B2

Cell membrane

Thin layer of cytoplasm that controls substances entering and leaving the cell.

Cytoplasm

Thick liquid containing water, dissolved molecules, and organelles that provide energy and make necessary substances.

Nucleus

Round structure enclosed in the cytoplasm that controls enzyme production, chemical changes, and cell division.

Cell wall

Tough, non-living layer outside the cell membrane in plant cells that prevents bursting and allows passage of water and salts.

Vacuole

Large fluid-filled space surrounded by a membrane that contains cell sap and helps maintain cell firmness.

Chloroplast

Organelle containing chlorophyll that traps light energy for photosynthesis.

Specialisation of cells

Cells that develop distinct shapes and perform specific functions due to changes in shape and chemical reactions in the cytoplasm.

Ciliated cells

Cells with tiny hairlike projections that create a stream of mucus to carry dust and bacteria away from the lungs.

Root hair cell

Cells in plant roots with hairlike projections that absorb water and mineral salts from the soil.

Palisade mesophyll cells

Cells underneath the upper epidermis of plant leaves that absorb light and perform photosynthesis.

Red blood cells

Cells in the circulatory system that carry oxygen, with adaptations such as containing hemoglobin, lacking a nucleus, and having a biconcave shape.

Sperm cells

Cells in males that carry genetic information to the ovum for reproduction, with adaptations such as a long tail, acrosome, and mitochondria for energy.

Egg cell

Cells in females that are fertilized by sperm cells and support the growth of a baby, with adaptations such as a large energy supply and many mitochondria.

Tissues

Groups of cells with similar structure and function that give the tissue a specific function, such as bone, nerve, and muscle in animals, and epidermis, xylem, and pith in plants.

Organs

Several tissues grouped together to perform a specific function, such as the stomach, lungs, and intestine in animals, and root, stem, and leaves in plants.

Organ Systems

Groups of organs that work together to perform a function, such as the circulatory system and nervous system in animals, and shoot system in plants.

Organisms

The combination of organs and systems working together to produce an independent plant or animal.

Magnification

The increase in size of an image compared to the actual size of the specimen, calculated by dividing the observed size of the image by the actual size of the specimen.

Diffusion

The net movement of particles from an area of higher concentration to an area of lower concentration down a concentration gradient, as a result of random movement.

Osmosis

The net movement of water from an area of higher water potential to an area of lower water potential through a partially permeable membrane.

Water potential

The measure of whether a solution is likely to gain or lose water from another solution, with dilute solutions having higher water potential than concentrated solutions.

Turgor pressure

The pressure exerted by the vacuole on the inelastic cell wall in plant cells, which helps maintain cell rigidity and support the plant.

Haemolysis

The bursting of animal cells due to excessive water entering the cell by osmosis.

Plasmolysis

The shrinking of animal cells due to water leaving the cell by osmosis, causing the cells to become flaccid.