CHSE Odisha Elective Biology flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Binomial nomenclature

Two-part scientific naming system where the genus is capitalized and the species is lowercase, both italicized, giving every organism a unique universal name.

Three-domain classification

Woese's system dividing life into Bacteria, Archaea, and Eukarya, distinguished by ribosomal RNA sequences and cell membrane chemistry.

Bryophyte sporophyte dependence

In bryophytes, the gametophyte is the dominant photosynthetic phase while the sporophyte remains attached to and nutritionally dependent on the gametophyte.

Vexillary aestivation

Papilionaceous arrangement with one large standard petal, two wing petals, and two fused keel petals, characteristic of pea flowers.

Open vascular bundle

A bundle containing cambium between xylem and phloem, permitting secondary growth, typical of dicot stems.

Intercalated discs

Specialized junctional structures in cardiac muscle that allow rapid electrical coupling and coordinated contraction of heart muscle cells.

Fluid mosaic model

Description of the plasma membrane as a phospholipid bilayer with proteins embedded in or attached to it, capable of lateral movement.

Km meaning

The substrate concentration at which an enzyme reaches half its maximum velocity; a low Km indicates high affinity for substrate.

Crossing over

Exchange of chromosome segments between homologous chromatids during pachytene of prophase I, generating genetic recombination.

Water potential

The sum of solute potential and pressure potential; water moves from regions of higher water potential to lower water potential.

Kranz anatomy

Arrangement in C4 leaves with bundle sheath cells surrounded by mesophyll, enabling spatial separation of carbon fixation and Calvin cycle.

Photorespiration

Wasteful process where RuBisCO binds oxygen instead of carbon dioxide, consuming ATP and releasing carbon without sugar production.

Counter-current mechanism

Opposite flow of filtrate in the loop of Henle and blood in the vasa recta that maintains a medullary osmotic gradient for urine concentration.

Cardiac output

Volume of blood pumped by one ventricle per minute, calculated as heart rate multiplied by stroke volume, roughly five litres at rest.

Double fertilization

In angiosperms, one male gamete fuses with the egg to form the zygote while another fuses with polar nuclei to form triploid endosperm.

LH surge

Sharp rise in luteinizing hormone around mid-cycle that triggers ovulation and formation of the corpus luteum.

Test cross

Crossing an organism showing the dominant phenotype with a homozygous recessive individual to determine whether it is homozygous or heterozygous.

Semiconservative replication

Each new DNA molecule contains one original parental strand and one newly synthesized strand, as demonstrated by the Meselson–Stahl experiment.

Hardy–Weinberg principle

Allele and genotype frequencies in a population remain constant without mutation, migration, selection, or genetic drift; p² + 2pq + q² = 1.

Lac operon

Inducible gene system in bacteria where lactose inactivates the repressor, allowing transcription of genes for lactose metabolism.

Passive immunity

Protection conferred by antibodies received from another source, such as maternal IgA in colostrum, without the recipient making them.

Biofertilizer

Microorganism-based preparation such as Rhizobium, Azotobacter, or mycorrhiza that improves soil nutrient availability for crops.

Single-cell protein

Protein extracted from mass-cultured microorganisms such as Spirulina, used as a protein-rich food supplement.

Sticky ends

Short single-stranded overhangs produced by staggered restriction enzyme cuts, allowing complementary DNA fragments to base-pair and ligate.

Polymerase chain reaction

Technique amplifying DNA through repeated cycles of denaturation, primer annealing, and extension by thermostable Taq polymerase.

Bt toxin activation

Cry protein from Bacillus thuringiensis is inactive in bacteria but becomes toxic in the alkaline midgut of susceptible insects.

RNA interference

Silencing of gene expression by complementary RNA molecules that bind and degrade target mRNA, used to engineer nematode resistance.

Logistic growth

Population growth that slows as density approaches carrying capacity, described by dN/dt = rN(K−N)/K.

Ecological pyramid

Graphic representation of number, biomass, or energy at successive trophic levels; the energy pyramid is always upright.

Species–area relationship

Species richness increases with habitat area according to S = C·A^z, where z is the slope on a log-log plot.

Biological oxygen demand

Amount of oxygen consumed by microbes decomposing organic matter in water; high BOD indicates heavy organic pollution.

In situ conservation

Protection of species within their natural habitats through biosphere reserves, national parks, and wildlife sanctuaries.