Plant Hormones & Homeostasis Flashcards
Name a plant growth hormone
Auxin is a plant groth hormone.
What does Auxin do?
Auxin is a plant hormone that controls growth near the TIPS of shoots and roots
What is phototropism?
PHOTOTROPISM is the growth of a plant in response to light.
What ios the word used to describe the growth of a plant in response to light?
Phototropism.
How does Auxin work?
Auxin is produced in the tips of plant shoots and moves backwards to stimulate the cell elongation (enlargement) process which occurs JUST BEHIND the tips
NOTE: if the tip is removed, no AUXIN is available and the shoot may stop growing.
NOTE: Extra auxin promotes growth in the shoot but inhinits growth in the root producing the desired result
Why does a plant shoot bend towards light?
When a plant shoot is exposed to light, more auxin accumulates on the side in the shade which makes the cells grow (ELONGATE) faster on the shaded side causing the shoot to bend towards the light.
Why do roots grow towards gravity?
A root growing sideways will always have more auxin on its lower side. but in a root the EXTRA AUXIN inhibits growth.
This means that the cells on top ELONGATE FASTER and the root bends downwards
Why do roots grow towards moisture?
An uneven amount of moisture either side of a root produces more auxin on the side with most moisture.
This INHIBITS GROWTH on that side, causing the root to bend in that direction, TOWARDS THE MOISTURE.
How does Plant Hormones assist argriculture?
- Most weeds in crops are broad-leaved unlike the crops which are narrow leaved. As such selective weedkillers are made of plant growth hormones that only affect broad leaved plants.
- Plant cuttings won’t grow in soil but if you add rooting pwoder (which contains auxin) they prooduce roots rapidly and start growing as new plants.
What is meant by Homeostasis?
Homeostasis is the functioning of your body to maintain a CONSTANT INTERNAL ENVIRONMENT.
Homeostasis: What things need to be constant in your body?
- Ion content.
- Water content
- Sugar content
- Body temperature.
What is ion content and how is it regulated in your body?
Ions (sodium) are taken into the body in food and then absorbd by the blood.
Too much ion needs to be removed from your body.
Some ions are lost through sweat (tastes salty)
Your kidneys will remove the excess from the blood and pee it out through urine.
How is water levels regulated within the body?
Water is taken into the body as food and drink and is lost in the following ways:
- through the SKIN as SWEAT
- via the LUNGS in BREATH
- via the KIDNEYS as URINE
How can the type of day impact upon the body’s regulation of water content?
On a cold day or when you’re not exercising you don’t sweat much so you’ll produce more urine which will be pale (since the waste carried in the urine is more diluted).
On a hot day or when your’re exercising a lot, and so you will produce less urine but this will be more concerntrated (hence a deeper colour) and you will lose more water through your breadth as you breathe faster.
Which organ controls body temperature?
Your brain ascts as your oen personal thermostat. It is sensitive to the blood temperature in the brain and it receives messages from the skin that provide information about skin temperature.
Body temperature is normally 37 C as enzymes work best at this temperature.
