Edexcel Biology GCSE Topic 1: Key Concepts in Biology

Vocabulary-style flashcards covering key terms and concepts from Edexcel Biology GCSE Topic 1: Key Concepts in Biology (cell structure, specialised cells, microscopy, enzyme action, transport, and core practicals).

Eukaryotic cell

A cell with a nucleus and membrane-bound organelles; includes animal and plant cells.

Prokaryotic cell

A small cell without a nucleus; bacteria; lacks membrane-bound organelles.

Organelle

A specialized sub-cellular structure within a cell that has a specific function.

Nucleus

Membrane-bound organelle containing DNA and coding for proteins.

Nuclear membrane

Double membrane surrounding the nucleus that controls entry and exit of substances.

DNA

Genetic material containing genes that code for proteins.

Cytoplasm

Jelly-like fluid where chemical reactions occur; contains enzymes and organelles.

Cell membrane

The phospholipid bilayer that controls what enters and leaves the cell.

Mitochondrion

Organelle where aerobic respiration occurs, providing energy for the cell.

Ribosome

Organelle where protein synthesis occurs; found mainly on rough endoplasmic reticulum.

Bacterial cell

A prokaryotic cell with features such as a cell wall, cell membrane, cytoplasm, circular DNA, and plasmids.

Cell wall

Rigid layer around cells; in bacteria made of peptidoglycan; plant cell walls are cellulose.

Circular DNA

Single, circular chromosome found in bacteria.

Plasmids

Small rings of DNA carrying extra genes in bacteria.

Flagellum

Long, whip-like tail allowing bacteria to move.

Chloroplast

Organelle where photosynthesis occurs; contains chlorophyll.

Chlorophyll

Green pigment in chloroplasts that captures light for photosynthesis.

Permanent vacuole

Large vacuole containing cell sap that helps maintain rigidity.

Cell sap

Fluid inside the permanent vacuole.

Root hair cell

Plant cell specialized for water uptake and mineral transport; large surface area.

Xylem

Plant tissue that transports water and minerals upward; hollow tubes formed as cells die; lignin strengthens walls.

Phloem

Plant tissue that transports sugars and other metabolites around the plant.

Sieve plates

End walls between phloem cells that break down to allow movement of substances.

Companion cell

Phloem cell providing energy to sieve tube elements via mitochondria.

Sperm cell

Male gamete specialized to deliver DNA; streamlined head, long tail, many mitochondria; acrosome; haploid nucleus.

Egg cell

Female gamete specialized to accept one sperm and support embryonic development; large cytoplasm and mitochondria.

Haploid

Cells containing 23 chromosomes (n) in humans; half the usual chromosome number.

Acrosome

Cap-like structure in sperm containing digestive enzymes to penetrate the egg.

Ciliated epithelial cell

Cells with cilia that move mucus and trapped bacteria toward the stomach.

Amylase

Carbohydrase that breaks down starch into maltose; produced in salivary glands, pancreas and small intestine.

Starch

Polysaccharide carbohydrate found in plants; a key testable substrate for amylase.

Iodine test

Chemical test for starch; iodine turns blue-black if starch is present.

Benedict’s test

Test for reducing sugars; colour changes from blue to green/yellow/orange/red depending on sugar amount.

Biuret test

Test for protein; blue to violet color indicates the presence of peptide bonds.

Emulsion test

Test for lipids; ethanol and water mix to form a cloudy emulsion indicating lipids.

Calorimetry

Measurement of energy change in a reaction, typically by heating water and measuring temperature change.

Energy transferred

Energy added to or taken from a system, calculated as mass of water × specific heat capacity × temperature change.

Mass of water

Mass of the water used in calorimetry, measured in grams.

Specific heat capacity (4.2)

Amount of energy required to raise 1 g of water by 1°C; constant used in calorimetry.

Temperature change

Difference between final and initial temperatures (ΔT) in °C.

Sucrose solution

A sugar solution used in osmosis experiments with potato discs.

Osmosis

Diffusion of water across a selectively permeable membrane from high water potential to lower.

Diffusion

Spontaneous movement of particles from a region of higher concentration to lower concentration; passive process.

Active transport

Movement of substances against a concentration gradient, requiring energy (ATP).

ATP

Adenosine triphosphate; the energy currency of the cell.

Independent variable

The variable deliberately changed in an experiment (e.g., sucrose concentration).

Dependent variable

The variable measured in an experiment (e.g., change in mass).

Control variable

Variables kept constant to ensure a fair test (e.g., disk diameter).