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BIO > P1: Module 5: Communication, Homeostasis, Energy > Flashcards

P1: Module 5: Communication, Homeostasis, Energy Flashcards

1
Q

Define excretion (a)

A

The removal and processing of waste from the body

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2
Q

Define metabolic waste (a)

A

Waste produced from metabolism eg urea + CO2

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3
Q

Define egestion (a)

A

Removal of undigested waste eg faeces by defacation

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4
Q

Define deamination (a)

A

Removal of ammonia from amino acids

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5
Q

Define secretion (a)

A

A process by which substances are produced and discharged from a cell, gland or organ for a particular function in the organism

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6
Q

Why is excretion important? (a)

A

-The main waste products are CO2 and nitrogenous waste in its form of urea
-These products are toxic and cause damage if not removed
-Excretion maintains normal metabolism and homeostasis by keeping levels of certain substances in blood

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7
Q

What happens if CO2 isn’t excreted? (a)

A

-CO2 is toxic
-Hydrogen carbonate ions can reduce the ability to transport oxygen
-This forms carbaminohaemoglobin which has a lower affinity for oxygen than normal haemoglobin
-This Leads to respiratory acidosis

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8
Q

Why should amino acids be removed? (a)

A

-Body cant store AA
-But they still contain energy so..
-In the liver potentially toxic AA are removed by deamination
-This makes a soluble and toxic compound = Ammonia
-Ammonia is then converted into a less soluble and less toxic compound = urea which is excreted from the body via urine

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9
Q

Role of hepatic artery? (b)

A

Delivers oxygenated blood from aorta to hepatocytes for aerobic respiration

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10
Q

Role of hepatic portal vein? (b)

A

Delivers deoxygenated blood from digestive tract, the blood is nutrients (eg glucose) rich, to HEPATOCYTES (DONT say liver say hepatocytes)

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11
Q

Functions of the liver (4)

A

-Detoxification, breakdown of toxic substances
-Produces bile
-Glycogenesis
-Deamination

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12
Q

Describe the adaptations of liver lobule (3)

A

-Blood from hepatic artery and hepatic portal vein mix
-Hepatocytes are arranged in thin rows, which allows for a shorter diffusion distance as they’re in direct contact w/ sinusoid

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13
Q

Why is faeces brown?

A

RBC’s broken down to make bilirubin

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14
Q

Role of bile:

A

-Emulsifies fat - gives fat a higher SA:Vol for lipase to break them down
-Neutralises stomach acid therefore lipase doesn’t denature

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15
Q

Role of Kupffer cells

A

Breakdown pathogens + RBC’s

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16
Q

Describe the process ultrafiltration?

A

-Blood in glomerulus is under high pressure
-This is because the afferent artierioles is wider than efferent
-This forces fluid into the bowman’s capsule
-The capillary endothelium has narrow gaps and offers little barrier
-The basement membrane is the filter (made of collagen fibres and glycoproteins)
-Proteins and blood cells cannot pass through it
-Epithelial cells of bowman’s capsule have pod oxygen which have finger like projections
-Fluid easily passed through these
-Water, AA, Glucose, urea and ions are filtered from blood into Bowman’s capsule

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17
Q

What processes occur in the cortex, medulla and pelvis of the kidney?

A

-Cortex: ultrafiltration

-Medulla: selective reabsorption

-Pelvis: where urines collected

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18
Q

Give two adaptions of PCT

A

-Cytoplasm has lots of mitochondria to provide ATP for active transport
-Cell membrane has microvilli to increase SA:Vol for reabsorption
-Cell membrane contains co-transporter proteins to transport glucose or AA

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19
Q

Why isn’t all of glucose reabsorbed from a diabetic patients filtrate? (3)

A

-Their glucose level is already high so there’s not much of a conc gradient
-Co-transporters are full so can’t get all of glucose by facilitates diffusion as filtrate is too sugary so some glucose gets left behind

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20
Q

What would the urine of someone w/ high blood pressure have?

A

-Protein: hbp can force proteins through
-Some filtrates

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21
Q

Selective reabsorption in PCT

A

-Sodium-potassium pumps actively transport sodium ions into tissue fluid (TF) from PCT cells
-This lowers conc of Na+ ions in cell
-Na+ then move into lumen of PCT into cells via facilitated diffusion
-This is coupled w/ transport of glucose and AA, as conc of AA and glucose rises they can diffuse into TF then into blood plasma
-Due to reabsorption of salts, glucose and AA, the water potential of cell is reduced so water moves by osmosis from PCT into nephron and into blood

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22
Q

How is water pot of blood monitored and controlled? (9)

A

-Water level of blood is controlled by monitoring level of water by receptors called osmoreceptors
-This is controlled by negative feedback
-Where osmoreceptors in hypothalamus detect the water pot of blood
-This sends a nerve impulse to pituitary gland
-Which releases ADH
-The level of ADH released depends on the amount of water needing to be reabsorbed
-ADH travels in blood and binds to complementary receptors on DCF and collecting duct
-This triggers squalor in to move into plasma mem and water moves back into blood via osmosis
—> If water pot of blood is high then walls of collecting duct become less permeable and less ADH is released so less water reabsorbed therefore a larger vol of urine produced and water pot of blood falls back down to normal level
—> If water pot of blood low then walls of CD become more permeable to water and more ADH is released so more waters reabsorbed and therefore smaller vol of urine produced and water pot increases back to normal level

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23
Q

Which limb of loop of henle is impermeable to water?

A

Ascending limb

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24
Q

A runner is dehydrated whilst running on a hot sunny day, He left his drink at home and is producing a lot of sweat during his run
-Why is the runner dehydrated?

A

-Because he’s sweated a lot and not replaced the fluids he’s lost
-This has caused his water pot to drop

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25
Q

A runner is dehydrated whilst running on a hot sunny day, He left his drink at home and is producing a lot of sweat during his run
-How does the runners body detect that he’s dehydrated?

A

-The low water pot of his blood is detected by osmoreceptors in his hypothalamus

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26
Q

A runner is dehydrated whilst running on a hot sunny day, He left his drink at home and is producing a lot of sweat during his run
-The runners pituitary gland releases ADH. Explain what effect ADH has on DCT and collecting duct of the runners kidneys

A

-ADH binds to receptors on plasma membranes of cells of the runners DCT and CD
-Aquaporins are inserted into plasma mem
-These channels allow water to pass thru via osmosis so walls of DCT and CD become more permeable to water
-This allows water to be reabsorbed from these tubules into medulla and into blood by osmosis therefore conserving water in runners body

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27
Q

A runner is dehydrated whilst running on a hot sunny day, He left his drink at home and is producing a lot of sweat during his run
-When he returns home he drinks a sports drink containing sodium and chloride ions. Explain how the presence of these ions help the runners kidneys to conserve water

A

-Presence of sodium and chloride ions in sports drink increases the conc of sodium and chloride ions in runners filtrate
-These ions are used to lower water pot of medulla in loop of henle
-To create a water pot gradient to drive reabsorption of water back into blood by osmosis

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28
Q

Describe a desert animals loop of Henle

A

-Larger loop of henle so more Na+/Cl- ions are actively pumped out so even lower water pot

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29
Q

How is CO2 produced?

A

Metabolism (all chemical reactions that happen in cells)

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30
Q

What can excess CO2 do to the blood and why?

A

Denatures RBC’s - change pH of blood because of carbonic acid

31
Q

A student designed an experiment to investigate the effect of temp on rate of glucose diffusion through dialysis fluid. State 2 factors that would need to be controlled (2)

A

-Initial glucose conc
-Vol of solution
-Length of dialysis tubing

32
Q

Nephrogenic diabetes insipidus affects regulation of water pot. in blood. One cause is Li poisoning which prevents cells in collecting duct responding to ADH in blood. Explain one symptom you’d expect of NDI

A

High vol of urine as fewer aquaporins on plasma membrane of collecting duct cells

33
Q

Explain why podocytes are usually unable to undergo mitosis (3)

A

They’re already differentiated so cant divide; if meiosis occurred it would alter number of genes

34
Q

What features of adult stem cells make them suitable for regeneration of tissues in kidney

A

They’re multipotent; so can differentiate to become any type of cell in kidney

35
Q

Describe similarities and differences between ultrafiltration and formation of tissue fluid (6)

A

-Both rely on high hydrostatic pressure to push out contents of capillary by mass flow
-However in ultrafiltration pressure is built by narrower efferent capillary than afferent
-Both capillary walls contain gaps to allow small molecules like glucose ions through.
However the pores of ultrafiltration has basement molecules and podocytes so molecules bigger than 69,000 cant pass through, lympocytes and small proteins can pass through tissue fluid but not into nephron
-Ultra occurs in glomerulus but tissue fluid is formed all over body

36
Q

Suggest 2 characteristics a patient must take into account when using GFR measurement to diagnose kidney damage (4)

A

-Age; as kidney function declines with age
-Gender; as men and women have diff muscle mass

37
Q

Explain why peritoneal dialysis can use active transport and diffusion whilst haemodialysis relies on diffusion alone

A

Peri. wall made up of living cells; so produces ATP to carry out active transport

38
Q

Advantages and disadvantages of kidney transplant compared to dialysis

A

-AD= doesn’t require repeated dialysis
-DIS= Organ rejection/ long use immunosuppressant drugs

39
Q

Explain why visible blood vessels are likely to be veins (3)

A

-Thin wall so will bulge; lumen wide so contains large vol of blood; found closer to surface of skin than arteries

40
Q

Explain the need for close matching of donated kidney to recipient (3)

A

If not closely matched donated kidney will be seen as foreign; antigens on donated kidney will be diff; causing rejection by immune system

41
Q

Explain how pregnancy sticks detect hCG (4)

A

-Testing for hCG: its a hormone so can pass from blood into filtrate at bowmans capsule; monoclonal antibodies on stick; which are attached to a dye; so when hCG binds to complementary antibody; it triggers the line to become visible

42
Q

Bilirubin makes faeces brown, explain why its production is an example of excretion

A

Bilirubin is a metabolic waste product; as produced during RBC breakdown; bilirubin is removed from body

43
Q

Why is it not a good idea to give alcohol to someone with hypothermia? (2)

A

Alcohol causes vasodilation which causes more blood nearer to the skins surface; so body will lose even more heat

44
Q

Name the type of differentiated cell that scientists would produce from stem cells in order to treat diabetes mellitus

A

Pancreatic beta cells

45
Q

Which type of diabetes mellitus is most likely to be improved by stem cell therapy?

A

Type 1 because type 1 results from a shortage of beta cells in the pancreas; so stem cell therapy may increase insulin production

46
Q

Describe the sequence of events leading to the secretion of insulin from beta cell (4)

A

-Glucose is respired to ATP
-ATP blocks K+ ion channels so K+ ions build up
-Voltage gated Ca2+ channels open and Ca2+ enter cell by diffusion
-More Ca2+ results in the movement of vesicles to plasma membrane for exocytosis

47
Q

After initial release of insulin from the beta cell, insulin secretion continues even when there’s no further glucose intake. Suggest and explain why cell continues to secrete insulin

A

-Insulin is still being secreted as long as blood glucose conc remains high; ATP is still present and so K+ channels remain closed so exocyotsis is still being triggered by Ca2+

48
Q

Gestational diabetes affect pregnant women results in high glucose levels even though women produces normal levels of insulin, What type of diabetes is it similar to?

A

Type 2; as insulin is still produced; beta cells still work but liver cell no longer responds to insulin; if it was type 1 then women wouldnt be able to produce normal levels of insulin

49
Q

Evaluate treatment for Type 1 diabetes thats been used in the past, current and potential future (6)

A

-PAST; insulin treatment from animal pancreas eg pig
>ADV: Early treatment kept people alive, its tried and tested=works
>DIS: Ethical issues of animal products

-PRESENT: Insulin from humans/ recombinant bacteria
>ADV: Overcomes ethical issues of animal and use of smart pumps eg can monitor on a app
>DIS: Some may not understand new technology of injection routine

-FUTURE: Transplant of pancreatic stem cells
>ADV: Improved quality of life as stem cells can be turned to functioning beta cells
>DIS: Risk of cancer w/ stem cells

50
Q

Describe 2 similarities in action of plant and animal hormones in cell signalling (2)

A

Hormone binds to receptor; causing a cascade of events

51
Q

When testing for diabetes mellitus why is it important that the patient doesnt eat 8 hrs before test?

A

Time is needed for blood glucose levels to restore to normal level

52
Q

Insulin is a polypeptide molecule where in pancreatic cell is it synthesised

A

RER (Rough endoplasmic reticulum)

53
Q

Outline the events that occurs after the synthesis of an insulin molecule until its ready to be secreted from pancreatic cell (3)

A

-Transported to GA; modified and processed in GA; packaged into vesicles which are transported t plasma membrane

54
Q

Homeostasis

A

Maintaining a stable internal environment; within narrow limits even though environment is changing

55
Q

Outline the ways in which structures of a sensory neurone and a motor neurone are similar (4)

A

Both have dendrites, axon, cell body w/ a nucleus and voltage gated channels

56
Q

Fever is usually accompanied by sweating. Explain the effect that sweating will have on the body?

A

Evaporation will have a cooling effect on the body decreasing body temp; heat is taken away from body when evaporation happens

57
Q

Outline roles of synapse in nervous system (3)

A

Allows neurones to communicate as it passes impulse to the next neurone; ensures transmission between neurones is one direction only; prevents over stimulation

58
Q

Describe and explain how resting potential is established and maintained in a sensory neurone (4)

A

Na+/ K+ pump uses ATP to actively pump; Na+ out of neurone and K+ in; K+ diffuse back out of cell; membrane becomes less permeable to Na+

59
Q

State 3 difference in structure of motor and sensory neurones (3)

A

-Motor= cell body at end of neurone Sensory= cell body in middle
-Motor= longer axon Sensory= shorter axon
-Motor= cell body in CNS Sensory= cell body in PNS

60
Q

Urine of someone w/ high blood pressure

A

-Protein= high pressure can force proteins through
-Cloudy pee= amino acids can dissolve in water however protein cant so pee is cloudy.

61
Q

Why would we need adrenaline to bind to hepatocytes?

A

Need more energy for flight or fight, adrenaline gets more glucose causing the breakdown of glycogen so it can be respired

62
Q

Why is it better for glucose to be stored as glycogen?

A

Glucose is soluble, glycogen isnt so glycogen doesnt affect water pot of cell

63
Q

Photosynthesis occurs in two stages: the light-dependent stage and the light-independent
stage. The light-independent stage is affected by temperature more than the light-dependent
stage.
Explain why temperature has a greater effect on the rate of the light-independent stage

A

Because light ind stage is enzyme controlled eg Rubisco. As temp increases kinetic energy of enzyme + substrate increases, leading to increased ESC

64
Q

Describe the production of ATP by substrate-level phosphorylation in different stages of
respiration with reference to the number of ATP molecules produced.

A

-Glycolysis produces 2 ATP net as a result of 4 ATP being made when 2 triose phosphate is converted into 2 pyruvate
-2 ATPs are also made by Substrate Level Phos in Krebs cycle when 5C compound is converted to oxaloacetate

65
Q

Suggest a role for coenzymes other than coenzyme A in beta oxidation.

A

NAD+FAD carry H atoms when reduced which dissociate to provide ETC w e-, + H+

66
Q

Some features of thermoregulation in naked mole rats are listed below:
* They live in complex underground tunnel systems, which tend to have a stable
temperature of 30–32°C. However, sometimes the environmental temperature
can increase or decrease outside this range.
* In experiments that examine environmental temperature changes, the core
body temperature of naked mole rats remains close to that of the environmental
temperature.
* When tunnel temperature increases they often move to cooler parts of the
tunnel system.
* When tunnel temperature decreases they often lie together in large groups.
Outline two ways in which thermoregulation in naked mole rats is different from
thermoregulation in most mammals.

A

-naked mole rats, have a lower body temperature
-naked mole rats use, more behavioural responses e.g. ‘they huddle together when temperature
falls whilst mammals shiver

67
Q

Positive feedback

A

positive feedback, is when an initial (biological) change is,
increased further/ exaggerated

68
Q

In humans, when core body temperature falls below 35°C, positive feedback causes this
decrease in core body temperature to continue. This process is known as hypothermia.
Explain how positive feedback could accelerate the process of hypothermia.

A

-positive feedback, is when an initial (biological) change is,
increased further / exaggerated
-lower temperature reduces kinetic energy (of molecules)
-enzyme activity, slowed / reduced
-respiration rate / metabolism, slowed / reduced
-less (metabolic / internal) heat generated
-(so that body) temperature drops further

69
Q

In normal glycolysis, the enzymes needed to convert glucose to triose phosphate
may be inhibited by lactate.
* Naked mole rats can use fructose as a respiratory substrate.
* Fructose is converted to triose phosphate.
* Triose phosphate can then enter the glycolysis pathway.
(i) Suggest why the use of fructose allows naked mole rats to survive without oxygen for a
long time.

A

-glycolysis / anaerobic respiration, can continue
-because, conversion of glucose to TP is not needed

70
Q

State one function of the distal convoluted tubule.

A

reabsorption of Cl- and Na+

71
Q

Water reabsorption in the kidney is controlled by the endocrine and nervous systems.
Aldosterone and ADH are hormones that act on the kidney.
Aldosterone causes sodium ions to be pumped from the collecting duct cells into tissue fluid.
Describe how the endocrine and nervous systems work together to increase water
reabsorption from the collecting duct (6)

A

Endocrine system
* hypothalamus causes release of ADH from pituitary
aldosterone released from adrenal cortex
* ADH released from pituitary gland
* ADH binds to receptors on the cell membranes of
collecting duct cells …
* … and this increases permeability to water (regulated by
aquaporins)
* role of cAMP

Nervous system:
* hypothalamus is part of nervous system
* osmoreceptors in the hypothalamus …
* … detect a low water potential in the blood
* ADH is produced in the hypothalamus
* posterior pituitary is extension of hypothalamus
* correct reference to negative feedback

Aldosterone:
* sodium ions pumped out of collecting duct cells (into
tissue fluid) (and potassium ions pumped in)
* lowers water potential in tissue fluid
* concentration gradient established
* sodium ions reabsorbed from the collecting duct lumen
* water diffuses into collecting duct cells / out of lumen via
osmosis.

72
Q

Outline why it is important that fetal haemoglobin has a higher oxygen affinity than adult
haemoglobin.

A

-low pO2 (O2 conc in placenta) in placenta
-adult haemoglobin releases oxygen at low pO2,
but fetal haemoglobin will pick up oxygen at the same
pO2

73
Q

Outline the importance of photosynthetic pigments in photosynthesis.

A

-(pigments) absorb , light
-electrons , excited
-accessory pigments pass energy to , reaction centres
-primary pigments pass electrons to ETC
-for light dependent reaction

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