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Biology Paper 2 > B5: Homeostasis & Response > Flashcards

B5: Homeostasis & Response Flashcards

1
Q

What is homeostasis?

A

An organism’s ability to regulate/control it’s internal conditions so crucial reactions (including those involving enzymes) can happen at optimal rates.

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2
Q

What 3 things need to be regulated

A

-Blood glucose concentration
-Internal temperature
-Water levels

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3
Q

What 2 things does the nervous system consist of?

A

CNS: Central Nervous System (brain & spinal chord
PNS: Peripheral Nervous System (all other nerves)

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4
Q

What does a receptor do?

A

Detects a change due to a stimulus

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5
Q

What does a sensory neurone do?

A

Transfers a signal from a receptor to the CNS

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6
Q

What does a motor neurone do?

A

Transfers a signal from the CNS to an effector

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7
Q

What does a relay neurone do?

A

Transfers a signal from a sensory neurone to a motor neurone

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8
Q

What is the order of the reflex arc?

A

stimuli -> receptor cells -> sensory neurone -> CNS -> relay neurone -> motor neurone -> effector
signal bypasses brain

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9
Q

How do signals travel between the synapse between neurones?

A

Via neurotransmitter chemicals

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10
Q

What are glands?

A

Effectors that secrete chemicals

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11
Q

What is the practical for reaction times?

A

-Drop ruler between finger & thumb
-Measure distance fallen before caught, repeat, calculate mean
-Independent variable:
Stimulant (e.g. energy drink) increases neurotransmission
Depressant (e.g. alcohol) decreases neurotransmission
-Could use s=1/2at2 to calculate reaction time

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12
Q

What is the cerebral cortex responsible for?

A

Higher functions (conscious activities):
-Memory
-Speech
-Problem-solving

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13
Q

What is the cerebellum responsible for?

A

Motor skills:
-Movement
-Balance
-Coordination

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14
Q

What is the medulla oblongata responsible for?

A

Unconscious actions:
-Heart & breathing rate
-Signals to adrenal glands to release adrenaline

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15
Q

What are MRI scans?

A

Allow doctors to see brain activity without surgery.

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16
Q

Why is treating the brain so difficult?

A

-It is complex (difficult to physically treat without damaging it)
-Things can go wrong (e.g. tumours, trauma, mental health problems)

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17
Q

What is accommodation?

A

The eye’s ability to change the shape of the lens to focus light that comes from different distances away on the retina.

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18
Q

How does the eye focus on objects that are far away?

A

-Ciliary muscles relax
-Suspensory ligaments tighten
-Results in the lens becoming thin
-Light only refracted a little bit

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19
Q

How does the eye focus on objects that are near?

A

-Ciliary muscles contract
-Suspensory ligaments slacken
-Results in the lens becoming thick
-Light is refracted more

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20
Q

What makes the pupil change size?

A

Light intensity
-More light smaller
-Less light bigger

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21
Q

What is the cornea?

A

The transparent outer layer of the eyes
It has no blood vessels

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22
Q

What are retina cells?

A

-Rods that only detect light intensity
-Cones sensitive to red, blue or green wavelengths of light provide colour information
-These signals travel to the brain via the optic nerve

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23
Q

What is the medical term for short-sightedness?

A

Myopia

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24
Q

What is the medical term for long-sightedness?

A

Hyperopia

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25
How can sight impediments be treated?
-Glasses -Contact lenses -Laser eye surgery
26
How does thermoregulation work?
The brain detects blood temperature then sends nervous & hormonal signals to effectors
27
What happens when you are too hot?
-Sweat glands produce water which evaporates, taking away heat -Blood vessels dilate: VASODILATION
28
What happens when you are too cold?
-Hairs stand on end to trap air - layer of insulation -Shivering - muscles produce more heat -Blood vessels contract - VASOCONSTRICTION
29
What is the endocrine system?
A system of glands that secrete hormones to send signals to effectors, transported via blood (slower than nervous system)
30
What is the pituitary gland?
The 'master' gland: sends signals to other glands
31
What does the pancreas do?
Secretes insulin (and glucagon) to control blood sugar
32
What does the thyroid gland do?
Controls growth, metabolism and more
33
What do the adrenal glands release?
Adrenaline
34
What do the ovaries do?
-Release eggs -Secrete hormones
35
What do the testes produce?
Sperm
36
What happens when blood glucose levels are high?
-Pancreas secretes insulin -Causes glucose to move from bloodstream into cells to be used for respiration -Excess glucose is converted into glycogen as an energy store
37
What happens when blood glucose levels are low?
-Pancreas secretes glucagon -Causes liver and muscles to convert glycogen back into glucose -(This is an example of NEGATIVE FEEDBACK)
38
What is type 1 diabetes?
-Pancreas cannot produce (enough) insulin -Injections needed
39
What is type 2 diabetes?
-Cells do not absorb glucose as they should -Obesity increases risk of it developing
40
What 3 processes result in water loss?
-Exhalation -Sweating -Urination
41
How is excess water removed?
From blood by kidneys to the bladder
42
What 2 things are mixed to make urine?
-Urea -Water
43
What does urea contain and how is it made?
Ammonia (NH3) from amino acids obtained from excess proteins broken down in the liver
44
What would happen if the body had too much water?
-Water moves into cells via osmosis -Cells become turgid, could burst
45
What would happen if the body had too little water?
-Water moves out of cells via osmosis -Cells become flaccid
46
What is the function of the kidneys?
-Keep water levels just right -Filter out glucose and useful minerals and ions for the body to use
47
What is ADH and where is it produced?
-Anti-diuretic hormone -Produced in the pituitary gland -Causes tubules in kidneys to reabsorb more water into bloodstream
48
What happens to ADH if water levels are too high?
-Less is made -More water is sent to the bladder to leave the body as urine -An example of NEGATIVE FEEDBACK
49
What is negative feedback?
The response to a change is such that conditions return to normal
50
What is needed if the kidneys are not working properly?
Dialysis: -Blood is filtered by a machine -If not done, ammonia/urea buildup will be poisonous
51
What is the process of the menstrual cycle?
-Females are born with eggs, which start to mature at puberty -FSH (follicle stimulating hormone) from pituitary gland causes an egg to mature, and the ovaries to produce -OESTROGEN causes uterus lining to thicken, and it inhibits FSH so no more eggs mature until the next cycle. It also causes the pituitary gland to secrete -LH (luteinising hormone) causes egg to be released, which starts to travel towards the uterus. A sperm cell can fertilise it while in the oviduct -PROGESTERONE secreted by the ovaries maintains the uterus lining
52
What are methods of contraception?
-FSH-inhibiting pills, no eggs mature -Progesterone injection/implant (convenient) to stop eggs being released -Condom/diaphragm: stops sperm meeting the egg (barrier contraception) -IUD (copper coil): stops egg embedding in lining -Abstinence -Clamping oviduct or vasectomy (cutting sperm tubes)
53
What are examples of fertility treatments?
-FSH/LH injections -IVF (in-vitro fertilisation)
54
How does IVF work?
-Eggs collected after inducing release with LH to be fertilised in an lab -Viable embryos inserted back into woman's uterus
55
What are cons of IVF?
-It's hard -Expensive -There is a low success rate -Can potentially cause multiple embryos to develop
56
What does adrenaline do?
Increases blood flow & breathing rate, to prepare you for 'fight or flight'
57
What does thyroxine control?
The body's metabolic rate
58
What happens when thyroxine levels are too low?
-Hypothalamus in brain releases TRH -Causes pituitary gland to release TSH -Causes thyroid to release more thyroxine - Example of NEGATIVE FEEDBACK
59
What do gibberellins do?
-Induce germination -Promote flowering -Increase fruit size
60
What does ethene do?
-Cause ripening
61
What do auxins control and how do they work?
-Shoot and root growth -Sunlight destroys it, so causes the cells on the shaded side of the shoot to grow/elongate more quickly -Shoot bends towards the sun (PHOTOTROPISM) -Gathers on bottom of roots, where it inhibits growth instead, meaning it grows downward (GEOTROPISM)
62
What are 3 things auxins be used as?
-Weedkillers -Rooting powders -Promoting growth in tissue cultures
63
What is the practical to observe geotropism in roots?
-Place seeds on damp cotton wool in petri dish stood on edge -Turn 90 degrees after a few days to observe geotropism in roots

Biology Paper 2 (3 decks)

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