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Need help for the B1 exam tommorow?

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Reply 20
Original post by Ishan_2000
Good detail....but you missed out CNS, or spinal cord/brain! Which is a crucial part of the reflex arc.
Also, (being picky, I know) you could add that the response is the muscle contraction.


In a reflex the brain is skipped because you need an immediate reaction. If the question is asking about a response then we should include the cns
Original post by hafsa23
Thank you!x


Hey we have the same name!
Reply 22
can I have some help on geo phot tropism tanks
Reply 23
Original post by Nihaj
In a reflex the brain is skipped because you need an immediate reaction. If the question is asking about a response then we should include the cns

no mate if the brain is nearer it will go there instead of the spinal cord
Reply 24
Original post by hafsa473
Hey we have the same name!

hahah that's cool! Hope you do well tomorrow fellow Hafsa!
Original post by Nihaj
In a reflex the brain is skipped because you need an immediate reaction. If the question is asking about a response then we should include the cns


How about if the receptor is in the eye? Wouldn't the brain be nearer, and therefore faster, than the spinal cord? (Just asking now, don't care about the question)
Original post by hafsa23
hahah that's cool! Hope you do well tomorrow fellow Hafsa!


Good luck to you too!
Reply 27
Original post by jeff213
can I have some help on geo phot tropism tanks


When plants grow in response to light it is known as phototropism

When plants grow in response to gravity it is known as geotropism

Phototropism:
When light shines at a plant auxin is produced in the shaded side of the shoot (the side opposite the light/sun) Auxin causes cells in the shoot of the plant to elongate as auxin promotes cell growth. Therefore the plant bend and grows towards the light.

Geotropism:
Auxin is produced in the root tip. Auxin will accumulate on the lower side of the root due to gravity. The auxin inhibits elongation in these cells so the root will eventually bend and grow in the direction of gravity
Reply 28
Original post by Ishan_2000
How about if the receptor is in the eye? Wouldn't the brain be nearer, and therefore faster, than the spinal cord? (Just asking now, don't care about the question)


Actually it probably will because the brain is nearer
(edited 7 years ago)
Original post by jeff213
no mate if the brain is nearer it will go there instead of the spinal cord


Yeah, that's what I though, makes sense for that to happen.
Reply 30
Original post by jeff213
can I have some help on geo phot tropism tanks


do you mean the response of plant shoots/roots to them?
Reply 31
Original post by Ishan_2000
Yeah, that's what I though, makes sense for that to happen.


But obviously its dependant on the question. If it was about the eye then it would include the brain. But In my answer i was thinking of a pinprick
Was thalidomide originally used as a sleeping pill and then used for morning sickness (causing the birth defects)?
Reply 33
Original post by jazz_xox_
Was thalidomide originally used as a sleeping pill and then used for morning sickness (causing the birth defects)?


Thalidomide was originally created as a sleeping pill. But it was discovered to have cured morning sickness in pregnant women. However no tests were conducted on the pill as a morning sickness drug. Many pregnant women took the drug and it caused their babies to have limb abnormalities. Thalidomide was banned as a result.
Thank you, also whereabouts is the CNS in a reflex action? Could you said the electrical impulse travels down the sensory neurone to the CNS?
Reply 35
Can someone please explain genetic modification in crops?
Reply 36
Original post by raeha_10
Can someone please explain genetic modification in crops?


Okay so lets say a bacteria has a gene that produces poison that kills insects. And we want this gene in plants so that the plants can have poison that kills insects. This would be a 4 mark question:

The gene from the bacteria that produces the poison is cut using enzymes. This gene is then transferred to the DNA of the plant cell at early stage of development. The plant now has the poison producing gene and can now kill insects which means the plant can live for longer.
Reply 37
Original post by jazz_xox_
Thank you, also whereabouts is the CNS in a reflex action? Could you said the electrical impulse travels down the sensory neurone to the CNS?


This link should help you out. It has an animated diagram

http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel/responses_to_environment/thenervoussystemrev3.shtml
Reply 38
Original post by jazz_xox_
Thank you, also whereabouts is the CNS in a reflex action? Could you said the electrical impulse travels down the sensory neurone to the CNS?


And yes you can say that

1.

sensory neurones carry signals from receptors to the spinal cord and brain.

2.

relay neurones carry messages from one part of the CNS to another.

3.

motor neurones carry signals from the CNS to effectors.

thank you!! good luck , are you sitting your exam tomorrow? :smile:

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