Organisation flashcards

Topic 1: Organisation

Functions of the nucleus, cytoplasm and cell membrane

Nucleus: controls the activities of the cell. Cytoplasm: where most of the chemical reactions take place. Cell membrane: controls the passage of substances into and out of the cell.

Functions of mitochondria and ribosomes

Mitochondria: where most energy is released in respiration. Ribosomes: where protein synthesis occurs.

Structures plant cells have that animal cells lack

Chloroplasts (absorb light energy to make food), a permanent vacuole filled with cell sap, and a cell wall made of cellulose, which strengthens the cell.

How does a bacterial cell differ from a plant or animal cell?

It is prokaryotic: the genes are not in a distinct nucleus, and some genes are in small circular structures called plasmids. It has cytoplasm and a membrane surrounded by a cell wall.

Tissue, organ and organ system

Tissue: a group of cells with similar structure and function. Organ: made of tissues; one organ may contain several different tissues. Organ system: a group of organs that perform a particular function.

Muscular, glandular and epithelial tissue

Muscular: contracts to bring about movement. Glandular: produces substances such as enzymes and hormones. Epithelial: covers some parts of the body.

Why is the stomach an organ?

It contains several tissues working together: muscular tissue moves the contents, glandular tissue produces digestive juices, and epithelial tissue covers the outside and the inside.

Roles of the liver, small intestine and large intestine in the digestive system

Liver: produces bile. Small intestine: digestion, and where soluble food is absorbed. Large intestine: water is absorbed from the undigested food, producing faeces.

Plant tissues: epidermal, palisade mesophyll, spongy mesophyll, xylem and phloem

Epidermal: covers the plant. Palisade mesophyll: carries out photosynthesis. Spongy mesophyll: air spaces help gases diffuse. Xylem and phloem: transport substances around the plant.

Diffusion, osmosis and active transport: what moves, which way, and is energy used?

Diffusion: particles in solution or of a gas, higher → lower concentration, no energy. Osmosis: water through a partially permeable membrane, dilute → more concentrated solution, no energy. Active transport: against a concentration gradient, energy from respiration.

Isotonic, hypotonic and hypertonic solutions: effect on a cell

Isotonic: no net movement of water. Hypotonic (more dilute): water enters the cell. Hypertonic (more concentrated): water leaves. A plant cell that takes in water is turgid; one that loses a lot shrinks from its wall (plasmolysis).

Features that make an exchange surface effective

A large surface area that is thin, giving a short diffusion path; in animals, an efficient blood supply; and for gas exchange in animals, ventilation. Examples: villi in the small intestine, alveoli in the lungs, root hair cells.