survival and response 2 Flashcards
(33 cards)
Describe and explain the positively phototrophic response of plants
1- Shoot tip produces IAA.
2- IAA diffuses down shoot.
3- IAA accumulates on shaded side of plant.
4- Causing more elongation of cells on shaded side.
5- Shoot bends towards the light.
Describe and explain the positive gravotropic response of plants
1- Root tip produces IAA.
2- IAA diffuses down root. IAA accumulates on lower side.
3- IAA inhibits cell elongation in roots, causing less elongation of cells on lower side.
4- root bends downwards.
What is a taxis
Directional response.
What is a kinesis
Non-direction, random response.
What is the prefix before a taxis
Positive or negative AND type of taxis (chemotaxis, phototaxic etc.).
What classifies a system as a reflex arc
Only involves three neurones, and doesn’t involve the brain.
Why are reflex arcs advantageous
Rapid. Doesn’t have to be learnt. Protects damage to body tissue.
What is the structure of the response to survival?
stimulus → Receptor → Coordinator → Effector → Response.
What is positive taxis?
Moving towards a stimulus.
What is negative taxis?
moving away from stimulus
What is negative phototaxis?
Moving away from light.
What is positive tropism?
Growing towards stimuli.
What is negative tropism?
Growing away from stimuli.
Where is IAA made?
At the tip of roots and shoots, and it diffuses to other cells.
Why did the student remove the shoot tip from each seedling?
tips produce IAA
Affects conc of IAA
affects shoots length/ elongation
Mitosis occurs in shoot tips
Affects length/ elongation
Describe a suitable procedure the student could follow to investigate the effect of different conc of GA on the growth of stem segments (5)
What is a reflex?
A response to a sensory stimulus.
What are the advantages of a simple reflex?
1- Only 3 neurons.
2. Rapid.
3. Protect against damage to body tissues.
4. Don’t have to be learned.
5. Help escape from predators.
6. Enable homeostatic control.
What are the two parts of the nervous system?
Central nervous system (CNS) and peripheral nervous system (PNS).
What is the central nervous system made up of?
The brain and spinal cord.
What does the peripheral nervous system consist of?
Pairs of nerves that originate from either the brain or the spinal cord.
What are the divisions of the peripheral nervous system?
Sensory neuron and motor neuron.
What does a sensory neuron do?
Carries nerve impulses from receptors towards the central nervous system.
What does a motor neuron do?
Carries nerve impulses away from the central nervous system to effectors (muscles or glands).
