أكاديميا - كولنز معاجم الجيب العلمية - البيولوجيا انكليزي - فرنسي - عربي الحرف ٢_ a

Academia - Collins Scientific Pocket Dictionaries - Biology
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alternation of generations
Alternation of generations

Alternation of generations. The life history of a plant in which a generation of haploid gametophyte through sexual reproduction produces a diploid sporophyte generation that reproduces asexually. The two generations are often very different. The drawing shows the life cycle of a fern, where n = the number of haploids. A similar process occurs in some animals, such as jellyfish, where there are two alternating phases in the history of life, but both are diploid.


alveoli
alveoles fpl. favorites fpl

Alveolus. Air sacs in the lung of a mammal in which gas exchange takes place. See -gas ex change (mammals)


amino acids
Acids and amino acids

Amino acids Organic compounds are subunits of proteins. The number of amino acids known so far is about seventy different ones, but the number of them found in living organisms is only twenty to twenty-four, which are linked to each other as chains called peptides, and form the basis of protein structure.


amnion
amnios m

Amino acid structure

R-C-H
Acid group COOH
Amino group NH2

beguile. It is a sac filled with fluid that surrounds and protects the embryos of mammals, birds, and reptiles. See .pregnancy

amylases
amylase mpl

Amylases. Enzymes break down starch or glycogen into disaccharides and glucose by hydrolysis. Examples of this are: “Salivary amylase. salivary amylase.

anabolism
Anabolism m

Structural metabolism. Adoption. See metabolism.

anaerobe
anaerobie

No antenna. Organisms that live in the absence of oxygen. Look . inspiration.

androecium
androcée m


masculine. A collective name for the male reproductive structures of a flower. flower stamens, i.e. stamens,


annual
annuel

around me. A flowering plant completes its life history, from germination to death in one germination season.

annual ring
Couch of the year

Annual ring. See secondary growth.

antagonistic muscles
muscles mpl antagonistes

Antagonistic Muscles Pairs of muscles that produce opposing movements, where the contraction of one muscle stimulates the relaxation of the other.

Articulated exoskeleton
flexor muscle
Extensor muscle
Vertebrate endoskeleton
Round muscle
Longitudinal muscle
Round muscle.
Shrinking
Annelid
Longitudinal contractile muscle -
I have my vertebrae

For example, at the joint, the flexor muscle (the muscle that bends the limb) stimulates the relaxation of the extensor muscle (the muscle that straightens the limb), and thus the limb flexes. When the limb straightens as a result of contraction of the extensor muscle, this leads to relaxation of the flexor muscle.

Likewise, the longitudinal and circular muscles in the gut of vertebrates and in annelid worms work in opposition, as the former causes peristalsis and the latter causes movement.