Yr 11 Biology Prelims

Vocabulary flashcards covering key terms from cells, organization of living things, biological diversity, and ecosystem dynamics.

Cell Theory

All living organisms are made of cells; cells are the basic units of life; new cells arise only from pre-existing cells.

Prokaryotic

Cells that lack a membrane-bound nucleus and other membrane-bound organelles; generally smaller and simpler.

Eukaryotic

Cells with a membrane-bound nucleus and organelles; generally larger and more complex.

Archaea

A group of extremophilic prokaryotes with unique membrane lipids; often in extreme environments.

Bacteria

Prokaryotes with cell walls (often peptidoglycan); may have flagella and endospores.

Nucleus

Double-membrane-bound organelle containing the cell’s DNA; controls cellular activities.

Nucleolus

Dense region inside the nucleus where ribosomal RNA (rRNA) synthesis occurs.

Chromatin

DNA bound to proteins inside the nucleus; condenses to form chromosomes during cell division.

Chromosome

Thread-like structure of DNA that carries genetic information; visible as distinct units during division.

Cytoplasm

Jelly-like fluid inside the cell where metabolic activities occur; contains cytosol and organelles.

Ribosome

RNA-protein complex; site of protein synthesis.

Endoplasmic Reticulum

Membrane network involved in protein and lipid synthesis; two forms: rough (with ribosomes) and smooth (no ribosomes).

Rough ER

ER with attached ribosomes; synthesizes and processes proteins.

Smooth ER

ER without ribosomes; synthesizes lipids and detoxifies compounds.

Golgi Apparatus

Stacks of flattened membranes that modify, sort, and package proteins for secretion or delivery.

Lysosome

Organelle containing digestive enzymes to break down waste and foreign substances.

Vacuole

Membrane-bound sac for storage; large in plants for water regulation and turgor.

Mitochondrion

Double-membrane-bound organelle; powerhouse of the cell; produces ATP via cellular respiration.

Chloroplast

Organelle in plant and algal cells where photosynthesis occurs; contains chlorophyll and its own DNA.

Chlorophyll

Green pigment that absorbs light for photosynthesis.

Plasma Membrane

Selective boundary of the cell; phospholipid bilayer with embedded proteins.

Fluid Mosaic Model

Description of the cell membrane as a dynamic mix of phospholipids, proteins, and cholesterol.

Phospholipid Bilayer

Two-layer arrangement of phospholipids forming the cell membrane.

Integral Protein

Membrane proteins embedded within the lipid bilayer; may form channels or transporters.

Peripheral Protein

Proteins attached to membrane surfaces; involved in signaling and support.

Cholesterol (membrane)

Sterol within animal membranes that stabilizes fluidity and permeability.

Carbohydrates (glycoproteins)

Carbohydrate chains on proteins/lipids that aid in cell recognition and adhesion.

Diffusion

Passive movement of solutes from high to low concentration across a membrane or medium.

Facilitated Diffusion

Diffusion through membrane via specific channel or carrier proteins; no energy required.

Osmosis

Diffusion of water across a semi-permeable membrane from high to low water concentration.

Isotonic

Solution with equal solute concentration to the cell’s interior; no net water flow.

Hypertonic

Solution with higher solute concentration than the cell; water leaves the cell.

Hypotonic

Solution with lower solute concentration than the cell; water enters the cell.

Passive Transport

Movement of substances across membranes without energy input (diffusion, osmosis, facilitated diffusion).

Active Transport

Movement of substances against their concentration gradient using energy (ATP) and transport proteins.

Endocytosis

Process of taking substances into the cell via vesicle formation.

Phagocytosis

Endocytosis of solid particles (cell eating).

Pinocytosis

Endocytosis of liquids (cell drinking).

Receptor-Mediated Endocytosis

Selective uptake of molecules via receptors that trigger vesicle formation.

Exocytosis

Process of releasing substances from the cell via vesicle fusion with the plasma membrane.

Surface Area to Volume Ratio

Proportion of membrane area to cell volume; higher ratios improve exchange with the environment.

Concentration Gradient

Difference in solute concentration between two regions; drives diffusion.

Autotroph

Organism that makes its own organic molecules from inorganic sources (e.g., photosynthesis).

Heterotroph

Organism that obtains organic molecules by consuming other organisms.

Photosynthesis

Process by which light energy is converted to chemical energy (glucose) in plants and some bacteria.

Light-Dependent Reactions

Photosynthesis stage in the thylakoid membranes that uses light to generate ATP and NADPH and releases O2.

Light-Independent Reactions (Calvin Cycle)

Photosynthesis stage in the stroma that fixes carbon dioxide into sugars using ATP and NADPH.

Cellular Respiration

Process of breaking down glucose to produce ATP; includes glycolysis, Krebs cycle, and ETC.

Glycolysis

Glucose is split into pyruvate in the cytosol, yielding ATP and NADH.

Aerobic Respiration

Respiration with oxygen; yields ~36 ATP per glucose in mitochondria.

Anaerobic Respiration

Respiration without oxygen; yields less ATP; lactic acid or ethanol/CO2 as byproducts.

ATP

Adenosine triphosphate; main energy currency of the cell.

NADH

Electron carrier produced during glycolysis/Krebs; donates electrons to the electron transport chain.

Xylem

Plant tissue that transports water and mineral ions from roots to shoots; dead cells at maturity.

Phloem

Plant tissue that transports sugars and other organic nutrients from sources to sinks.

Transpiration-Cohesion-Tension Theory

Water transport in xylem driven by transpiration, cohesion between water molecules, and tension.

Pressure-Flow Mechanism

Phloem transport model driven by pressure differences between source and sink.

Leaves (structure)

Main site of photosynthesis comprising epidermis, mesophyll, and cuticle.

Stomata

Pores in leaf epidermis controlled by guard cells to regulate gas exchange and water loss.

Guard Cells

Pair of cells that regulate stomatal opening in response to turgor.

Epidermis

Outer cell layer of leaves; secretes cuticle and protects inner tissues.

Mesophyll

Photosynthetic tissue inside leaves; includes palisade and spongy layers.

Palisade Mesophyll

Tightly packed chloroplast-rich cells under the upper epidermis for efficient photosynthesis.

Spongy Mesophyll

Loosely arranged photosynthetic tissue with air spaces to facilitate gas exchange.

Cuticle

Waxy waterproof layer on the leaf surface that limits water loss.

Vascular Bundle

Stem tissue containing xylem and phloem for transport.

Xylem Vessel

Dead, hollow tubes in xylem that transport water upward from roots.

Tracheids

Long, thin cells in xylem with tapered ends aiding water transport.

Sieve Tube Cells

Phloem cells that transport sugars; connected by sieve plates.

Companion Cells

Supportive cells in phloem that help maintain sieve tube function.

Root Hairs

Extensions of root epidermal cells increasing surface area for uptake of water and minerals.

Gas Exchange

Movement of O2 and CO2 between organisms and the environment, often via diffusion.

Alveoli

Tiny air sacs in lungs where gas exchange with blood occurs.

Gills

Respiratory organs in aquatic animals that extract dissolved oxygen from water.

Spiracles

External openings in insect exoskeletons that regulate air entry into tracheal system.

Tracheae/Tracheoles

Insect respiratory tubes that branch into fine tubes delivering air to tissues.

Lenticel

Raised pores on woody stems that allow gas exchange with the environment.

Blood

Circulatory fluid in animals; transports gases, nutrients, and wastes.

Red Blood Cells (RBC)

Erythrocytes; carry oxygen via hemoglobin; often lack a nucleus in mammals.

White Blood Cells (WBC)

Leukocytes; immune cells defending against pathogens.

Platelets

Cell fragments that assist in blood clotting.

Plasma

Liquid component of blood containing ions, nutrients, hormones, and waste.

Lymph

Fluid of the lymphatic system; returns interstitial fluid to the bloodstream.

Arteries

Blood vessels that carry blood away from the heart; thick elastic walls.

Veins

Blood vessels that carry blood toward the heart; contain valves to prevent backflow.

Capillaries

Small vessels where material exchange with cells occurs; single-cell wall.

Endosymbiosis

Theory that mitochondria and chloroplasts originated as absorbed prokaryotes.

Endosymbiotic Theory (mitochondria/chloroplasts)

Mitochondria and chloroplasts originated from engulfed bacteria providing energy and photosynthetic capability.

Biogeography

Study of the geographic distribution of organisms and their evolutionary history.

Gondwana

Ancient southern supercontinent; distribution evidence for shared species.

Darwin's Finches

Finches on the Galápagos illustrating adaptive radiation and beak variation.

Natural Selection

Process by which heritable traits that enhance survival and reproduction become more common.

Mutation

Heritable change in DNA sequence; a source of genetic variation.

Gene Flow

Movement of genes between populations via migration or interbreeding.

Genetic Drift

Random changes in allele frequencies, more pronounced in small populations.

Variation

Differences in traits among individuals in a population.

Fitness

Reproductive success of an organism relative to others; contribution to the gene pool.

Adaptation

Heritable trait that increases an organism’s chance of survival and reproduction.

Speciation

Formation of new species from existing populations, often via isolation and selection.

Convergent Evolution

Unrelated species evolve similar traits due to parallel environmental pressures.