Glossary  (Page 8/18)

Gaseous exchange Swopping oxygen from the air with the carbon dioxide made by the body; compare this with breathing and respiration

Gastric Of the stomach

Gene A short length of a chromosome that contain a unit of genetic information; often each gene carries the code for making one protein

Genetic code The way the information about an organism is stored in DNA molecules; each amino acid is represented by a triplet of N bases

Genetics The study of inheritance

Genome The full set of genes that an individual has; also the range of genes in a species

Genotype The set of alleles for a characteristic that an organism has inherited

Genus A group of different species with many features in common

Germinal epithelium A layer of tissue in the sex organs of animals that makes new cells by meiosis

Gland A part of the body which makes a useful substance for the body

Global warming The recent rise in average temperature all over the world caused by extra

greenhouse gases in the air

Globulin A blood protein with a folded shape so that it forms a ball shaped molecule

Glomerulus A knot of very narrow capillaries that sits in Bowman’s capsule of the kidney

Glucagon A hormone from the alpha cells of the Islets of Langerhans in the pancreas; it causes an increase in the amount of glucose in the blood

Glucose A common, simple hexose sugar that is made by photosynthesis and is the main respiratory substrate. Its formula is C ₆ H ₁₂ O ₆

Glycerol An alcohol with three hydroxyl units (CH ₂ OH CHOH CH ₂ OH) that is part of the molecule of all fats

Glycogen A polysaccharide used as the store of carbohydrates in animal cells

Glycolysis The first stage of respiration when 1 molecule of glucose changes into 2 pyruvic acid molecules

Gonad A sex organ that produces gametes

Graafian follicle A structure in the ovary that is filled with fluid; the female gamete develops inside it until ovulation

Gracile Delicately formed; compare with ‘robust’

Granulocyte A white blood cell with a large irregular nucleus and granules in the cytoplasm

Granum The structure holding chlorophyll in a chloroplast, made of a pile of thylakoids.

Grey matter Nervous tissue that is mostly cell bodies with few myelinated fibres (see white matter)

Growth hormone A hormone (from the anterior pituitary gland in animals) which promotes an increase in size

Guard cell One of the two curved cells that surround the pore (or hole) of a stoma, allowing it to open and close.

Guttation When water drops are squeezed out of hydathodes on a leaf onto its surface

Haemoglobin The red coloured conjugated protein that can carry oxygen; it is found in erythrocytes

Haemophilia The genetic bleeding disease, caused by a person not being able to make clotting factor so wounds do not heal

Health The state of being well, with body systems working efficiently

Helper cell The kind of T-lymphocyte that helps B-lymphocytes to produce antibodies

Heat exchanger A system where heat is moved from one place to another

Hepatic Of the liver

Herbicide A chemical substance that can kill green plants

Heredity The process in which characteristics are passed on from parents to their offspring