Paper 2 Biology Flashcards
(112 cards)
1
Q
What is homeostasis
A
homeostasis is the regulation of the internal conditions of a cell or organism to maintain optimum
conditions for function in response to internal and external changes
2
Q
Order of negative feedback
A
Receptors - detect a stimulus
Coordination centre - receives and processes information then organises a response
Effectors - produce a response which counteracts the change level and restore the optimum level
3
Q
Effectors can be either
A
Muscles or glands
4
Q
What is stimulus
A
A change in environment
5
Q
Examples of coordination center
A
Brain
Spinal cord
Pancreas
6
Q
What part of the body is the CNs
A
Brain and spinal cord
7
Q
How is the CNS connected to the body
A
By sensory neurones and motor neurones
8
Q
What does CNS stand for
A
Central nervous system
9
Q
What is the sensory neurone
A
The neurone that carries information as electrical impulses from the receptors to the CNS
10
Q
What are motor neurones
A
The neurones that carry electrical impulses from the CNS to effectors
11
Q
What are the effectors
A
All your muscles and glands as they respond to nervous impulses
12
Q
Why are muscles and glands known as effectors
A
Muscles - cuz they contract in response to a nervous impulse
Glands - cuz they secrete hormones
13
Q
Example of a receptor
A
The retina of the eye is covered in light receptor cells
Taste receptors
Sound receptors
14
Q
Reflex actions
A
Are automatic and rapid
Not involving the conscious part of the brain
15
Q
Synapses
A
The connection between two neurones are called synapses
The nerve signal is transferred by chemicals which diffuse across the gap
These chemicals set off a new electrical signal in the next neurone
16
Q
A reflex arc
A
The passage of Information in a reflex ( from receptor to effector )
17
Q
What is the cerebral cortex
A
It is the outer wrinkly bit and it is responsible for the intelligence,memory , consciousness and language
18
Q
Medulla
A
Controls unconscious activities like breathing and heartbeat
19
Q
Cerebellum
A
Responsible for muscle coordination
20
Q
Methods used by scientists to study the brain
A
MRI scan
Studying people with brain damage
Electrically stimulating the brain
21
Q
Explain how to electrically stimulate the brain
A
By pushing an tiny electrode into the tissue and giving it small zaps of electricity
By observing what stimulating different parts of the brains does it is possible to get an idea of what those parts of the brain do
E.g when the motor area in the brain is stimulated it causes muscle contraction and movement
22
Q
What does mri stand for
A
Magnetic resonance imaging
23
Q
What is an mri scanner
A
It is a machine that produces detailed images of the brain structure and detects what part is being stimulated when doing certain activities like listening to music or trying to recall a memory
24
Q
Studying people with brain damage
A
For instance if a small part of the brain is damaged and it results in vision loss we can come to the conclusion that the part of the brain that was damaged has to do with vision loss
25
Difficulty with investigating brain function and treating brain damage /disease
Physical damage to the brain
Increased problem with brain function eg difficulty with speech
26
Sclera
The tough supporting wall of the eye
27
What is the eye
The eye is a sense organ containing receptors sensitive to light intensity and colour
28
Cornea
The transparent outer layer found at the front of the eye
It refracts light into the eye
29
The iris
Contains muscles that allow it to control the diameter of the pupils and therefore how much light enters the eye
30
The lens
Focuses the light onto the retina
31
Retina
Contains receptor cells sensitive to light intensity and colour
32
What controls the shape of the lens
Ciliary muscles
Suspensory ligaments
33
The optic nerve
Carries impulses from the receptors on the retina to the brain
34
What is accommodation
The process of changing the shape of the lens to focus on near or distant objects
35
To focus on a near object
• the ciliary muscles contract
•the suspensory ligaments loosen
• the lens is then thicker and refracts light rays strongly.
36
To focus on a distant object
• the ciliary muscles relax
• the suspensory ligaments are pulled tight
• the lens is then pulled thin and only slightly refracts light rays.
37
Myopia
Shortsightedness
38
Explain the iris reflex
When the light receptors in your eyes detect a very bright light , a reflex is triggered causing the pupil to become smaller
The circular muscle in the iris contracts and the radial muscle relaxes
This reduces the amount of light that can enter the eye
And the opposing the light is too dim
39
Hyperopia
Longsightedness
40
What causes long sighted ness
When the lens is the wrong shape and doesn’t refract the light enough or the eye ball is too short
The image of near objects are brought into focus behind the retina
41
What type of glasses do long sighted people wear
Cortex lens glasses
( a lens which curves outwards to correct it
The lens refracts the light rays so they focus on the retina
42
What causes shortsightedness
This occurs when the lens is the wrong shape and refracts too much light into the light or the eye is too long
The image of distant objects is brought into focus in front of the retina
43
What type of glasses do short sighted people use
Concave lens glasses
A lens which curves inwards to correct it so that the light rays focus on the retina
44
The treatment for vision defects
Contact lenses
Laser eye surgery
Replacement lens surgery
45
What are contact lenses
Thin lenses that sit on the surface of the eye and are shaped to compensate for the fault in focusing
46
Why are contact lenses popular
Light weight
Almost invisible
More convenient than glasses especially when doing activities like sports
47
What are the 2 main types of contact lenses
Soft lenses which are more comfortable and higher risk of eye infection
Hard lenses which are less comfortable and less risk of eye infection
48
Laser eye surgery
A laser can be used to vaporise tissue which will change the shape of the cornea
Slimming it down makes it less powerful and improve short sight
Change the shape so it is more powerful helps long sight
49
Risk of laser eye surgery
Eye infection
Eye may react in a way that will cause further vision impairment
50
Replacement lens surgery
The natural lens of the eye is removed and an artificial lens (made of clear plastic) is inserted in its place
51
Risk factors of replacement lens surgery
Possible damage to the retina which could lead to loss of vision
52
Body temperature is controlled by ?
Thermoregulatory centre in the brain
53
Thermoregulatory centre has receptors which are ?
The thermoregulatory centre contains receptors sensitive to the temperature of the blood
54
The skin contains what type of receptors
The skin contains temperature receptors and sends nervous impulses to the Thermoregulatory centre
55
What happens when your body temp is too hot
Temperature receptors detect that the core body temperature is too high,
so the thermoregulatory centre, receives the information from the receptors and triggers The effectors automatically
blood vessels Dilates (vasodilation)
sweats is produced from the sweat glands.
These mechanisms cause a transfer of energy from the skin to the environment
56
When your body temp is too low /cold
Temperature receptors, detect the core body temperature is too low
The thermal regulatory centre acts as a coordination centre and receives information from the receptors and triggers the effectors automatically
Blood vessels, constricts,(vasoconstriction)
Sweating stops and skeletal muscles contract (shiver )
57
The endocrine system
Composed of glands which secrete chemicals called hormones directly into the blood stream
The blood carries the hormones to the target organ where it produces an effect
They are slower compared to the nervous system but act for longer
58
The pituitary gland
Produces many hormones that regulate body conditions
Called the master gland
Cuz these hormones act on other glands , directly them to release hormones that bring about change
59
Ovaries (female only )
Produces oestrogen
Which is involved in the menstrual cycle
60
Testes (male only )
Produces testosterone
Which controls puberty and sperm production in males
61
Thyroid
Produces thyroxine
Which is involved in regulating things like rate of metabolism, heart rate and temperature
62
Adrenal gland
Produces adrenaline
Which is used to prepare the body for a “fight or flight “ response
63
Pancreas
Produces insulin
Which is used to regulate the blood glucose levels
64
Differences between hormones and nerves
Nerves
Very fast action
Acts for a short time
Acts on a very precise area
Hormones
Slower reaction
Acts for a long time
In a more general way
65
How are blood sugar concentrations controlled and monitors
By the pancreas
66
Where is excess glucose stored
It is stored as glycogen in the liver and in the muscles
67
Using insulin in negative feedback cycle
If the blood glucose levels is too high
The pancreas produces the hormone insulin that causes glucose to move from the blood to the cells
In the liver and muscles excess glucose is turned into glycogen for storage
68
Type 1 diabetes
Is a disorder in which the pancreas fails to produce sufficient insulin
Making the blood glucose levels rise to a level that could cause them hard
Treatment is insulin injections
69
Type 2 diabetes
The body cells no longer respond to insulin produced by the pancreas
A carbohydrate controlled diet and exercise regime are common treatments
Risk factor - obesity
70
Using glucagon in negative feedback loop
If the blood glucose levels is too low
The pancreas produces the hormone glucagon that causes glucose to move from the liver to the blood
Glucagon turns glycogen into glucose
71
Urea
Proteins can’t be stored in the body
So any excess amino acids are converted into fats and carbohydrates which can be stored
It Occurs in the liver in a process called deamination
Ammonia is produced as a waste product from this process
Ammonia is toxic so it converted to urea in the liver
Urea is then transported to the kidney
Where it is filtered out of the blood and excreted from the body in urine
72
Water
We lose water from the skin in sweat
From the lungs in breathing out
We can’t control the amyotrophic water we lose during these ways so it is balanced by the amount we consume and the amount removed by the kidney in urine
73
Ions
Ions like sodium are brought into the body through food and then absorbed into the blood
Some ions are lost in sweat
But it is not regulated so the kidney has to maintain the right balance
The right amount is reabsorbed after filtration and the rest is removed in urine
74
What is ADH
Anti-diuretic hormone
It is released into the blood by the pituitary gland
It controls the concentration of urine
75
Negative feedback for adh
Receptors in The brain monitors the water content of the blood as they detect the water content is too high
Coordination centre in the brain instructs the pituitary gland to release adh into the blood according to how much is needed
76
Kidney transplant
Risk
The kidney can be rejected by the patient’s immune system
Transplants are cheaper than dialysis
77
dialysis
time consuming
expensive
can cuase blood clotting and infection
78
what is the menstral cycle
the monthly release of an egg from a womans ovaries
79
the main reproductive hormone in men
testosterone
produced by testes and stimulates sperm production
80
the main reproductive hormone in women
oestrogen
produced in the ovaries
involed in the menstral cycle
81
the stages of a menstral cycle
stage 1 - day 1 menstruation starts , the uterus lining breaks down for about 4 days
stage 2- the uterus lining builds up again,from day 4-14, into a thick spongy layer full of blood vessels , ready to recieve the fertilised egg
stage 3- an egg develops and is released from the ovary at day 14 [ovulation]
stage 4 - the wall is then maintained for about 14 days [til day 28] if no fertilised egg is received in the uterus the wall begins to break and the cycle starts
82
fsh
follicle-stimulating hormones
produced in the pituitary gland
causes an egg to mature in one of the ovaries , in the structure of a follicle
stimuates the oestrogen
83
LH
luteinsing hormone
produced in the pulumary gland
stimulates the release of an egg at day 14
84
oestrogen
produced in the ovaries
causes the lining of the uterus to grow
stimulates the release of LH [which causes the release of an egg ]
and inhibits release of fsh
85
progesterone
produced in the ovaries by the remains of the follicle after ovuation
maintains the lining of the uterus during the second half of the cycle
when progesterone level falls the lining breaks down
inhibits the release of lh and fsh
86
what are the two types of contraception
hormonal and non-hormonal
87
condoms - barrier method
worn over the penis during intercourse to prevent the sperm entering the vegina
only form of contarception that protects against stds
88
diagrapm - barrier method
a shallow plastic cup that fits over the certix to form a barrier
but it has to be used with spermicide
89
spermicide
can be used alone as a form of contraception
but not as effective [70-80percent ]
it kills the sperm
90
sterilization
cutting or tying the fallopian tube in a female or the sperm duct in a male
this is a parmanent procedure
91
abstinence
only 100 percent way to prevent fertiliation
92
contraceptive patch
contains oestrogen and progesterone
it is small [5cmx5cm] patch
each patch lasts a week
93
contraceptive implant
inserted under the skin of the arm
it releases a continuous amount of progesterone [ which stops the ovaries from releasing eggs ]
makes it hard for the sprm to swim to the egg and stops fertilised egs from getting to the uterus
can last 3 years
94
contraceptive injection
contains progesterone
lasts 2 to 3 months
95
iud
intrauterine device
is a t shaped device that is inserted into the uterus to kill sperm and prevent implantaion of a fertilised egg
plastic iud- releases progesterone
copper iud - that prevents the sperm surviving in the uterus
96
oral contraceptive
the pill
contains oestrogen and progesterone or just progesterone
99 perecnt effective
side effects - headache and neausea and doesnt stop std
97
pro and cons of fertility drugs
it helps women who find it hard to get pregnat]nt get pregant
it doesnt always work - it is expensive
too many eggs may be stimulated causing multiple births
98
what does IVF stand for
in vitro fertilisation
99
explain IVF
IVF involves giving a mother FSH and LH to stimulate the maturation of several eggs.
* The eggs are collected from the mother and fertilised by sperm from the father in the laboratory.
* The fertilised eggs develop into embryos in a lab incubator
* At the stage when they are tiny balls of cells, one or two embryos are inserted into the mother’s uterus (womb)
FSH and LH are given before egg collection to stimulate several eggs to mature
100
icsi
intra-cytoplasmic sperm injection
sperm is injected directly into the egg
useful if the male has a low sperm count
101
cons of IVF
multiple births [higher risk of miscarriage ]
success rate for IVF is low
26% in UK
strong reactions to hormones - stomach pain, vomiting and dehydration
102
pros of IVF
fertility treatment helps infertile couples have a child
103
why is it unethical
because it involves destroying unused embryos
could lead to selecting preferred characteristics
104
adrenaline in negative feedback
Adrenaline is produced by the adrenal glands in times of fear or stress.
It increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for ‘flight or fight’.
105
thyroxine
Thyroxine from the thyroid gland stimulates the basal metabolic rate. [the speed chemical reaction in the body ]
It plays an important role in growth and development.
106
what controls thyroxine
Thyroxine levels are controlled by negative feedback.
107
auxin
a plant hormone that controls growth near the tips of shoots and roots
it contrls the growth of a plant in response to light[phototropism]and gravity [geotropism]
auxin is produced in the tip and moves backwards to stimu,ate cell elongation [enlargement]which takes place in the cell just behind the tip
108
what direction does the shoot grow towards
when a shot tip is exposed to the light , more auxin accumilates towards the shady side than the exposed side
this makes the cells grow faster on the side that is shady causing the shoot to grow towards the light
109
what direction does the shoot and shoot grow in relation to gravity
when the shoot is growing sideways , gravity produces an unequal distribution of auxin in the tip, with more auxin on the lower side
so the lower side grows faster bnding the shoot upwards
a root growing sideways will also have more auxin on its lower side
in a root with extra auxin inhibits growth , so the cells on top elongate faster and the root bends downwards
110
uses of auxin
killing weeds- broad leaved weeds
growth from cutting with root powder-- adding this powder to a cutting makes it grow and helps make clones
grwing cells in tissue - adding auxin in the growth medium stimulates the cells to divide to form both roots and shoots
111
uses of gibberellin
it stimulates seed germination , stem growth and flowering
controlling dormancy-it helps seeds germinate at the same time or at conditions when they woud normally not grow
inducing flowering - helps flowers grow bigger or without changing the enviroment
growing larger fruits- seedless fruits dont usually groe as bigg as the seeded ones so this helps that
112
ethene uses
stimulates enzymes that cause ripening of fruit
during transportation or storage
