinberg equilibrium
- A model in which allele and genotype frequencies remain constant across generations when there is no mutation, migration, selection, or drift and mating is random.
- Genetic drift
- Random change in allele frequencies due to chance, most pronounced in small populations; examples include the bottleneck effect and the founder effect.
- Natural selection
- Differential survival and reproduction of individuals based on heritable variation, causing adaptive traits to become more common in a population over generations.
- Allopatric speciation
- Formation of new species when a population is geographically separated, preventing gene flow and allowing independent evolution and reproductive isolation.
- Homologous structures
- Body parts in different species sharing similar underlying anatomy due to common ancestry, such as the forelimbs of humans, whales, and bats.
- Energy pyramid
- A diagram showing energy transfer among trophic levels, in which only about ten percent of energy passes to the next level, producing a tapering shape.
- Nitrogen fixation
- Conversion of atmospheric nitrogen gas into ammonia by bacteria such as Rhizobium in root nodules, making nitrogen available for building amino acids and nucleic acids.
- Carrying capacity
- The maximum population size an environment can sustain indefinitely given available resources; logistic growth levels off at this value.
- Mutualism
- A symbiotic relationship in which both interacting species benefit, such as pollinators obtaining nectar while transferring pollen for the plant.
- Negative feedback
- A regulatory mechanism in which a change triggers a response that counteracts the change, maintaining homeostasis such as stable blood glucose or body temperature.
- Xylem and phloem
- Vascular plant tissues: xylem transports water and dissolved minerals upward from roots, while phloem transports sugars from leaves to other plant parts.
- Stomata
- Pores on leaf surfaces, controlled by guard cells, that regulate gas exchange and water loss through transpiration in plants.
- Adaptive immunity
- The specific immune response involving B cells that produce antibodies and T cells that destroy infected cells, and which creates immunological memory.
- Semiconservative replication
- DNA replication in which each new double helix contains one original parental strand and one newly synthesized complementary strand.
- Codon
- A sequence of three nucleotides in messenger RNA that specifies a particular amino acid or a stop signal during translation at the ribosome.