Organisms Respond to their Environment (3.6) Flashcards
Survival & Response (AO1)
Organisms [1] their chance of survival by responding to [2] in their environment.
[1] increase
[2] changes
Survival & Response (AO1)
List two simple responses by small organisms such as insects
Taxis
Kinesis
Survival & Response (AO1)
Function of taxis and kinesis for mobile organisms?
1. Keep organisms in a favourable environment.
(e.g. more food, more mates, less predators, less desiccation)
2. Increase chances of survival
Survival & Response (AO1)
Define taxis
Directional movement in response to a stimulus
Survival & Response (AO1)
Positive taxis
Directional response with movement towards the stimulus
Survival & Response (AO1)
Negative taxis
Directional response with movement away from the stimulus
Survival & Response (AO1)
Define kinesis
Random OR non-directional movements in response to the stimulus
Survival & Response (AO2)
Behaviour:
(Positive photo) taxis;
Advantage:
Avoid competition / to find a mate / increase dispersal / to avoid predators;
Survival & Response (AO2)
1. Kinesis;
2. Movement is random / non-directional
Survival & Response (AO2)
Taxis
Survival & Response (AO1)
Give one similarity and one difference between a taxis and a tropism.
Similarity − directional response to a stimulus / movement towards OR away from a stimulus;
Difference − in taxis whole organism moves whereas tropism a growth response in part of the plant (e.g. shoot or root tips).
OR
Difference - taxis occurs in animals whereas tropisms occurs in plants
Survival & Response (Maths)
11.1%
Survival & Response (AO2)
Taxis
B moves towards stimulus / light
Survival & Response (AO2)
kinesis;
random / non-directional movements;
Survival & Response (AO1)
In flowering plants, specific [1] factors move from growing regions to other tissues, where they regulate growth in response to directional [2].
[1] growth
[2] stimuli
Survival & Response (AO1)
Which organisms demonstrate tropisms?
Plants
Survival & Response (AO1)
Define tropism
Response of a plant to a directional stimulus
Survival & Response (AO1)
Stimuli that cause tropisms
Light
Gravity
Water
Salinity
Survival & Response (AO1)
Positive phototropism
Directional response of shoot tips towards light
Survival & Response (AO1)
Directional response of root tips away from light
negative phototropism
Survival & Response (AO1)
Positive gravitotropism
Directional response of root tips towards gravity
Survival & Response (AO1)
Auxis are a family of growth factors that cause tropisms. Which specific auxin must you know.
IAA
Full name: Indoleacetic acid
Survival & Response (AO1)
Where is IAA synthesised?
Shoot tips &
root tips
Survival & Response (AO1)
How does IAA move into the growing region of the shoot or root tip?
Diffusion
Survival & Response (AO1)
Where does IAA build up in the shoot tips in response to light?
On the shaded side
Survival & Response (AO1)
Effect of IAA in the shoot tips
- Stimulates elongagation of cells on the shaded side;
- Causes shoot to bend towards the light;
(this is a positive phototropism)
Survival & Response (AO1)
Where does IAA build up in the root tips in response to gravity?
On the side closest to gravity / on the underside
Survival & Response (AO1)
Effect of IAA in the root tips
- Inhibits elongagation of cells on the underside;
- Cells on opposite side (away from gravitiy) can elongate and cause the root tip to bend towards gravity;
Survival & Response (AO2)
1. Tip produces/synthesises IAA;
2. IAA diffuses (into growing region of shoot);
3. Stimulates elongation of cells on one side (than other);
Survival & Response (AO2)
1. Tip produces IAA;
2. Affects concentration of IAA
OR Affects (shoot) length/growth/elongation;
Survival & Response (Maths)
0.4cm^3 stock IAA + 39.6cm^3 water
Step by step working:
C1 x V1 = C2 x V2
C1 = stock concentration
V1 = volume of stock
C2 = desired concentration
V2 = desired volume
1 x V1 = 0.01 x 40
V1 = 0.4cm^3 of IAA stock + 39.6cm^3 of water
Survival & Response (AO2)
1. Grow in direction of / towards (pull of) gravity;
Accept: tropism for growth
Accept: positively geotropic / gravitropic
2. Grow away from salt;
3. Salt has more effect than gravity;
Survival & Response (AO2)
1. Seedlings / root tips respond to light;
2. Only measuring the effect of gravity;
Survival & Response (AO2)
When a young shoot is illuminated from one side, IAA stimulates growth on the shaded side.
Explain why growth on the shaded side helps to maintain the leaves in a favourable environment (2 marks).
1. Causes plant to bend / grow towards light / positive phototropism;
2. Light energy required for photosynthesis;
Survival & Response (AO1)
TRUE or FALSE:
IAA is only produced in the light
FALSE
IAA is produced in the light AND dark
Survival & Response (AO1)
Draw out a simple reflex arc
(include the neurons and an effector)
Survival & Response (AO1)
Which neuron in the simple reflex arc contains receptors to the stimulus?
Sensory
Survival & Response (AO1)
Suggest two advantages of simple reflexes
- Rapid;
- Protect against damage to body tissues;
- Do not have to be learnt / innate behaviour / involuntary;
- Help escape from predators;
- Enable homeostatic control;
- Finding suitable conditions / keep organism in favourable environment;
Survival & Response (AO1)
Give two types of cell that act as effectors.
Muscles
Glands
(which produce hormones)
Survival & Response (AO1)
Only 3 neurones
Survival & Response (AO1)
What is found between the sensory neuron and relay neuron
Synapse