Paper 1 - Co-ordination and Response

Question 1

How does the eye function to focus on close-by objects?

Answer 1

• Ciliary muscles contract
• Suspensory ligaments become slack
• Lens becomes more rounded

Question 2

Describe the phototropic response of stems

Answer 2

• Positive response
• Stems bend and grow towards light source

Question 3

Describe phototropic response of roots

Answer 3

• Negative response
• Roots grow away from light source

Question 4

Describe the structure and functioning of the reflex arc

Answer 4

• Pain detected by receptors and transduced to an electrical signal
• Sensory neurone carries impulse to CNS
• Relay neurones transfer impulse to the motor neurone
• Motor neurones carry impulse from CNS to effector organ
• Effector brings about a response and muscle contracts

Question 5

What is a tropism?

Answer 5

A directional movement made by a plant, as a result of stimulus such as sunlight, gravity or water

Question 6

Describe the structure of the eye as a receptor

Answer 6

• Iris
  -Lens
• Cornea
• Conjunctiva
• Suspensory ligaments
• Chloroid
• Sclera
• Blind spot
• Optic nerve
• Fovea
• Retina
• Ciliary muscles

Question 7

How does hormonal communication control responses?

Answer 7

• Impulse initiated by a change in internal/external environment
• Hormone secreted into blood
• Hormones bind to receptors in target organ
• A change in brought aboutt

Question 8

Describe geotropic response of stems

Answer 8

• Negative response
• Stems grow upwards

Question 9

Give 2 examples of homeostasis

Answer 9

• Regulating blood-water content
• Regulating internal body temperature

Question 10

Define homeostasis

Answer 10

The maintenance of a constant internal environment

Question 11

What is the source/role/effect of progesterone?

Answer 11

Source : Corpus Luteam
Role : Support a fertilized egg
Effect : Maintains uterus lining

Question 12

What does stimulation of receptors inside the sense organ do?

Answer 12

Sends electrical impulses along nerves into and out of the CNS, resulting in rapid responses

Question 13

What is the role of a neurotransmitter at the synapse?

Answer 13

Binds to the receptors on the post-synaptic membrane

Question 14

How are organisms able to respond to a change in their surroundings?

Answer 14

• Stimulus - detectable change in environment
• Receptor - detects change and acts as a transducer
• Coordination - electrical impulse travels to brain or spinal cord
• Effector - organ or gland that brings about a response
• Response - a reaction to a change in internal/external envronment

Question 15

How does the eye function to focus on distant objects?

Answer 15

• Ciliary muscles relax
• Suspensory ligaments get pulled tight
• Lens becomes flatter

Question 16

What is the role of auxin in the phototropic response of stems?

Answer 16

• Auxin causes plant growth
• Concentration of auxin causes bending towards light

Question 17

What is the source/role/effect of oestrogen?

Answer 17

Source : Ovaries
Role : Promotes female pubescent growth
Effect : Builds up uterus lining

Question 18

How does the eye respond to high light intensity?

Answer 18

• Circular muscles in iris contract
• Radial muscles relax
• Pupil gets smaller to let in less light

Question 19

How does the eye respond to low light intensity?

Answer 19

• Circular muscles in iris relax
• Radial muscles contract
• Pupil dilates to let in more light

Question 20

What is the source/role/effect of testosterone?

Answer 20

Source : Testicles
Role : Promote male pubescent growth
Effect : Produces sperm

Question 21

How is the CNS linked to sense organs?

Answer 21

Via nerves

Question 22

Describe the geotropic response of roots

Answer 22

• Positive response
• Roots grow downwards

Question 23

What is the source/role/effect of insulin?

Answer 23

Source : Pancreas
Role : Regulate blood-glucose levels
Effect : Reduces blood-glucose levels

Question 24

How does a plant respond to a stimulus?

Answer 24

With a tropism

Question 25

What are the differences between the nervous and endocrine systems?

Answer 25

- Nervous system uses electrical impulses but endocrine system uses hormones - Electrical impulses travel along neurones and synapses but hormones travel in blood stream - Electrical impulses are initiated from receptor muscles/organs but hormones are secreted from glands - Nervous system brings about a rapid response but endocrine system brings about a slower and more gradual response - Electrical-based changes and reversible but hormonal changes are not - Nervous-based changes cannot change physical appearance but hormone-based changes can

Question 26

What is the source/role/effect of adrenaline?

Answer 26

Source : adrenal glands Role : prepare body for fight or flight Effect : Increases heart rate to initiate a response

Question 27

Describe the role of the skin in thermoregulation

Answer 27

**DecreasingTemperature** - Sweat glands produce sweat which draws heat out of the blood when it evaporates - Vasodilation - blood vessels at the surface of the skin widen to increase heat loss via radiation **Increasing Temperature** - Body stops producing sweat - Shiver to increase respiration in muscles to produce heat - Hairs on skin stand up on ends to trap air and insulate the skin - Vasoconstriction - blood vessels at the surface of the skin narrow to reduce heat loss via radiation

Question 28

What does a coordinated response require?

Answer 28

- Stimulus - Receptor - Effectpr

Question 29

How does nervous communication control responses?

Answer 29

- Electrical impulse arrives and pre-synaptic membrane causing the production of neurotransmitter chemicals - Neurotransmitter is released and diffuses across the synapse - Neurotransmitter binds to the receptors on the post-synaptic membrane - A new electrical impulse is generated

Question 30

What does the central nervous system consist of?

Answer 30

- Brain - Spinal cord

Question 31

How could you describe the reflex arc/rapid reflex response?

Answer 31

Involuntary response