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GCSE Biology Revision > B5 - Homeostasis - Paper 2 > Flashcards

B5 - Homeostasis - Paper 2 Flashcards

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1
Q

What is body temperature controlled by (in the brain)?

A

Thermoregulatory centre - hypothalamus

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2
Q

Give the two ways we detect temperature of the body

A

Thermoregulatory centre in the brain detects blood temp
Skin detects skin temp and sends these signals to the thermoregulatory centre

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3
Q

Why is it important to maintain optimum body temperature?

A

To Maintain optimum enzyme activity

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4
Q

What is the main mechanism for control of homeostasis (general)

A

Negative feedback

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5
Q

Give one way body temp can be decreased once it reaches an above optimum temperature (not to do with blood vessels)

A

Sweat

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6
Q

How does sweat cool us down

A

Layer of liquid perspiration which evaporates taking heat energy away from the skin

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7
Q

How does shivering warm us up

A

Body movement = respiration = release of thermal energy

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8
Q

How does hair standing on end (goosebumps) help to warm up?

A

Traps body heat as a layer of air insulation

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9
Q

What controls the response of blood vessels to heat or cold

A

The hypothalamus

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10
Q

Give 2 things which happen if body is detected as too hot

A

Vasodilation of blood vessels close to the skin
Shunt vessels further from the skin constrict

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11
Q

What are shunt vessels?

A

Vessels below the skin (further from the surface than others)

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12
Q

Why does vasodilation of blood vessels close to the surface of the skin help to reduce body temperature

A

More blood is travelling through them
Heat is lost through radiation through the skin

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13
Q

What happens to blood vessels when too cold?

A

Vasoconstriction of blood vessels close to the skin
Shunt vessels further from the skin become dilated

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14
Q

How does vasoconstriction work to maintain body temperature

A

Diverting blood away from the skin means less heat is lost through radiation

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15
Q

Describe the reflex arc of stimulus to response on a hot day

A

Hot day->skin receptor->sensory neurone -> relay neurone (in spine) ->motor neurone -> gland effector (sweat)

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16
Q

What is the optimum temperature of the human body?

A

37 degrees

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17
Q

When talking about homeostasis in an exam always describe what?

A

Negative feedback loops

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18
Q

Why is it important to maintain blood glucose concentration?

A

Regulation of cellular respiration
High levels of blood glucose are poisonous

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19
Q

What organ is blood glucose concentration controlled by?

A

The pancreas

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20
Q

What is the name for the store of glucose?

A

Glycogen

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21
Q

How do you remember what glycogen is?

A

It has an e on it and glucose does as well but glucagon doesn’t have an e

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22
Q

Where is glycogen found?

A

Liver and muscles

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23
Q

What is insulin?

A

A hormone that increases the amount of glucose stored as glycogen

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24
Q

How do you remember what insulin goes to glucose?

A

Insulin ‘insulates’ the glucose as glycogen

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25
Q

What hormone breaks glycogen back into glucose?

A

Glucagon

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26
Q

How do you remember that glucagon breaks down glycogen to glucose?

A

GlucAgon Attacks the glycogen to make glucose

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27
Q

Explain a negative feedback loop for blood sugar levels (increase in glucose back to optimum)

A

Increase in blood sugar due to eating
Detected by pancreas
Increases insulin secretion (hence glucose stored as glycogen in muscle and liver)
Blood glucose levels decrease back to normal

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28
Q

Describe the negative feedback loop after a decrease in blood sugar levels (the going back to optimum)

A

Decrease in blood sugar due to exercise
Detected by pancreas cells
Increase in glucagon secretion (breaking down glycogen in liver/muscles back to glucose and glucose released into blood
Glucose increases back to normal

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29
Q

What is diabetes

A

When blood glucose levels can’t be regulated

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30
Q

True or false: type 1 diabetes is genetic

A

True

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31
Q

Give 5 issues with too much blood glucose

A

Toxic
Decreases blood vessel elasticity
Glucose left as deposits (atherosclerosis)
Miscarriage risk
Dehydration

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32
Q

What 2 negative effects can result from narrowing of blood vessels due to excessively high blood glucose concentrations

A

Impeding blood flow to the eyes
Could lead to nerves stopping sending signals

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33
Q

True or false: blood vessels also have to supply nerves with glucose and oxygen

A

Trye

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34
Q

What is another word for the process of glucose being left as deposits?

A

Atherosclerosis

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35
Q

What can atherosclerosis lead to?

A

CHD

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36
Q

Why can there be a miscarriage risk if blood glucose too high (2 details)

A

Less supply of oxygen for the baby
Excess amniotic fluid puts pressure on organs

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37
Q

Why does high blood glucose concentration lead to dehydration?(4 steps)

A

Kidneys usually take required amount of glucose out of urine to be retained
Can’t keep up with very high glucose concentrations
Excess glucose has to be expelled in high volumes of urine
Leading to dehydration

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38
Q

Type 1 diabetes is when ___cant produce any/enough ____ due to the destruction of ____ producing cells

A

The pancreas
Insulin
Insulin

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39
Q

Give 5 things type 1 diabetes could lead to

A

Kidney damage
Heart problems
Blindness
Nerve damage
Damage to circulation

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40
Q

Give 4 symptoms of type 1 diabetes

A

Tiredness
Losing weight
Passing lots of urine
Feeling very thirsty

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41
Q

Give 3 treatments for type 1 diabetes

A

Insulin injection/insulin pump (which monitors blood glucose levels and adjusts insulin to fit)
Healthy diet
Regular exercise

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42
Q

What is an insulin pump?

A

Monitors blood glucose levels and adjusts insulin injection to fit the requirement

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43
Q

What is type 2 diabetes?

A

Pancreas produces insulin but cells aren’t sensitive/don’t respond to it
Glucose uptake (into glycogen) doesn’t happen so blood glucose concentration stays high

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44
Q

True or false: symptoms and potential after effects of type 1 and type 2 diabetes are different

A

False - they are the same

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45
Q

Give 3 treatments for type 2 diabetes

A

Healthy diet
Exercise regimes
Oral medications to control blood glucose concentrations

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46
Q

Give 2 risk factors for type 2 diabetes

A

Obesity
Poor diet + minimal exercise

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47
Q

Digestion of proteins results in excess ____ ____ (which contain ____) which need to be excreted _____

A

Amino acids
Nitrogen
Safely

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48
Q

What is deamination?

A

The removal of an amino group from an amino acid

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49
Q

What is the main product after the deamination of an amino acid?

A

Ammonia

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50
Q

True or false: ammonia is highly toxic for the body

A

True

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51
Q

What is ammonia converted into following deamination?

A

Urea

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52
Q

How is urea excreted?

A

In urine

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53
Q

What is water potential?

A

The likelihood of water molecules to move by osmosis into or out of a solution

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54
Q

Give 3 ways water can be lost by the body

A

Breathing OUT (can’t just say breathing)
Sweat
Urine

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55
Q

During exhalation what leaves the body via the lungs

A

Water vapour

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56
Q

Give 3 things lost through the skin via sweat

A

Water, ions, urea

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57
Q

What 3 things are removed via kidneys through urine

A

Excess water, ions and urea

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58
Q

Give 2 things which the kidney does to regulate water, glucose, ion concentrations in the body

A

Filtration and selective reabsorption

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59
Q

Describe what happens when the kidney filters blood

A

All small molecules (water, glucose, urea, ions) filtered from blood by kidney

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60
Q

What is selective reabsorption?

A

Right amount of water and ions and glucose re absorbed back into the blood depending on the body’s needs

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61
Q

What are the kidney tubules?

A

The part of the kidney where filtration and selective reabsorption occurs

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62
Q

What is ADH?

A

Controls the amount of water re absorbed back into blood

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63
Q

What is ADH produced by?

A

Pituitary gland

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64
Q

More ADH = more/less permeable

A

More permeable

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65
Q

More permeable kidney tubules = more/less water reabsorbed into the blood and more/less water lost via urine

A

More
Less

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66
Q

What is water concentration in the blood detected by

A

The hypothalamus

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67
Q

Blood water concincreases = more/less ADH

A

Less ADH - less permeable tubules - more dilute urine

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68
Q

What is a dialysis machine?

A

Removes waste products and excess fluid from the blood

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69
Q

What is dialysis used for?

A

Kidney failure

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70
Q

What would happen if your kidneys failed and why?

A

Damage to several organs and organ systems/ eventually death because
- waste substances would build up
- water content uncontrolled
- ion levels uncontrolled

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71
Q

Give 2 necessary dietary changes while on dialysis

A

Avoid salty foods (prevent ion build up between dialysis sessions)
Limit fluid content (prevent water content being too high, diluting blood and increasing blood pressure)

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72
Q

Give the 5 stages of a dialysis machine

A

Arterial Blood leaves arm
Anticoagulants (blood thinners) administered to prevent clotting
Blood runs through dialysis machine
Clean blood runs through bubble trap to get rid of bubbles
Clean blood returns to the arm

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73
Q

Dialysis fluid has the ____ concentration of glucose and mineral ions as healthy blood but is _____ in ____ and ____

A

Same
Low
Salt
Urea

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74
Q

Excess salt and urea moves out of the blood into the dialysis fluid through a partially permeable membrane in a dialysis machine by _____

A

Diffusion (along a concentration gradient)

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75
Q

True or false: there is a net movement of glucose and mineral ions in a dialysis machine

A

False

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76
Q

What is the function of a dialysis machine?

A

Filter blood and maintain safe ion concentration in the blood by removing excess ions and waste substances such as urea

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77
Q

Give 2 disadvantages of dialysis

A

Requires 3 sessions per week per patient
Costs around £300 per session

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78
Q

Give 1 advantage of dialysis

A

Readily available

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79
Q

Give 1 advantage of kidney transplants

A

Long term solution to kidney damage + a one time operation

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80
Q

Give a disadvantage of kidney transplants

A

Take a long time to be found
As an exact tissue match has to be found

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81
Q

What is thyroxine

A

A hormone released by the thyroid gland

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82
Q

What is thyroxine released by

A

The thyroid gland

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83
Q

What does thyroxine control

A

Basal metabolic rate (rate of energy transfers/chemical reactions in cells)

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84
Q

What is TSH?

A

Thyroid stimulating hormone

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85
Q

What is TSH released by

A

The pituitary gland

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86
Q

What does TSH do?

A

Controls how much thyroxine the thyroid gland produces

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87
Q

Give the negative feedback loop of thyroxine and TSH

A

Thyroxine levels too high - TSH secretion stops to reduce thyroxine back to optimum
Thyroxine levels too low - TSH secretion increases to increase thyroxine back to optimum

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88
Q

What recognises that thyroxine levels are too high?

A

Hypothalamus

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89
Q

What is adrenaline released by?

A

The adrenal gland

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90
Q

Why is adrenaline released?

A

In response to stressful situations

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91
Q

What does adrenaline do?

A

Gets body ready for fight or flight

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92
Q

Give the reflex arc for the release of adrenaline and it’s physical effects

A

Brain detects fear/stress
Sends nervous impulse to the adrenal glands
Adrenal glands release adrenaline
This increases heart rate to increase supply of oxygen and glucose to brain and muscles

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93
Q

What does adrenaline do physically?

A

Increase heart rate to increase supply of oxygen and glucose to the brain and muscles

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94
Q

What is oestrogen secreted by?

A

Ovaries

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95
Q

Where is oestrogen secreted to?

A

The uterus
And pituitary gland

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96
Q

What is testosterone secreted by

A

The testes

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97
Q

Where is testosterone secreted to?

A

Sex organs

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98
Q

What does oestrogen control the development of?

A

Female secondary sexual characteristics

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99
Q

Give 3 examples of female secondary sexual characteristics

A

Menstruation every 28 days
Development of breasts
Widening of hips
(Puberty basically)

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100
Q

Give 3 examples of make secondary sexual characteristics

A

Muscle development
Hair growth
voice breaking
Sperm production
(Puberty basically)

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101
Q

How long is the menstrual cycle?

A

28 days

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102
Q

Days 1-7 of the cycle what happens?

A

Uterus lining shed through the vagina

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103
Q

Days 8-13 what happens?

A

Uterus lining rebuilds

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104
Q

What happens on day 14

A

Egg released from ovaries = ovulation

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105
Q

What happens days 15-28

A

Uterus lining stays thick

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106
Q

If the egg is fertilised then uterus lining stays __ and there is __- period

A

Thick
No

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107
Q

If it is not fertilised the egg ____ via the ____

A

Leaves
Period

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108
Q

What does FSH do?

A

Causes the egg to mature in the ovary

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109
Q

What is FSH produced by?

A

The pituitary gland

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110
Q

What does FSH stimulate?

A

Release of oestrogen from ovaries

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111
Q

What does oestrogen do?

A

Repairs and thickens uterus lining

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112
Q

What is oestrogen produced by?

A

The ovaries

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113
Q

What does oestrogen stop being produced?

A

FSH

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114
Q

Why does oestrogen stop the release of FSH?

A

So only one egg matures

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115
Q

What does oestrogen stimulate?

A

Stimulates the pituitary gland to release LH

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116
Q

What is LH triggered by?

A

Oestrogen

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117
Q

What is LH released by?

A

The pituitary gland

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118
Q

What does progesterone do?

A

Maintains uterus lining

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119
Q

What is progesterone produced by?

A

By the follicle (which releases the egg - its a yellow body)
It is then released by the ovaries

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120
Q

At the start of the cycle ___ is high as an egg is maturing in the ovaries?

A

FSH

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121
Q

After FSH is high at the start then ____ peaks, stopping ___ production so the egg matures and ____ the uterus lining

A

Oestrogen
FSH
Develops

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122
Q

After oestrogen peaks ___ peaks and the ___ is released

A

LH
Egg

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123
Q

After the egg is released then ___ peaks to maintain the ___ uterus lining

A

Progesterone
Thick

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124
Q

What type of contraceptive method is the combined pill?

A

Hormonal

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125
Q

Give 3 ways in which the combined pill works as a contraceptive

A

Leaves thick cervical music to stop sperm entering
Consistent high levels of oestrogen to stop FSH
Progesterone stops LH production

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126
Q

Oestrogen presence inhibits what?

A

FSH

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127
Q

Progesterone stops ___ production

A

LH

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128
Q

Give 4 advantages of the combined pill

A

Free on the NHS
99% effective
Reduces risks of some cancers
Makes bleeds light and regular

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129
Q

Give 5 disadvantages of the combined pill

A

Not effective if vomiting
Not 100% effective
Side effects
No STD Protectiom
Can increase risk of blood clots and some cancers

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130
Q

Give 3 possible side effects of the combined pill

A

Nausea
Headaches
mood swings

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131
Q

The progesterone only pill is a ___ method of contraception

A

Hormonal

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132
Q

Give 2 ways the progesterone only pill works as a contraceptive

A

Ensures thick cervical mucus
Prevents ovulation by limiting LH production

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133
Q

Give 4 advantages of the progesterone only pill

A

At least 99% effective
Fewer side effects than the combined pill
Free on the NHS
Suitable if you have high blood pressure/a history of blood clots

134
Q

Give 3 disadvantages of the progesterone only pill

A

Disadvantages
Just take it same time each day
No STD protection
Some medications make it less effective

135
Q

How do surgical methods of contraception work?

A

Cutting or tying fallopian tubes or sperm duct

136
Q

Give 2 advantages of the surgical method

A

Permanent
100% effective

137
Q

Give 2 disadvantages of the surgical method

A

Permanent
Risks of surgery

138
Q

Is spermicide a hormonal or non hormonal method

A

Non hormonal

139
Q

How does spermicide work?

A

Kills or disables sperm

140
Q

Give 2 advantages of spermicides

A

Non invasive
Short term

141
Q

Give 2 disadvantages of spermicide

A

Only 70-80% effective
No STI protection

142
Q

What is abstinence

A

Avoiding sex during most fertile periods

143
Q

Give 1 advantage of abstinence

A

Popular with those that consider hormonal/barrier methods unnatural

144
Q

Give 2 disadvantages of abstinence as a contraceptive technique

A

Not very effective
No protection from STIs

145
Q

How does a condom work?

A

Prevents sperm entering vagina (worn over penis)
Female condoms also available

146
Q

Give 3 advantages of condoms

A

Advantages
Only contraceptive that effective against STDs
98% effective
No side effects

147
Q

Give 3 disadvantages of condoms

A

Disadvantages
Costs money (if not at sexual health clinic)
Can tear
Some have allergies to latex

148
Q

What is a diaphragm?

A

Shallow plastic cup over cervix (entrance of uterus)+combines with a spermicide (substance disabling/killing sperm)

149
Q

What % effective is a diaphragm?

A

92-96% effective

150
Q

Give 2 advantages of a diaphragm

A

92-96% effective
No side effects

151
Q

Give 2 disadvantages of a diaphragm

A

Limited protection against STDs
Limited effectiveness

152
Q

Is the contraceptive patch a hormonal method?

A

Yes

153
Q

How does the contraceptive patch work?

A

Contains oestrogen and progesterone - small patch stuck on skin for a week
Progesterone stops egg release
High levels of oestrogen prevent egg maturing so not released

154
Q

Give 5 advantages of the contraceptive patch

A

Easy to use
Still effective if vomiting
Over 99% effective
Lighter and regular periods
Free on the NHS

155
Q

Give 4 side effects of the contraceptive patch

A

Nausea
Headaches
Mood swings
Increased risk of breast cancer
Visible skin irritation

156
Q

Give 1 disadvantage of the contraceptive patch.

A

No STD protection

157
Q

Give 3 ways the contraceptive implant works

A

Continuous progesterone
Makes uterus lining thin
Thickens mucus at cervix to prevent sperm entering uterus

158
Q

What is fertility?

A

The ability to conceive a child

159
Q

What is a contraceptive

A

Method for preventing pregnancy

160
Q

How do hormonal methods work?

A

Prevent fertilised egg implanting in uterus lining

161
Q

How do barrier methods work

A

Stop sperm meeting egg

162
Q

How can fertility be increased?

A

Hormones can be injected

163
Q

Give 2 hormonal fertility drugs for women

A

FSH and LH

164
Q

What does IVF stand for

A

In vitro fertilisation

165
Q

True or false:IVF can happen in a lab without any beforehand treatment

A

False - hormone treatment with LH/FSH must be used

166
Q

During IVF the best _____ embryos are selected using _____

A

1 or 2
Genetic screening (checking for genetic disorders)

167
Q

How much can a single cycle of IVF cost?

A

£10 000 - 30 000

168
Q

What is the success rate for IVF?

A

26%

169
Q

Give the 6 stages of IVF

A
  1. Injection of hormones to stimulate egg maturation and release (FSH/LH)
  2. Eggs removed from ovary using fluid filled needle (ultrasound used to guide needle)
  3. Sperm from donor injected
  4. Fertilisation occurs
  5. Embryos develop
  6. Best embryo planted
170
Q

What are extra embryos from IVF used for?

A

Embryonic stem cells

171
Q

What is the human endocrine system?

A

Group of glands that secrete hormones directly into the blood

172
Q

What is a gland?

A

And organ that secretes a hormone

173
Q

What is a hormone

A

A chemical messenger that travels in the blood to target organs to bring about an effect

174
Q

True or false: hormones are large proteins

A

True

175
Q

What is the pituitary gland also called?

A

Master gland

176
Q

Where is the pituitary gland situated

A

At the base of the brain

177
Q

Where are the adrenal glands?

A

Above the kidneys

178
Q

What does the ovaries produce

A

Oestrogen

179
Q

What do the testes produce?

A

Testosterone

180
Q

What do the adrenal glands produce?

A

Adrenaline

181
Q

What does the pancreas produce?

A

Insulin

182
Q

What does the thyroid gland produce?

A

Thyroxine

183
Q

Where is the thyroid gland?

A

In the neck

184
Q

Where is the pancreas

A

Above the kidneys

185
Q

What else does the pancreas produce?

A

Glucagon

186
Q

Give 3 things the thyroid gland controls

A

Metabolism
Weight
Energy

187
Q

Give two parts of the CNS

A

Brain and spinal chord

188
Q

What does the brain do

A

Controls complex behaviour

189
Q

True or false: the brain has regions which carry out different functions

A

True

190
Q

What is the brain made of?

A

Billions of interconnected neurones

191
Q

What does the cerebral cortex do?

A

Controls consciousness
Memory
Language
Intelligence

192
Q

Where is the cerebral cortex

A

The outer layer of the cerebrum

193
Q

What does the cerebellum do?

A

Controls muscle coordination

194
Q

How do you remember what the cerebellum does?

A

Llum sounds like run

195
Q

What does the medulla do

A

Controls unconscious activities

196
Q

How do you remember what the medulla does?

A

‘Me’ = unconscious me

197
Q

Give 3 unconscious activities that the medulla controls

A

Breathing, heartbeat, blood pressure, sneezing, coughing

198
Q

Give 3 methods of investigating the brain

A

Studying patients with brain damage
Electrical stimulation of parts of the brain
Using MRI scanning

199
Q

How does studying patients with brain damage help to learn about the brain

A

Working out the area damaged and then linking this area to symptoms experienced by the patient

Hence working out what the area controls

200
Q

How does stimulating the brain with electricity help to investigate the brain

A

Observing patients response to certain patterns of stimulation

201
Q

How does MRI scanning help us learn about the brain?

A

Observing what areas of brain are active when talking, eating, recalling memories etc

202
Q

What does MRi stand for

A

Magnetic resonance imaging

203
Q

Give 3 advantages of investigating the brain

A

Successful treatments can be discovered and implemented
Symptoms reductions can be found following some procedures
Less need of other medications to manage systems following these procedures
Improvements to quality of life

204
Q

Give 3 issues with investigating the brain

A

Side effects - risk of damage to patients
Many are invasive procedures which require the patient to be awake
Financial implications
Both for the patient and the NHS

205
Q

Give a scientific issue with investigating the brain

A

Highly complex and delicate
Very small scale

206
Q

What is the sclera?

A

Tough and strong outer layer to protect the eye and ensure it isn’t easily damaged

207
Q

What colour is the sclera?

A

White

208
Q

What is the cornea

A

Clear outer layer at the front of the eye

209
Q

True or false: the cornea helps to focus light on the retina by refracting it slightly

A

True

210
Q

What is the pupil?

A

A hole (made bigger or smaller by this iris)

211
Q

What is the iris?

A

A muscle

212
Q

What does the iris do?

A

Controls pupil size

213
Q

How does iris control pupil size?

A

By contracting and relaxing (changing the amount of light allowed into the retina)

214
Q

What is the retina?

A

Light sensitive receptor cells (stimulated by light/colour)
Area where the light is supposed to hit

215
Q

What is the optic nerve?

A

Sends nervous impulses to the brain
Which then interprets these as a visual image

216
Q

What is the lens and what does it do?

A

Fine tunes the focussing of light rays onto the retina

Lens held in place by ciliary muscles and suspensory ligaments

217
Q

What is lens held in place by

A

Ciliary muscles and suspensory ligaments

218
Q

Why does the iris reflex exist?

A

To prevent bright light damaging the retina

219
Q

What are the two muscles of the iris?

A

Radial and circular

220
Q

Describe the reflex arc of bright light to the reflex response

A

Light receptors in retina detect bright light
Circular muscles contract + radial muscles relax
Makes pupil smaller
Less light enters retina

221
Q

Radial muscles contract or relax for bright light

A

Relax - go inwards to cover more

222
Q

What happens to circular muscles when bright light?

A

Contract and cover more

223
Q

What happens to circular muscles in dim light?

A

Relax - cover less

224
Q

What happens when dim light?

A

Radial muscles contract - more light let in

225
Q

When light hits retina _____ turn light into _____ signals

A

Photoreceptors
Electrical

226
Q

Electrical signals are transmitted to the brain by the ____ nerve

A

Optic

227
Q

What is accommodation

A

Changing the shape of the lens to focus on near or distant objects

228
Q

Give the 2 ways the lens can be adjusted for accommodation

A

Ciliary muscles contract or relax and
Suspending ligaments slacken or stretch to adjust lens

229
Q

What happens to ciliary muscles to focus on near objects?

A

Contract - move closer to the lens

230
Q

What happens to suspensory ligaments to focus on near objects

A

Loosen to become longer and make lens thicker

231
Q

Refraction increases or decreases for accommodation for near objects?

A

Increases - as lens thicker

232
Q

To focus on distant objects ciliary muscles contract or relax?

A

Relax - moving further back from the lens

233
Q

What happens to suspensory ligaments when focussing on distant objects

A

Tense - pulled tight

234
Q

What happens to lens shape to focus on distant objects

A

Pulled tighter and thinner

235
Q

Refraction is more or less for distant?

A

Less

236
Q

How do you remember more refraction for closer and less refraction for further?

A

More refraction = less distance
Less refraction = more distance
(Opposite)

237
Q

What does ciliary muscles relaxing and suspensory ligaments tensing do to the lens?

A

Ciliary muscles relaxing = pulls away from the lens
Suspenseful tensing = pulls the lens apart

238
Q

When ciliary muscles contract suspensory ligaments do what?

A

Slacken

239
Q

What is myopia?

A

Short sightedness

240
Q

Does light focus before or after the retina in myopia

A

Before

241
Q

Give 2 reasons for myopia

A

Lens is too thick
Eyeball is too long

242
Q

What type of lens is used to correct myopia?

A

Concave lenses

243
Q

Do concave lenses refract light less or more?

A

Less

244
Q

Less refraction in concave lenses means light rays focus further forward or backwards?

A

Backwards

245
Q

What is hyperopia

A

Long sightedness

246
Q

With hyperopia you can’t focus on near/far objects

A

Near

247
Q

Where does light focus (before or after retina) with hyperopia?

A

Focuses behind retina

248
Q

Give 2 reasons for hyperopia

A

Eyeball too short
Lens too thin

249
Q

What type of lens corrects for hyperopia

A

Convex lens

250
Q

Convex lens increases or decrease refraction?

A

Increases

251
Q

Increasing refraction with convex lens means light focuses further back or further forward

A

Forward

252
Q

What is homeostasis?

A

Regulation of internal conditions of a cell or organism to maintain optimum conditions

(In response to internal and external changes)

253
Q

Give 5 things the body regulates

A

Temperature
Water
Salts
Waste
Glucose

254
Q

What is the optimum temp of human body

A

37.5 degrees

255
Q

What is an example of a water product?

A

CO2

256
Q

Where is glucose moved to and from

A

Blood to cells

257
Q

What is the CNS?

A

Central nervous system

258
Q

What is the CNS made up of?

A

Brain and spinal chord

259
Q

What is the PNS?

A

Peripheral nervous system

260
Q

What is the peripheral nervous system physically?

A

Nerves coming out of spinal chord

261
Q

What is a stimulus?

A

Change in environment

262
Q

What is a receptor?

A

Thing that detects a stimulus

263
Q

What are the 5 sensory organs?

A

Skin
Nose
Eyes
Tongue
Ears

264
Q

What does skin detect

A

Pressure, temperature, pain

265
Q

What does the tongue detect?

A

Chemicals in food/drink

266
Q

What does the nose detect

A

Chemicals

267
Q

What do control centres do?

A

Receive and process information from receptors

268
Q

What are effectors?

A

Muscles or glands which bring about a response to restore optimum conditions/levels of

269
Q

What can effectors do?

A

Contract, release chemicals, secrete hormones

270
Q

Give 3 adaptions of the nerve cell

A

Dendrites
Axon
Myelin sheath

271
Q

Describe how dendrites are useful for the nerve cell

A

Create branched connections which increase surface area (forming a network)

272
Q

What is the advantage of the axon for the nerve cell

A

Long body to cover more distance

273
Q

How does the myelin sheath help the nerve cell

A

Insulation which lines the axon and speeds up electrical impulses

274
Q

What is a synapse

A

Gap between neurones (all neurones have the synapse between)

275
Q

How are electrical impulses transferred across neurones

A

Neurotransmitters diffuse across the gap (synapse)

276
Q

What are the 3 stages of a reflex arc in terms of neurones

A

Sensory neurones
Relay neurones
Motor neurones

277
Q

What are the stages of a reflex arc

A

Stimulus
Receptor
Sensory neurone
Relay neurone
Motor neurone
Effector
Response

278
Q

Describe the reflex arc for eating food

A

Food
Sensory receptors in mouth
Sensory neurone
Relay neurone (pancreas)
Motor neurone
Salivary gland effector (releasing amylase)

279
Q

Give 5 reflexes

A

Pupil dilation
Moving away from a source of pain
Knee jerk
Secretion of adrenaline in shock

280
Q

What do reflexes help us to do

A

Respond quickly in dangerous situations

281
Q

What is reaction time?

A

Time taken for an individual to respond to a stimulus

282
Q

What is reaction time measured in

A

Milliseconds

283
Q

Give 3 control variables for an investigation into reaction time

A

Caffeine intake
Alcohol/drug consumption
Amount of sleep/tiredness

284
Q

Describe a method for a required practical about reaction time

A

Student A sits with elbow on a table edge - non dominant hand
Student B golds a ruler at 0cm, level with the thumb of student A
Student B drops it without warning
Student A catches it and records the distance in cm it has moved down
Repeats steps 1-4 and calculate mean
Compare mean to a conversion chart for redaction time

285
Q

Why is non dominant hand used?

A

Less trained/more challenged (slower time, more likely to be accurate)

286
Q

Why is ruler dropped without warning

A

Ensure not prepared

287
Q

Why don’t we use a stopwatch of reaction time?

A

Time period too short
Adds another person’s reaction time to the results

288
Q

Give another method of measuring reaction time

A

Computer program

289
Q

Why is a computer program used

A

Higher resolution/more precise technique

290
Q

What is an example of a computer program which can be used to measure reaction time

A

Pressing shapes when seen on a screen

291
Q

How could you create an extra independent variable in this practical

A

Check caffeine/water/sugar intake and the difference it makes to reaction time

292
Q

What effect is caffeine likely to have on reaction time

A

Increase reaction time

293
Q

What is a tropism

A

Growth in a plant in response to a stimulus

294
Q

Why do tropisms happen

A

To help a plant survive (like a human reflex)

295
Q

What is an auxin?

A

Plant hormone that controls growth near tips of shoots and roots in response to stimuli

296
Q

What is plant response to light called

A

Phototropism

297
Q

Why do plants grow towards light

A

Maximise light absorption for photosynthesis

298
Q

What does gravitropism do?

A

Ensure roots grow downwards

299
Q

What is gravitropism?

A

Plant growth into response to gravity

300
Q

What do tropisms happen as a response to?

A

The plant hormone auxin

301
Q

Phototropisms happen due to ______ auxin distributions

A

Unequal

302
Q

Auxins cluster on the ____side of the shoot

A

Shaded

303
Q

Auxins cause the shoot to elongate/inhibits growth in shoots

A

Elongates

304
Q

How do phototropism’s work?

A

Makes cells on shaded side longer
Pushes shoot towards sunny bit
Bends towards the light

305
Q

In gravitropism, where do auxins go? (Upper or lower side of the root)

A

Lower side

306
Q

Auxins have the ____ effect in the root compared to the ____ and ____ growth

A

Opposite
Shoot
Inhibit

307
Q

How does gravitropism work?

A

Auxins accumulate on lower side of root
Top cells elongate more quickly
So root bends down towards gravity

308
Q

What is negative gravitropism?

A

Root grows upward

309
Q

Why might root grow upwards

A

To get more water

310
Q

In negative gravitropism, auxins cluster on the upper/lower side of the root

A

Upper

311
Q

How do negative gravitropisms work?

A

Auxins cluster on upper side
Inhibit growth on upper side
Lower side has more growth and so root curves upwards

312
Q

What do gibberellins do?

A

Initiate seed germination, stem growth and flowering

313
Q

What is ethene?

A

Gas produced by parts of the plant which are ageing

314
Q

Give 2 things ethane controls?

A

Controls cell division
Controls ripening of fruits by stimulating enzymes

315
Q

Give 3 ways auxins are used in agriculture/horticulture

A

Weed killers
Rooting powders
Promoting growth in a tissue

316
Q

Give 3 ways gibberellins used

A

Ending seed dormancy
Promoting flowering
Increasing fruit size

317
Q

How is ethene used in the food industry

A

Controls ripening of fruit during storage and transport

318
Q

Give 4 commercial uses of plant hormones

A

Synchronised fruiting
Weed killing
Seedless fruit production
Cuttings

319
Q

How do plant hormones help synchronised fruiting

A

Spraying hormones onto fruits makes them develop at the same rate

320
Q

How does synchronised fruiting help the food industry

A

Efficient crop picking by machines

321
Q

True or false: weed killing can be used to clear vegetation

A

True - this is how agent orange worked

322
Q

How do plant hormones kill weeds?

A

Spraying with high concentrations of hormone upsets normal growth patterns

323
Q

How can plant hormones allow for selective weed killing

A

As auxins affect different plant species differently

324
Q

How do plant hormones help seedless fruit production

A

Hormone spray can make fruits develop without fertilisation (without fertilisation no seeds are formed)

325
Q

True or false: plant hormones can reduce the plants dependence on pollinating insects

A

True

326
Q

How are plant hormones used for cuttings and plant clonings

A

They can be stimulated to grow roots (hormone rooting powder)

327
Q

What is the enquiry question of the tropisms required practical?

A

How does the light/direction of light affect plant growth

328
Q

Give the independent variable in the tropisms required practical

A

Direction of light

329
Q

Give the dependent variable in the tropisms required practical

A

Direction of plant growth/growth of plant

330
Q

Give the 3 control variables in the tropisms required practical

A

Intensity of light
Type of plant
CO2 concentration

331
Q

Give a method for the tropisms required practical

A
  1. Several seedlings in each batch and measure initial heights of shoots (with a piece of string or pull them straight and measure with a ruler)
  2. Leave some in a dark box with a small opening of light through a hole from the right side, one on the left, one with complete light from all sides, and one in the dark
  3. Ensure they are at the same temperature, given the same water and have the same soil type
  4. After 48 hours record the appearance of the seedlings (the direction they are facing by using a protractor to estimate the angle of bending
  5. Remeasure the shoot heights
    Calculate the mean height increase for each group (by measuring 5 and taking an average)
    Compare groups and the direction/amount by which they have grown

GCSE Biology Revision (10 decks)

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