Co-ordination and response

Question 1

What is homeostasis?

Answer 1

• the maintenance of constant internal conditions in response to the internal and external environment

Question 2

What happens if conditions are not optimal in the body?

Answer 2

-enzymes denature resulting in their ability to catalyse chemical reactions slower

Question 3

What are the 5 processes for homeostasis?

Answer 3

• water levels
• blood sugar levels
• internal body temp
• CO2 levels
• urea concentration

Question 4

What is a stimulus + 2 examples?

Answer 4

• a change in environmental conditions that brings about a response.
• Sunlight and temperature are examples

Question 5

What is the receptor?

Answer 5

-detect stimuli

Question 6

What is the effector + 2 examples?

Answer 6

• carry out responses to stimuli that help to restore optimum levels
• muscles and glands

Question 7

What is the difference between positive and negative phototropisms?

Answer 7

• positive=plant grows towards the light

- negative=plant grows away from light source

Question 8

What is the difference between positive and negative geotropisms?

Answer 8

• positive=grow against gravity

- negative=grow in direction of gravity

Question 9

What does light cause the auxins to do?

Answer 9

-concentrate on the darker side of the shoot tip and spread down the root=cells on darker side grow faster

Question 10

What does gravity cause the auxins to do?

Answer 10

• to concentrate on the lower side of the root

- auxins inhibit growth on the lower side=grows slower

Question 11

What are the stages in the reflex arc?

Answer 11

-

Question 12

What are the stages of nerves transmitted?

Answer 12

-receptors>sensory neuron>synapse>relay neurone>synapse>brain>motor neurone>effectors

Question 13

What is the synapse?

Answer 13

-gaps between neurones that nerve impulses must travel across (they can only do so in one direction)

Question 14

How are neurotransmitters produced?

Answer 14

-electrical impulse reaches the end of the neurone before the synapse which triggers the release of chemicals called neurotransmitters

Question 15

What do neurotransmitters do?

Answer 15

• diffuse across the synapse and bind to receptors on the next neurone.
• The presence of the neurotransmitter causes the production of an electrical impulse in the next neurone

Question 16

What is the nervous system made up of?

Answer 16

-brain, spinal cord, neurones

Question 17

stages of reflex arc.

Answer 17

-receptor>sensory neurone>spinal cord>synapse>relay neurone>synapse>motor neurone>effector

Question 18

What are the purpose of reflex actions?

Answer 18

• allow us to respond to dangerous situations rapidly and automatically. For reflex actions, the nervous system responds to stimuli via a reflex arc

Question 19

What is the purpose of a receptor?

Answer 19

-detect the change in the environment and initiate a signalling process within the body

Question 20

What do the 3 types of neurone do?

Answer 20

• sensory neurone=electrical impulse to spine
• relay neurone=in the spine. Relays the electrical impulse from the sensory neurone to the appropriate motor neurone
• motor neurone=electrical impulse to effector

Question 21

Role of optic nerve.

Answer 21

-Transmits visual information, in the form of electrical impulses, from the retina to the brain

Question 22

Role of cornea + what is it.

Answer 22

-The transparent frontal portion of the eye responsible for refracting light

Question 23

What is the retina?

Answer 23

-Filled with receptor cells, which are sensitive to both the brightness (light intensity) and the colour of light

Question 24

What is the pupil?

Answer 24

-hole in the centre of the iris through which light passes to get to the retina

Question 25

Role of iris.

Answer 25

-controls pupil diameter and therefore, the quantity of light reaching the retina

Question 26

What is the sclera?

Answer 26

-white of the eye and the opaque protective outer layer of the eye

Question 27

What is the role of the cornea?

Answer 27

-the transparent frontal portion of the eye responsible for refracting light

Question 28

What is accommodation?

Answer 28

• the process of the lens in your eye changing shape to focus on an object as it’s distance from the eye changes
• done by suspensory ligaments + ciliary muscle

Question 29

How do we focus on close objects?

Answer 29

-ciliary muscles contract + suspensory ligaments loosen=lens becomes thicker and rounder resulting in significant refraction of light rays

Question 30

How do we focus on far away objects?

Answer 30

-relaxation of ciliary muscles, suspensory ligaments loosen= lens becomes thinner and flatter resulting in minor refraction

Question 31

What is the hypothalamus?

Answer 31

-Receptors in the thermoregulatory centre of our brain which monitor the internal body temperature as blood flows through the brain

Question 32

What does thermal regulation control?

Answer 32

-body temp

Question 33

How does shivering warm us up?

Answer 33

• When we are too cold, muscles start to contract automatically. This makes us shiver.
• This process needs energy, which is generated through respiration.
• Respiration produces heat, which warms us up

Question 34

How does sweating cool us down?

Answer 34

• Sweat glands (in the middle layer of skin, called the dermis) release sweat, which covers the outer layer of skin (the epidermis).
• Heat energy from the body is transferred to the water in this sweat and, when it has enough energy, it evaporates.
• As it evaporates, it takes the heat energy with it. This lowers the average temperature of the body

Question 35

What is vasoconstriction?

Answer 35

• when muscular walls contract because we are too cold

- this reduces blood flow to the skin surface and heat energy is kept inside the body

Question 36

What is vasodilation?

Answer 36

• muscular walls relax when we are too hot
• This allows more blood to enter and flow through capillaries close to the skin surface.
• The excess heat energy is transferred to the surroundings

Question 37

What is meant by vasodilation?

Answer 37

-Blood vessels dilate to allow more blood to enter capillaries

Question 38

What is meant by vasoconstriction?

Answer 38

-Blood vessels constrict to reduce blood flow in capillaries