Mawhiba Biology Level 1: Cellular Biology, Physiology, and Ecology

Comprehensive vocabulary flashcards covering the core topics of the Mawhiba Level 1 Biology curriculum: cell structure and transport, biochemistry, energy metabolism, cell division and genetics, human body systems, and ecological concepts.

Prokaryotic Cells

Cells in which the genetic material is free and not enclosed by a membrane, possessing a single circular chromosome and lacking membrane-bound organelles, such as in bacteria.

Eukaryotic Cells

Cells in which the genetic material is enclosed within a true nucleus bounded by a nuclear membrane, possessing linear DNA organized into chromosomes and membrane-bound organelles.

Protoplasm

The complete substance located inside the plasma membrane of a cell, comprising both the cytoplasm and the nucleus.

Cytoskeleton

A network of protein filaments that supports the cell, maintains its shape, anchors organelles in place, and regulates internal organelle motility.

Golgi Apparatus

A cellular system of stacked membrane-bound sacs that modifies, sorts, and packages substances into vesicles, and produces lysosomes.

Smooth Endoplasmic Reticulum (SER)

A network of interconnected membranous channels lacking ribosomes, specialized in the synthesis of carbohydrates and complex lipids (including phospholipids), protein transport, and the detoxification of drugs and harmful substances in the liver.

Lysosomes

Membrane-bound digestive vesicles originating from the Golgi apparatus and endoplasmic reticulum that perform intracellular digestion and mediate programmed cell death (apoptosis).

Selective Permeability

The property of the plasma membrane that regulates and controls the transit of specific substances into and out of the cell.

Osmosis

The diffusion of solvent molecules (water) across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Hypertonic Solution

A solution with a higher solute concentration relative to the cytoplasm of a cell, resulting in the net outward movement of water and cellular shrinkage.

Hypotonic Solution

A solution with a lower solute concentration relative to the cytoplasm of a cell, resulting in water entry that causes animal cells to swell and lyse, and plant cells to become turgid.

Facilitated Diffusion

The passive movement of polar or large molecules along their concentration gradient across a membrane mediated by transport proteins, without cellular energy consumption.

Active Transport

The energy-requiring movement of substances against their concentration gradient, from an area of low concentration to high concentration, utilizing membrane transport proteins.

Phagocytosis

A type of endocytosis referred to as cell eating, occurring when the plasma membrane engulfs solid particles to internalize them inside a cytoplasmic vesicle.

Pinocytosis

A type of endocytosis referred to as cell drinking, occurring when the plasma membrane invaginates to take in droplets of extracellular fluid containing dissolved substances.

Exocytosis

The cellular process of discharging substances outside the cell by packaging them within internal vesicles that fuse directly with the plasma membrane.

Peptide Bond

A rigid planar amide linkage formed between the amino group of one amino acid and the carboxyl group of another via the condensation-driven elimination of a water molecule.

Activation Energy ($E_A$)

The minimum energy barrier that reacting molecules must overcome to initiate a chemical transformation, which biological catalysts (enzymes) lower to accelerate reaction rates.

Catabolism

The metabolic pathway of biochemical reactions that breaks down complex molecules into simpler constituents, releasing chemical energy.

Anabolism

The metabolic pathway of constructive biochemical reactions that utilizes energy to synthesize complex organic molecules from simpler precursors.

Adenosine Triphosphate (ATP)

The primary universal cellular energy currency, consisting of an adenine nitrogenous base, a ribose sugar, and three phosphate groups linked by high-energy phosphoanhydride bonds.

Thylakoids

Flattened, disc-shaped membranous sacs within chloroplasts arranged in columns called grana, housing chlorophyll and protein complexes for light-dependent reactions.

Calvin Cycle

The light-independent cyclic biochemical reactions occurring in the stroma of chloroplasts that fix carbon dioxide into carbohydrates using ATP and NADPH generated by light reactions.

Glycolysis

The anaerobic cytoplasmic breakdown of one glucose molecule into two pyruvic acid molecules, yielding a net production of $2\text{ ATP}$ and $2\text{ NADH}$.

Krebs Cycle

The cyclic aerobic metabolic pathway occurring in the mitochondrial matrix where acetyl-CoA is oxidized, generating carbon dioxide, ATP, NADH, and $FADH_2$.

Lactic Acid Fermentation

An anaerobic pathway in which pyruvate is reduced to lactic acid by NADH without producing carbon dioxide, occurring in muscle cells undergoing oxygen deficit.

Alcoholic Fermentation

An anaerobic pathway in yeasts and certain bacteria where pyruvate is decarboxylated to acetaldehyde and subsequently reduced to ethanol and $CO_2$, regenerating $NAD^+$.

Binary Fission

The predominant asexual reproductive process in prokaryotes, wherein a single circular chromosome is replicated bidirectionally and partitioned into two genetically identical daughter cells by an FtsZ ring.

Mitosis

The equational division of eukaryotic somatic cells resulting in two genetically identical diploid ($2n$) daughter cells with the exact chromosome number of the parent cell.

Cytokinesis

The final stage of the cell cycle involving division of the cytoplasm, executed by a cleavage furrow in animal cells and a cell plate in plant cells.

Cyclins

A family of regulatory proteins whose concentrations fluctuate to bind cyclin-dependent kinases (CDKs), activating enzymatic complexes that control cell cycle progression and checkpoints.

Apoptosis

An orderly, genetically programmed sequence of events leading to controlled cell death, characterized by cell shrinkage and nuclear condensation.

Stem Cells

Unspecialized precursor cells capable of perpetual self-renewal and differentiation into diverse mature, specialized cell types.

Homologous Chromosomes

Pairs of matching chromosomes carrying genes for the same inherited traits at corresponding loci, one derived from each biological parent.

Synapsis

The intimate pairing of homologous chromosome pairs during prophase I of meiosis, facilitating the reciprocal exchange of genetic segments termed crossing over at chiasmata.

Threshold Stimulus

The minimum stimulus intensity required to depolarize a excitable neuron membrane sufficiently to initiate an all-or-none action potential.

Ball and Socket Joint

A synovial joint type formed by a spherical bone head fitting into a cuplike cavity, allowing rotational freedom and movement along nearly all axes (such as the shoulder and hip).

Peristalsis

Rhythmic, coordinated waves of smooth muscle contraction and relaxation that advance ingested food through the digestive tract.

Calorie

The unit of measurement representing the amount of thermal energy required to elevate the temperature of $1\text{ mL}$ of water by $1^\circ\text{C}$.

Alveoli

Microscopic, single-cell-thick saclike functional units in the lungs surrounded by dense capillary beds where respiratory gas exchange occurs.

Biosphere

The global ecological zone of life encompassing all interacting living organisms (biotic factors) and their physical environments (abiotic factors) on Earth.

Ecological Niche

The precise role, functional position, and environmental resource interactions of a species within its biological community.

Mutualism

A reciprocal symbiotic interspecies interaction in which both participating organisms derive mutual fitness or survival benefits.

Commensalism

An ecological symbiotic interaction in which one organism derives benefit while the other experiences neither benefit nor measurable detriment.

Primary Succession

The sequential ecological development of a biotic community beginning on a newly exposed, completely sterile surface lacking soil, initiated by pioneer organisms such as lichens.

Secondary Succession

The orderly recolonization and ecological change occurring in an ecosystem following an environmental disturbance that destroyed the preexisting biological community while leaving the soil layer intact.

Climax Community

A mature, self-sustaining biological community that exhibits long-term ecological stability and minimal composition shifts over time.

Bioremediation

The ecological restoration technique that utilizes living organisms, such as prokaryotes, plants, or fungi, to degrade or sequester environmental toxins from contaminated sites.

Biological Augmentation

The practice of introducing natural predatory or parasitic organisms into an ecologically degraded ecosystem to suppress pest populations and reestablish balance.

Innate Behavior

Genetically inherited, instinctual behaviors exhibited by animals without the requirement for prior experience or learning.