Cytokinesis Definition Cytokinesis is the final process in eukaryotic cell division, which divides the cytoplasm, organelles, and cellular membrane. Cytokinesis typically occurs at the end of mitosis, after telophase, but the two are independent processes. In most animals, cytokinesis begins sometime in late anaphase or early telophase, to ensure the chromosomes have been completely segregated. … Read more
Nonvascular Plant Definition Species of plants without specialized vascular tissues are nonvascular plants. It includes everything from higher-structured forms of green algae with plant-like characteristics to mosses (Bryophyta), liverworts (Marchantiophyta), and hornworts (Anthocerotophyta). Nonvascular plants are those that live both on land and in marine environments. Lifecycle of a Nonvascular Plant All plants and some … Read more
Adenosine Triphosphate Definition Adenosine triphosphate, also known as ATP, is a molecule that carries energy within cells. It is the main energy currency of the cell, and it is an end product of the processes of photophosphorylation (adding a phosphate group to a molecule using energy from light), cellular respiration, and fermentation. All living things … Read more
Conditioned Stimulus Definition A conditioned stimulus is a substitute stimulus that triggers the same response in an organism as an unconditioned stimulus. Simply put, a conditioned stimulus makes an organism react to something because it is associated with something else. Conditioned stimuli begin as neutral stimuli that do not illicit a response until conditioning has … Read more
Extirpation Definition Extirpation (also known as ‘local extinction’) describes the situation in which a species or population no longer exists within a certain geographical location. Unlike extinction, whereby a species no longer exists anywhere, extirpation means that at least one other population of the species still persists in other areas. Most species of plants and … Read more
Each cell contains specialized subcellular structures adapted to keep it alive. In addition to releasing energy, some of these structures produce proteins, transport substances, and control cellular activity. Organelles are collectively referred to as these structures. Both plant and animal cells contain organelles, many of which are similar. Plant cells, however, contain some organelles (such … Read more
The original cell theory states that the cell is the basic structural and functional unit of living organisms and all cells come from other cells. The scientists Matthias Schleiden and Theodor Schwann are credited with establishing the cell theory in 1839. However, there was a lot of work done over the previous centuries which paved … Read more
Bone tissue is made up of four different types of bone cells; osteoblasts, osteocytes, osteoclasts, and osteoprogenitor cells. Together these cells comprise the compact and spongy bone layers and work together to maintain the mineral composition and structure of the bones. What Are Bone Cells? Bone cells are the cells that make up bone tissue. … Read more
Every student experiences the feeling at least once, staring into the stucco walls of a way-too-brightly lit classroom. They count down the minutes until the clock strikes three P.M., yearning to escape the burden of learning for the day. In 1888, the great poet William Wordsworth encapsulated the feeling of the school bell ringing in … Read more
The MCAT or the Medical College Admissions Test is a standardized test that is used as a part of the admissions process for medical schools. There are four MCAT sections: Biology, Chemistry, Psychology, and Critical Analysis and the test is 7.5 hours long. It is administered several times a year all over the United States. … Read more