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iGCSE Biology > 2J (Co-ordination and response) > Flashcards

2J (Co-ordination and response) Flashcards

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1
Q

STIMULI

A

Change in environment

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2
Q

RECEPTOR

A

Specialised cells that detect changes in environment
E.g, Sensory Neurones in the finger detect heat

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3
Q

EFFECTOR

A

Part of body that carries out response to Stimuli
E.g Muscles in finger that contract to pull finger away from heat

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4
Q

Sensitivity in organisms:

A
  • All living organisms need to respond to changes in environment for survival
  • Nervous system coordinated by the brain allows body to respond to changes in environment
  • Organisms additionally have reflexes for fast involuntary actions that protect body from damage
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5
Q

Homeostasis definition

A

Maintenance of constant water level in body

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6
Q

Examples of homeostasis:

A
  • Osmoregulation
  • Thermoregulation
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7
Q

Osmoregulation

A
  • Maintenance of constant water level in the body
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8
Q

Thermoregulation

A
  • Maintenance of optimum body temperature for optimum enzyme activity
  • Decreased body temperature –> shivering, vasoconstriction –> will increase body temp to normal (37)
  • Increased body temp –> increased sweating, vasodilation –> will decrease body temp to normal (37º)
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9
Q

Coordinated response definition

A

Process in which a reaction is carried out in response to a change in environment (stimuli)

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10
Q

Do plants respond to stimuli?

A

Plants are living organisms and therefore respond to change in environment (stimuli) for survival. E.g. Abiotic factors (light, water…) and biotic facotrs (predators, diseases…)

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11
Q

Geotropic response

A

Growth in response to direction of gravity

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12
Q

Phototopic response

A

Growth in response to direction of light

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13
Q

2.84

A

explan in stem and roots

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14
Q

Auxins

A
  • Plant hormone produced in the tip of stem and roots which control the direction of growth
  • Auxin changes the elasticity of cells to alter the growth of cells, therefore changing the direction of growth (increase in elasticity will allow cell to absorb more Water, causing size of cell to increase and bend towards specific direction)
  • Factors including light and gravity can alter the distribution of Auxin within stem and root, causing different responses
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15
Q

Nervous communication

A

Nervous system comprising a network of nerve cells that carry impulses between parts of body

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16
Q

Hormonal communication

A

Endocrine system comprising glands that produce and secrete Hormones to stimulate change in the body

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17
Q

Diferences between nervous and hormonal communication

A
  • Nervous communication is electrical, while Hormonal communication is chemical
  • Nervous Communication is faster, while Hormonal communication is slower
  • Nervous communication is short - lived, while Hormonal communication is long - lived
18
Q

Central nervous system

A

Nervous system comprising the Brain and Spinal Cord that is linked to a network of nerve cells that carry impulses around the body

19
Q

Process of CNS

A
  • Central Nervous System (CNS) determines the response for a stimulus detected by the receptor
  • Stimuli is detected by receptors, stimulating Sensory Neurons that send electrical impulses to the - —Central Nervous System - Brain and Spinal cord
  • Central Nervous System relays impulse across the synpase (gaps between Neurones) to Relay Neurons via synaptic transmission
  • Relay Neurons relays impulse to Motor Neurons in the Effector, which will quickly carry out rapid response
20
Q

Synapse

A
  • Junction that separates Neurons from other cells (other Neurons and Receptor or Effector cells)
  • As electrical impulses cannot pass across the Synapse, Neurons transmit information across by converting the electrical signal into a chemical signal called Neurotransmitters
21
Q

Neurotransmitters

A

Chemical messengers that are released from Neurons to transmit signals across the Synapse

22
Q

Role of neurotransmitters

A
  • When an electrical impulse reaches the end of an Axon on pre-synaptic Neuron, this triggers the release of chemical messengers called Neurotransmitters via exocytosis
  • Neurotransmitter will diffuse across the Synapse and bind to receptors on the membrane of the post-synaptic Neuron
  • As a result, post-synaptic Neuron continues to transmit electrical impulse along Axon of Neuron
23
Q

Reflex

A

Fast involuntary reaction that protects body from damage

24
Q

WITHDRAWAL OF FINGER FROM HOT OBJECT:

A
  • When Hand is near a hot object, heat (stimuli) is detected by the Finger (receptor), stimulating Sensory Neurons to send electrical impulses to the Central Nervous System - Brain and Spinal Cord
  • Central Nervous System will receive and interpret message, determining the appropriate reaction of pulling hand away from the hot object
  • This impulse is relayed across the Synpase to Relay Neurons via synaptic transmission
  • Relay Neurons relays impulse to Motor Neurons in the Bicep
  • As a result, Bicep will contract to quickly draw hand away from the heat, allowing a rapid response to prevent harm to the body
25
Q

Cornea

A

Transparent convex lens that refracts light

26
Q

Iris

A

Pigmented membrane that controls the diameter and size of Pupil to alter the quantity of light reaching the Retina

27
Q

Lens

A

Transparent disc that changes shape to focus light onto the Retina

28
Q

Retina

A

Light-sensitive nerve tissue containing Rods (night vision) and Cones (colour vision) to convert light into electrical impulses to be interpreted by the brain for visual recognition

29
Q

Optic nerve

A

Nerve located in the back of the eye that contains Sensory Neurons to send electrical impulses to be interpreted by the brain for visual recognition

30
Q

Pupil

A

Opening in the centre of Iris that allows light to enter the Eye

31
Q

Ciliary muscles

A

Circular muscle surrounding the lens that that contracts and relaxes to adjust the thickness of lens

32
Q

Response of eye to distance of near object

A
  • When looking at a near object, incoming light is divergent
  • In response, Ciliary Muscles will contract, while Suspensory Ligaments slack
  • As a result, the Lens become thicker and more curved, refracting light rays more strongly to meet the Retina
33
Q

Response of eye to distance of distant object

A
  • When looking at a distant object, incoming light is parallel
  • In response, Ciliary Muscles will relax, while Suspensory Ligaments stretch
  • As a result, the Lens become thinner and less curved, refracting light rays less strongly to converge on the Retina
34
Q

Response of eye to changes in light intensity (dark)

A
  • When in dark environment, Photoreceptors - Rods and Cones, detect the change in light intensity
  • As a result, reflex occurs involving Muscles in the Iris - Radial Muscles contract and Circular Muscles relax to increase the diameter of the Pupil
  • As Diameter of Pupil increases, Pupil dilates to allow more light to enter the Eye to be refracted onto Retina for vision
35
Q

Response of eye to changes in light intensity (bright)

A
  • When in bright environment, Photoreceptors - Rods and Cones, detect the change in light intensity
  • As a result, reflex occurs involving Muscles in the Iris - Radial Muscles relax and Circular Muscles contract to decrease the diameter of the Pupil
  • As diameter fo Pupil decreases, Pupil contracts to allow less light to enter the Eye to be refracted onto Retina for vision
36
Q

Response of Skin to Hot Environment

A
  • When in hot environment, increase in body temperature is detected by Thermoreceptors
  • As a result, series of changes occurs in body via thermoregulation
  • Blood vessels near skin dilate via Vasodilation to increase blood flow to surface for heat loss
  • Sweat glands excrete sweat to cool skin via evaporative cooling
  • Hair Erector Muscles relax to lower Skin hair, trapping a thin insulating layer of air above the Skin for heat loss
37
Q

Response of Skin to Cold Environment

A
  • When in Cold environment, decrease in body temperature is detected by Thermoreceptors
  • As a result, series of changes occurs in body via thermoregulation
  • Blood vessels near skin contract via Vasoconstriction to reduce blood flow to surface to minimise heat loss
  • Sweat glands do not excrete sweat to prevent evaporative cooling
  • Hair Erector Muscles contract to raise Skin hair, trapping a thick insulating layer of air above the skin to prevent heat loss
38
Q

Adrenaline

A
  • Source: Adrenal Gland
  • Role: Prepares body for ‘fight or flight’ response
  • Effect: Increases heart and breathing rate
39
Q

Insuline

A
  • Source: Pancreas
  • Role: Lowers blood Glucose levels
  • Effect: Initiates the conversion of blood Glucose into Glycogen to be stored in Liver and Skeletal muscle
40
Q

Testosterone

A
  • Source: Testes
  • Role: Primary sex hormone in Males
  • Effect: Increased levels initiate development of secondary sexual characteristics
41
Q

Progesterone

A
  • Source: Ovaries
  • Role: Primary sex hormone in females to maintain pregnancy
  • Effect: Maintains the Uterus lining to cushion fertilised Egg cell
42
Q

Oestrogen

A
  • Source: Ovaries
  • Role: Primary sex hormone in Females
  • Effect: Increased levels initiate development of secondary sexual characteristics including the menstrual cycle

iGCSE Biology (20 decks)

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