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Biology Paper 2 > B5 > Flashcards

B5 Flashcards

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1
Q

What is homeostasis

A

The regulation of the internal body condition ls and the maintaining of it

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2
Q

Give 3 things that are controlled by homeostasis

A

Water levels
Body temp
Glucose conectration in blood

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3
Q

Homeostasis consists of automatic control systems. why is it important that the internal conditons of body remain constant as possible

A

For enzymes and cells

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4
Q

What 2 parts form the CNS (cental nervous system)?

A

Brain
Spinal cord

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5
Q

What is a stimuli

A

Change in environment

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6
Q

Name the 5 sense organs

A

. Skin
. Tongue
. Eyes
. Ears
. Nose

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7
Q

Where are receptors found

A

In the 5 sense organs

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8
Q

What is a synapse

A

Gap between 2 nerve cells

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9
Q

What is a reflex action and why is it important

A

. It is a reaction
. It involves the subconscious part of the brain
. Automatic and rapid

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10
Q

What is the endocrine system

A

It is a system consisting of glands. These send secrete hormones which send chemical messages that travel through the blood to target organs to produce an effect

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11
Q

What are the glands in an endocrine stystem?

A

Thryroid, testes, adrenal, pitruitry, ovary, pancreas

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12
Q

What hormone does thyroide produce?

A

Thyroxine - for growth + regulates metabolic reactions

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13
Q

What hormone does testes produce?

A

Testosterone - produced in puberty. For reproduction

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14
Q

What hormone does adrenal produce?

A

Adrenalin - produced in fear or stress. Fight or flight

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15
Q

What hormone does ovary produce?

A

Oestrogen - produced in puberty for reproduction. Produced in menstrual cycle

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16
Q

What hormone does pancreas produce?

A

Insulin + glucagon - controll blood glucose concentration

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17
Q

How do we controll high blood glucose concentration

A

. First the person eats a meal with carbohydrates
. Then blood glucose increases
. Pancreas detects this increase and starts producing insulin
. Insulin travel through the blood to the body cells and triggers them to take in glucose
. Insulin then travel through the blood to liver and muscles cells and tries them to take in glucose and store it as glycogen
. Then makes blood glucose concentration decrease to a regular level

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18
Q

How does body controll low blood glucose concentration

A

. When glucose concentration low, pancreas detects this and starts producing glucagon
. Glucagon then travels through the blood to liver and muscle cells
. Triggers them to convert glycogen back into glucose
. Blood glucose concentration increases

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19
Q

What is type 1 diabetes and how do we treat it

A

Pancreas doesn’t produce enough insulin. To treat, inject person with insulin

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20
Q

What is type 2 diabetes and how do we treat it

A

Body cells stop responding to insulin produced by pancreas
Treat by containing diet. Controll level of carbohydrates and exersise
Risk factor - obesity

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21
Q

How long is the menstrual cylce

A

28 days

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22
Q

What does ovulation mean

A

When ovaries release egg into uterus

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23
Q

What day does a woman ovulate usually

A

Day 14

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24
Q

What are the 4 hormone ld involved in the menstrual cycle

A

FSH, LH, oestrogen, progestrogen

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25
Q

Where is FSH produced and what does it do

A

Produced in pitruitry gland. Matures an egg

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26
Q

Where is LH produced and what does it do

A

Produced in pitruitry gland. For ovulation, egg is released

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27
Q

Where is oestrogen produced and what does it do

A

Produced in ovary. Builds up lining of uterus (thick and spongy)

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28
Q

Where is progesterone produced and what does it do

A

Produced in ovary. Maintains lining of uterus

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29
Q

What is the difference between fertility and inferitity

A

Fertility - able to reproduce, concieve
Inferitity - unable to reproduce, can’t conceive

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30
Q

Name an describe a treatment of infertility

A

Infertility drug:
FSH and LH are given to woman
This causes woman to ovulate more than usual
This increases chances of becoming pregnant

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31
Q

What is IVF (in-vitro pertilisation) and how is it carried out

A

. Firtilistation takes place outside of body
. Mother is treated with FSH and LH causing several agfs to mature
. Eggs are collected. Sperm is collected by the father and is used to firtilise egg in lab
. Once embryos are tiny balls of cells they are inserted into women’s uterus

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32
Q

What are the advatanges of IVF

A

gives woman chance to have her own baby
Works where other fertility treatment might fail
Can use donated egg or sperm

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33
Q

What are the disadvantages of IVF

A

. Success rate not high
. Expensive
. Emotionally very stressful for moth parents
. Physically demanding on mother eg: in treatment with firtilty drugs and in the collection of eggs
. Can lead to multiple births (risk for baby and mother)
. Mot all embryos created are transfered into mother

34
Q

What is ment by contraception

A

Something Used to prevent prevent a woman from getting pregnant. 2 types - hormonal and barrier

35
Q

How does Implants, patches or injections prevent pregnancy

A

Hormonal
Contain progesterone which stop egg from maturing. More convenient than taking daily pill and longer lasting but does not protect against STIs

36
Q

How does contraceptive pills prevent pregnancy

A

Contain hormone which prevent body from producing hormone FSH
hormonal method
Highly affective if taken correctly
Must be taken daily, can forget it, increase risk breast cancer

37
Q

How does IUD (intrauterine device) prevent pregnancy

A

Prevent embryo from implanting. Some have morn ones wich reduce risk of pertilisation. Highly affective, prevent pregnancy for 10 years however do not protect against STIs

38
Q

How does spermicide prevent pregnancy

A

Kills or reduces sperm and reduce risk of firtilistation. Prevents peehanacy but doesn’t protect against STIs

39
Q

How does condoms prevent pregnancy

A

Barrier method
Prevents sperm from reaching egg
Doesn’t use hormones
No side affects
Protects against STIs

40
Q

How does natural prevent pregnancy

A

Don’t have intercourse - won’t get pregnant but hard to know when woman is ovulating

41
Q

How does sterilisation prevent pregnancy

A

Prevent egg reaching uterus/prevent sperm from leaving. Highly effective but doesn’t protect against STIs

42
Q

What is thermoregulation

A

Maintaining body regulation -
. Normal body temp is 37°c
. Body temp monitored by brain
. Thermoregulatory centre contains receptors which are sensitive to temp of blood
. Skin contains temp receptors. They send electrical impulses down the sensory neurons to the Thermoregulatory centre

43
Q

How to cool body temp if too high

A

. Sweating - sweat is on surface of skin a nd evaporates using heat energy which cools body down
. Vasodilation - blood vessels dilate/widen which allows more blood to pass through. This transfers heat out of body to the surroundings

44
Q

How body warms up when body temp too low

A

Shivering - when shiver, skeletal muscles contract. To generate energy for this, muscle cells do more respiration which which releases heat which warms up body
. Vasoconstriction - blood vessels constrict and become narrower (less blood flows through capillaries and less heat is lost from body)

45
Q

How does our body maintain water balance if water level too low?

A

If blood too concentrated (level of water in blood too low) then pitruitry gland release ADH (anti duretic hormone)
. ADH causes kidney tubules to become more permeable to water so more water can pass out of kidney tubules
. More water is reabsorbed back into blood so less urine is made
. One water level returns to normal, the pitruitry gland stops releasing ADH

46
Q

How does sour body maintain water balance when water level is too high

A

. When blood becomes dilute (water in blood to high)
. Water conectration in blood rises and pitruitry gland stops releasing ADH
. This means kidneys reabsorb less water in the blood
. Now more water is produced and the concentration of water in the blood returns back to normal

47
Q

How do the kidneys work

A

. Blood enters capillaries
. Some molecules are filtered out of the blood and are passed onto kindney tubules (small pores) such as glucose, water, ions and urea
. Selective reabsorption occurs. This is when all glucose, some water and no urea is absorbed.
. All the excess ions, water and all the urea exits the body through the bladder where it Is stored

48
Q

What are the 3 ways in wich the body can loose water?

A

. Lungs when we exhale - no way to control this water loss
. Sweat through skin - sweat also contains ions like sodium ions and waste product (urea). The body can’t controll this water loss because this is part of the bodies tempurature controll system
. Through the kidneys and urine - body can controll this

49
Q

How does the body deal with excess amino acid

A

. When we digest protien, amino acid passes into the blood
. Excess - we eat more protien than what is needed
. The liver breaks down the excess amino acid and produces ammonia. This is called deamination
. Ammonia is very toxic so liver immediately converts it to urea. Urea is then safely excreted by the kidneys

50
Q

What happens if a person kidneys fail?

A

Blood will contain higher concentration of water, ions and urea them it should. To correct this, person should get dialasis or kidney transplant

51
Q

What is dialasis? How does it work?

A

. Persons blood passes over semi permeable membrane
. It allows water, ions and urea to pa’s through but not larger molecules like protein and blood cells
. Dialisis fluids contial normal water and ions but not urea
. Urea then diffuses from the blood into the dialysis fluid
. The dialysis fluid is constantly refeshed so there is always a large concentration gradient for urea

52
Q

What is kidney transplant

A

Affected kidney is replaced with a donated one

53
Q

What are the advantages and disadvantages of dialysis

A

. No shortage of dialysis machines
. However requir frequent treatment and controlled diet
. Expensive in the long term
. Patient need visit hospital several times a week

54
Q

What are the advantages and disadvantages of kidney transplant

A

. Allow pateint to lead a normal life
. Only expensive initially
. However they is shortage of donners
. Patient has to take anti rejectal drugs for test of life

55
Q

Why is it dificult to investigate the brain function and treat brain damage and disease?

A

. Brain is protected by the skull so it is tricky to access
. The structure of the brain is extremely complex
. It is dificult to work out exactly which parts of the brain carry out specific functions
. The brain is delecate and easy to damage

56
Q

What are 3 ways scientist use to investigate the brain?

A

. Look at the patients who have brain damage. By finding where the damage happened, scientists can link the brain part with specific functions
. Electricaly stimulate different parts of the brain. Look at the effects of the persons behaviour. This allows us to narrow down the specific regions to there functions
. MRI scanning - look at parts of brain which are most active during acivities

57
Q

What does the cerebral cortex do

A

This is the outer wrinkly bit, it is responsible for things like consiousness, intlegence, memory and language

58
Q

What does the medulla do

A

Controlls unconsious activities (things we don’t have to think about) like breathing and heart beat

59
Q

What does the cerabellum do

A

Responsible for muscle coordination

60
Q

What kind of organ is the eye and what does it contain?

A

. It is a sense organ
. It contains receptors senesetive to light intensity and colour of light

61
Q

What is the function of the cornea

A

Transparent front of eye which light rays pass through. It starts the focusing of light rays

62
Q

What is the function of the pupil and iris

A

The light rays pass through the pupil wich is the centre of the iris. The iris is the coloured part of the eye.

63
Q

What is the function of the lense

A

This focuses the light rays onto the back of the eye. It changes shape to allow us to focus on near and distance objects. This is called accommodation

64
Q

What is the function of the retina

A

Light rays ae now focused on the back of the eye where the retina is. The retina contains receptor cells for light. This allows us to detect light intensity and light colour

65
Q

What is the function of the optic nerve

A

The receptor cells send electrical impulses down rbe optic nerve to the brain

66
Q

What is rbe function of the sclera

A

Tougher outer structure which protects the eye

67
Q

What is the function of the ciliary muscle and suspensory ligaments

A

Allow us to focus on distant and near objects

68
Q

What is function of iris and how does it work

A

Iris controlls the size of the pupil. Eg in a dark room:
. In dark room there is low amount of energy entering eye
. This did sensed by receptors in the retina and an electrical impulse to The brain
. The brain then sends electrical impulses to certain muscles in the iris
. The muscles contract and become larger

69
Q

What is accommodation

A

The ability to change the shape of the lense in order to focus on near or distant objects

70
Q

How does The eye focus

A

. The eye is surrounded by a circular muscle called the ciliary muscle
. It is connected the the lense by fibres called suspensory ligaments
. By contracting and relaxing, the ciliary muscle can change the thickness of the lense

71
Q

How does our eyes focus on distant objects

A

. Light from distant objects needs to be focused only a small amount
. The ciliary muscle relaxes and the suspensory ligaments are pulled tight
. The lense is thin, the light rays are only slightly refracted
. The light rays are focused on the retina

72
Q

How does our eyes focus on hear objects

A

. Light from near objects needs to be focused a large amount
., the ciliary muscle contracts and the suspensory ligaments loosen
. The lense is thicker, the light rays are refracted more strongly
. The light rays are focused on the retina

73
Q

What is hyperopia (longsighted) and how do we treat it

A

It is whenth eye can’t focus on near at objects.
. The eye ball is too short and the lense may be too thin so the light rays focus at a point behind the retina.
. To treat use glasses with convex lense
This will focus the light before jt enters the eye

74
Q

What is myopia (shortsighted) and how do u treat it

A

. Eye can’t focus on far objects
. The eye ball is too long. The lense could be too thick so the light rays focus at a point in front of the retina
. Treated with glasses with concave lenses
. They partially unfocuse the light before it reaches the eye

75
Q

What are some other ways to treat eye conditons

A

. Hard and soft contact lenses
. Lazer surgery (used to change shape of cornea so it refracts light at a greater or lesser extent)
. The lense inside the eye can be replaced with an artifical lense

76
Q

What is phototropism and what was the investigation to see how it works

A

. This is when plant shoots grow towards the light
. Light shorn from one side of plant shoots. Result: shoots grow towards the light. Scientists thought this was controlled by hormones
. Ssceintists wanted to see where in plant hormone was produced so they removed the tips of the shoots. Shoots did jot grow and bend towards light so it is concluded that the tips produce a hormone called auxin.
To ensure plant was making auxin, scientist ls covered shoot tips with foil to block out light. Result: shoot tips did not grow towards the light so shoot tips are semsetive to light
. Used foil to cover bottom of shoot tips. Result: shoot tips grew toward slight, bottom Is not semsetive to light

77
Q

What is auxin and what does it do

A

It is produced at the tip of the shoot and triggers cell growth
Light causes auxin to concentrate on the darker side if shoot tip and spread down. Cells on darker side grow faster than on Lighter side.
This causes the shoot tip to grow towards the light

78
Q

What is gravotropism/geotropism

A

. Plant roots grow towards the force of gravity
. Auxin is produced in the root but gravity causes auxin to concentrate on the lower side
Auxin is roots prohibits cell growth
. The power side now grows more slowly than the upper side. The roots grow towards gravity

79
Q

What is auxin used for

A

Used as weed killers eg: In hardens
Used as rooting powders (plant cutting - cloning)
Used for promoting growth In tissue culture

80
Q

What is the plant hormone gibberelin and what is it used for

A

. Important in starting the germination of seeds
. Used to end seed dormancy (allow seed to germinate earlier than it would)
. Used to encourage plants to flower
. Used to make fruits grow larger

81
Q

What is the plant hormone ethene and what is it used for

A

. It is a chemical that controlls cell division and the ripening of friut
. Used in food industry

Biology Paper 2 (3 decks)

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