أكاديميا - كولنز معاجم الجيب العلمية - البيولوجيا انكليزي - فرنسي - عربي الحرف ١ _ d

Academia - Collins Scientific Pocket Dictionaries - Biology
English - French - Arabic letter 1 _ D


deamination
desamination f

Deamination is the removal of the amino group (NHz) from excess amino acids. In mammals, it occurs in the liver, where the amino group is automatically transformed into the toxic compound ammonia (NH3), which is then transformed into urea and excreted. The remaining group containing carbon is transformed into useful carbohydrates.


decomposers
décomposeurs mpl

Heterotrophic decomposers cause the breakdown of dead animals and plants, releasing their constituent compounds that can be used by other living organisms. Soil decomposers include bacteria, earthworms, etc. See carbon. nitrogen cycle, cycle.

denaturation
dénaturation f

Corruption, denaturation, changes that occur in the structure and function of proteins (enzymes, for example) when subjected to extreme limits of temperature or pH.


dendrite (or dendron)
dendrite f

A twig. See nerve cell and synapse.


denitrification
denitrification f

Removal of nitrates. Denitrifiying bacteria convert nitrates into nitrogen, which can re-enter the atmosphere. See nitrogen cycle.


dental formula
formula for dentist

Sunni formula. A formula that describes the dentition of mammals and is expressed by writing the number of teeth in the upper jaw on one side of the mouth over the number of teeth in the lower jaw on the same side. The dental formula refers to a correct animal. For an adult mammal with a number of teeth, the total number of teeth is obtained by doubling the dental formula.

Human teething
Boycott
Najaz
A millstone
tusk

Dental formula - incisors 2/2 canines 1/1 molars 2/2 molars 3/3 Total number of teeth = 2 x dental formula 2 x 32 = 16.
See carnivore and herbivore.


dentition
dentition f

Ingar. Teeth: The number and types of teeth in a mammal expressed in the dental formula. The dental system reflects the animal's diet, meaning that each animal has a type of teeth that is compatible with the food it feeds on. See carnivore, herbivore, and omnivore.


diaphragm
diaphragm m

The diaphragm is a dome-shaped muscle that separates the thorax and abdomen in mammals. The contraction and relaxation of the diaphragm is important in ventilating the lung. See breathing.


diastema
Diastème f

Break. A toothless gap in the mouths of many herbivores allows the tongue to move easily to move food.


diastole
diastole f

Extraversion See heartbeat.


dicotyledons
dicotyledones fpl

Dicots. One of the two subgroups of flowering plants, the other subgroup is the monocotyledons. The properties of dicots are:

(a) The presence of two cotyledons in the seed.
(b) A network of branched veins in leaves.
(c) Broad leaves.
(d) A ring of vascular bundles in the stem.
(e) The parts of the flower are quadrilateral, pentagonal, or multiples of these two numbers.
Examples include: hardwood trees, fruit trees, and herbaceous plants. See secondary growth.