A: Cells & Classification Flashcards
Active transport
The process by which dissolved molecules (solutes) move across a cell membrane from a lower to higher concentration. This requires energy from respiration.
Animal kingdom
Kingdom of organisms which can (usually) move around but cannot photosynthesise so must obtain food from other organisms.
Animal cell
Animal cells have a nucleus but do NOT have cell walls or chloroplasts and only have small vacuoles (if any). They store food as glycogen.
Bacteria
Single-celled micro-organisms with no nucleus. Most are beneficial as decomposers, a few cause disease. Singular = bacterium.
Cell
Basic unit of life that can carry out all life’s processes. Unicellular organisms only have one cell. Multicellular organism have many cells.
Cell membrane
Partially permeable surface layer of a cell; the cell membrane [ also called plasma membrane] controls what enters and leaves the cell.
Cell wall
Permeable cellulose ‘box’ surrounding cells of plants; fungi also have walls but not of cellulose. The wall offers support to the cell and stops it from bursting.
Cellulose
A carbohydrate which forms the cell wall in plant cells.
Chloroplast
Organelle containing chlorophyl found in green plant cells. Chloroplast perform photosynthesis.
Cilia/ciliated
Ciliated cells are covered with cilia - tiny hairs which beat continuously to move mucus (e.g. carrying dirt up the bronchi and trachea)
Cytoplasm
The jelly-like substance inside a cell, but outside the nucleus. Most of the cell’s chemical reaction occurs here, in various organelles.
Diffusion
The movement of particles (molecules or ions), by random heat energy from an area of higher or lower concentration.
Element
A substance consisting of one kind of atom only.
Epidermis
The outer protective layer of the skin.
Fungi
Kingdom of non-photosynthesising organisms with cell walls made of chitin. They have nuclei in their cells, which usually form long strands called hyphae.
Goblet cells
Cells in the lining of the trachea and bronchi which make mucus.
Impermeable
Not allowing water to pass through
Membrane
A very thin layer of tissue; be careful not to confuse with with ‘cell membrane’.
Metabolism
The sum of all chemical processes taking place in our cells, and the rate at which these proceed.
Mitochondria
Structures of the cytoplasm of all cells where respiration takes place. Singular is mitochondrion.
Molecules
A collection of two or more atoms held together by chemical bonds. The fundamental unit of compounds.
Multicellular
Having more than one cell.
Nucleus
Large organelle, often near the centre of a cell, where generic information is stored. This information controls all the cell’s activities.
Organ
Group of tissues doing a particular job between them, e.g. the heart.
Organ system
Group of organs doing a particular job between them, e.g. the circulatory system.
Organelle
Microscopic structure which does a particular job in a cell, e.g. the nucleus or chloroplast.
Organism
A living being - plant, animal, fungus or bacterium. Some people include viruses.
Osmosis
The movement of water molecules across a partially permeable membrane down a concentration gradient; a special type of diffusion.
Partially permeable
Allowing some particles to pass through but not others; e.g. the cell membrane.
Permeable
Allowing water to pass through
Plant
Type of organisms with chloroplasts and cellulose cell walls. By photosynthesis, plants are the ‘producers’ of food for all other organisms.
Protoctista/Protozoa
Kingdom of minute, usually single-celled, organisms with a nucleus, e.g. Amoeba (protozoa is an old term).
Sperm
Swimming male sex cell, which carries genetic information to the ovum (egg).
Tissue
Group of cells of the same type doing a particular job, e.g. the blood (a liquid tissue)
Unicellular
Having only one cell
Vacuoles
A space within the cytoplasm of plant cells that contains cell sap. Vacuoles help support the cell by outward pressure on the wall.
Virus
Parasitic non-cellular organism (no cytoplasm, just DNA in a protein coat). Too small to see with a light microscope, viruses infect living cells and ‘high-jack’ their metabolism ro replicate inside the cell.
