Textbook of Biology Grade 12 Review Flashcards

This set of vocabulary flashcards summarizes critical terms, physiological processes, genetic concepts, and developmental stages detailed in the Grade 12 Biology curriculum.

Internal Respiration

A catabolic process at the cellular level involving the breakdown of complex organic molecules to release energy.

External Respiration

The organismic process of inhaling oxygen and exhaling carbon dioxide into the environment.

Respiratory Surface

The thin, permeable area where gas exchange occurs, typically requiring a distance of $1\,\text{mm}$ or less for efficient diffusion.

Surfactant

A lipoprotein film that lowers surface tension in the alveoli to prevent collapse and facilitate gas transport.

Tidal Volume

The amount of air inhaled or exhaled during regular breathing at rest, which averages $500\,\text{ml}$.

Total Lung Capacity

The maximum amount of air the human lungs can hold, totaling approximately $6000\,\text{ml}$.

Chloride Shift

The movement of chloride ions into red blood cells to balance the outward diffusion of bicarbonate ions, also known as the Hamburger phenomenon.

Myoglobin

An oxygen-storing pigment found in muscles that consists of one polypeptide chain and one iron-containing haem group.

Pneumonectomy

The surgical removal of a lung or a lobe of a lung, often used as a treatment for localized lung cancer.

Homeostasis

The regulation of internal conditions, such as chemical composition of body fluids, to maintain stability regardless of external environment.

Osmoregulation

The maintenance of constant osmotic conditions through the regulation of water and solute concentrations.

Osmoconformers

Animals that adjust their internal osmotic concentration to remain isotonic with their surrounding external medium.

Anhydrobiosis

The ability of certain desert animals, like the kangaroo rat, to tolerate extreme dehydration via metabolic adaptations.

Ammonotelic

Organisms that excrete ammonia as their primary nitrogenous waste, necessitating roughly $500\,\text{ml}$ of water per gram of nitrogen.

Uricotelic

Animals that excrete uric acid, requiring only $1\,\text{ml}$ of water per gram of nitrogen, an adaptation common in terrestrial invertebrates.

Nephron

The functional unit of the kidney, which includes the renal corpuscle, proximal convoluted tubule, loop of Henle, and distal convoluted tubule.

Glomerular Filtration

The process where water and small solutes are filtered from blood into the Bowman's capsule under hydrostatic pressure.

Ectotherms

Animals that rely mainly on external environmental heat to regulate their body temperature, such as reptiles and amphibians.

Osteoblasts

Bone-forming cells responsible for synthesizing and secreting unmineralized ground substance.

Axial Skeleton

The portion of the skeleton along the central axis, including the skull, rib cage, and a vertebral column consisting of $33$ vertebrae.

Synovial Joints

Freely moveable joints where bone ends are covered in hyaline cartilage and enclosed in a capsule secreting synovial fluid.

Sarcomere

The contractile unit of a myofibril located between two adjacent $Z$ lines.

Rigor Mortis

The state of muscular rigidity after death caused by the depletion of $\text{ATP}$, preventing the breakdown of cross-bridges between actin and myosin.

Nissl's Granules

Ribosome and rough endoplasmic reticulum groups in the neuron cell body associated with protein synthesis.

Resting Membrane Potential

The electrical potential across a non-stimulated neuron membrane, typically measured at $-70\,\text{mV}$.

Saltatory Conduction

The rapid transmission of nerve impulses where action potentials jump between the nodes of Ranvier in myelinated axons.

Limbic System

A complex set of brain structures involving the hypothalamus, amygdala, and hippocampus that regulates emotions and memory.

Acromegaly

A condition in adults caused by the over-secretion of growth hormone, resulting in the thickening of hand, foot, and jaw bones.

Islets of Langerhans

Endocrine tissue patches in the pancreas containing beta cells that secrete insulin and alpha cells that secrete glucagon.

Circadian Rhythms

Biological cycles lasting approximately $24$ hours that regulate physiological processes like sleep and hormone secretion.

Altruism

Behavior that benefits other members of a species at the expense of an individual's own reproductive success or safety.

Spermatogenesis

The process of sperm production occurring within the germinal epithelium of the seminiferous tubules.

Corpus Luteum

A glandular mass formed from a ruptured follicle that produces progesterone to maintain the uterine lining during pregnancy.

Morula

The solid ball of small cells formed during the early stages of cleavage, roughly the same size as the original zygote.

Embryonic Induction

The phenomenon where specific cells evoke a developmental response in adjacent cells, first reported by Hans Spemann and Hilde Mangold.

Placenta

The organ formed from fetal chorionic villi and maternal endometrium that manages nutrient uptake and waste elimination for the fetus.

Hardy-Weinberg Theorem

A principle stating that allele and genotype frequencies in a population remain constant provided conditions like random mating and no selection are met.

Genetic Drift

Unpredictable fluctuations in allele frequencies between generations, often occurring through bottleneck or founder effects.

Speciation

The evolutionary process by which new biological species arise, occurring via allopatric, sympatric, or parapatric mechanisms.

Restriction Endonucleases

Enzymes that cleave DNA at specific palindromic recognition sites, used as molecular scissors in recombinant $DNA$ technology.

Polymerase Chain Reaction

An in vitro technique for multiplying specific $DNA$ fragments into thousands of copies using heat-stable $\text{Taq}$ polymerase.

Genomic Library

A collection of bacterial or bacteriophage clones that together represent the entire genome of an organism.

Sanger-Coulson Method

A chain-termination sequencing technique utilizing $\text{ddNTPs}$ to stop $DNA$ synthesis at specific bases.

Gene Therapy

A medical technique involving the insertion of normal genes into a patient's cells to correct genetic defects.

Integrated Disease Management

An approach to combating disease by utilizing all appropriate methods and ensuring community participation.