Bihar BSEB Intermediate Biology key terms

The event in flowering plants where one male gamete fuses with the egg to form the zygote and a second male gamete fuses with two polar nuclei to form the triploid primary endosperm nucleus.

The nourishing tissue of a seed, usually triploid in angiosperms, formed from the primary endosperm nucleus and supplying food to the developing embryo.

The two haploid nuclei lying in the central cell of the embryo sac that fuse with one male gamete during double fertilisation to give rise to the primary endosperm nucleus.

A form of asexual reproduction in plants in which seeds are produced without fertilisation, so the offspring are genetically identical to the parent plant.

The development of fruit without fertilisation, giving seedless fruits such as banana; it can occur naturally or be induced by growth hormones.

The yellowish glandular body formed from the ruptured ovarian follicle after ovulation; it secretes progesterone, which prepares and maintains the uterine lining for pregnancy.

The release of a mature secondary oocyte from a ruptured Graafian follicle at about the middle of the menstrual cycle, usually around day 14.

The roughly 28-day repeating cycle of hormonal changes in human females that thickens the uterine lining, releases an egg, and sheds the lining if pregnancy does not occur.

A steroid hormone secreted mainly by the corpus luteum and later the placenta; it maintains the endometrium and supports pregnancy.

A prenatal diagnostic test in which a sample of amniotic fluid containing fetal cells is withdrawn and analysed for chromosomal and genetic abnormalities.

A state of physical, mental and social well-being in all matters relating to the reproductive system, including safe sexual behaviour, fertility control and freedom from disease.

A cross between an individual showing a dominant phenotype and a homozygous recessive individual, used to reveal whether the dominant individual is homozygous or heterozygous.

Mendel's principle that the two alleles of a gene separate during gamete formation, so each gamete carries only one allele of each pair.

One of two or more alternative forms of a gene occupying the same locus on homologous chromosomes and controlling the same character.

The tendency of genes located close together on the same chromosome to be inherited together, reducing the frequency of recombination between them.

The production of new allele combinations in offspring, arising from crossing over between homologous chromosomes during meiosis or from independent assortment of chromosomes.

The process in which RNA polymerase synthesises a strand of RNA using one strand of DNA as a template, transferring genetic information from DNA to RNA.

The process at ribosomes in which the sequence of codons on messenger RNA directs the assembly of amino acids into a polypeptide chain.

The set of rules by which triplet base sequences called codons in messenger RNA specify particular amino acids or stop signals during protein synthesis.

The process by which individuals with inherited traits better suited to their environment survive and reproduce more successfully, so those traits become more common over generations.

The rapid diversification of a single ancestral lineage into many species occupying different ecological niches, as seen in Darwin's finches of the Galapagos Islands.

A protein produced by plasma cells in response to an antigen; it binds specifically to that antigen and helps neutralise or destroy the pathogen.

Protection against a pathogen acquired when the body's own immune system produces antibodies after natural infection or vaccination, and which develops slowly but lasts long.

A flammable mixture consisting mainly of methane, produced when anaerobic bacteria decompose cattle dung and other organic waste in a sealed digester.

Breeding crops to raise their content of essential nutrients such as vitamins, minerals and proteins, for example iron-rich bajra or vitamin A enriched carrots.

An enzyme that cuts double-stranded DNA at a specific recognition sequence, producing fragments with sticky or blunt ends for use in genetic engineering.

A small circular DNA molecule found in bacteria, separate from the main chromosome, that replicates independently and is widely used as a vector in genetic engineering.

A DNA molecule formed by joining fragments of DNA from different sources, typically a gene of interest inserted into a vector such as a plasmid.

A laboratory technique that repeatedly copies a chosen DNA segment in vitro using primers and a heat-stable DNA polymerase, amplifying it into millions of copies.

The maximum population size of a species that a given environment can support indefinitely with the resources available, shown as the plateau of a logistic growth curve.

The number of individuals of a species present per unit area or per unit volume of habitat at a given time.

A graphical representation of the numbers, biomass or energy at successive trophic levels of a food chain, showing the quantitative relationship between them.

The position an organism occupies in a food chain, such as producer, primary consumer or secondary consumer, determined by its source of food and energy.

Excessive enrichment of a water body with nutrients such as nitrates and phosphates, causing algal blooms that deplete oxygen and harm aquatic life.

The movement of water molecules across a semipermeable membrane from a region of higher water potential to one of lower water potential.

The shrinking and pulling away of the protoplast from the cell wall when a plant cell loses water to a hypertonic surrounding solution.

Double-membraned organelles with folded inner cristae that carry out aerobic respiration and generate most of the cell's ATP.

The final stage of aerobic respiration in which electrons passed along the electron transport chain drive ATP synthesis, using oxygen as the final electron acceptor.

A wasteful process in C3 plants in which RuBisCO binds oxygen instead of carbon dioxide, consuming energy and releasing carbon dioxide without producing sugar.

The light-independent reactions of photosynthesis in which carbon dioxide is fixed by RuBisCO and reduced to sugar using ATP and NADPH from the light reactions.

The functional filtering unit of the kidney, consisting of a glomerulus and a tubule, which filters blood and forms urine.

The pressure-driven process in the renal corpuscle by which water and small solutes are forced out of the blood into the Bowman's capsule, forming the filtrate.

The junction between two neurons, or between a neuron and a muscle or gland, across which a nerve impulse is transmitted by chemical neurotransmitters.