Multicellular: Organisms consisting of multiple cells which are specialised, forming tissues and organs.
Organism: All the systems of the body working together make an organism, which is a discrete individual.
Differentiation: A process by which a stem cell becomes specialised into a specific type of cell.
Divisions of Labour: The adaptation of different parts of an organism that carry out different functions. The more advanced the organism, the greater the division of labour.
Tissues: A group of specialised cells with the same structure, working together to perform a specific function. E.g. Epithelial (Squamous, Cuboidal & Columnar), connective, and muscle (Smooth, Skeletal & Cardiac.)
Organ: An aggregation of several tissues that carry out a specific function of the whole organism.
Organ system: Composed of two or more different organs that work together to provide a common function. E.g. Skeletal, muscular, circulatory, reproductive, endocrine, excretory, digestive, nervous, respiratory & immune.
Atom < Molecule < Macro-molecule < Organelle < Cell < Tissue < Organ < Organ system
In plants-
Xylem: Transports water and minerals.
Phloem: Produced sugars and transports them.
Palisade mesophyll: Photosynthesis mainly occurs here.
Spongy mesophyll: Provides air space for diffusion of gases in/out of the leaf.
Upper epidermis: Contains cells found at the top of the surface of the leaf coated by a waterproof waxy cuticle.
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