Plant Biology Notes: Key Terms (Vocabulary)

Vocabulary flashcards covering key plant biology concepts from the lecture notes, including plant structure, growth, biochemistry, membranes, and organelles.

Plant

A multicellular, chlorophyll-containing organism with cellulose cell walls; adapted to life on land and capable of photosynthesis.

Chlorophyll

Green pigment in plants that absorbs light energy for photosynthesis.

Photosynthesis

Process by which plants convert light energy into chemical energy stored in organic molecules.

Terrestrial adaptation

Traits that enable plants to live and reproduce on land.

Cell wall

Rigid layer around plant cells made of cellulose.

Cellulose

Polysaccharide of glucose that forms the main component of plant cell walls.

Energy flow

The transfer and use of energy stored in chemical bonds within ecosystems.

Carbon dioxide (CO2)

Greenhouse gas taken up by plants during photosynthesis; released by respiration.

Methane

Greenhouse gas produced by certain microbes; part of the greenhouse effect.

Water vapor

Greenhouse gas contributing to the Earth's heat retention.

Greenhouse effect

Warming of Earth as infrared heat is trapped by atmospheric gases.

Organ system

A group of organs working together to perform major plant functions (e.g., above- vs below-ground structures and organs like buds, fruits).

Bud

An undeveloped shoot that can grow into a new branch or flower.

Ovary

Flower structure containing ovules; develops into fruit after fertilization.

Fruit

Mature ovary that contains seeds after fertilization.

Seed

A fertilized plant embryo packaged with protective layers for dispersal and growth.

Growth

Increase in size through production of new cells/tissues and cell enlargement.

Meristem

Region of undifferentiated cells that generate new tissues and organs.

Primary meristem

Meristem that generates the plant's primary tissues at tips of roots and shoots (apical) and at sites of new branches.

Apical meristem

Primary meristem at the tips of roots and shoots responsible for lengthening growth.

Axillary bud

Bud located in the axil (angle between stem and leaf) that can form a branch or flower.

Axil

Angle between stem and leaf stalk.

Secondary meristem

Meristem that increases girth in woody plants (e.g., vascular cambium and cork cambium).

Vascular cambium

Secondary meristem producing xylem and phloem, increasing stem girth.

Cork cambium

Secondary meristem producing cork tissue, contributing to bark growth.

Cell expansion

Growth by uptake of water into the vacuole, loosening cell walls to enlarge cells.

Expansin

Proteins that loosen cell wall linkages, allowing wall stretching and growth.

Covalent bond

Chemical bond formed when atoms share electrons.

Double bond

Covalent bond where two pairs of electrons are shared between atoms.

Ionic bond

Electrostatic attraction between oppositely charged ions after electron transfer.

Hydrogen bond

Weak attraction between a partially positive hydrogen and an electronegative atom; important in water and DNA structure.

Monosaccharide

A single sugar unit (e.g., glucose) that forms carbohydrates.

Disaccharide

Carbohydrate formed by two monosaccharides linked by a glycosidic bond (e.g., sucrose).

Starch

Storage polysaccharide in plants with alpha bonds; energy reserve.

Alpha bond

Glycosidic linkage in which glucose monomers are oriented in the alpha configuration (as in starch).

Beta bond

Glycosidic linkage in which glucose monomers are oriented in the beta configuration (as in cellulose).

Lipids

Fats and oils; energy storage and membrane structure; hydrophobic.

Triglyceride

Lipid molecule composed of glycerol bonded to three fatty acids; main form of fat.

Glycerol

Three-carbon backbone of triglycerides.

Fatty acid

Long hydrocarbon chain with a carboxyl group; saturation varies (saturated/unsaturated).

Saturated

Fatty acids with no double bonds between carbons; typically solid at room temperature.

Monounsaturated

Fatty acids with one double bond.

Polyunsaturated

Fatty acids with two or more double bonds.

Lipid bilayer

Two-layer sheet of phospholipids forming the cell membrane; hydrophobic tails inward, hydrophilic heads outward.

Protein

Large biomolecules built from amino acids; act as enzymes, machines, and structural components.

Amino acid

Building block of proteins containing an amino group, carboxyl group, central carbon, and a side chain (R).

ATP

Adenosine triphosphate; primary energy currency of the cell.

ADP

Adenosine diphosphate; product of ATP hydrolysis that can be re-energized to ATP.

Osmosis

Diffusion of water across a selectively permeable membrane in response to solute differences.

Isotonic

Solute concentration is equal on both sides of a membrane; no net water movement.

Hypotonic

Lower solute concentration outside the cell; water tends to flow in.

Hypertonic

Higher solute concentration outside the cell; water tends to flow out.

Motor proteins

Proteins that move along cytoskeletal tracks to transport cargo and perform work.

Chloroplast

Organelle with a double membrane containing chlorophyll; site of photosynthesis; contains thylakoids and stroma; descended from cyanobacteria.

Thylakoids

Flattened membrane-bound sacs within chloroplasts where light reactions occur.

Stroma

Fluid within chloroplasts where the Calvin cycle takes place.

Cyanobacteria

Photosynthetic bacteria believed to be the ancestors of chloroplasts via endosymbiosis.

Endosymbiosis

Theory that organelles like chloroplasts and mitochondria originated as free-living bacteria engulfed by a host cell.

Mitochondria

Organelle producing energy through cellular respiration; powerhouse of the cell.

Cristae

Folds of the inner mitochondrial membrane that increase surface area for energy metabolism.

Matrix

Fluid-filled interior of mitochondria where metabolic reactions occur.