Transcript Survival and response

Survival and response
Aim: To understand the responses
animals and plants make in order, to
increase their chance of survival
What changes in the environment
do organisms respond to?
Are these responses fast, slow, long or short duration
Are these responses chemical or electrical
Which chemicals are involved in
responses
• Hormone – Chemical messages
• Neurotransmitters – Chemicals that pass a message from one
neurone to another at a synapse
• Histamine – Released as a result of infection/injury – causes
inflammation due to dilation of blood capillaries- plasma
containing antibodies then escapes into the tissue
• Prostoglandins – Hormones which help sperm reach the oocyte
by causing muscular contractions of the uterus and oviducts
Which chemicals are involved in
responses
• Hormone
• Neurotransmitters – 271-272
• Histamine
• Prostoglandins
Tropisms
• Tropisms – A growth movement in
response to a directional stimulus
• Keeps the roots and shoots in
favourable conditions
• Plant shoots grow towards light – positive
phototrophism
• Plant roots grow away from light (negative
phototrophism) and towards gravity (positive
geotrophism)
• Plant roots grow towards water (positive
hydrotrophism)
TASK
Copy and give explain how these keep the roots and shoots in
favorouble positions for the plant
Auxins
• Plant growth is controlled by the growth
hormone auxin. The most common type
of auxin is IAA.
• Task: Using 431 – 432 summarise how
scientists discovered how plant growth
is regulated
Phototrophism
Auxins (IAA)
Indoleacetic acid
• Plant hormone that
controls plant growth
• Produced in shoot
tips
• Causes elongation of
shoot cells
Phototrophism
Light destroys auxin
- This encourages growth on the
shaded side
- This makes the shoot bend towards
the light
Geotrophism
• The main plant root always grows
downwards towards gravity
How geotrophism works
• In roots auxin accumulates on the
lower side of the root
• In roots auxins INHIBIT cell
elongation
Auxin accumulates
Cells continue
to elongate
Cell elongation
inhibited
Plant growth factors
• The most common growth hormone is IAA
Indoleacetic acid (IAA).
Pg 157 copy final 3 bullet points and the 2
sentences below it
Read application and how science works
and answer the questions as you go
through
Taxes and Kinesis
• Responses to stimuli (change in the
environment)
• Taxes - Directional response to stimulus ie –
moves toward (positive taxes) or away (negative
taxis to the stimulus
• Kinesis – Non directional response to stimulus ie
– speeds up, slows down or changes direction
more often
Task
• Plan an investigation into the kinesis
response of woodlice to a stimuli
• Title
• Hypothesis