Science / Biology Glossary

Root Hairs: Extensions of the root epidermis that increase the roots ability to absorb water.

Root System: Plant organ systems that anchors the plant in place, stores excess sugars, and absorbs water and mineral nutrients. That part of the plant below ground level.

Root-Leaf-Vascular System Axis: Refers to the arrangement in vascular plants in which the roots anchor the plant and absorb water and nutrients, the leaves carry out photosynthesis, and the vascular system connects the roo . . . View Full Definition

Roots: Organs, usually occurring underground, that absorb nutrients and water and anchor the plant; one of the three major plant organ systems.

Rubp: Ribulose biphosphate; the 5-carbon chemical that combines with carbon dioxide at the beginning of the Calvin Cycle.

S Phase: That period of interphase when new DNA is synthesized as part of replication of the chromatin.

Salivary Amylase: An enzyme secreted by the salivary glands that begins the breakdown of complex sugars and starches.

Salivary Glands: Glands that secrete salvia into the mouth.

Saprophytes: Organisms that obtain their nutrients from decaying plants and animals. Saprophytes are important in recycling organic material.

Sapwood: Layers of secondary xylem that are still functional in older woody plants; visible as the outer lighter areas in the cross section of a tree trunk.

Sarcomeres: The functional units of skeletal muscle; consist of filaments of myosin and actin.

Saturated Fat: A fat with single covalent bonds between the carbons of its fatty acids.

Schwann Cells: Specialized glial cells that form the myelin sheath that coats many axons. Cells surrounding the axons of some neurons, thus forming the myelin sheath.

Scientific Method: Systematic apporach of observation, hypothesis formation, hypothesis testing and hypothesis evaluation that forms the basis for modern science.

Sclereids: Plant cells with thick secondary walls that provide the gritty textures in pears.

Sclerenchyma: One of the three major cell types in plants; have thickened, rigid, secondary walls that are hardened with lignin; provide support for the plant. Sclerenchyma cells include fibers and sclere . . . View Full Definition

Scrotum: In mammals, a pouch of skin located outside the body cavity into which the testes descend; provides proper temperature for the testes.

Second Law Of Thermodynamics (Entropy): The energy available after a chemical reaction is less than that at the beginning of a reaction; energy conversions are not 100% efficient.

Page: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74