IGCSE Biology - Characteristics of Living Organisms, Cells, and Digestion Vocabulary

Vocabulary flashcards covering core concepts from IGCSE Biology notes including life processes, cell structure, transport, enzymes, biological molecules, digestion, teeth, liver function, and scientific variables.

Movement

Change in place or position of an organism or part of the organism.

Respiration

Chemical reaction involving the break down of food, mainly glucose, to release energy.

Sensitivity

The ability to detect a stimulus (change in the environment) and show a response.

Growth

Permanent increase in number and size of cells as well as dry mass (mass without water).

Reproduction

Process of making more of the same kind of organism.

Nutrition

The ability of organisms to obtain or make organic compounds needed to provide energy for growth and development.

Excretion

Removal of toxic metabolic waste products or substances found in excess out of the body.

Metabolic reaction

A chemical reaction taking place inside the cell.

Deamination

The breakdown of excess amino acids in the liver to produce urea and carbohydrates.

Nucleus

Cell organelle that contains genetic material, controls cell activities, and controls cell division.

Mitochondria

Site of aerobic respiration to release energy within the cell.

Ribosomes

Cell organelles attached to the endoplasmic reticulum or in the cytoplasm that serve as the site of protein synthesis.

Vesicles

Structures that transport materials around the cell or out of the cell.

Cell membrane

Structure made from proteins and lipids that acts as a barrier, keeps cell contents inside, and controls the movement of substances in and out of the cell.

Cell wall

Structure made from cellulose in plant cells that gives strength and support, prevents the cell from bursting, and helps keep its shape.

Vacuole

Plant cell organelle containing a sap solution (water with dissolved salts and sugars) that keeps the cell turgid by pressing outwards on the cytoplasm and cell wall.

Chloroplast

Plant cell organelle containing chlorophyll which absorbs light energy to carry out photosynthesis.

Tissue

A group of similar cells working together to perform a specific function.

Organ

A group of different tissues that work together to perform a specific function or group of functions.

Acrosome

Structure on the head of a sperm cell that secretes enzymes to dissolve the jelly-like layer around the egg to help penetrate it.

Xylem vessels

Plant tissue made of dead hollow cells with no cytoplasm or nucleus and walls thickened with lignin, functioning to transport water and minerals and support the plant.

Lignin

Waterproof substance in xylem cell walls that prevents the leakage of water and provides support.

Pits

Non-lignified parts in the walls of xylem vessels that allow lateral movement of water to nearby cells.

Diffusion

Movement of molecules from an area of high concentration to an area of low concentration due to the random movement of molecules.

Osmosis

Diffusion of water molecules from an area of high water potential to an area of low water potential (down a water potential gradient) through a partially permeable membrane via protein pores.

Active transport

Movement of molecules from an area of low concentration to an area of high concentration against their concentration gradient using energy from respiration through carrier proteins.

Plasmolysed

The condition of a plant cell when it loses water, causing the vacuole and cytoplasm to shrink and the cell membrane to detach from the cell wall.

Turgid

The state of a plant cell when swollen with water, where the vacuole presses outwards on the cytoplasm and cell wall.

Enzyme

A protein molecule that acts as a biological catalyst to speed up chemical reactions by lowering activation energy without being changed.

Active site

The region on an enzyme with a specific shape complementary to a specific substrate, where the substrate fits and binds to form an enzyme-substrate complex.

Denature

The loss of the specific shape of an enzyme's active site at high temperatures or extreme pH, making it no longer complementary to the substrate so no enzyme-substrate complex can form.

Autotrophs

Organisms that make their own food by photosynthesis.

Heterotrophs

Organisms that obtain organic compounds by feeding on plants or other animals.

Balanced diet

Taking in all nutrients in correct amounts to provide the energy needed for growth and development according to age, gender, and physical activity.

Peristalsis

Waves of contractions and relaxations of circular and longitudinal muscles in the alimentary canal walls that squeeze and push food forward.

Gene

A length of DNA made from a specific sequence of bases that codes for a specific protein to give a specific characteristic.

Ingestion

Taking in of food into the body through the mouth.

Digestion

Breaking down large insoluble food molecules into small soluble ones using enzymes.

Mechanical digestion

Breakdown of large food pieces into smaller ones with no chemical change to increase surface area for faster chemical digestion by enzymes.

Chemical digestion

Breakdown of large food molecules into small soluble ones by enzymes to be absorbed into the blood.

Absorption

Movement of small digested food molecules from the walls of the small intestine into the blood.

Assimilation

Movement of digested food molecules into cells to become part of the cells.

Egestion

Removal of undigested food molecules out of the body through the anus in the form of faeces.

Diarrhea

Excessive loss of water and salts in watery faeces when not enough water is absorbed back into the body.

Incisor

Chisel-shaped tooth with a flat and sharp edge used for biting.

Canine

Pointed tooth used for tearing.

Premolars

Teeth with 4 or 5 cusps and 2 or more roots used for crushing and chewing food.

Molars

Teeth with 2 or 3 cusps used for chewing and grinding food.

Independent variable

The changeable variable in an experiment.

Dependent variable

The outcome variable that is measured, recorded, counted, or observed in an experiment.

Control experiment

An experiment carried out under the same conditions without the factor under investigation to compare results and confirm its specific effect.