Glossary  (Page 6/18)

Deoxyribose A five carbon sugar with one atom of oxygen less in its molecule than a normal sugar; one of the building blocks of each DNA nucleotide

Destarch To take starch out; leave a plant in the dark for 24 hours to move starch out of its leaves

Diabetes A disease when insulin does not function properly causing blood sugar to rise when carbohydrates are eaten. In type 1 diabetes no insulin is made, in type 2diabetes the insulin loses its effect on the cells.

Diaphragm A sheet of tendon, with muscles on it, that separates the thorax from the abdomen

Diastole The relaxed part of the heart beat

Dicotyledon (Dicot) One of the large group of plants that has two cotyledons in each seed, flower parts in fives and net veined leaves

Diffusion The spread of a substance caused by the natural random movement of its molecules

Digestion Breaking down complex foods into simple, soluble nutrients

Dilate To get wider

Disaccharide A sugar with molecules of two sugar units joined; it can split into two parts which are still both sugars (compare with monosaccharide)

Dissolve To make something into a solution (become mixed with a liquid)

Distal Far (or distant) from the main part of the body

Dominant In genetics a characteristic that appears in the phenotype whenever it is present on at least one homologous chromosome compare with‘recessive’

Dorsal On the upper side of the organism

Double fertilisation The special fertilisation process in which two male nuclei are needed; it is unique to flowering plants

Duodenum The first part of the small intestine, it is about 30 cm long. The bile and pancreatic juice run into it.

Dura mater The strong outer membrane of the three that cover the brain and spinal cord

Dynamic Of movement; dynamic balance is the force of acceleration on the body

Ectothermic Getting body heat from the surroundings (compare with endothermic)

Effector A cell or organ (usually muscle or gland) that an animal responds with

Efferent Carries something away from a structure; for example efferent arterioles carry blood away from Bowmans Capsule

Egestion Removal from the body of the waste products that could not be digested

Electron A tiny, negatively charged particle that is a part of all atoms

Element A substance made from only one of the 92 different sorts of atom that exist naturally; it cannot be split into simpler substances

Emulsion A colloidal mixture of two liquids that do not dissolve, one of which is spread through the other

Enamel The hard resistant substance on the outer surface of a tooth

Endocrine Of the system of ductless glands that release hormones directly into the blood

Endolymph The fluid that fills the canals made of membrane found in the inner ear

Endoplasmic reticulum A complex system of membranes throughout the cytoplasm; they act as channels for transporting materials

Endosmosis Osmosis of water into a cell; compare with Exosmosis.

Endosperm The food supply of a seed that is not inside a cotyledon

Endothermic Getting body heat from the working of the body; that is, the body heat is from inside the body