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Biology Flashcards > Responding To Internal And External Environments > Flashcards

Responding To Internal And External Environments Flashcards

1
Q

What is kinesis?

Yr2 Topic 8: Chemical Control

A

The random behaviour pattern where an animal responds to a change in stimulus by increasing or decreasing activity.

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2
Q

Define taxes

Yr2 Topic 8: Chemical Control

A

The movement of an organism either towards or away from a directional stimulus. Can be positive (moving towards the stimulus) or negative (moving away from the stimulus).

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3
Q

Explain why woodlice which don’t clump together have a greater percentage loss in mean mass compared to woodlice which do clump together? (3)

Yr2 Topic 9: Nervous System

A
  1. (More mass loss) linked to losing more water
  2. Gills (more) exposed to air/ covered (less) by other woodlice so greater surface area (exposed)
  3. (Not clumped) so lower humidity (around each woodlouse) so greater evaporation/ diffusion (of water)
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4
Q

What is the function of the nervous system?

Yr2 Topic 9: Nervous System

A
  • detection of stimuli by receptors
  • transmission of nerve impulses by neuroes
  • response by effectors
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5
Q

What is a neurone?

Yr2 Topic 9: Nervous System

A

They are specialised cels that carry electrical impulses from one part of the body to another.

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6
Q

What are the different types of neurone?

Yr2 Topic 9: Nervous System

A
  • Sensory
  • Inter or bipolar (or intermediate or relay)
  • Motor
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7
Q

What is the reflex arc order?

Yr2 Topic 9: Nervous System

A

Receptor -> sensory neurone -> relay neurone -> motor neurone -> effector -> response

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8
Q

What is the function of the dendrite?

Yr2 Topic 9: Nervous System

A

Receives information from other neurones or the environment

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9
Q

What is the function of the axon?

Yr2 Topic 9: Nervous System

A

carries electrical impulses

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10
Q

What is the function of an axon terminal?

Yr2 Topic 9: Nervous System

A

he site of neurotransmitter release

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11
Q

What is the function of the myelin sheath?

Yr2 Topic 9: Nervous System

A

Allows for quick & effective transition of nerve cells

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12
Q

What is the function of the node of ranvier?

Yr2 Topic 9: Nervous System

A

Allow for generation of fast electrical impulses

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13
Q

What is the function of the Schwann cells

Yr2 Topic 9: Nervous System

A

They produce myelin

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14
Q

What is a synapse?

Yr2 Topic 9: Nervous System

A

The gaps between neurones

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15
Q

How do synapses work?

Yr2 Topic 9: Nervous System

A
  1. Calcium ions open after moving into the synaptic knob via facilitated diffusion
  2. Neurotransmitters are released as the influx of calcium activates enzymes and the vesicles fuse with the presynaptic membrane
  3. Sodium channels open after neurotransmitters are released into the synaptic cleft and diffuse across to the post synaptic membrane, binding with sodium ions and depolarisation occurs
  4. New action potential
  5. Acetylcholinesterase breaks up acetylcholine into acetyl and choline which are reabsorbed by the presynaptic neurone
  6. Acetylcholine is remade
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16
Q

How does the pacinian corpuscle work?

Yr2 Topic 10: Receptors

A

Pressure on the skin changes the shape of the corpuscle and layers re distorted
The layers contain stretch mediated sodium ion channels which are pressure sensitive.
The change in shape causes the sodium channels to open, increasing the permeability to sodium ions, which diffuse in.
The charge changes across the membrane and decreases polarity, more positive ions on inside leads to depolarisation.
This produces a generator potential and reaches above the threshold of an action potential, which leads to nerve impulses passing along the neurone

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17
Q

What are receptors?

Yr2 Topic 10: Receptors

A

They are cells which can detect a specific stimulus and convert some sort of energy into a generator potential

18
Q

What are the different types of receptors?

Yr2 Topic 10: Receptors

A

Pressure, temperature and chemical

19
Q

What type of receptor is a pacinian corpuscle?

Yr2 Topic 10: Receptors

A

Pressure receptor

20
Q

Describe ow a Pacinian corpuscle produces a generator potential when stimulated? (3)

Yr2 Topic 10: Receptors

A
  1. (Increased pressure) deforms/ changes stretch mediated sodium channel
  2. (Sodium channels open and) sodium ions flow in
  3. Depolarisation (leading to generator potential)
21
Q

Explain how resting potential is maintained in the sensory neurone when no pressure is applied? (2)

Yr2 Topic 10: Receptors

A
  1. Membrane more permeable to potassium ions and less permeable to sodium ions.
  2. Sodium ions actively transported/ pumped out and potassium ions in.
22
Q

The membrane potential at the end of the neurone was the same whether medium or heavy pressure was applied to the finger tip. Explain why. (2)

Yr2 Topic 10: Receptors

A
  1. Threshold is reached
  2. (Threshold or above) causes maximal response/ all or nothing principle
23
Q

Multiple sclerosis is a disease in which parts of the myelin sheaths surrounding neurones are destroyed. Explain how this results in slower response to stimuli.

Yr2 Topic 9: Nervous System

A
  1. Less/no saltory conduction/action potential/impulse unable to ‘jump’ from node to node.
  2. More depolarisation over length/area of membranes
24
Q

Define homeostatis.

Yr2 Topic 12: Homeostasis

A

The maintenance of a constant internal environment.

It ensures that the internal cells of the body are in an environment that meets their needs and allows them to function normally despite internal or external changes.

25
Q

What are examples of factors controlled by homeostasis?

Yr2 Topic 12: Homeostasis

A
  • Temperature
  • pH
  • Blood glucose levels
  • Water potential
26
Q

Why is homeostasis important for controlling temperature?

Yr2 Topic 12: Homeostasis

A

Low temperatures lead to little kinetic energy so chemical reactions involving enzymes are slowed down, which can cause death.
High temperatures lead to too much kinetic energy so enzymes denature due to its bonds breaking, changing the active site/denaturing it. Prevents E-S complexes so chemical reactions slowed.

27
Q

Why is homeostasis important for controlling temperature?

Yr2 Topic 12: Homeostasis

A

pH effects the amount of hydrogen ions present, causing tertiary structure changes in enzymes if too high. This changes the active site shape and prevents E-S complexes so chemical reactions slowed.

28
Q

What is a negative feedback loop?

Yr2 Topic 12: Homeostasis

A

Def: When something changes the opposite effect is instigated. A movement away from the norm priduces a response to return it to norm.

  1. Stimulus produces change in variable
  2. Change detected by receptor
  3. Information send along afferent pathways to the control centre
  4. Information sent along afferent pathways to effectors
  5. Response of effector feeds back to influence magnitude of stimulus and returns variable to homeostasis.
29
Q

Why is low blood glucose concentrations bad?

Yr2 Topic 12: Homeostasis

A

Too little glucose for respiration

30
Q

Why is high blood glucose concentrations bad?

Yr2 Topic 12: Homeostasis

A

Decreased water potential in blood, leading to dehydration.

31
Q

Where are the receptors that detect changes to blood glucose concentration?

Yr2 Topic 12: Homeostasis

A

Beta and alpha cells found in the islets of Langerhans within the pancreas

32
Q

What do alpha cells do?

Yr2 Topic 12: Homeostasis

A

They detect a fall in blood glucose levels and cause the horomone glucagon to be released.

33
Q

What do beta cells do?

Yr2 Topic 12: Homeostasis

A

They detect an increase in blood glucose levels and cause the horomone insulin to be released.

34
Q

Provide an overview of how glucagon alters the blood glucose levels.

Yr2 Topic 12: Homeostasis

A
  1. Missing meal brings down glucose levels below normal.
  2. Pancreas secretes glucagon into blood.
  3. Glucagon signals the liver to cobert glycogen to glucose
  4. Blood glucose raised to normal
35
Q

Provide an overview of how insulin alters the blood glucose levels.

Yr2 Topic 12: Homeostasis

A
  1. Eating meal icreases glucose levels above normal.
  2. Pancreas releases insulin into blood.
  3. Insulin signals the liver to take in glucose and store it a glycogen (in glycogenesis)
  4. Blood glucose drop to normal
36
Q

How does insulin make glucose enter the cell more?

Yr2 Topic 12: Homeostasis

A
  1. Insulin binds to receptor on liver cells.
  2. Activates the creation of a vesicle containing extra glucose carriers.
  3. This vesicle fuses with the liver cell membrane , adding extra glucose carrier proteins.
  4. More glucose moved into the liver cell via facilitated diffusion.
37
Q

What happens to glucose after it moves into the liver cells?

Yr2 Topic 12: Homeostasis

A

It cannot stay glucose as it will alter the water potential so it is converted into glycogen in a condensation reaction. This is called glycogenesis.

38
Q

How does glucagon increase blood glucose levels?

Yr2 Topic 12: Homeostasis

A

It binds to liver cells which:
1. Causes glycogen stored in liver cells to be converted into glucose in glycogenolysis.
2. Causes glycerol and amino acids to be converted to glucose in gluconeogenesis.

39
Q

Apart from glucagon, what horomone increases blood glucose levels and how?

Yr2 Topic 12: Homeostasis

A

Adrenaline increases blood glucose, often in fight or flight scenarios.
1. Adrenaline and glucagon can bind to receptors on the cell membrane (first messengers)
2. A horonome-receptor complex is formed
3. Adenylate cyclase is activated, which causes the conversion of ATP to cAMP/cyclic AMP) (second messenger)
4. cAMP actiivates protein kinase, an enzyke that allows for the conversion of glycogen to glucose.

This is called the ‘second messenger model of horomone action’

40
Q

What are the two forms of diabetes and what causes them?

Yr2 Topic 12: Homeostasis

A
  • Insulin-dependent/Type 1 diabetes = Insulin deficiency due to autoimmune system killing beta cells.
  • Non insulin-dependent/Type 2 diabetes = Insulin is produces but insulin receptors dont work so it has no effect.
41
Q

Symptoms of diabetes.

Yr2 Topic 12: Homeostasis

A
  • High thirst = due to osmosis of water from cells to blood as it has a low w.p
  • Copious urine = high amounts of excess water in blood
  • Poor vision = Osmotic loss of water from eye lens
  • Tiredness = loss of glucose in urine and poor uptake by liver and muscle cells
  • Muscle wasting = due to gluconegenesis occuring too much

Biology Flashcards (10 decks)

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