Maharashtra HSC Biology flashcards
Maharashtra HSC 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.
- Law of segregation
- Mendel's principle that the two alleles of a gene separate during gamete formation, so each gamete carries only one allele and offspring regain two at fertilization.
- Test cross
- A cross of an individual showing a dominant phenotype with a homozygous recessive partner to determine whether the unknown genotype is homozygous or heterozygous.
- Semiconservative replication
- DNA replication in which each daughter double helix retains one parental strand and one newly synthesized strand, confirmed by the Meselson-Stahl nitrogen-15 experiment.
- Restriction endonuclease
- An enzyme that recognizes a specific palindromic DNA sequence and cuts the sugar-phosphate backbone, producing sticky or blunt ends used in gene cloning.
- Polymerase chain reaction
- An in vitro technique that amplifies DNA through repeated cycles of denaturation, primer annealing, and extension by thermostable Taq polymerase, doubling copies each cycle.
- Cloning vector
- A DNA molecule such as a plasmid that carries an insert into a host cell and must possess an origin of replication, selectable marker, and cloning site.
- S phase
- The synthetic phase of interphase in which chromosomal DNA replicates, doubling DNA content while chromosome number and ploidy remain unchanged.
- Crossing over
- Exchange of segments between non-sister chromatids of homologous chromosomes during pachytene of prophase I, generating new allele combinations in gametes.
- Double fertilization
- An angiosperm event in which one male gamete fuses with the egg forming a diploid zygote and another fuses with polar nuclei forming triploid endosperm.
- Corpus luteum
- A temporary endocrine structure formed from the ruptured follicle after ovulation that secretes progesterone to maintain the endometrium for possible implantation.
- LH surge
- A sharp mid-cycle rise in luteinizing hormone that triggers ovulation around day fourteen and converts the ruptured follicle into the corpus luteum.
- Water potential
- The free energy of water per unit volume, expressed as solute potential plus pressure potential; pure water at atmospheric pressure equals zero.
- Cohesion-tension theory
- Explanation of xylem transport in which transpiration creates tension, and cohesion between water molecules pulls a continuous water column up the plant.
- C4 pathway
- A photosynthetic adaptation using PEP carboxylase to fix CO2 into four-carbon acids before Calvin cycle entry, reducing photorespiration in tropical grasses.
- Oxidative phosphorylation
- ATP synthesis driven by a proton gradient across the inner mitochondrial membrane, generated as electrons pass along the electron transport chain to oxygen.
- Apical dominance
- Inhibition of lateral bud growth by auxin produced in the shoot apex, which maintains a single dominant main shoot until the tip is removed.
- Vernalization
- Low-temperature exposure of seeds or seedlings that promotes or accelerates flowering, as seen in winter varieties of wheat and biennial plants.
- Bohr effect
- The shift of the hemoglobin oxygen dissociation curve to the right, reducing oxygen affinity when carbon dioxide, hydrogen ion, or temperature rises.
- Vital capacity
- The maximum volume of air a person can exhale after a maximal inhalation, equal to tidal volume plus inspiratory and expiratory reserve volumes.
- Cardiac output
- The volume of blood pumped by one ventricle per minute, calculated as stroke volume multiplied by heart rate, about five liters at rest.
- Counter-current mechanism
- The arrangement of loop of Henle and vasa recta in opposite directions that maintains an osmotic gradient in the renal medulla for urine concentration.
- Sliding filament theory
- Muscle contraction model in which actin filaments slide over myosin filaments, shortening the sarcomere, powered by ATP and triggered by calcium ions.
- Action potential
- A rapid all-or-none electrical change along an axon caused by sodium influx followed by potassium efflux, propagating a nerve impulse.
- Negative feedback
- A homeostatic control mechanism in which a deviation from the set point triggers responses that reverse the deviation and restore normal conditions.
- Thyroxine
- A thyroid hormone containing iodine that raises basal metabolic rate, supports growth and development, and is deficient in goitre.
- Miller-Urey experiment
- A 1953 experiment passing electric sparks through methane, ammonia, hydrogen, and water vapor, producing amino acids and supporting chemical evolution of life.
- Hardy-Weinberg equilibrium
- The condition in which allele and genotype frequencies remain constant across generations in a large, randomly mating population without mutation, migration, or selection.
- Natural selection
- The differential survival and reproduction of individuals with heritable variations better suited to their environment, proposed by Darwin as the mechanism of evolution.
- Ten percent law
- Lindeman's rule that only about ten percent of energy at one trophic level is transferred to the next, limiting food chain length.
- Ecological pyramid
- A graphical representation of number, biomass, or energy at successive trophic levels; the energy pyramid is always upright.
- Eutrophication
- Nutrient enrichment of a water body, often by nitrates and phosphates, causing algal blooms, oxygen depletion, and loss of aquatic life.
- Biodiversity hotspot
- A region with exceptionally high species richness and endemism that has lost a large proportion of its original habitat, such as the Western Ghats.