B1. Cell Structure and Transport

Key terms for AQA combined science

ventilated

movement of air or water into and out of the gas exchange organ

active transport

movement of substances against a concentration gradient

algae

simple aquatic organisms that make their own food by photosynthesis

alveoli

tiny air sacs in the lungs that increase surface area for gaseous exchange

bacteria

single-celled prokaryotic organisms

cell membrane

membrane that controls what moves in and out of a cell

cell wall

rigid structure around plant and algal cells

cellulose

complex carbohydrate that makes up plant and algal cell walls

chlorophyll

green pigment contained in chloroplasts

chloroplasts

organelles in which photosynthesis takes place

cytoplasm

water-based gel in which organelles of all living cells are suspended

diffusion

spreading out of particles from an area of higher concentration to an area of lower concentration

eukaryotic cells

cells from eukaryotes with a cell membrane

hypertonic (osmosis)

solution more concentrated than the cell contents

hypotonic (osmosis)

solution less concentrated than the cell contents

isotonic (osmosis)

solution same concentration as the cell contents

mitochondria

site of aerobic cellular respiration in a cell

nucleus

organelle containing genetic information surrounded by the nuclear membrane

osmosis

diffusion of water through a partially permeable membrane from a dilute solution to a concentrated solution

partially permeable membrane

membrane that allows only certain substances to pass through

permanent vacuole

space in the cytoplasm filled with cell sap

phloem

living transport tissue in plants that carries dissolved food around the plant

plasmolysis

state of plant cells when water is lost

prokaryotic cells

cells from prokaryotic organisms with a cytoplasm surrounded by a cell membrane and a cell wall

resolving power

measure of the ability to distinguish between two separate points

ribosomes

site of protein synthesis in a cell

sperm

male sex cells or gametes that carry genetic material

stomata

openings in the leaves of plants that allow gases to enter and leave

turgor

pressure inside a plant cell exerted by the cell contents pressing on the cell wall

ventilated

movement of air or water into and out of the gas exchange organ

xylem

non-living transport tissue in plants that transports water from roots to leaves and shoots