OFFICIAL OCR A2 Biology - F214 Thread

Outline the need for communication
systems withing multicellular organism,
with reference to the need to change in the internal and external environement and to cordinate the activities of different organs.

let's start off:

1) what is are the things that the body needs to keep constant?
2)what is meant by stimulus and response?
3)How does arctic fox adapt to winter weater and how does desert fox adapt to souring heat of the sun?

4) what makes a good communication system?

5) why is cell signalling important in cells?

no more than 10min answering these questions.

guys you've to move at quick pace and post your answers.

Reply 1822

here is my answers:

1) the things that the body needs to keep constant are the
body temperature, blood glucose concentration, the water potential of the blood, blood salt concentration.

2) stimulus is any changes that causes an organism to respond to its environement.

a response is a change in behaviour or physiology as a result of a change in the environement.

3) artic fox have much thicker coat that enables them not to lose heat by radiation, convection and conduction. Desert mammals have a longer loop of henle to conserve water and more water can be
re-absored in the collecting duct.

4) a good communication is one that covers the whole body and enable cells to communicate with each other and also enable rapid/long term responses.

5) cell signalling makes sure that only specific cells communicate with each and both have receptors that is complimentary in shape to each other.

Reply 1823

Remarqable M

Outline the need for communication
systems withing multicellular organism,
with reference to the need to change in the internal and external environement and to cordinate the activities of different organs.

let's start off:

1) what is are the things that the body needs to keep constant?
2)what is meant by stimulus and response?
3)How does arctic fox adapt to winter weater and how does desert fox adapt to souring heat of the sun?

4) what makes a good communication system?

5) why is cell signalling important in cells?

no more than 10min answering these questions.

guys you've to move at quick pace and post your answers.

1) Temperature, blood glucose conc. water potential in blood

2) Stimulus is the change in energy that is detected by a sensory receptor.
Response is the action taken after the stimulus has been detected, to ensure conditions return back to normal.

3) Arctic fox has more hair, which erects to trap a layer of air for insulation.
Desert fox has a longer loop of Henle, so more salt transfer in ascending limb; therefore the water pot. in medulla is lower, more water can be reabsorbed.

4) Good communication means rapid response, long and short term effects, covers the whole body.

5) Cell signalling is important in cells so they can communicate and inform diff parts of the body of different conditions so homeostasis can be maintained by means of neg. feedback. (and so only certain cells communicate with each other, without others being affected)

Reply 1824

5min until i move on to the next questions :smile:

Reply 1825

quick question: one book says it is adenyl cyclase another says adenylyl cyclase.
which is it?

Reply 1826

CreativeBass

quick question: one book says it is adenyl cyclase another says adenylyl cyclase.
which is it?

just stick with adenyl cyclase :smile:

they are both the same thing but spelt differently
so just choose the one you're most comfortable with

Reply 1827

mohamed aden

CreativeBass

quick question: one book says it is adenyl cyclase another says adenylyl cyclase.
which is it?

ITS adenyl cyclase

Reply 1828

Remarqable M

just stick with adenyl cyclase :smile:

they are both the same thing but spelt differently
so just choose the one you're most comfortable with

oh okay thanks :smile:

Reply 1829

mohamed aden

ITS adenyl cyclase

Thanks

Reply 1830

ok i've decided that we are gonna start the next set of questions at 8am, so in the meantime ask any random questions you like.

Reply 1831

hazu121

deoes anyone think that the strectch and challenge stuff is pretty tough??

Reply 1832

1) Explain what is meant by negative feedback.
2) Explain what is meant by positive feedback.
3) define homeostasis.

4) Explain the priniciples of homestasis in terms of receptor, effectors and negative feedback.

no more than 10min.

Reply 1833

Chunkeymonkey62

2

Remarqable M

ok i've decided that we are gonna start the next set of questions at 8am, so in the meantime ask any random questions you like.

Why do we need to maintain a bodt temperature?

Just for enzyme activity?

Reply 1834

Chunkeymonkey62

2

Remarqable M

1) Explain what is meant by negative feedback.
2) Explain what is meant by positive feedback.
3) define homeostasis.

4) Explain the priniciples of homestasis in terms of receptor, effectors and negative feedback.

no more than 10min.

Negative feedback - A process that brings about the reversal of any change in conditions. It usually helps maintain homeostasis.

Positive feedback - A process that increases any change in conditions. It is usually harmful and doesnt lead to homeostasis, but is not always harmful.

Homeostasis - The maintenance of a internal environment in a constant state, despite external changes.

A change in condition is detected by the receptors. It then sends a signal to an effector to implement a change. It does this by cell signaling, which can be neuronal or hormonal. It is an example of negative feedback.

Reply 1835

Remarqable M

1) Explain what is meant by negative feedback.
2) Explain what is meant by positive feedback.
3) define homeostasis.

4) Explain the priniciples of homestasis in terms of receptor, effectors and negative feedback.

no more than 10min.

1. Negative feedback is the process that brings about the reversal of any change, to return the conditions to a norm. leading to homeostasis.

2. Positive feedback is the process that increases any change that has taken place. It leads away from homeostasis.

3. Homeostasis is the control and maintaining of internal conditions, keeping them at a constant, despite external environment.

4. Homeostasis occurs when the receptors in the body detect a change in the body. They then use cell signalling to inform the effector by means of a communication system (hormonal or nervous) that allows the change to be reversed and brought back to normal, this is done by negative feedback.

Reply 1836

My answers to the questions:

1) negative is the homeostatic mechanism that brings about a reversal of any change in conditions. for example, when the body temperature is low, the body activates several processs that
restores the body temperature to normal.
2) Positive amplifies any changes in conditions. It does not lead to homeostasis, however it is beneficial in some cases e.g. pregnancy birth

3) homeostasis is the maintenance of the internal environment in a constant state despite external changes.

4) In order to detect changes in the body the body needs receptors, then it needs to have a way of exhanging information between cells in order to find out the changes in the
body so that it can iniate the correct response a communication system e.g. nervous and hormonal system. After this the body then iniates a negative feedback to restore conditions in the body back to normal.

Reply 1837

haha well done chunkey and creative bass! our answers are almost identical :smile:

which is good.
the next round of questions in 15min and i want you to read up on maintaining the body temperature of ectotherms.

Reply 1838

Chunkeymonkey62

2

Can someone give me a definition of cell signalling please?

Reply 1839

uer23