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Biology A2 > Unit 1: Module 1 > Flashcards

Unit 1: Module 1 Flashcards

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0
Q

Define Response

A

It is the change in behaviour or physiology as a result of a change in the environment

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1
Q

Define Stimulus

A

It is any change in the environment which causes a response

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2
Q

What is needed for a good communication system? State 5 things.

A

1) Must cover the whole body
2) Must enable cells to communicate
3) Must enable specific communication
4) Must enable rapid communication
5) Must enable ST and LT responses

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3
Q

Cell signalling includes which systems?

A

The neuronal system and the hormonal system

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4
Q

What are the features of a neuronal system?

A
  • It has interconnected network of neurones
  • Signals each other across a synapse junction
  • Conduct signals really quickly and responds quickly
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5
Q

What are the features of the hormonal system?

A
  • Uses blood to transport signals
  • Cells in endocrine organ release signals (hormones) directly into blood
  • Signals are carried all over the body but recognised only by target cells
  • Allows LT responses to be coordinated
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6
Q

Define Homeostasis

A

It is the maintenance of internal environment despite external changes

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7
Q

Define Negative feedback

A

It is the process that brings about a reversal of any change in condion.

E.g. ^temp = Sweating : Cool down

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8
Q

What must be kept constant for homeostasis? List 6 things.

A

1) Body temp
2) Blood glucose conc.
3) Blood salt conc.
4) Water potential of blood
5) Blood pressure
6) CO2 Conc.

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9
Q

Define positive feedback

A

Is the process that ^any change detected by receptors. Tends to be harmful and doesn’t lead to homeostasis.

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10
Q

Provide an example of a Positive feedback mechanism

A

1) During birth Cervix begins to stretch
2) This signals the pituitary gland
3) This stimulates the secretion of the hormone Oxytocin
4) This increases Uterine contractions
5) This enables Cervix to stretch more which stimulates the secretion of more Oxytocin
6) Then this allows Cervix to dilate more until the baby is born

Oxytocin is also known as the “Tend or befriend” hormone, because it prompts mother to protect her children

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11
Q

Define endotherm

A

Organisms that can maintain their own body temp. despite of external temperatures

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12
Q

Define Ectotherms

A

Organisms that rely on external sources of heat to regulate its body temp.

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13
Q

List features of an Ectotherm

A
  • Can generate heat internally by ^ in respiration
  • Use less food in respiration
  • Can survive long periods without eating e.g. Snakes
  • Most of their energy from food is used in growth
  • Less active in winter (Predation)
  • Must have sufficient energy store to survive through winter
  • Can change physiology to ^ absorption of heat from environment e.g. Lizards bask in sun, orientate their body towards or away from sun, shade etc
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14
Q

Why are sensory receptors called energy transducers?

A

Because they can change one form of energy to another form. For example light energy to electrical (Nerve impulse)

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15
Q

By what receptors are light and colour detected?

A

Rods and Cones

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16
Q

By what cells are volatile chemicals detected?

A

Olfactory cells

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17
Q

By what receptors are soluble chemicals detected?

A

Taste buds

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18
Q

By what receptors are pressure detected on the skin?

A

Pacinian corpuscles

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19
Q

By what receptor are vibrations in the air detected?

A

Cochlea

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20
Q

Neurones have specialised channel proteins that are specific to what?

A

To Na and K

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21
Q

Define a polarise mem. And state how this is achieved.

A

A polarised mem. is one that has a potential difference across it. This is the (r.p). It is achieved by moving more Na ions out of cell than K ions in. Which causes inside of cell to e more (-ve) charged.

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22
Q

How is a nerve impulse created?

A

By the opening of Na ion channels to increase permeability across the cell membrane to allow more Na ions to move across down their conc. gradient and into the cell. Thus inside of cell becomes less negative compared to outside

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23
Q

Define depolarisation

A

This is the period when Na ions entering the cell make inside less negative with respect to outside

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24
Q

Define generator potential

A

This is a small depolarisation that is caused by the movement of Na ions into the cell

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25
Q

When do more gated channels open?

A

When there is a greater stimilus. Therefore allows enough Na ions to enter cell, which causes a significant change in (P.d) and initiates an impulse or (a.p)

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26
Q

Define Action Potential

A

This is achieved when mem. is depolarised to a value of about +40mV. This is known as all or nothing event, events leading up to membrane depolarising and reaching a threshold. Which allows Na ions enter axon and for (a.p) to be reached

27
Q

What happens in terms of energy when an stimulus is detected?

A

Energy is converted to depolarise the receptor cell mem. which can then travel around body. The impulse is passed on along neurones as (a.p)

28
Q

Where do Sensory receptors carry the impulses?

A

To the CNS

29
Q

What do the relay neurones do?

A

They connect the sensory and motor neurones

30
Q

What do motor neurones do with the impulses?

A

They carry the (a.p) from CNS to effector (Muscle/ Gland)

31
Q

List features of a neurone

A
  • Many are very long to transmit (a.p) over a long distance
  • Cell surface mem. (Plasma) has many gated ion channels that control entry/exit of (Na, K, Ca) ions
  • Have Na/K pumps that use ATP to actively transport Na ions out of cell and K ions in
  • Maintain (P.d) across cell surface (plasma) mem.
  • Surrounded by fatty sheath (Myelin) which consists of a series of cells called Schwann cells. These insulate neurone from electrical activity in nearby cells.
  • There are gaps where Schwann cells meet called Nodes or Ranvier which allows nerve impulses to be conducted quickly by jumping from Node to Node
  • Cell body contains Nucleus, many mitochondria and ribosomes
32
Q

Where is the cell body of a motor neurone located? And why do they have a long axon?

A

Their cell body is found in the CNS. An have long axon to carry (a.p) out to effector

33
Q

What do the dendron of a sensory neurone do? And where are the possitioned? Finally why do sensory neurones have short axon?

A

Long dendron to carry (a.p) from sensory receptor to cell body. Positioned just outside of the CNS. Have short axon to carry (a.p) into CNS

34
Q

What is a (r.p)?

A

It is the potential difference or voltage across neurone cell mem. whole neurone at rest. The value is about -60mV inside cell

35
Q

Define Voltage- gated channels

A

It is a passage of charged particles/ions. Gates open due to (p.d)

36
Q

Define Threshold

A

This is when the (p.d) value across mem. is -50mV. If there is no Threshold then there is no (a.p)

37
Q

Define Local currents

A

This is the movement of ions along neurone

38
Q

Define Neurotransmitter

A

Are chemicals that diffuse across synaptic cleft of synapse to transmit signal to post- synaptic neurone. An example of a neurotransmitter is acetylCholine

39
Q

Define Cholinergic Synapses

A

Are synapses that use acetylCholine as their transmitter substance

40
Q

Define synaptic Knob

A

This is a swelling at end of pre-synaptic neurone

41
Q

Which channels respond to transmitter substance?

A

Specialised Na ion channels

42
Q

How do transmissions occur across a synapse?

A

1) (a.p) arrives at synaptic knob
2) Voltage gated Ca ion channels open
3) Ca ions diffuse into synaptic knob
4) Ca ions cause synaptic vesicles to move and fuse with pre-synaptic mem.
5) Acetylcholine is released (Exocytosis)
6) these diffuse across Synaptic cleft and bind with receptor sites on Na ion channels in post-synaptic mem.
7) Na ion channels open
8) Na ions diffuse across post-synaptic mem. into post-synaptic neurone
9) (G.p) or excitatory post-synaptic potential (EPSP) is created
10) if enough (G.P) combine then (P.d) across post-synaptic mem. reaches Threshold potential
11) New (a.p) is created in Post-synaptic neurone

43
Q

What does enzyme Acetylcholinesterase do?

A

Hydrolyses acetylcholine to its products of ethanoic acid + choline
Which then become recycled

44
Q

Define All or nothing

A

Neurone either conducts an a.p or not

45
Q

Define Summation

A

Several small potential changes combine to form one large change in p.d. across mem.

46
Q

What are the advantage of myelinated neurones? List 2.

A

1) a.p. Conducts much more quickly

2) more rapid response to stimulus

47
Q

Define Hormones

A

Are chemical messengers released from endocrine glands directly into blood to activate target cells

48
Q

Define Exocrine glands

A

Glands that have no ducts and secrete hormones directly onto blood

49
Q

Define Exocrine gland

A

Gland that has ducts and secretes molecules to be carried to where it is needed

50
Q

Define First messenger

A

Are hormones that transmit signals around the body

51
Q

Define secondary messenger

A

cAMP that transmits signals inside cell

52
Q

Define Pancreatic duct

A

This is the tube that collects secretion from exocrine cells and carries fluid to small Intestine

53
Q

Define Insulin

A

Hormone that causes blood glucose levels to decrease

54
Q

Define Glucagon

A

It is a hormone that causes blood glucose levels to increase. (Opposite to Insulin)

55
Q

What is the normal conc. of glucose in blood?

A

90mg 100cm^-3

56
Q

What cells detect high conc. of blood glucose?

A

B - Cells

57
Q

Which cell detects low conc. of blood glucose?

A

a - cells

58
Q

Define Diabetes mellitus

A

This is a disease where blood glucose conc. cannot be controlled effectively

59
Q

Define Hyperglycaemia

A

This is a state where blood glucose conc. is too high

60
Q

What defines Genetically engineered bacteria?

A

The fact that their DNA has been altered

61
Q

Define stem cells

A

Are unspecialised cells that have the potential to develop into any type of cell

62
Q

Define cell metabolism

A

This is the result of all the chemical reactions taking place in the cytoplasm

63
Q

Define Myogenic

A

Is the muscle tissue of the heart that can initiate its own contractions

64
Q

Define pacemakers

A

Is region of tissue in the R.atrium wall = generate impulse and initiate contractions of chambers in heart

65
Q

Define medulla oblongata

A

This is found at base of brain. Coordinates unconscious functions e.g. Breathing rate, heart rate

Biology A2 (2 decks)

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