Year 9 Science Revision - Vocabulary

A set of vocabulary flashcards defining key biological organelles, chemical classification concepts, physical processes, and structural components from the Year 9 science booklet.

Cytoplasm

The region in a cell where chemical reactions take place.

Nucleus

Organelle that contains genetic material (genes and chromosomes) and controls cell activity.

Cell membrane

Structure that controls what enters and leaves the cell.

Mitochondria

Organelles that contain the enzymes for respiration, where most energy is released in respiration.

Ribosomes

Tiny structures where protein synthesis occurs.

Chloroplast

The site of photosynthesis in plant cells.

Cell wall

Structure that strengthens plant cells.

Vacuole

Structure that acts as a store of water and nutrients in plant cells.

Diffusion

The movement of a substance from an area of high concentration to an area of low concentration.

Osmosis

The passive movement of water or another solvent through a plasma membrane from a region of low solute concentration to a region of high solute concentration.

Active transport

The movement of molecules across a membrane from a region of lower concentration to a region of higher concentration against the concentration gradient, requiring cellular energy.

Eukaryotic cells

Cells that contain membrane-bound organelles, including a nucleus.

Prokaryotic cells

Cells that do not contain a nucleus or any other membrane-bound organelle.

Therapeutic cloning

The replication of human embryos to harvest stem cells for medical uses, often performed using somatic cell nuclear transfer.

Scanning electron microscope (SEM)

An electron microscope with a large field of view used to examine the surface structure of specimens.

Transmission electron microscope (TEM)

An electron microscope used to examine thin slices or sections of cells or tissues, reaching maximum magnifications around $\times 1\,000\,000$ and a limit of resolution under $1\,\text{nm}$.

Enzymes

Protein molecules in cells that act as biological catalysts to speed up chemical reactions without being used up.

Arteries

Muscular, three-layered blood vessels lined by endothelium that deliver oxygen-rich blood from the heart to the tissues of the body.

Veins

Elastic blood vessels operating in a low-pressure system that transport blood from various regions of the body back to the heart.

Capillaries

Very thin blood vessels approximately $5\,\mu\text{m}$ in diameter, composed of an inner layer of endothelial cells and an outer layer of epithelial cells.

Transpiration

The process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere.

Mixture

A combination of two or more substances that have not reacted chemically with each other and can be separated by physical methods.

Element

A substance made from only one type of atom.

Compound

A molecule made of atoms from different elements bonded together.

Plum Pudding Model

An atomic model proposed by J.J. Thomson suggesting that atoms are made of positively and negatively charged pieces, with tiny negatively charged electrons embedded within.

Group 0 elements

Unreactive non-metal gases in the periodic table, also known as the noble gases.

Group 1 elements

Elements in the periodic table known as alkali metals that react vigorously with water to produce an alkaline solution.

Group 7 elements

Elements in the periodic table known as halogens that form salts when they react with metals.

Principle of Conservation of Energy

The law stating that energy can neither be created nor destroyed, but can only be changed from one form to another.

Convection

Heat transfer in a fluid where heated fluid expands, becomes less dense, and rises, carrying thermal energy away from the heat source.

Biogas

A renewable energy source consisting of methane and carbon dioxide produced through the anaerobic decay of organic waste or crops.