2c Blog

Neild Joseph

2.C.1 – Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes.

·      Discuss how negative feedback works. Discuss the following two examples – Thermoregulation in animals and plant responses to water limitations. Negative feedback is a mechanism to maintain dynamic homeostasis it is used to set your body back to its normal conditions. Thermoregulation is when your body either gets too cold or too hot your body will send out signals to create a negative feedback to return back to its stability of 98.7 Fahrenheit. Plant response to water limitation is when the plant has a lack of water it begins to shrivel up.

·      Discuss how positive feedback works. Discuss the following three examples – lactation in mammals, onset of labor in childbirth, and ripening of fruit. Positive feed is a mechanism to amplify responses and processes. Lactation in mammals is an example of positive feedback because the suckling stimulates nerve endings in nipple and goes on carrying the process to provide milk for the offspring. Onset of labor in childbirth is when the head of fetus pushes against cervix then nerve impulses from cervix transmitted to brain and brain stimulate pituitary gland to secrete oxytocin and oxytocin carried in bloodstream to uterus and finally oxytocin stimulates uterine contractions and pushes fetus towards cervix. The ripening of fruit is also an example of positive feedback because the tree will go on sending stimulates to amplify the fruits ripeness so it can look better.

·      Discuss how an alteration in the mechanism of feedback can result in dire consequences by using the following three examples: diabetes mellitus in response to decreased insulin, dehydration in response to decreased antidiuretic hormone and Grave’s disease. Diabetes mellitus in response to decrease insulin is dire because your body needs it to level the blood glucose. Dehydration in response to decreased antidiuretic hormone and grave’s disease and graves disease is a dire consequence because its drain your body of the glucose it needs and soon can result in death.

2.C.2 – Organisms respond to changes in their external environments.

·      Discuss how organism respond to changes in their environment by using the following examples:

o   Photoperiodism and phototropism Photoperiodism and phototropism are a physiological response to photoperiod, such as flowering.

o   Hibernation and migration in animals Hibernation and migration in animals is almost automatic response in animals to move or sleep through rough weather conditions. Estivation lets animals survive periods of high temperature and scarce water.

o   Taxis and kinesis in animals Kinesis is a simple no directional, change in activity or turning rate in response to a stimulus. Taxis is a less automatic oriented move toward or away from stimulus such as removing a rock with pill bugs under they scatter to search for a similar habitat.

o   Chemotaxis in bacteria, sexual reproduction in fungi