Phloem Definition A vascular plant’s phloem serves as a transport system for soluble organic compounds. The phloem is made up of living tissue, which uses turgor pressure and energy in the form of ATP to actively transport sugars to the plant organs such as the fruits, flowers, buds and roots; xylem, the other component of … Read more
Autotroph Definition Autotrophs are organisms that can produce their own food, using materials from inorganic sources. The word “autotroph” comes from the root words “auto” for “self” and “troph” for “food.” An autotroph is an organism that feeds itself, without the assistance of any other organisms. Autotrophs are extremely important because without them, no other … Read more
Myelin Sheath Definition The myelin sheath is a fatty insulating later that surrounds the nerve cells of jawed vertebrates, or gnathostomes. All extant members of the Gnathostomata, from fish to humans, have a myelin sheath on the axon of their nerve cells. The oldest known members of the jawed fishes, the exinct placoderms, were armored … Read more
Law of Segregation Definition Gregor Mendel’s law of segregation states that the two alleles for each trait segregate, or separate, during the formation of gametes, and that during the formation of new zygotes, the alleles will combine at random with other alleles. The law of segregation ensures that a parent, with two copies of each … Read more
Fossil Record Definition A fossil record is a group of fossils which has been analyzed and arranged chronologically and in taxonomic order. Fossils are created when organisms die, are incased in dirt and rock, and are slowly replaced by minerals over time. What is left is a mineral impression of an animal which once existed. … Read more
Basics of Homeostasis In general, homeostasis refers to the balance within a system that keeps it operating within a range of conditions. Homeostasis helps animals maintain stable internal and external environments with the best conditions for it to operate. It is a dynamic process that requires constant monitoring of all systems in the body to … Read more
Compact Bone Definition Compact bone, also known as cortical bone, is a denser material used to create much of the hard structure of the skeleton. As seen in the image below, compact bone forms the cortex, or hard outer shell of most bones in the body. The remainder of the bone is formed by cancellous … Read more
Deciduous Forest Definition A deciduous forest is a biome dominated by deciduous trees which lose their leaves seasonally. The Earth has temperate deciduous forests, and tropical and subtropical deciduous forests, also known as dry forests. Another name for these forests is broad-leaf forests because of the wide, flat leaves on the trees. Trees in tropical … Read more
The building blocks of centrosomes are microscopic cylinders (microtubules). The centriole consists of nine microtubule triplets arranged in the shape of a cylinder, with each centrosome containing two centrioles. As cells divide, centrioles are thought to contribute to the completion of cytokinesis by organizing the spindle fibers in the mitotic spindle apparatus. If the centrosome … Read more
A resident assistant (RA) holds a long list of responsibilities in the residential halls of your college. RAs are also students at the college but are usually in the later years of the undergraduate degree or they are graduate students. Resident assistants are there to enforce school policies in the living spaces, put together social … Read more