Glossary  (Page 4/18)

chondrocytes

Casparian strip A layer of waterproof suberin on the walls of endodermal cells in a plant root that stops water moving through cell walls, directing it into the stele

Catalyst Substance that speeds up a chemical reaction but does not get used up itself

Cerebellum Swollen part of the hind brain that controls muscle movement and balance

Cerebro-spinal Of the brain and spinal cord; cerebro-spinal fluid fills the spaces in these organs

Cerebrum Swollen part of the front brain that controls voluntary actions, memory, reasoning etc

Chemical bond The link of one atom to another in a molecule; the most common bonds are ionic bonds and covalent bonds

Chemical energy The ability to do work which is held inside a molecule; for example. in a chemical substance like ATP

Chemotherapy A medical treatment that uses poisonous chemicals to kill cancerous cells

Chlorophyll A green substance that has the ability to convert radiant energy into chemical energy

Chloroplast The green organelle containing chlorophyll found in some plant cells

Chlorosis A disease of plants when the leaves are yellow instead of green. It is caused by lack of light, or iron or magnesium deficiency

Cholesterol A waxy substance found in all cells, it can cause disease if there is too much in the blood

Chorion The outer extra-embryonic membrane; it protects the foetus and helps form the placenta

Choroid The middle of the three layers of the eye; it is black to reduce reflection and carries blood vessels to feed the tissues

Chromatin The substance that chromosomes are made of; in interphase it is very thin threads of DNA together with five special proteins called histones

Chromosome One of a fixed number of thread-like structures in a cell nucleus; it carries genes and is seen during nuclear division

Chyme The liquid mixture of food and juices that moves down the gut from the stomach

Cilia Tiny hair-like structures on the surface of some cells; they move to push things along

Ciliary body The swollen region of the choroid of the eye near the lens that holds theciliary muscles

Ciliary muscle Muscles that control the shape of the lens of the eye, they contract for

accommodation

Ciliated epithelium A thin internal skin whose cells are covered in cilia

Cochlea A coiled tube that is a part of the inner ear and contains the receptors for the sense of hearing

Codominance When there is the full expression of both of two alleles because neither of them is dominant to the other

Coenzyme A substance that helps an enzyme to work properly

Cohesion When a substance sticks to itself.

Collecting duct A tube that collects urine from the nephrons and feeds it into the kidney pelvis

Colon The main part of the large intestine where water and some mineral salts are

absorbed and the faeces form; rich in bacteria producing vitamins B and K

Comet A lump of frozen dusty material that orbits around the sun

Compound A substance that it made from two or more different elements

Concentration The strength of a substance in a mixture. It is a measure of the number of

molecules present.