Back
to top
b1 edexcel SCIENCE for tomorrow
Watch
Announcements
Page 1 of 1
Go to first unread
Skip to page:
Hello If anyone needs help hit me up with questions and I'll try my best to help
0
reply
Report
#3
(Original post by Cadburyworld)
Can u help me with reflex arc and plant hormones.
Can u help me with reflex arc and plant hormones.
0
reply
Report
#4
(Original post by Zafirah.1)
Hello If anyone needs help hit me up with questions and I'll try my best to help
Hello If anyone needs help hit me up with questions and I'll try my best to help
0
reply
Report
#5
Apologies if I'm butting in but I'd like to give this a go.
1) A reflex action is triggered by a change in the environment (stimulus) which is detected by a receptor (light/sound/pressure/temperature). This receptor sends an electrical impulse down the sensory neurone, across a synapse, through a relay neurone and into the central nervous system. The CNS will coordinate a response and this will be sent through the relay neurone, across a synapse and through the motor neurone to the relevant affector. Usually, this is a muscle (the muscle will contract) or a gland (hormones will be secreted). Across a synapse, the electrical impulses are converted to chemical messengers which diffuse across the synapse and become electrical impulses again at the other end.
2) The main plant hormone you need to know about is auxin. It is present on the tips of shoots and roots.
Auxins encourage growth in the shoots and inhibit growth in the roots.
- Shoots will grow toward sunlight. Auxin accumulates on the side that has the least sunlight, causing that side to grow more and making the plant grow in the direction of the sunlight. (phototropism)
- Shoots will grow away from gravity. Auxin accumulates on the bottom of the shoot, thus promoting upward growth. (gravitropism/geotropism)
- Roots grow towards moisture. Auxin accumulates on the side with the most moisture, inhibiting growth on that side, causing the plant to grow towards the moisture. (hydrotropism)
- Roots grow towards gravity. Auxin accumulates on the bottom of the root, inhibiting growth there, thus promoting growth downwards. (gravotropism/geotropsim)
Auxin can be added to clones grown as plant cuttings as it helps them to grow roots. These hormones are in rooting powder.
1) A reflex action is triggered by a change in the environment (stimulus) which is detected by a receptor (light/sound/pressure/temperature). This receptor sends an electrical impulse down the sensory neurone, across a synapse, through a relay neurone and into the central nervous system. The CNS will coordinate a response and this will be sent through the relay neurone, across a synapse and through the motor neurone to the relevant affector. Usually, this is a muscle (the muscle will contract) or a gland (hormones will be secreted). Across a synapse, the electrical impulses are converted to chemical messengers which diffuse across the synapse and become electrical impulses again at the other end.
2) The main plant hormone you need to know about is auxin. It is present on the tips of shoots and roots.
Auxins encourage growth in the shoots and inhibit growth in the roots.
- Shoots will grow toward sunlight. Auxin accumulates on the side that has the least sunlight, causing that side to grow more and making the plant grow in the direction of the sunlight. (phototropism)
- Shoots will grow away from gravity. Auxin accumulates on the bottom of the shoot, thus promoting upward growth. (gravitropism/geotropism)
- Roots grow towards moisture. Auxin accumulates on the side with the most moisture, inhibiting growth on that side, causing the plant to grow towards the moisture. (hydrotropism)
- Roots grow towards gravity. Auxin accumulates on the bottom of the root, inhibiting growth there, thus promoting growth downwards. (gravotropism/geotropsim)
Auxin can be added to clones grown as plant cuttings as it helps them to grow roots. These hormones are in rooting powder.
2
reply
Report
#6
(Original post by Cadburyworld)
I have a feeling exams will be hard this year. As we are the last year following this spec right.
I have a feeling exams will be hard this year. As we are the last year following this spec right.
0
reply
X
Page 1 of 1
Go to first unread
Skip to page:
Quick Reply
