HOMEOSTASIS CGP

Question 1

-what is homeostasis
-what does homeostasis controlx3
-homeostasis maintans optimum conditions for cell functions and…….

Answer 1

regulation of internal conditions of cell/organism to maintain optimum conditions for function - in response to internal/ external changes.
-blood glucose concentration
-body temp
-water levels

enzyme action

Question 2

all automatic control systems contains 3 things- what do each do

what 2 types of Responses can automatic control systems involve

Answer 2

• receptors, detect stimuli (changes in
  environment)
• coordination centres (brain, spinal cord, pancreas) receive + process info from receptors
• effectors, muscles / glands, produce responses to restore optimum levels.

-nervous, chemical

Question 3

describe reflex arc from stimulus to effector - 6 steps
reflex arc similar to what happens when CNS coordinates a response but in reflex arc, its automatic/rapid so X involve consious part of brain, there’s an extra neurone instead.

Answer 3

-receptors detect stimulus
-electrical impulses pass along sensory to relay to motor neurones
-at synapse btwn neurones, chemicals cross the gap by diffusion and continue the electrical signal.
-the relay neurone is in spinal chord(CNS) so there are synapses there to carry the impulse to motor
-impulse travels from motor neurone to effector
-mucsle contracts/ gland secrete hormones

Question 4

If level of something becomes too high/low body uses negative feedback- describe this for a high level
- the effector will keep producing response if stimulated by co-ord centre. What happens then

Answer 4

-receptor detects stimulus- level too high
-coordination centre processes info and organises response
-effector produces response which counteracts change . level decreases

-levels change too much the other way . receptors detect this, negative feedback happen again

Question 5

4 parts of the nervous system- describe what they are/ do

Answer 5

-sensory neurones- carry electrical impulses from receptor cells to CNS
-cns- brain+spinal chord
-motor neurones-carry electrical impulses from CNS to effectors
-effectors-muscles/ glands -respond to impulses

Question 6

what responses do glands/ muscles have
7 parts of how the CNS coordinates a response- from stimulus to response

Answer 6

• secreting hormones. contracting
  1-stimulus, 2-receptor, 3-sensory neurone, 4-cns, 5-motor neurone, 6-effector, 7-response

Question 7

what is synapse
what happens at a synapse

Answer 7

-connection btwn 2 neurones
-when electrical impulse reaches end of neurone, stimulates release of chemical.
-chemicals diffuse across synapse to activate electrical impulse in next neurone

Question 8

why are reflex actions important- what are they

Answer 8

-automatic, rapid responses - don’t involve consious part of the brain- reduce chance of injury

Question 9

RP reaction time- 5 steps

Answer 9

-sit with arm resting on edge of table
zero end should be level with persons thumb and forefinger
-let go- no warning
-measure reaction time by number on ruler when caught
-repeat few times, calculate mean distance ruler fell
*conversion table shows reaction time in Seconds using mean distance
-person drink caffeinated drink + after 10 mins repeat

Question 10

4 control variables for RP reaction time

what else u should make sure x1

*- how else can u do this experiment
*- pros of testing like this instead

Answer 10

-same person catching
-same hand to catch
-always drop from same height
-person tested X had caffeine before experiment

-person X have more caffeine after- has side effects

-computer tests- eg click mouse as soon as they see a stimulus

-more precise- remove human error
-more accurate- time in milliseconds
-person can’t predict when to respond by reading body language

Question 11

what is brain made of + control
3 parts of the brain + where they are

Answer 11

billions of interconnected neurones- controls complex behaviour
-cerebral cortex- front (outer wrinkly bit)
-mudulla- front of line going down from brain
-cerebellum- back- fuzzy ball in sack under wrinkly bit

Question 12

what does cerebellum, cerebral cortex + medulla each do

Answer 12

-cerebral cortex-responsible for consciousness,intelligence, memory, language
-medulla-controls unconscious activities eg breathing
cerebellum- responsible for muscle contraction

Question 13

3 methods used to study brain+ explain

Answer 13

-studying patients with brain damage-
certain part of brain damaged, effects on patient tell us what that part has to do with

-electrically stimulating different brain parts
put tiny electrodes in brain tissue and zap w/ electricity. See what this causes- gives idea on what that part does.

-MRI scans- produce detailed pic of brain structure- find which parts active when doing certain things eg recalling memory

Question 14

difficulties investigating brain function/treating brain damage+ disease. x2

Pro of knowing how brain works from investigating

Answer 14

-brain complex + delicate-
difficult to investigate + treat brain
-risk of physically damaging brain + causing more problems

-allows development of treatment for disorders of the nervous system

Question 15

what is the eye
name all 9 parts of eye
salty cats in palaces love rainbows cos sun out

Answer 15

a sense organ
Sclera
Cornea
Iris
pupil
Lens
Retina
Ciliary muscles
Suspensory ligaments
Optic nerve

Question 16

describe what these do:
Sclera
Cornea
Iris
pupil
Lens

Answer 16

sclera- tough supporting wall/tissue
cornea-transparent layer @ front of eye- refracts light into eye
iris-has muscles to control diameter of pupil- how much light enters eye
pupil- hole in middle of eye
lens-focuses light on retina

Question 17

describe what these do:
Retina
Ciliary muscles
Suspensory ligaments
Optic nerve

Answer 17

retina-contains receptor cells sensitive to light+colour
Cilliary muscles-controls shape of lens
suspensory ligaments- controls shape of lens
optic nerve-carries impulses from receptors to brain

Question 18

-what happens when bright light shone in eye
x3 points
-harm of bright light=

Answer 18

-light receptors detect light and send impulse to brain
-brain sends impulses to muscles in iris .reflex triggered- pupil made smaller
-circular muscles in iris contract + radial muscles relax. -reduces amount of light that can enter

-damage retina

Question 19

3 alternatives to glasses

Answer 19

contact lenses
laser eye surgery
replacement lens surgery

Question 20

what happens to eye in dim light x3
-why

Answer 20

radial muscles contract
circular muscles relax
pupil becomes wider

-light receptors in retina sense low light
sends electrical impulse to brain
brain sends impulses to muscles in iris

Question 21

what is accommodation in eye
To focus on a near object: x3

Answer 21

changing shape of the lens to focus on near or distant objects
-ciliary muscles contract
-suspensory ligaments loosen
-lens becomes thicker (curved) + refracts light more (strongly)

Question 22

To focus on a distant object: x3

Answer 22

*ciliary muscles relax
*suspensory ligaments pulled tight
* the lens pulled thin + only slightly refracts light rays

Question 23

what is Hyperopia-
- why does it happen
-what happens
-what lenses correct it- -what do they do

Answer 23

-longsighted x focus close
-lens wrong shape/ doesn’t refract light enough OR eyeball too short
- near object image brought into focus behind retina
-convex lens (curves out)
-refract light rays to focus on retina

Question 24

what is myopia
- why does it happen
-what happens
-what lenses correct it- what do they do

Answer 24

-short sighted-x focus far
-lens refracts light too much OR eyeball too long
-images of distant objects brought into focus infront of retina
-concave lenses (curve inwards)
-refract light rays to focus on retina

Question 25

3 alternatives to glasses- briefly describe -pros of contact lenses and different types -disadvantage of each surgery

Answer 25

-contact lenses- thin lenses on eye surface lightweight,almost invisible, convenient hard lenses OR soft lenses- more comfy, higher risk of infection -laser eye surgery- change cornea shape w/ laser- change power of refraction -laser eye-risk of complications eg infection -replacement lens surgery-replace lens with plastic one- more effective in long sightedness -replacement lens-more risky than laser eye-could damage retina- (+infection)

Question 26

what does the thermoregulatory centre do- where is it what does it contain where does it recieve impulses from

Answer 26

monitors + controls body temp - -in brain -contains receptors sensitive to temp of blood flowing through brain and -gets impulses from receptors in skin that give info on skin temp

Question 27

describe how body temp controlled via negative feedback if too high 3 points And then if too low. 3 points

Answer 27

-temp receptors detect temp is too high/low -thermoregulatory centre recieves info and + triggers effectors -blood vessels dilate, sweat produced to counteract change -OR blood vessels constrict , sweating stops, skeletal muscles shiver

Question 28

*what are antagonistic effectors

Answer 28

effectors that do opposite things at same time to keep precise temp levels. This allows more sensitive response

Question 29

3 mechanisms that lower body temp explain 2 of them

Answer 29

hairs flatten, sweat, vasodilation -sweat gland produce sweat- evaporates from skin + transfers energy to environment -blood vessels dilate - more blood flows close to skin surface, more energy transferred to environment

Question 30

4 mechanisms that increase body temp -explain them

Answer 30

-hairs stand up -sweating stops -vasoconstriction -skeletal muscles contract(shiver) -hairs stand up- trap insulating layer of air -sweating stops- reduce energy lost -blood vessels constrict + close off skins blood supply -shivering needs respiration which transfers some energy to warm body

Question 31

-what are hormones + how do they get to target organs -differences of hormones to nerves x2

Answer 31

chemicals secreted by endocrine glands directly into blood stream. carried by blood to target organ(to produce an effect) -effects slower, effects last longer, act in more general way (nerves act on precise area)

Question 32

what gland is 'master gland' -what does it do -why is it 'master gland' x2

Answer 32

pituitary gland- secretes hormones to regulate body conditions- -these hormones act on other glands -directs other glands to release hormones that bring a change

Question 33

-6 parts of endocrine system u need to know -what do they produce and the purpose of these.

Answer 33

*pituitary gland-hormones-that act on other glands * pancreas-insulin-regulate blood glucose levels * thyroid-thyroxine-regulates metabolism rate, heart rate, temp * adrenal gland-adrenaline -prepares fight/flight response * ovary-oestrogen-involved in menstrual cycle * testes-testosterone-controls puberty/ sperm production in males

Question 34

-organ that controls blood glucose concentration -what happens when blood glucose levels too high x3

Answer 34

pancreas produces -insulin secreted by pancreas -insulin causes glucose to be taken in by cells out of blood -In liver + muscle cells,excess glucose converted + stored as glycogen (so blood glucose reduced)

Question 35

what happens when blood glucose conc. too low x3 . . . what do glucagon and insulin form eating what type of food increases glucose levels

Answer 35

-glucagon secreted by pancreas -glucagon triggers liver cells to convert glycogen into glucose -liver releases glucose into blood. (blood glucose level increases) -negative feedback cycle bcse they have opposing effects -carbs (type of sugar)

Question 36

-what is type 1 diabetes- common treatment -what is type 2 diabetes - what is a risk factor -common treatments

Answer 36

-pancreas X produce enough insulin -insulin injections (helps to limit carb intake+ excercise) -body cells X respond to insulin pancreas produces -obesity -carb-controlled diet -regular exercise- removes excess glucose in blood

Question 37

insulin injection- things u know about it how does it help

Answer 37

-very effective -several injections -mainly meal time- -makes sure glucose removed quickly once food digested -stops level getting too high

Question 38

how do kidneys carry out their function x2

Answer 38

-filter waste products out of blood -blood reabsorb useful substances to produce urine (selective reabsorption) eg water, glucose, ions (basically all glucose is reabsorbed. barely any in urine)

Question 39

-how is urea made starting with protein digestion x5 -what happens to urea made in liver x3

Answer 39

-digesting proteins=excess amino acids- can't be stored -in liver, deamination happens -amino acids broken down+stored - ammonia is by-product of deamination - Ammonia = toxic quickly converted to urea- -urea sent to kidneys in blood -filtered out -excreted in urine

Question 40

-what happens to ions you take in from food. 1 eg -what happens if water/ion content in body wrong x2 -where are ions+ urea lost from x2 -where is water lost from x3 -how do we balance amount of water in body x2 how do we balance amount of ions in body x1

Answer 40

absorbed into blood- eg sodium -too much/ too little water enters cells by osmosis -cells dont work properly/ damaged -skin in sweat -kidneys urine -exhalation, sweat, kidneys in urine -consume water, remove water in urine -Kidneys- reabsorb ions / remove them

Question 41

-water level/ urine concentration controlled by hormone... -this is released into..... from ...... - The hormone is released when.... - What does this hormone do --this process is controlled by x2

Answer 41

-ADH hormone- -released into bloodstream from pituitary gland -when blood is too concentrated -causes kidney tubules to become more permeable so more water reabsorbed into blood from kidney tubules (increases blood water content and urine concentration - brain(receptors monitor water content in blood) -negative feedback

Question 42

what happens when blood water content too high x3

Answer 42

-receptor in brain detect level too high -Coordination centre in brain receives info + coordinates response -pituitary gland release less ADH- Kidney tubules less permeable, less water reabsorbed into kidney tubules

Question 43

what happens if kidneys X work right x2 2 ways to keep kidney failure person alive

Answer 43

-waste substances build up in blood -X control ion+ water levels in body - eventual death dialysis, kidney transplant

Question 44

-Describe how dialysis works-4 -why are useful substances not lost from blood -how often -down sides x3 - positive

Answer 44

-blood flows btwn partially permeable membrane- not permeable to large molecules (like membrane in kidney) (eg protien) -and dialysis fluid- same conc. of ions+ glucose as healthy blood -waste substances diffuse across -useful substances X lost from blood- no concentration gradient- fluid +persons blood have same levels of useful substances -3 times a week for 3/4 hrs -risk blood clots/ infections -unpleasant experience -costly for NHS ---- allows valuable time till donor organ found

Question 45

-who are kidney transplants taken from x2 -risks x2 - why is transplant better than dialysis x2 -con

Answer 45

-ppl who died suddenly + r on donor register/have donor card (their relatives must agree too) -ppl still alive (kidneys ideally matched by blood type) -small risk to donor -kidney rejected by immune system- treated w/ to drugs prevent this- can still happen -cheaper in long run -X spend hours on dialysis -long waiting list for kidneys

Question 46

female reproductive hormone+what it does male reproductive hormone+ what it does reproductive hormones cause......... ....... ...... to develop

Answer 46

oestrogen- causes physical changes+involved in menstrual cycle testosterone-stimulates sperm production -secondary sex characteristics

Question 47

4 stages in menstrual cycles

Answer 47

1- menstruation starts-uterus lining breaks down for 4 days 2- day 4-14 uterus lining builds up to layer of blood vessels- ready to receive fertilised egg 3-Ovulation-egg develops and released from ovary on day 14 4- wall maintained for 14 days. if fertilised egg doesn't land on uterus wall, cycle starts again

Question 48

4 hormones involved in menstruation in order and what they do( not hormones they stimulate) what happens when progesterone level falls

Answer 48

-FSH-causes maturation of egg -Oestrogen-causes uterus lining to grow -LH stimulates release of egg (day 14) -Progesterone- maintains uterus lining during second half of cycle (after egg released) level falls-lining breaks down(cycle restarts)

Question 49

2 menstrual hormones produced in pituitary gland 2 menstrual hormones produced in ovaries -what hormone does FSH stimulate ovaries to produce -what does oestrogen stimulate + inhibit -what hormone does LH inhibit -what does progesterone inhibit

Answer 49

FSH LH progesterone oestrogen FSH stimulates-oestrogen Oestrogen- stimulates LH, Inhibits FSH LH -X inhibit or simulate any hormone Progesterone- inhibits release of LH + FSH

Question 50

6 methods of contraception-

Answer 50

oral contraceptives injections/implants/skin patches barrier methods intrauterine devices spermicidal agents abstaining surgery

Question 51

what hormones are in oral contraceptive pill. how do both these hormones reduce fertility How do they do this individually

Answer 51

progesterone + oestrogen -both inhibit FSH so no eggs mature progesterone- stimulates thick mucus-preventing sperm reaching egg oestrogen- if taken everyday to keep level high-inhibits FSH production. Eventually egg X develop + FSH X produced

Question 52

1pro + 2cons of combined oral contraceptive pill (progesterone + oestrogen)

Answer 52

-over 99% effective -side effects- headaches, nausea -X protect against STD's

Question 53

what pill is better than the combined oral contraceptive pill--- why---

Answer 53

Progesterone only pill- same effectiveness, less side effects

Question 54

what is the contraceptive patch. how long does it last

Answer 54

-small patch w/ oestrogen + progesterone stuck to skin. Lasts 1 week

Question 55

describe contraceptive implant how long does it last

Answer 55

implant inserted under arm skin. continually releases progesterone . last for 3 yrs

Question 56

describe contraceptive injection how long does it last

Answer 56

-injection w/ progesterone -lasts for 2-3 months

Question 57

what is an Intrauterine device- what does it do- what are the two types-

Answer 57

- T shaped device put in uterus kills sperm + stop fertilised egg being implanted -Plastic IUD release progesterone -Copper IUD stop sperm surviving in uterus

Question 58

what do all barrier methods do 3 methods of barrier contraception

Answer 58

stop sperm getting to egg -Condoms-Male/Female -Diaphragm (used w/ spermicide) -Spermicide- used alone

Question 59

-what do condoms do -a pro of condoms -what is a diaphragm what is spermicide- con of spermicide-

Answer 59

-prevent sperm entering vagina -only contraception that protect against STD's -plastic cup put over cervix as a barrier. used with spermicide spermicide-substance that kill/disable sperm -not very effective when used alone

Question 60

-describe Sterilisation to stop having a child -important thing to remember with this method

Answer 60

cut/tie fallopian tubes or sperm duct permanent procedure- very small chance tubes can rejoin

Question 61

3 ways other than barrier + hormonal methods what is 'natural method' pro con

Answer 61

sterilisation, abstinence, natural methods find out when in cycle woman is most fertile + avoid sex -popular w/ ppl who think barrier+hormonal methods r unnatural -not very effective

Question 62

what is in the 'fertility drug' given to women -why is it given -how does it help- -pro of 'fertility drug' -cons x2

Answer 62

FSH, LH woman has low FSH - eggs X mature-- no eggs released (by LH) + can't get pregnant -stimulates ovulation -woman can become pregnant in normal way- effective -X always work- may have to do it many times- expensive -too many eggs stimulated- unexpected multiple pregnancy

Question 63

why is IVF used- 4 steps to IVF-

Answer 63

if 'fertility drug' or medication X work *give mum FSH + LH to stimulate maturation of several eggs. * eggs collected + fertilised by fathers sperm in lab OR sperm injected into egg (if man has low sperm count) * fertilised eggs develop into embryos in incubator * When embryos are tiny balls of cells, 1 or 2 inserted in mothers uterus/womb

Question 64

pro of IVF 3 cons and describe these

Answer 64

can give infertile couple child -emotionally + physically stressful (vomit, abdominal pain, dehydration) -low success rate-upsetting if multiple failures -lead to multiple births-risky for mum+ babies (

Question 65

what has helped IVF success rate what tools have been developed, how do they help how does time lapse imaging help

Answer 65

advanced microscopy techniques help Improve IVF techniques + so success rates micro-tools- used on egg and sperm + remove cells from embryo for genetic testing monitor embryo growth to identify ones likely to cause successful pregnancy

Question 66

why r ppl against IVF x2

Answer 66

-results in many unused embryos- destroyed Unethical as each embryo is a potential life -ethical issues on genetic testing before implanting. Could lead to selection of preferred characteristics

Question 67

when is adrenaline released where are adrenal glands What does adrenaline do x3

Answer 67

-times of stress/ fear -above kidneys -increases heart rate -boosts supply of O2 + glucose to brain cells + muscles -preparing body for fight/flight

Question 68

how is adrenaline released x3 body controls levels of hormones in blood using....

Answer 68

-brain detects fear/ stress -sends nervous impulses to adrenal glands -glands respond + secrete adrenaline negative feedback

Question 69

where is the thyroid gland what does thyroxine do x2

Answer 69

in the neck -regulates basal metabolic rate- speed that chemical reactions occur when body is resting -stimulates protein synthesis for growth + development

Question 70

thyroxine is released in response to which hormone. where is this hormone released from- what is thyroxine made of-

Answer 70

TSH (thyroid stimulating hormone) -pituitary gland -iodine+amino acids

Question 71

describe how negative feedback is used to control level of thyroxine in blood x3

Answer 71

when level higher than normal- -secretion of TSH from pituitary gland is inhibited Less thyroxine released from thyroid level of thyroxine in blood falls

Question 72

what is auxin, how does it produce desired results- what does it control

Answer 72

plant hormone- -promotes growth near tips of shoots+ inhibits growth in roots -controls growth in response to light-(phototropism) and gravity ( gravitropism)

Question 73

where is auxin produced, where does it move to, why

Answer 73

-produced in tips. moves backwards for cell elongation process (occurs behind tips)

Question 74

what happens if tip of shoot removed -what happens when shoot tip exposed to light 3 points

Answer 74

no auxin available so shoot can stop growing -more auxin accumulates on shaded side -cells elongate/grow faster on shaded side -so shoot bends towards light

Question 75

what happens when shoot is growing sideways- 3 points

Answer 75

-gravity produces unequal auxin distribution in tip- more on lower side -lower side grows faster -shoot grows upwards

Question 76

what happens when root is growing sideways- 3 points

Answer 76

-gravity produces more auxin on lower side -extra auxin inhibits growth so cells on top elongate faster -cell bends downwards

Question 77

RP effect of light on growth x7

Answer 77

-10 seeds in 3 labelled petri dishes -line each w/ moist cotton wool -let seeds germinate in warm place -make sure same amount have germinated in each dish, if not, remove some so equal number -measure height of each seedling and work out mean for each dish -place in different conditions -work out new mean for each dish

Question 78

RP effect of light on growth -what is independent variable what are the 5 control variables- explain how to control them

Answer 78

light no.of seeds-use same no. type of seeds-seeds from same packet temp-keep petri dishes in stable temp water-add same amount of water to dampen cotton wool. water them w/ same amount each day light intensity- distance btwn seed and bulb the same

Question 79

what are three different conditions for RP effect of light on growth what are the effects on growth x3

Answer 79

full sunlight in box with partial light darkness -full light + partial light grow similar height -partial light bent to light -darkness- grow longest- bcse they grow rapidly to reach light -darkness- leavs small/yellow-X photosynthesise

Question 80

Rp effect of gravity on plant growth 3 steps

Answer 80

-place seedlings on damp cotton wool in petri dish with roots pointing in different directions -store vertically in dark -all roots will grow down

Question 81

uses of auxins x3 explain them

Answer 81

-weed killers Weedkillers developed using auxins -disrupt growth of broad leaved plants (weeds) -kill them -rooting powders-contain auxins. Added to cuttings, roots produced quickly and grow as new clone plants -promoting growth in tissue culture-auxins added to growth medium -plant cells divide into roots +shoots

Question 82

what are giberellins, what do they do x3 what is ethene what does it dox2

Answer 82

plant growth hormone stimulates seed germination, stem growth, flowering -gas produced by aging plant parts -effects growth by controlling cell division -stimulates enzymes that cause ripening

Question 83

Gibberellins can be used to: x3 describe each

Answer 83

* end seed dormancy * promote flowering * increase fruit size. some Seeds X germinate till been through certain conditions - dormancy. Giberellins alter dormancy- make seeds germinate at different time- all seeds in batch germinate together some plants need certain conditions to flower. Treated w/ gibberellin- flower w/out change in environment + grow bigger flowers -seedless fruit grow smaller than seeded.Gibberellins increase growth to match seeded type

Question 84

use of ethene. what do some fruits do as they ripen?

Answer 84

used in food industry to control fruit ripening during storage+transport. -produce more ethene

Question 85

a pro of using ethene to ripen fruit

Answer 85

fruit picked when unripe, less fragile, gas added on way to store

Question 86

what is the cns what is a coordination centre

Answer 86

CNS- brain + spinal chord (where reflexes + actions are coordinated) Coordination centre- An organ that processes info from receptors and organises response from effectors