Survival And Response- Paper 2

Question 1

Define stimulus

Answer 1

A detectable change in environment. These can either be external or internal

Question 2

What is an effector

Answer 2

It responds to stimulation by the never cells- a muscle, a gland, an organ and a cell

Question 3

State the simple reaction pathway

Answer 3

Stimulus—-> receptor—> coordinator—> effector —> response

Question 4

Why do organisms need to respond to changes in environment: increase survival and reproduction by

Answer 4

Avoiding harmful environments, competition and predators
Keep in favourable environment such as correct temperature and humidity
Grow towards or away from stimuli such as flowering plants
Dispersing to find new mates

Question 5

Behaviour patterns

Answer 5

Instinctive behaviour is an innate response to stimuli
Innate behaviour is genetically determined and is not learned
Members of a species which inherit alleles for a particular behaviour will produce the same response to a particular stimulus

Question 6

What is kinesis and give an example using wood lice

Answer 6

A behaviour pattern where an animal responds to a change in stimulus by increasing or decreasing activity. It is a change in the rate of movement and is random
Woodlice move around more when the humidity is low. The rate of movement is related to the intensity of the stimulus. The movement is random and not directional

Question 7

What experiment can be used to investigate kinesis in an organism

Answer 7

Choice chamber- organism is released into the chamber and after a set amount of time, the position of woodlouse would be recorded. The pattern of movement of the organism can also be recorded and the speed at which it moves

Question 8

What is taxes and give an example using earthworms

Answer 8

The directional movement of an organism either towards or away from a stimulus
Positive taxis- towards the stimulus
Negative taxis- away from stimulus
Earthworms move away from light which is negative phototaxis, they have more chance of survival as when move into soil they are more likely to find food, more likely to avoid predators and less likely to dehydrate

Question 9

What is a reflect action and what is its purpose/ what can it allow the organism to do

Answer 9

An example of a behaviour in which a certain stimulus produces a specific short lived response
They may allow the organism to protect against damage to body tissues, help escape from predators,enable homeostatic control, find food, mates or suitable environmental conditions

Question 10

What is the normal process and what happens instead when a reflex action is happening

Answer 10

Normal: stimulus, coordinator, effector
Reflex: sensory, relay, motor

Question 11

Describe what is meant by the term taxis

Answer 11

Moves towards or away from directional stimulus

Question 12

Describe what is meant by the term kinesis

Answer 12

Movement is random/non-directional or animal does not move towards a particular stimulus

Question 13

Explain the advantages of simple reflex arcs

Answer 13

Rapid
Protect against damage to body tissue
Do not have to be learnt
Help escape from predators
Enable homeostatic control

Question 14

What is positive trophism and give an example using plant growth

Answer 14

Growth towards a stimulus
Plant shoots grow towards the light as there is an increase chance of light falling on leaves and increase rate of photosynthesis

Question 15

What is a negative tropism and give an example using plant growth

Answer 15

Growth away from stimulus- plant roots grow away from plants and instead grow into the soil where they are most likely to absorb water and mineral ions

Question 16

Plant growth factors and examples

Answer 16

Specific growth factors are synthesised in cells located throughout the plant, they then diffuse from growing regions to other tissues, where they regulate growth in response to directional stimuli
Examples:
Fibre lines, auxins, which cause cell elongation as the cell wall gets loose allowing the cell to grow. Uneven distribution of auxins within the growing region causes uneven growth. IAA

Question 17

Describe IAA

Answer 17

IAA is produced in tips of roots and shoots which are actively growing
Diffuses to growing region
Causes cell elongation in shoots
Inhibits cell elongation in roots
IAA transported to more shaded part of roots and shoots (phototrophism)
IAA moves to underside of roots and shoots (geotrophism)

Question 18

IAA in the shoots

Answer 18

Promotes cell elongation
IAA synthesised in shoot tips
IAA diffuses into growing/elongating region
Light causes movement of IAA from light to shaded side
Higher concentration of IAA on shaded side
Causes directional growth as there is greater cell elongation on shaded side
Shaded side grows faster and causes roots to bend towards light

Question 19

IAA in the roots

Answer 19

Inhibits elongation
IAA synthesised in the root tips
IAA diffuses into the growing region
Light causes movement of IAA from light side to shaded side and towards gravity
Higher concentration of IAA on the shaded side
Cell elongation inhibited on the shaded side
Results in directional growth away from light and towards gravity

Question 20

Halo

Answer 20

Salt

Question 21

Geo

Answer 21

Gravity

Question 22

Photo

Answer 22

Light

Question 23

Hydro

Answer 23

Water