أكاديميا - كولنز معاجم الجيب العلمية - البيولوجيا انكليزي - فرنسي - عربي الحرف ٦_ s

Academia - Collins Scientific Pocket Dictionaries - Biology
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spongy mesophyll
mésophylle m spongieux

Spongy mesophyll tissue in the leaf is present between the lower palisade cells. The epidermis and mesophyll cells, the spongy middle tissue, are rarefied and separated by air spaces that allow gas exchange between the leaf and the atmosphere through stomata.
See leaf.


spore
spore f

Spore A reproductive unit, usually microscopic, consisting of one or more cells that separates from a mother organism and ultimately produces a new individual. Spores play a role in asexual and sexual reproduction, such as gametes alike, and are produced by certain plants, fungi, bacteria, and protozoa. Some spores constitute a resistant resting stage in the life history, while others allow rapid settlement of new habitats.
Example of spore release in bread mold (Mokr)


sporophyte
sporophyte m

Spore plant. A phase in the life cycle of a plant that produces spores. This phase may be prevalent first in plants that show alternation of generations, and it results from diploid zygote.


stamen
etamine f

stamen. The male part of the flower that produces
Pollen grains. Each stamen consists of a petiole (filament) bearing an anther.


starch
amidon m

We want. Polysaccharide carbohydrate consists of chains of glucose units and is important as an energy store in plants. Starch is synthesized during the process of photosynthesis and is immediately converted into glucose by amylase enzymes. See polysaccharides.

stem
tige f

The stem of the part of a flowering plant that carries buds, leaves, and flowers. Its functions are: (a) transporting water, mineral salts, and carbohydrates.
(b) Raising the leaves above the soil to obtain maximum air and light,
(c) Raising flowers, which helps in pollination, (d) photosynthesis in green stems.

Boys' leg, longitudinal section
Young stem structure (dicot)


sternum (or breastbone)
sternum m

The sternum (or breastbone). The thorax bone in the center of the ventral side of the thorax in tetrapods to which most of the ventral ribs are attached. See endoskeleton.


stimulus
stimulus m

alarm clock. A stimulus is any change in the environment
Organic may elicit a response at
Membership. See sensitivity.

stolon
stolon m. trainant m

Major. A vegetative reproduction organ in flowering plants consists of a horizontal stem that grows from a bud on the stem of the mother plant. The shoots grow on top of the soil, then the head of the shoots eventually settles in it and develops into an independent plant.

An example of the gall is the shown strawberry gall
below.
Strawberry plant with arad


stoma (ta)
stomate m

A change in one of the many small pores found in the epidermis of plants, especially in the leaves.
Water evaporation occurs during transpiration and gas exchange occurs through changes. See guard cell.

stomach
estomac m

stomach. Muscular sac in the anterior part of the canal
Alimentary canal.

In vertebrates, food passes into the stomach by peristalsis through the esophagus (oesophagus).
In the stomach, food is mechanically crushed by the peristaltic action of the stomach walls and protein digestion begins.

As for the stomach of herbivores, it has several chambers for digesting cellulose, and food passes from the stomach to the small intestine via the pyloric sphincter.
See pepsin.


striated muscle
muscle pain

Striated muscle.
See voluntary muscles.