AQA BIOL5 Biology Unit 5 Exam - 22nd June 2011

Original post by Cyanohydrin

chemoreceptors detect pH - that is all (as far as I know)

Ok but that didn't answer anything :frown:

Pretty sure the aortic and cartoid ones also detect CO2 and O2 concentrations tho

Reply 2101

Original post by Phalange

1) Chemoreceptors are found in medulla, aorta and cartoid artery. Say the chemoreceptor in aorta detected high CO2, low O2 and low pH. It would send impulse via sensory neurone to medulla to decide what to do. What would happen if the medulla detected the high CO2 etc? Would it "skip" the sensory neurone part or...?

2) IAA inhibits growth in roots but stimulates growth in tips right? Wouldn't gravity cause IAA to accumulate at the tip of the root causing it to stop growing downwards? Unless the root growing region is NOT the tip? :|

Thanks if anyone can help! Quote me

Yp, chemo receptors are found in the aorta and carotid body. If we excercise we increase our metabolic activity, namely respiration. This produces co2. Co2 lowers ph of the tissue fluid in the blood by dissolving to form carbonic acid. This lower acidity is detected by the chemoreceptors, which send increase frequncy of nervous impulses to the cardio-accelotary centre of the medulla oblongata. This inturn sends increased waves of exitatory nervous implulses via the symapthtic nervous system to the sino atrial node. The sinoatrial node increases the rate at which the heart beats and so the cardiac output increases, leading to more co2 being exchenged in the alveoli of the lungs and back in to environment through exhalation.

I think

Reply 2102

stephenc

Original post by Phalange

1) Chemoreceptors are found in medulla, aorta and cartoid artery. Say the chemoreceptor in aorta detected high CO2, low O2 and low pH. It would send impulse via sensory neurone to medulla to decide what to do. What would happen if the medulla detected the high CO2 etc? Would it "skip" the sensory neurone part or...?

2) IAA inhibits growth in roots but stimulates growth in tips right? Wouldn't gravity cause IAA to accumulate at the tip of the root causing it to stop growing downwards? Unless the root growing region is NOT the tip? :|

Thanks if anyone can help! Quote me

With regard to 2), IAA elongates cells in shoots and diffuses away from the light side to the shaded side, causing the shoot to bend towards the light side. In roots, it does the inverse - causing roots to bend away from light.

Reply 2103

NRican

Original post by NRican

You know when reading Gel E it says from the bottom up - do you read the smallest eg. the one that's furthest first and so on?

Anyone? Sorry I'm being so impatient with panic!

Reply 2104

Original post by Phalange

Ok but that didn't answer anything :frown:

Pretty sure the aortic and cartoid ones also detect CO2 and O2 concentrations tho

Not sure about that one really. But I gues when theres an increase in heart rate, there is an increase in blood flow and so more o2 is transported to respiring cells due to tha saturation of o2 in heameglobin in the red blood cells upon transfer of co2 out to the environment.

Reply 2105

Carpet21

12

So how come the NT book claims that only DNA fragments with up to 500 bases can be sequenced by gel electrophoresis, but then goes on to talk about how thousands of bases are sequenced in the same way??

Reply 2106

Original post by NRican

Anyone? Sorry I'm being so impatient with panic!

Yep thats correct. smallest to the largest :cool:

Reply 2107

Original post by Jin3011

Yp, chemo receptors are found in the aorta and carotid body. If we excercise we increase our metabolic activity, namely respiration. This produces co2. Co2 lowers ph of the tissue fluid in the blood by dissolving to form carbonic acid. This lower acidity is detected by the chemoreceptors, which send increase frequncy of nervous impulses to the cardio-accelotary centre of the medulla oblongata. This inturn sends increased waves of exitatory nervous implulses via the symapthtic nervous system to the sino atrial node. The sinoatrial node increases the rate at which the heart beats and so the cardiac output increases, leading to more co2 being exchenged in the alveoli of the lungs and back in to environment through exhalation.

I think

As great as that was (it really was :smile:

) umm I wanted to know what would happen if the medulla detected this as it has chemoreceptors. SInce the medulla is the centre that the sensory neurones go to, would the chemoreceptors in the medulla not have to send impulses along sensory neurones? since it is ALREADY at the medulla.. if that makes sense

Reply 2108

choc1234

in the NT textbook it says (pg 265)
most recent trreatments involve using bone marrow stem cells rather than t cells for scid treatment
bone marrow stem cells divide to provide a constant supply of the ADA gene and hance the enzyme ADA.
can someone explain this to me thanks

Reply 2109

Tericon

8

Original post by stephenc

With regard to 2), IAA elongates cells in shoots and diffuses away from the light side to the shaded side, causing the shoot to bend towards the light side. In roots, it does the inverse - causing roots to bend away from light.

Please can you explain that in more detail with regards to the roots? thanks :smile:

Reply 2110

Carpet21

12

Original post by NRican

Anyone? Sorry I'm being so impatient with panic!

Yes you do read it from the bottom up as that is the one that has travelled the furthest and is therefore the shortest. :smile:

Reply 2111

Original post by stephenc

With regard to 2), IAA elongates cells in shoots and diffuses away from the light side to the shaded side, causing the shoot to bend towards the light side. In roots, it does the inverse - causing roots to bend away from light.

I'm talking about geotropism, not phototropism. I know that roots bend towards gravity (so "downwards") and shoots do the opposite. But ya if you have IAA at the tip of the ROOT, wouldn't it inhibit growth? Say the root was vertically down. Unless the growing region of the root is not the tip, it would stop growing I think?

Reply 2112

Pixiefairy

15

hey guys i'm saying this for a last time in cased any one has missed out!, i have like over 20 synoptic essays and analysis on them it's really helpful!, pm me and i will email you :biggrin:

Reply 2113

NRican

Original post by choc1234

in the NT textbook it says (pg 265)
most recent trreatments involve using bone marrow stem cells rather than t cells for scid treatment
bone marrow stem cells divide to provide a constant supply of the ADA gene and hance the enzyme ADA.
can someone explain this to me thanks

Stem cells constantly replicate so if you insert gene into it it will keep producing them unlike other body cells.

Reply 2114

won-derer

just wanted to ask if the question asks, "give the sequence of bases on the pre-mRNA transcribed from a strand (which was given in the question)", would you just write the complementary bases on would you write both the complementary and the original bases?

Reply 2115

Original post by Phalange

As great as that was (it really was :smile:

) umm I wanted to know what would happen if the medulla detected this as it has chemoreceptors. SInce the medulla is the centre that the sensory neurones go to, would the chemoreceptors in the medulla not have to send impulses along sensory neurones? since it is ALREADY at the medulla.. if that makes sense

Are you talking about chemo receptor in the medulla itself?
If so, I'm not really sure. For our syllabus I don't think we're expected to know that...I may be wrong though :tongue:

Reply 2116

choc1234

what is the purpose of the blind spot?

Reply 2117

Original post by Jin3011

Are you talking about chemo receptor in the medulla itself?
If so, I'm not really sure. For our syllabus I don't think we're expected to know that...I may be wrong though :tongue:

Yep I am
Ok dw I'll ask my teacher tomorrow. It's just that my book mentioned the medulla having it so I thought about what if it gets a stimulus. Thanks anyway :smile:

Reply 2118