Bored of Studies - www.boredofstudies.org

Jay Paul

Biology definitions for Maintaining a balance _REVISION• Activation energy- the energy necessary to start a chemical reaction• Active transport- Movement of substances across a membrane by a

process requiring expenditure of energy.• Ammonia- Main nitrogenous waste product of bony fish; excreted in

large amounts of water.• Parts of the mammalian kidney:

• Buffer-a solution of 2 or more chemicals, which prevent markedchanges in hydrogen ion concentration (pH) when either acid or base(alkali) is added to the system.

• Cambium- Group of cells, which divide to form new xylem andphloem cells.

• Chromosome- structure made up of genetic material (DNA) andprotein found mainly in the nucleus.

• Cohesion- attraction between molecules of water.• Denatured- structural change in proteins.• Diffusion- movement of particles in gases, liquids or solutions from

where they are more concentrated, to where they are less concentrated.• Effector- Part of an organism which produces a response.• Endocrine system- hormonal system that produces internal secretions

which act upon organs.• Enzyme- a highly specialised cellular protein that reduces the amount

of energy required to initiate a chemical reaction, thereby increasingthe speed of the reaction; the names of enzymes often end in ‘ase’. Eg.cellulase, an enzyme which digests cellulose.

• Eucaryotic- cells which have their genetic material (chromosome)inside a nucleus bounded by a membrane and which have othermembrane-bound organelles, includes cells of protists, fungi, animalsand plants.

• Evaporative cooling- removing of heat from the body by chagingliquid water to water vapour using heat from the skin surface(eg.sweating) or from respiratory surfaces (eg.panting).

Bored of Studies - www.boredofstudies.org

Jay Paul

• Excretion- the elimination of harmful and unwanted products ofmetabolism.

• Excretory organs- organs involved in the removal of wastes eg.kidneys, lungs, skin.

• Gymnosperms- cone-bearing plants.• Herbaceous- characteristic of a soft plant, having no woody tissue.• Homeothermy- maintainence of a stable body temperature

independent of changes in the environmental temperature.• Lignin- a material which strengthens and keeps xylem vessels open,

the major component of wood.• Lymphatic system- system of thin-walled vessels and groups of tissue

(lymph nodes) which drain the fluids from around cells back to thebloodstream (as a fluid called lymph); the system is also involved inthe immune response with transport of the breakdown of products ofdigestion.

• Metabolic pathway- A series of step-wise chemical reactionsoccurring in the cells of the body; heat is produced as a by-product ofmetabolism.

• Optimum- conditions at which enzymes work best; includestemperature and pH.

• Organelle- any part of a cell which has a specific functional role, ineukaryotic cells. Organelles are usually bound by a membrane.

• Pituatary- small structure in the brain which secretes hormones,including ones which control the functions of other endocrine glands(eg. thyroid glands).

• Rate of reaction- speed at which a reaction proceeds. It is normallymeasured as the amount of subsrate(s) used up or the amount ofproduct(s) formed in a given a amount of time.

• Rennin- an enzyme found in the stomachs of mammals (especiallyyoung ones), which makes milk go solid (coagulate). It if found injunket tablets used to make a desert out of milk and flavouring (sort ofyoghurt desert).

• Respiratory surface- a special surface for gaseous exchange.• Salt gland- a structure found in marine birds and turtles which permits

excretions of salts.• Stomates- holes (pore) in plant leaves. These pores are controlled by 2

guard cells which regulate the loss of water from leaves(transpiration).

• Temperature gradient- difference in temperature. Heat energy flowsfrom an area of higher temperature to one of lower temperature.

• Thyroid gland- endocrine gland in the throat area which producesthyroid hormones.

Bored of Studies - www.boredofstudies.org

Jay Paul

• Thyroid hormones- hormones involved with regulating the level ofbody metabolism.

• Urea- breakdown (deamination) of excess amino acids; diluted bywater and excreted in urine.

• Uric acid- main nitrogneous waste product of insects, reptiles andbirds; largely insoluble and excreted in a paste with little water.

• Urea- a waste product containing 2% urea.• Vascular plant- plants which have conducting vessels, xylem and

phloem, including the plants ferns, gymnosperms and angiosperms.• Vasodilation- increase in the diameter of the blood vessels to increase

blood flow.• Vasoconstriction- decrease in blood vessel diameter, to decrease blood

flow.