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AA biology a level - pippa > Section 6: Organisms respond to change in their enviroments (only homeostasis added) > Flashcards

Section 6: Organisms respond to change in their enviroments (only homeostasis added) Flashcards

1
Q

What is homeostasis?

A

The process by which a living organism maintains a stable internal environment.

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2
Q

True or False: Homeostasis only involves temperature regulation.

A

False

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3
Q

What is primarily responsible for thermoregulation in humans?

A

The hypothalamus.

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4
Q

Fill in the blank: The maintenance of blood glucose levels is an example of ________.

A

homeostasis.

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5
Q

What is the role of negative feedback in homeostasis?

A

To counteract changes from a set point to maintain stability.

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6
Q

Which hormone decreases blood glucose levels?

A

Insulin.

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7
Q

What is the primary function of the kidneys in homeostasis?

A

To regulate water and electrolyte balance.

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8
Q

True or False: Positive feedback mechanisms are commonly used in homeostasis.

A

False

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9
Q

What is the role of the pancreas in homeostasis?

A

To regulate blood sugar levels by secreting insulin and glucagon.

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10
Q

What is the term for the body’s ability to respond to changes in the internal environment?

A

Responsiveness.

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11
Q

Multiple Choice: Which of the following is NOT a component of homeostasis? A) Sensor B) Control Center C) Effectors D) Stimulus

A

D) Stimulus

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12
Q

What happens when body temperature rises above the normal range?

A

Sweating occurs to cool the body down.

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13
Q

Fill in the blank: The ________ is responsible for thermoregulation in the human body.

A

hypothalamus.

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14
Q

What is osmoregulation?

A

The regulation of water and solute concentrations in the body.

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15
Q

True or False: The body can tolerate significant deviations from its set points.

A

False

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16
Q

Which part of the brain regulates thirst?

A

The hypothalamus.

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17
Q

What is the effect of glucagon on blood glucose levels?

A

It increases blood glucose levels.

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18
Q

Multiple Choice: Which hormone is responsible for water reabsorption in the kidneys? A) Aldosterone B) Insulin C) Glucagon D) Testosterone

A

A) Aldosterone

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19
Q

What is the function of baroreceptors?

A

To detect changes in blood pressure.

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20
Q

Fill in the blank: The ________ feedback mechanism amplifies a response.

A

positive.

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21
Q

True or False: Homeostasis is only important for survival in extreme environments.

A

False

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22
Q

What is the primary role of the adrenal glands in homeostasis?

A

To respond to stress and regulate metabolism.

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23
Q

Multiple Choice: Which of the following processes helps in thermoregulation? A) Evaporation B) Condensation C) Filtration D) Respiration

A

A) Evaporation

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24
Q

What is the role of the liver in blood glucose homeostasis?

A

To store and release glucose as needed.

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25
Q

Fill in the blank: The ________ senses changes in temperature.

A

hypothalamus.

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26
Q

What is the main function of the integumentary system in homeostasis?

A

To protect the body and help regulate temperature.

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27
Q

True or False: All organisms maintain homeostasis in the same way.

A

False

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28
Q

What role do effectors play in homeostasis?

A

They carry out responses to restore balance.

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29
Q

What is the function of the thyroid gland in homeostasis?

A

To regulate metabolism and energy levels.

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30
Q

Multiple Choice: Which system is primarily involved in chemical signaling for homeostasis? A) Nervous B) Endocrine C) Muscular D) Skeletal

A

B) Endocrine

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31
Q

What is thermogenesis?

A

The process of heat production in organisms.

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32
Q

Fill in the blank: ________ is the process of maintaining a stable internal environment.

A

Homeostasis

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33
Q

True or False: Maintaining pH balance is a part of homeostasis.

A

True

34
Q

What does the term ‘set point’ refer to in homeostasis?

A

The normal range or level for a physiological parameter.

35
Q

What is the role of the hypothalamus in regulating body temperature?

A

It acts as the body’s thermostat.

36
Q

Multiple Choice: Which of the following is a method of heat loss? A) Conduction B) Convection C) Radiation D) All of the above

A

D) All of the above

37
Q

What is the significance of homeostasis for organisms?

A

It allows them to function optimally despite external changes.

38
Q

Fill in the blank: The ________ system plays a key role in controlling homeostasis.

A

nervous.

39
Q

True or False: Homeostatic mechanisms can be overridden by conscious thought.

A

True

40
Q

What is the primary purpose of feedback systems in homeostasis?

A

To maintain equilibrium in the body.

41
Q

What is the role of sweat glands in homeostasis?

A

To cool the body through evaporation.

42
Q

Multiple Choice: Which part of the nephron is primarily responsible for water reabsorption? A) Glomerulus B) Loop of Henle C) Collecting duct D) Proximal tubule

A

C) Collecting duct

43
Q

What is the function of the respiratory system in homeostasis?

A

To regulate oxygen and carbon dioxide levels in the blood.

44
Q

Fill in the blank: Homeostasis involves the regulation of ________ in the body.

A

internal conditions.

45
Q

True or False: All homeostatic processes are automatic and do not require energy.

A

False

46
Q

What is the function of the circulatory system in homeostasis?

A

To transport nutrients, gases, and wastes throughout the body.

47
Q

Explain the importance of Homeostasis

A

Enzymes and other proteins are sensitive to temperature and ph changes this these factpros must be controlled
Changes in water potential of the blood and tissue fluids may cause cells to shrink and expand as a result of osmosis
Organisms with the ability to maintain a constant internal environment internal environment are more independent of changes in the external environment

48
Q

Why is maintaining a constant temperature so important in mammals

A

Because enzymes function within a narrow range of temperatures
Fluctuations from optimum temperature means enzymes function less efficiently. If the variation is extreme the enzyme may be denatured and cease function all together
A constant temperature means that reactions occur at a predictable and constant rate

49
Q

Suggest why maintaining a constant blood glucose might be important in mammals

A

Ensures constant water potential
Could cause cells to shrink or expand due to osmosis
In both situations cells cannot operate normally

50
Q

Explain the advantage of having separate negative feedback mechanisms to control deviations away from normal

A

It gives a greater degree of homeostatic control

51
Q

Explain why negative feedback is import at in maintaining a system at a set point

A

If the information is not fed back once an effector has corrected any deviation and returned the system to the set point, the receptor will continue to stimulate the effector and an over-correction will lead to a deviation in the opposite direction from the original one

52
Q

What does the hormone Adrenaline do. in short

A

Break glycogen down to glucose

53
Q

How does Adrenaline cause the conversion of glycogen to glucose

A

Adrenaline binds to receptor site in liver cell
The binding causes the protein to change shape which activates adenyl cyclase
The activated adenyl cyclase converts ATP to cyclic AMP
The cAMP acts as a second messenger that binds to kinase enzyme catalysing the conversion of glycogen to glucose

54
Q

What does the active protien kinase enzyme catalyse

A

the conversion of glycogen to glucose

55
Q

How is the enzyme kinase activated

A

When cAMP acts as a second messenger and binds to it changing its shape

56
Q

When adrenaline binds to a protein what enzyme does it activate and what does that enzyme do

A

adenyl cyclase converts ATP to cyclic AMP

57
Q

How does glucagon convert glycogen to glucose

A

Binds to receptor in cell surface membrane
Changes shape of protein
Enzyme adenyl cyclase activated
adenyl cyclase converts ATP to cAMP
cAMP activates protein kinase which catalyses conversion of glycogen to glucose

58
Q

What is the 1st and 2nd messenger in the blood regulation second messenger system.

A

1st messenger is glucagon or adrenaline
2nd messenger is cAMP

59
Q

What is the advantage of using a 2nd messenger in the control of blood glucose

A
  1. Signal amplification allows a small amount of hormone to produce a large response.
  2. Enables a faster response as the second messenger rapidly diffuses through the cell to trigger a response.
  3. More than one hormone can activate it
60
Q

What is glycogenesis

A

Conversion of glucose into glycogen
insulin

61
Q

What does insulin activate

A

Glycogenesis - conversion of glucose to glycogen in liver and muscles
increases permeability of muscle cell membranes so they can absorb more glucose
increases rate of repiration in muscle cells
increases fat synthesis

62
Q

If the blood glucose concentration is too high what happens

A

B cells in the islet of langerhans detect change
Hormone insulin secreted
which activates - glycogenesis, inc rate of respiration, inc fat synthesis, inc permeability of muscle membrane so they absorb more glucose

63
Q

What is the break down on glycogen to glucose called and what triggers it

A

glycogenolysis
glucagon or adrenaline

64
Q

What happens when blood glucose levels are low

A

A-cells in islets of langerhans detect change
release hormone glucagon
glucagon binds to receptor activates adenyl cyclase which converts ATP to cAMP which activates glycogenolysis that converts glycogen to glucose
also acticvates enzymes involved in formation of glucose from non-carbs - glyconeogenesis
decreases rate of respiration of glucose in cells

65
Q

What is gluconeogenesis and what hormone activates it

A

production of glucose from sources other than carbohydrates
glucagon

66
Q

What cells produce glucagon and insulin and where are they

A

Islets of langerhans in the pancreas
a cells produce glucagon
b cells produce insulin

67
Q

what three factors influence blood glucose concentration

A

diet
hydrolysis in the small intestine of glycogen = glycogenolysis
gluconeogenesis = production of glucose from sources other carbohydrates

68
Q

______ lowers the blood glucose concentration

A

Insulin

69
Q

______ increases glucose concentration

A

glucagon

70
Q

What are 2 symptoms of diabetes

A

tiredness
increased thirst and hunger

71
Q

State one difference between the causes of type 1 and type 2 diabetes

A

Type 1 is caused by an inability to produce insulin
Type 2 is caused by receptors on body cells losing their responsiveness to insulin

72
Q

Describe how both type 1 and 2 diabetes are controlled

A

Type 1 is controlled by the injection of insulin
Type 2 is controlled by regulating carbohydrate intake in the diet and matching this to the amount of exercise taken

73
Q

Suggest why tiredness is a symptom of diabetes

A

Diabetes is a condition where insulin is not produced by the pancreas, leading to fluctuations in blood glucose levels. Id the level is below normal there may be insufficient glucose for eh release of energy by cells during respiration
Muscle and brain cells in particular may therefore be less active, leading to tiredness

74
Q

Suggest lifestyle changes to reduce you risk of developing type 2 diabetes

A

Match your carbohydrates intake to the amount of exercise that you take. Avoid becoming overweight by not consuming excessive quantities of carbohydrate and by taking regular exercise

75
Q

List the structure of the nephron in order the blood is filtered

A

afferent arteriole
Renal (bowman’s) capsule - cells called podocytes
Glomerulus
efferent arteriole
Proximal convoluted tube
Loop of Henle
distal convoluted tube
Collecting duct

76
Q

Describe the process of ultrafiltration in the kidney. (3 marks)

A
  1. High hydrostatic pressure in the glomerulus forces small molecules out of the blood.
  2. Molecules pass through the capillary endothelium, basement membrane, and podocytes.
  3. Large molecules like proteins and blood cells are too big to pass through.
77
Q

How is the proximal convoluted tubule adapted for reabsorption? (3 marks)

A
  1. Microvilli increase surface area for absorption.
  2. Many mitochondria provide energy for active transport.
  3. Carrier proteins for facilitated diffusion and active transport.
78
Q

Explain the role of the loop of Henle in producing concentrated urine. (4 marks)

A

• Sodium ions are actively transported out of the ascending. limb.
• This creates a water potential gradient in the medulla.
• Water leaves the descending limb by osmosis.
• Filtrate becomes more concentrated as it moves down.

79
Q

What is the role of ADH in osmoregulation? (4 marks

A

• ADH binds to receptors in the collecting duct walls.
• Aquaporins are inserted into the membrane.
• This increases water reabsorption by osmosis.
• Urine becomes more concentrated.

80
Q

How does a longer loop of Henle benefit desert animals? (2 marks)

A

• Creates a steeper water potential gradient in the medulla.
• Allows more water reabsorption, producing very concentrated urine.

81
Q

Describe the differences in composition between blood plasma, glomerular filtrate, and urine. (3 marks)

A

• Blood plasma: Contains proteins and cells (not filtered).
• Glomerular filtrate: Similar to plasma but lacks large proteins and cells.
• Urine: High in urea and salts, low in glucose and amino acids (reabsorbed).

82
Q

State where the cells which monitor the water potential of the blood are located

A

hypothalamus

AA biology a level - pippa (7 decks)

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