UPMSP Intermediate Biology key terms

A form of asexual reproduction in which a single cell divides into two identical daughter cells, as seen in bacteria and Amoeba. The parent cell's nucleus and cytoplasm split into two separate individuals.

Asexual reproduction in plants where new individuals arise from vegetative parts such as roots, stems, or leaves. Examples include runners in grass, tubers in potato, and bulbs in onion.

An artificial propagation technique joining the stem (scion) of one plant onto the rooted stem (stock) of another so they unite and grow as one plant. Used in mango and rose to combine desirable traits.

Reproduction by spores, which are single cells that can develop into new individuals without fusion. Common in fungi like Rhizopus, mosses, and ferns, and in some bacteria forming resistant endospores.

The process of forming haploid gametes from diploid germ cells through meiosis. In males it produces sperm (spermatogenesis); in females it produces eggs (oogenesis).

The fusion of a haploid male gamete with a haploid female gamete to form a diploid zygote. In flowering plants, one sperm fuses with the egg and another with two polar nuclei (double fertilisation).

The diploid cell formed when two haploid gametes fuse during fertilisation. It is the first cell of a new individual and develops into an embryo by repeated mitotic divisions.

A reduction division producing four haploid cells from one diploid cell. It involves two successive divisions with one round of chromosome replication, generating genetic variation through crossing over and independent assortment.

The exchange of segments between non-sister chromatids of homologous chromosomes during prophase I of meiosis. It produces new combinations of alleles and is a major source of genetic variation.

The tendency of genes located close together on the same chromosome to be inherited together, deviating from independent assortment. Recombination frequency between linked genes reflects their distance apart.

The principle that alleles of different genes assort independently during gamete formation when the genes are on different chromosomes. It explains the 9:3:3:1 ratio in a dihybrid cross.

A cross between an individual of unknown genotype and a homozygous recessive individual. The phenotypes of the offspring reveal whether the unknown parent was homozygous dominant or heterozygous.

A sudden heritable change in the DNA sequence of a gene or chromosome. Mutations may be spontaneous or induced by mutagens and provide the raw material for evolution.

The process by which individuals with heritable traits better suited to their environment survive and reproduce more successfully, so those traits increase in frequency over generations. Proposed by Darwin and Wallace.

A random change in allele frequencies in a small population due to chance events rather than selection. It can eliminate or fix alleles and reduces genetic variation over time.

The process of making a person resistant to a disease, either by vaccination with antigens to stimulate antibody production (active) or by injecting ready-made antibodies (passive).

A preparation containing weakened, killed, or subunit antigens of a pathogen that stimulates an immune response and creates memory cells, giving protection against future infection without causing the disease.

A protein produced by plasma cells (differentiated B lymphocytes) in response to a specific antigen. It binds that antigen and helps neutralise or remove the pathogen or toxin.

Techniques for joining DNA fragments from different sources and inserting them into a host cell, often using vectors such as plasmids. Used to produce insulin, vaccines, and genetically modified crops.

A bacterial enzyme that cuts DNA at specific recognition sequences called palindromic sites. It produces sticky or blunt ends and is a key tool for inserting genes into vectors.

A small circular extrachromosomal DNA molecule in bacteria that replicates independently. In genetic engineering it is used as a vector to carry a foreign gene into a host cell.

A vessel in which cells or microorganisms are grown under controlled conditions to produce a desired product. Stirred-tank and airlift types are used in industrial fermentation.

An in vitro method that amplifies a specific DNA segment through repeated cycles of denaturation, primer annealing, and extension by Taq polymerase. It produces millions of copies from a tiny sample.

The variety of life at all levels, including genetic variation within species, species richness in a habitat, and the range of ecosystems. It underpins ecosystem stability and human welfare.

A graphical representation of the numbers, biomass, or energy at each trophic level of a food chain. Energy pyramids are always upright because energy is lost at each transfer.

The position an organism occupies in a food chain, such as producer, primary consumer, or secondary consumer. Each level receives only about ten percent of the energy from the level below.

The cycling of chemical elements such as carbon, nitrogen, and phosphorus between living organisms and the non-living environment. Microbes often drive key steps like nitrogen fixation and decomposition.

The selectively permeable phospholipid bilayer with embedded proteins that surrounds every cell. It controls the movement of substances into and out of the cell and carries out cell recognition.

The diffusion of water molecules across a semipermeable membrane from a region of higher water potential to one of lower water potential. It drives water uptake by plant roots and cell turgidity.

A double-membraned organelle with folded inner cristae where aerobic respiration and ATP synthesis occur. It is called the powerhouse of the cell and contains its own DNA.

Cell division producing two genetically identical diploid daughter cells. It is responsible for growth, repair, and asexual reproduction, and has four stages: prophase, metaphase, anaphase, and telophase.

The loss of water vapour from plant leaves, mainly through stomata. It creates the pulling force that draws water up the xylem and cools the leaf.

The process by which green plants use light energy to convert carbon dioxide and water into glucose and oxygen in chloroplasts. It has light-dependent and light-independent (Calvin cycle) phases.

Tiny pores in the leaf epidermis bounded by guard cells that open and close them. They allow carbon dioxide to enter for photosynthesis and water vapour and oxygen to leave.

The structural and functional unit of the kidney that filters blood and forms urine. It includes the glomerulus, Bowman's capsule, and tubules where reabsorption and secretion occur.

A tiny air sac in the lungs where gaseous exchange occurs. Its thin walls and rich capillary network allow oxygen to diffuse into blood and carbon dioxide to diffuse out.

The junction between two neurons or between a neuron and a muscle cell. A nerve impulse crosses it by release of a neurotransmitter such as acetylcholine across the synaptic cleft.

A chemical messenger secreted by an endocrine gland into the blood, which travels to target cells bearing specific receptors and regulates their activity. Examples include insulin, thyroxine, and auxin in plants.