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AQA Biology > Paper 2: Quizlet Import > Flashcards

Paper 2: Quizlet Import Flashcards

1
Q

define homeostasis

A

regulation of internal conditions of cell or organism to maintain optimum conditions for function in response to internal and external changes

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2
Q

examples of homeostasis in body

A

-blood glucose concentration -body temperature -water levels

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3
Q

what components do all control systems include

A

-receptors -coordination centres -effectors

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4
Q

what are receptors

A

cells that detect stimuli

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5
Q

define stimuli

A

changes in environment

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6
Q

what are coordination centres and examples

A

-brain, spinal cord, pancreas -receive and process info from receptors

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7
Q

what are effectors and examples

A

-muscles or glands -bring about responses to restore optimum levels

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8
Q

what is negative feedback

A

body produces response which counteracts a change to restore optimum levels

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9
Q

what is the function of the nervous system

A

-enables humans to react to surroundings and coordinate behaviour

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10
Q

what is the CNS and function

A

-brain and spinal cord -coordiante response of effectors

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11
Q

what are sensory neurones

A

cells that carry info as electrical impulses from receptors to CNS

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12
Q

what are motor neurones

A

cells that carry electrical impulses from CNS to effectors

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13
Q

what are relay neurones

A

link sensory and motor neurones, carry nerve impulses within CNS

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14
Q

how do muscles carry out a response

A

contract

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15
Q

how do glands carry out a response

A

secrete hormones

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16
Q

how is the CNS connected to the body

A

by motor and sensory neurones

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17
Q

nervous system pathway

A

stimulus –> receptor –> sensory neurone –> relay neurone (in CNS) –> motor neurone–> effector –> response

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18
Q

what is a reflex

A

rapid, automatic response to stimuli not involving conscious part of brain

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19
Q

how are sensory neurones adapted to their function

A

-long axon (move impulse from one part of body to other) -many dendrites to make contact with other nerves -cell body in middle

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20
Q

what is a synapse and what happens

A

-gap between neurones -electrical impulse transferred by chemicals that diffuse across gap -trugger new electrical signal in next neurone

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21
Q

how is the relay neurone adapted to its function

A

-long axon -many short dendrites

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22
Q

how is the motor neurone adapted to its function

A

-many short dendrites -long axon -myelin sheath

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23
Q

explain reflex arc x4

A

-receptors detect stimuli (change in environment) -information from receptors pass along neurones as electrical impulses to coordination centre (CNS) -CNS is brain and spinal cord -CNS coordinations a response of effectors, may be muscles contracting or glands secreting hormones

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24
Q

required practical for reaction time

A

-person sit with arm resting on edge of table -other person hold ruler vertically between the others thumb and forefinger, zero end is level with thumb -let go with no warning -person tested must catch ruler as soon as possible, reaction time measured by number on top of thumb on ruler -the higher the number, the slower the reaction time -repeat several times and calculate mean distance in cm -repeat after caffeinated drink taken -keep person, height of ruler dropped from same

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25
Q

more accurate way of measuring reaction time and why

A

-computer tests -click mouse as soon as stimulus seen -more precise reaction time (less human error) -more accurate measurement due to higher resolution (milliseconds) -remove possibility of prediction due to body language

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26
Q

what is the brain made up of

A

billions of interconnected neurones and different regions

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27
Q

3 regions in brain

A

-cerebellum -medulla -cerebral cortex

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28
Q

function of cerebellum

A

responsible for msucle coordination

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29
Q

function of medulla

A

control unconscious activities such as breathing and heartbeat

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30
Q

function of cerebral cortex

A

responsible for consciousness, intelligence, memory, language

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31
Q

function of brain

A

-controls complex behaviours

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32
Q

methods used to study the brain

A

-studying patients with brain damage -electrically stimulating brain -MRI scans

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33
Q

how does studying patients with brain damage help neuroscientists

A

-if area in brain damaged by stroke causes patient to go blind for example, then this area is responsible for vision -effect of damage relates to function

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34
Q

how does electrically stimulating the brain help scientists

A

-insert electrode into tissue -give small zap of electricity -observe in effect eg if causes muscle contraction and movement

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35
Q

how do MRI scans help scientists

A

-machine showing detailed picture of brain -can observe which parts of brain active when carrying out a certain action

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36
Q

benefits of studying brain

A

lead to development of treatments for disorders of nervous system

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37
Q

why is investigating and treating brain disorders difficult

A

-brain is complec and delicate, can cause physical damage to brain and further problems such as impaired speech

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38
Q

function of eye

A

sense organ containing receptors sensitive to light intensity and colour

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39
Q

what is accomodation

A

-changing shape of lens to focus on near or distant objects

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40
Q

what is adapation

A

adjusting of eye to dim or bright light

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41
Q

components of eye x9

A

-sclera -cornea -retina -pupil -iris -ciliary muscles -suspensory ligaments -lens -optic nerve

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42
Q

function of sclera

A

-tough, supporting wall of eye -protection

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43
Q

function of cornea

A

-transparent, outer layer -in front of eye -refracts light into eye

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44
Q

function of iris

A

-contain muscles -control diameter of pupil -therefore controls how much light enters eye

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45
Q

what is the pupil

A

-hole in the middle of eye -where light enters through

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46
Q

function of lens

A

-focus light onto retina

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47
Q

function of retina

A

-contains receptor cells -cones sensitive to colour -rods sensitive to light intensity

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48
Q

function of ciliary muscles and suspensory ligaments

A

-control shape of lens

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49
Q

function of optic nerve

A

-carry impulses from receptors on retina to brain

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50
Q

how does the eye adjust to bright light

A

-circular muscles contract -radial muscles relax -pupil smaller= reduce light entering eye

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51
Q

how does the eye adjust to dim light

A

-circular muscles relax -radial muscles contract -pupil is wider=more light enters eye

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52
Q

eye changes to look at near objects

A

-ciliary muscles contract -suspensory ligaments slacken -lens=fatter (more curve) -light refracts more strongly

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53
Q

eye changes to look at distant objects

A

-ciliary muscles relax -suspensory ligaments tighten -lens is thin (less curve) -light refracts less strongly

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54
Q

why are some people long sighted or short sighted

A

-lens cannot refract light by right amount -light not focussed on retina

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55
Q

what is hyperopia

A

-long sightedness -cannot focus on near objects

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56
Q

causes of hyperopia

A

-lens is too thin (not refract light enough) -eyeball too short

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57
Q

result of hyperopia

A

-image formed behind retina

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58
Q

correction for hyperopia

A

-convex lens -refract light more strongly to focus on retina

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59
Q

what is myopia

A

-short sightedness -cannot focus on distant objects

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60
Q

causes of myopia

A

-lens too thick and refract light too much -eyeball too long

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61
Q

effect of myopia

A

-image of far objects brought to focus in front of retina

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62
Q

correction of myopia

A

-concave lens -refract lgiht rays less strongly to focus on retina

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63
Q

different treatments for vision defects

A

-contact lenses -laser eye surgery -replacement lens surgery

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64
Q

positives of contact lenses

A

-more convenient for sports than glasses -lightweight -invisible

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65
Q

negatives of contact lenses

A

-prescription can be expensive -soft lenses can cause risk of eye infection

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66
Q

how does laser eye surgery correct vision and benefits

A

-use laser to change shape of cornea -more precise and can completely correct vision -permanent solution, less maintenance

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67
Q

negatives of laser eye surgery

A

-has complications -cause dry eye -cause infections, worsen vision

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68
Q

what happens in replacement lens surgery and positive

A

-natural lens removed, replacement plastic lens inserted -may be more effective in treating long sightedness than laser eye surgery

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69
Q

negatives of replacement eye surgery

A

-cause possible retina damage -could lead to loss of sight

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70
Q

control centre for regulating temperature

A

-thermoregulatory centre in brain

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71
Q

what does the thermoreulatory centre contain

A

receptors sensitive to temp of blood flowing through brain

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72
Q

what does the skin contain to monitor body temp

A

temperature receptors, send nerbous impulses to thermoreulatory centre

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73
Q

response of body when too hot

A

-blood vessels dilate (vasodilation) -blood flows closer to surface of skin + sweat produced from sweat glands (evaporate from surface of skin) = more energy transferred from skin to environment (heat radiated out)

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74
Q

body response when too cold

A

-hairs erect=trap insulating lsyer of air -no sweat -vasoconstriction= blood vessels constrict, close off skin blood supply -shivering= skeletal muscles contract, requires respiration, releases energy (some transferred to warm body)

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75
Q

what is the endocrine system

A

-composed of glands which secrete chemicals (hormones) directly into bloodstream -blood carries hormones to target organ producing effect

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76
Q

defien hormone

A

chemical messenger released by glands and carried in blood to target organs

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77
Q

nervous system vs endorcrine system

A

NERVOUS: -short term effects -very fast reponse -act on precise area -involves electrical impulses via neurones ENDOCRINE: -long term effects -slower response -involves chemical messengers (hormones) via blood

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78
Q

control system of endocrine system and body temperature

A

hypothamlamus

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79
Q

what is the master gland and its function

A

-pituitary gland in brain -secretes sevral hormones in blood -act on other glands to stimulate other hormones to be released to bring effects

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80
Q

thyroid location and function

A

-in neck -produces thyroxine

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81
Q

purpose of thyroxine

A

-regulates heart rate -regulates temperature -regulates rate of metabolism

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82
Q

location and function of adrenal glands

A

-on top of both kidneys -produce adrenaline

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83
Q

purpose of adrenaline

A

-prepare body for ‘fight or flight’ response

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84
Q

function of ovaries

A

-produce oestrogen, involved in menstrual cycle

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85
Q

function of testes

A

-produce testosterone -control puberty and sperm production

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86
Q

function of pancreas

A

-produce insulin and glucagon -regulate blood glucose level

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87
Q

define metabolism

A

-sum of all chemical reactions in cells of organism

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88
Q

what is blood gluvose concentration regulated by in the body

A

pancreas

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89
Q

what is a negative feedback cycle

A

-levels of a certain factor kept steady -responds when conditions change from ideal point, aims to return conditions back to this set point

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90
Q

what happens when blood glucose levels are too high

A

-pancreas produces hormone insulin -causes glucose to move from blood into liver and muscle cells -liver and msucle cells convert excess glucose into insoluble glycogen which is stored (in liver and muscles) -therefore, blood glucose level decreases

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91
Q

what happens when blood gluvose levels are too low

A

-pancrease secretes hormone glucagon into blood -causes liver to convert glycgoen into glucose -glucose released into blood by liver -blood glucose level increases

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92
Q

what is type 1 diabetes and treatment

A

-pancreas fails to produce sufficient insulin -blood glucose level can rise to a level that can kill them -treated with insulin injections mainly at mealtimes -makes sure glucose is removed from blood quickly once food difested

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93
Q

other treatment for type 1 diabetes

A

-limiting intake of food rich in simple carbohydrates

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94
Q

what is type 2 diabetes and a risk factor

A

-body cells no longer respond to insulin produced by pancreas -obesity is a risk factor

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95
Q

treatment for type 2 diabetes

A

-carbohydrate controlled diet -regular exercise

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96
Q

what does eating foods containing carbs do

A

-puts glucose into blood

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97
Q

where is glycogen stored

A

-liver and muscles

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98
Q

what does vigorous exercise do in relationship to glucose

A

removes more glucose from blood

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99
Q

what happens when when cells are surrounded by fluids with a low concentration

A

-water enters cells -swell and eventually burst

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100
Q

what happens when cells are surrounded by fluids that are very concentrated

A

-shrivel

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101
Q

what happens when body cells lose/gain too much water by osmosis

A

-do not function efficiently

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102
Q

how is water, ions and urea lost in the body

A

-water lost via lungs during exhalation -water, ions, urea lost from skin in sweat -NO CONTROL OVER THESE

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103
Q

role of kidneys

A

-make urine -take waste producst out of blood (filtered out of blood as it passes through kidneys) =filtration

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104
Q

what is selective reabsorption

A

-useful substances such as glucose, some ions and water absorbed back into blood

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105
Q

how is water obtained

A

via food and drink

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106
Q

how are ions obtained

A

via food and drink

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107
Q

how is urea produced and where

A

-in LIVER excess proteins broken down into amino acids -converted to fats and carbohydrates, stored =DEAMINATION -ammonia produced as waste product (TOXIC) -converted to urea in liver -urea transported to kidneys, filtered out of blood and excreted in urine

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108
Q

what upsets the osmotic balance of the body

A

-too much water -too many ions

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109
Q

what is water, ion and urea concentration regulated by

A

kidneys

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110
Q

example of ion taken in body

A

sodium

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111
Q

how is blood filtered

A

-glucose, water, ions filtered out of blood through semi permeable membrane of kidney tubules (red blood cells etc not small enough to pass through) -glucose diffuses back out into blood until equilibrium reached -rest of glucose is actively transported back into blood (selective reabsorption)

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112
Q

water content off blood too high

A

-receptor in brain detect too high water content -coordiantion centre in brain receives info and cooridnates response -pituitary gland in brain instructed to release less ADH -less water reabsorbed from kidney tubules

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113
Q

water content of blood too low

A

-receptor in brain detect water content too low -coordination centre in brain receive info and coordinates response -pituitary gland release more ADH -more water reabsorbed from kidney tubules

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114
Q

what does ADH affect

A

permeability of kidney tubules

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115
Q

where is ADH released from

A

-pituitary gland

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116
Q

what does ADH stand for

A

anti-diuretic hormone

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117
Q

what are examples of diuretics

A

-coffee -alcohol

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118
Q

what is the reabsorption of water controlled by

A

negative feedback loop

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119
Q

what are the effects of kidney failure

A

-waste substances build up in blood -lose ability to control level of ions and water in body

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120
Q

treatments for kidney failure

A

-kidney dialysis -kidney transplant

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121
Q

what happens in kidney dialysis

A

-person’s blood flows between partially permable membranes surrounded by dialysis fluid (membrane only allows ions and waste substances to flow through, not proteins) -dialysis fluid has same concentration of dssiolved ions and glucose as healthy blood -only waste substances such as urea, excess ions and water diffuse across into fluid -waste products removed from the blood, and returned back to body

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122
Q

negatives of kidney dialysis

A

-expensive for NHS -each session runs for couple of hours -uncomfortable experience -done regularly, multiple times a week

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123
Q

positive of kidney dialysis

A

-buy patient valuable time before donor organ found -readily available

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124
Q

negatives of kidney transplanted

A

-can be rejected by patient immune system -must take immunosuppressant drugs -often long waiting lists

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125
Q

what is added to blood in dialysis

A

-blood thinners to stop coagulation of blood outside body

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126
Q

what does dialysis fluid include

A

-same water, sugar, ion concentration as healthy blood -no urea

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127
Q

positives of kidney transplants

A

-permanent cure -no nedd to long hospital stay -no need to control diet

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128
Q

what do reproductive hormones cause in puberty

A

secondary sex characteristics to develop (facial hair, breasts)

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129
Q

on what day does ovulation occur

A

day 14

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130
Q

what is the duration of the menstrual cycle

A

28 days

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131
Q

what is ovulation

A

release of an egg

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132
Q

interaction of hormones in menstrual cycle

A

-F= FSH causes egg to mature, stimulates production of oestrogen -O= oestrogen stimulates release of LH, inhibits FSH -L= LH stimulates release of egg and progesterone -P= progesterone inhibits release of LH and FSH

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133
Q

role of FSH and where produced

A

-cause maturation of egg -produced in pituitary gland

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134
Q

role of oestrogen and where produced

A

-cause uterus lining to thicken -produced in ovaries

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135
Q

role of LH and where produced

A

-stimulates release of egg -produced in pituitary gland

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136
Q

role of progesterone and where produced

A

-maintains lining of uterus -produced in empty egg follicle

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137
Q

what happens when progesterone levels fall

A

-uterus lining breaks down

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138
Q

when does the uterus lining break downn

A

when no fertilised egg implants on uterus wall

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139
Q

stages of menstrual cycle

A

-stage 1= menstruation (4 days) -stage 2=uterus lining build up -stage 3= egge develops and released on day 14 -stage 4=wall maintained for 14 days until day 28, lining starts to break down again

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140
Q

methods of contraception x 7

A

-oral contraceptives -injection/ implant/ skin patch -barrier methods -intrauterine devices -spermicidal agents -abstaining from intercourse -surgical male and female sterilisation

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141
Q

how do oral contraceptives work

A

contain hormones to inhibit FSH production so no eggs mature

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142
Q

positives of oral contraceptives

A

-easily available -stops eggs maturing

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143
Q

negatives of oral contraceptives

A

-have to remember to take everyday -effectiveness affected by vomiting

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144
Q

how do injections/implants/ skin patches work

A

-slow release progesterone, inhibit maturation and release of eggs

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145
Q

positive of injection/implants/ patches

A

-lower dosage of pill=less side effects -implant left for multiple months or years

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146
Q

negative of injection/implant/patch

A

-cut into skin=risk of infection -have to go to gp

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147
Q

how do barrier methods work and examples

A

-diaphrams and condoms -prevent sperm form reaching egg

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148
Q

positives of barrier methods

A

-easily available -protect against STIs -often free

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149
Q

negatives of barrier methods

A

-short term and must be disposed -can break

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150
Q

how do inauterine devices work

A

-prevent implantation of embryo -or release a hormone (prevent egg maturation)

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151
Q

positives of IUDs

A

-one of most effective contraceptives -can be inserted any time of cycle -copper ones last many years

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152
Q

what do spermicidal agents do

A

-kill or disable sperm

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153
Q

positives of spermicidal agents

A

-if in condom, kill sperm even if it breaks

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154
Q

how does abstaining from intercourse work

A

-avoid sex before and after ovulation (when egg in oviduct)

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155
Q

negative of abstaining from intercourse

A

-lowest success rate -menstrual cycles vary

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156
Q

male surgical method of sterilisation name

A

vasectomy

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157
Q

what happens in a vasectomy

A

-sperm ducts cut and sealed

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158
Q

what happens in female sterilisation

A

-oviducts cut and sealed

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159
Q

positive of male and female sterilisation

A

-last a lifetime

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160
Q

negatives of sterilisation

A

-painful procedure -difficult to reverse -female sterilisation requires operation

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161
Q

ways of increasing fertility

A

-hormones in fertility drugs -IVF

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162
Q

how do fertility drugs work

A

-hormones FSH and LH given in fertility drug to women to stimulate ovulation

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163
Q

positive of fertility drug

A

result in pregnancy

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164
Q

negatives of fertility drug

A

-not always work (has to be done multiple times, expensive) -can stimulate too many eggs, multiple pregnancies

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165
Q

how does IVF work

A

-giving mother FSH and LH to stimulate maturation of several eggs -collect eggs from mother and fertilise by sperm from father in laboratory -fertilised develop into embryos -when they are tiny balls of cells, one or two embryos inserted into mother’s uterus

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166
Q

positive of IVF

A

result in pregnancy

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167
Q

negatives of IVF

A

-very emotionally and physically stressful -success rates not high -multiple births can occur, high risk to mother and babies

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168
Q

when is adrenaline released

A

-when brain detects fear or stress, send nervous impulses to adrenal glands which secrete adrenaline

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169
Q

what does the ‘fight or flight’ response include

A

-increases heart rate -boosts delivery of oxygen and glucose to brain and muscles

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170
Q

what does thyroxine do in the body

A

-stimulates basal metabolic rate -stimulate protein synthesis for growth and development

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171
Q

define basal metabolic rate

A

speed at which chemical reactions occur in body at rest

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172
Q

what are thyroxine levels controlled by

A

negative feedback loop

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173
Q

what happens in the negative feedback loop of thryoxine

A

-level of thyroxine higher than normal detected -TSH (thyroid stimulating hormone) release from pituitary gland is inhibited -level of thyroxine in blood falls back towards normal

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174
Q

what causes more thyroxine to be released

A

-TSH =thyroid stimulating hormone

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175
Q

what is auxin and where found

A

-plant hormone -control growth of plant in response to light (phototropism) and gravity (gravitropism) -tips of shoots and roots

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176
Q

what does auxin do in the roots

A

-inhibits cell growth -more auxin on lower side due to gravity= cells on top elongate faster -root bends downards

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177
Q

how do shoots grow away from gravity

A

-gravity produces unqual distributionof auxin in tip, more auxin on lowr side -lower side grows faster, shoot bends upwards (negative gravitropism)

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178
Q

effect of auxin on shoots

A

encourages cell growth

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179
Q

what happens when a shoot is exposed to light

A

-more auxin on shaded side -cells grow (elongate) faster on shaded side -shoot bends towards light

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180
Q

practical for response of plant to varying light intensities

A

-pour fixed volume of water into 3 petri dishes and add cotton wool -place 10 seeds into each dish and place in warm location -allow seeds to germinate -place one dish in complete sunlight by window, second in partual sunlight and other in darkness in cupboard -use ruler to measure height of each seedling each day for a week in mm (hold up plant) -find mean height of seedlings each day and compare

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181
Q

control variables for platn responses to light practical

A

-number of seeds -type of seed -volume of water -temperature

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182
Q

commercial uses of auxin and how they work

A

-weed killer ( disrupt normal growth patterns) -growing from cutting with rooting powder (produce clones of plant quickly) -growing cells in tissue culture (grow clones by stimulating cells to divide to form roots and shoots)

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183
Q

what does giberellins do and use in agriculture

A

-initiate seed germination -induce flowering -grow larger fruit

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184
Q

what is ethene and what is it used for

A

-gas, controls cell division and ripening of fruits -used to speed up ripening of fruits in transport

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185
Q

use of nutrients in plants

A

-making chlorophyll -making protein/amino acids -for respiration

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186
Q

what are the male and female gametes in animals

A

sperm and egg cells

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187
Q

what are the male and female gametes in flowering plants

A

pollen and egg cells

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188
Q

who investigated inheritance

A

Mendel

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189
Q

what did gregor mendel do to investigate genetic inheritance

A

cross pea plants

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190
Q

define phenotype

A

physical characteristics of an organism

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191
Q

define genotype

A

collection of genes/alleles for a particular trait

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192
Q

define allele

A

different forms of the same gene

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193
Q

what must happen with recessive alleles to be expressed

A

allele must be present on both chromosomes

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194
Q

what must dominant alleles be to be expressed

A

present on at least one chromosome

195
Q

define homozygous

A

when alleles are both identical for same characteristic

196
Q

define heterozygous

A

two different alleles for characteristic

197
Q

chromosomes of boy

A

XY

198
Q

chromosomes of girl

A

XX

199
Q

mitosis daughter cells

A

two genetically identical daughter cells

200
Q

purpose of mitosis

A

produce identical cells for growth and repair

201
Q

number of cell divisions in mitosis

A

1

202
Q

meiosis daughter cells

A

4 genetically different daughter cells

203
Q

number of chromosomes in mitosis daughter cells

A

46

204
Q

number of chromosomes in meiosis daughter cells

A

23

205
Q

number of cell divisions in meiosis

A

2

206
Q

speed of mitosis reproduction

A

FAST

207
Q

speed of meiosis reproduction

A

SLOW

208
Q

why does mitosis not increase chance of species survival

A

as if a new disease or change in environment affects an individual, as all the cells are clones they will all be affected

209
Q

why does meiosis increase chance of species survival

A

as there in genetic variation in the population, allows natural selection to take place and evolution

210
Q

what is meiosis used for

A

producing gametes

211
Q

where mitosis occurs

A

-bacteria= binary fission -humans=everywhere except in sex organs

212
Q

where meiosis occurs

A

-sex organs (testes and ovaries)

213
Q

where does mitosis occur in plants

A

meristem cells in tip of roots and shoots

214
Q

what does asexual reproduction involve

A

-1 parent -no fusion of gametes -mitosis -produce clones

215
Q

why is asexual reproduction quicker

A

-no need to find mate -produces large number of offspring

216
Q

why is sexual reproduction slower

A

-have to find mate -few offspring produced

217
Q

advantages of sexual reproduction

A

-produce variation in offspring -if environment change theres survival advantage due to variaiton by natural selection -natural selection sped up by humans through selective breeding (increase food production)

218
Q

advantages of asexual reproduction

A

-faster than sexual -only one parent needed -time and energy efficient as no mate needed -many identical offspring produced in favourable conditions

219
Q

how do malarial parasites reproduce

A

-asexually in human host -sexually in mosquito

220
Q

how do fungi reproduce

A

-asexually by spores -sexually to give variation

221
Q

how do plants reproduce

A

-seeds produces sexually -reproduce asexually by runners in strawberry plants (side shoot goes into ground, takes roots, forms clone) -daffodils reproduce asexually by bulb division

222
Q

process of meiosis

A

-cells in reproductive organs copies of genetic info made -cell divides twice to form four gametes with 23 chromosomes each -genetically different

223
Q

what happens at fertilisation

A

-gametes join, restore full number of chromosomes (46) -new cell divides by mitosis= increase cells -as embryo develops, cells differentiate

224
Q

how many sets of chromosomes do body cells have

A

two sets

225
Q

how many sets of chromosomes do sex cells have

A

one set

226
Q

define germination

A

process where plant grows from seed

227
Q

number of chromosomes in nucleus

A

46

228
Q

what does dna stand for

A

deoxyribonucleic acid

229
Q

what is DNA

A

chemical composing all genetical material in a cell

230
Q

where is dna contained

A

in chromosomes

231
Q

what is DNA material wise and its structure

A

-polymer -two strands coiled to form a double helix

232
Q

define gene

A

small section of DNA on a chromosome

233
Q

what does each gene code for

A

particular sequence of amino acids to make specific protein

234
Q

what do gene tell cells

A

what order to make put amino acids together in

235
Q

what does DNA determine

A

-what proteins the cell produces -therefore what type of cell it is ( red blood cell produce haemoglobin, skin cell produce keratin)

236
Q

define genome

A

entire set of genetic material of an organism

237
Q

how does understanding the entire human genome help

A

-use in tracing human migration patterns of past (see where new populations split) -search for genes linked to different types of inherited disease -understand and develop new effective treatments for inherited disease

238
Q

what are the monomers that make up DNA

A

nucleotides

239
Q

what do nucleotides consist of

A

-one phosphate molecule -one sugar molecule -one base

240
Q

what are the four bases and their pairs

A

Adenine-Thymine Guanine-Cytosine

241
Q

what is the code for an amino acid

A

sequence of 3 bases

242
Q

what do non-coding prts of DNA do

A

control whether or not a gene is expressed (switch genes on and off)

243
Q

what is DNA made up of

A

repeating nucleotide units

244
Q

what is the the ‘backbone’ of DNA called

A

sugar-phosphate backbone

245
Q

shape of DNA

A

double helix

246
Q

where are proteins made

A

in ribosomes contained in cell cytoplasm

247
Q

what happens in protein synthesis

A

-two nucleotide DNA polymers seperate -enzyme copies code of DNA on template strand to form mRNA strand with complimentary bases to template strand -small enough to leave nucleus and go to ribosome -sequence of bases are read by ribosome -amino acids brought down by carrier molecules (have anti codons) -ribosomes join chain of amino acids in correct order -when chain is complete, folds up to form unique shape -enable to do job

248
Q

different functions of proteins

A

-enzymes= biological catalysts speed up chemical reactions in body -hormones= carry messages around body -structural proteins= collagen, strengthen tissues

249
Q

what do variations in non-coding parts of DNA cause

A

-affect how genes are expressed

250
Q

how often do mutations occur

A

continuously

251
Q

what do most mutations do

A

most do not alter proteins, or alter slightly so appearance and functions not changed

252
Q

what do a few mutations code for and how does this affect enzymes

A

-an altered protein with different shape -enzyme no longer fit substrate binding site

253
Q

what happens when mutations occurs to structural proteins

A

may lose their strength, no longer provide structure and support

254
Q

define mutation

A

change in gene or chromosome

255
Q

what are most characteristics a result of

A

multiple genes interacting

256
Q

what do genetic diagrams show

A

possible alleles of offspring

257
Q

two inherited disorders

A

-Cystic Fibrosis -Polydactyly

258
Q

what is cystic fibrosis caused by

A

recessive allele

259
Q

what is polydactyly caused by

A

dominant allele

260
Q

effects of cystic fibrosis

A

-thick sticky mucus in pancreas and air passages

261
Q

effects of polydactyly

A

extra fingers or toes

262
Q

what is cystic fibrosis a disorder of

A

genetic disorder of cell membranes

263
Q

what is an inherited disorder

A

condition caused by genetic change passed on from parents to offspring

264
Q

what is cystic fibrosis caused by

A

mutation in protein in cell membranes (responsible for viscosity of mucus)

265
Q

what can embryos be screened for

A

genetic disorders

266
Q

what is analysed for disorders in IVF

A

DNA of IVF embryo cell

267
Q

arguments for embryo screening

A

-prevents suffering due to disorders -less money has to be spent by government and tax payers on treatment for disorders -there are laws to prevent destroying embryos based on sex for example

268
Q

arguments against embryo screening

A

-implies people with genetic disorders are undesirable (prejudice) -screening is expensive -may be a point where people screen embryos for characteristics such as hair colour -destroying embryos is unethical and screening can damage healthy individuals

269
Q

what is done for embryo screening

A

-cell removed from each IVF embryo -genes analysed

270
Q

what three conclusions did mendel reach

A

-characteristics determined hy hereditary units -hereditary units passed on to offspring unchanged from both parents (one from each) -hereditary hnits can be dominant or recessive

271
Q

why did it take a while for people to understand mendels work

A

-no idea of genes, DNA or chromosomes

272
Q

define variation

A

differences in characteristics of individuals in population

273
Q

what can variation be caused by

A

DIFFERENCES IN: -genes inherited -conditions in which they have developed (environment) -combination of both

274
Q

what is there usually in a population

A

genetic variation

275
Q

what is variation a result of in terms of DNA

A

constant, random mutations in DNA

276
Q

define species

A

group of organisms with similar characteristics that can breed to produce fertile offspring

277
Q

examples of variation caused by genes passed down

A

-eye colour -sex -dimples

278
Q

examples of variation caused by environmental AND genetic causes

A

-height -weight

279
Q

examples of variarion caused by environmental causes

A

-accent -tan

280
Q

how does natural selection occur

A

-variation existing in population -due to mutations (random, continuous changes in DNA) affecting characteristics -individuals with characteristics most suited to environment survive (survival of the fittest) -survivors have more chance of reproducing -offspring inherit the characteristics most suited to environment -organisms less suited to environment= less likely to survive -over time characteristics most suited to environment become more common and species evolves

281
Q

what is the theory of evolution

A

all species of living things evolved from simple life forms that first developed over three billion years ago

282
Q

what happens if the phentoypes of two populations of one species becomes too different

A

can no longer interbreed to produce fertile offspring, form two new species

283
Q

what is evolution

A

change in inherited characteristics of population

284
Q

when does natural selection occur

A

when mixed population faced with environmental challenge, some versions of gene more advantageous

285
Q

what is selective breeding

A

humans breed plants and animals for particular generic characteristics

286
Q

what does selective breeding involve

A

-choose parents with desired characteristic from mixed population -bred together -from offspring those with desired characteristic bred together -continues over many generations until all offspring show desired characteristic

287
Q

4 examples of chosen characteristics in selective breeding

A

-disease resistance in food crops -animals to produce more meat or milk -domestic dogs with gentle nature -large or unusual flowers

288
Q

what is a negative of selective breeding

A

-can lead to inbreeding ( some breeds prone to disease or inherited defects)

289
Q

how does selective breeding affect gene pool of species

A

reduces variation in species

290
Q

why is a reduced gene pool bad

A

-more difficult for species to adapt to environmental changes

291
Q

define genetic engineering

A

-modifying genome of organism by introducing gene from another organism to give desired characteristic

292
Q

examples of genetic engineering

A

-plant crops genetically engineered to be resistant to disease or produce bigger fruits -bacterial cells genetically engineered to produce useful substances like human isnulin to treat diabetes

293
Q

what are GM crops

A

crops that have had their genes modified through genetic engineering

294
Q

benefits of genetic engineering

A

-increased yield -crops resistant to insect attack or herbicides

295
Q

negatives of genetic engineering

A

-effects of eating GM crops on human health not fullt explored or understood -affects number of wild flowers and crops and populations of insects (decreased biodiversity) -transplanted genes can get into environment, picked up by weeds

296
Q

example of GM crop specific

A

Golden Rice= contains nutrient to help with sight

297
Q

what is a future medical possibility of genetic modification

A

-overcome some inherited disorders

298
Q

process of genetic engineering

A

-enzymes used to isolate desired gene -inserted into vector (bacterial plasmid or virus) -vector used to insert gene into required cells -genes transferring at early stage if development to develop with desired characteristics

299
Q

what is a clone

A

individual produced asexually and is genetically identical to parent

300
Q

what is tissue culture

A

using small groups of cells from part of plants to grow identical new plants

301
Q

what is tissue culture used for

A

-preserving rare species of plants -commercially im nurseries

302
Q

what is the process of cuttings

A

-older simple method used by gardeners to produce many identical new plants from parent plant -take cutting from original parent plant -placing cutting in hormone rooting powder (auxin) and compost -plant grows into mature plant genetically identical

303
Q

limitation of using cuttings

A

-can only clone one plant from one cutting

304
Q

how does the process of tissue culture work

A

-few cells scraped off parent plant -put into growth medium with auxin and nutrients -cells divide by mitosis -differentiate into range of tissues types into plantlets -can be transferred carefully into compost, grow into many clones

305
Q

negative of usinf tissue culture

A

-must be done under sterile conditions or there is risk of infection from disease

306
Q

what is embryo cloning

A

-animals given fertility hormones to produce many eggs -eggs fertilised in womb using sperm from prize bull -embryo can be washed out of womb, contain desires genes -embryos split into individual cells ( by mitosis) -produce many embryos -embryos transferred to wombs of surrogate cows, develop into cows that are identical

307
Q

negative of embryo transplants

A

-expensive -no guarantee that embryo is worth it as the genotype is not guaranteed

308
Q

advantages of embryo transplants

A

-allows good cows to produce alot more offspring that it could

309
Q

process of adult cell cloning

A

-nucleus removed from unfertilised egg cell -nucleus from adult body cell inserted into egg cell -electric shock stimulates egg cell to divide to form embryo -embryo cells contain same genetic informarion as adult skin cell -embryo develop into ball of cells, inserted into womb of adult female to continue development

310
Q

issues of cloning

A

-reduced gene pool -cause inherited diseases -may be unsuccesful

311
Q

advantages of cloning

A

-protect endangered species -lead to greater understanding of development of embryo

312
Q

who proposed the theory of evolution

A

charles darwin

313
Q

why was the theory of evolution by natural selection only gradually accepted

A

-challenges idea that god made all animals and plants living on earth -insufficient evidence at the time to convince scientists -inheritance and variation not known until years after theory published

314
Q

what are organisms with the most suitable characteristics to the environment

A

more successful competitors

315
Q

three scientists that proposed ideas on evolution, speciation etc

A

-charles Darwin -Lamarck -Alfred Russel Wallace

316
Q

what did lamarck propose

A

-changes that occur in organism during its lifetime can be inherited

317
Q

why was lamarcks theory rejected

A

-experiments didnt support his hypothesis

318
Q

what has the theory of evolution been developed by

A

-new discoveries about variation, inheritance and mutations

319
Q

define speciation

A

-development of a new species due to change of phentotypes

320
Q

when does speciation occur

A

-populations of same species change enough that they cannot interbreed to produce fertile offspring

321
Q

define extinction

A

no surviving individuals of a species remaining

322
Q

causes of extinction

A

-quick environment changes (too quick for evolution of species) -new predator -new disease -new competitor -catastrophic event

323
Q

process of speciation

A

-two populations of same species isolated (seperated) -due to physical barrier (conditions on either side slightly different) -populations adapt to new environments through natural selection (alleles of beneficial characteristics passed down) -individuals from different populations changed so much that they can no longer breed to produce fertile offspring= seperate species

324
Q

who came up with the theory of speciation

A

Alfred Russel Wallace

325
Q

what did wallace independently come up with

A

idea of natural selection

326
Q

how did darwin and wallace develop the theory of evolution by natural selection

A

-publish joint writings -darwin published On the Origin of Species -wallace gathered evidence for evolutionary theory ( warning colouration)

327
Q

factors of speciation

A

-isolation -natural selection

328
Q

how did our understanding of genetics develop

A

-mendel carried out breeding experiments( discover hereditary units passed onto inheritors unchanged, determine characteristics) -behaviour of chromosomes in cell division observed

329
Q

when did mendel carry out breeding experiments

A

mid 19th century

330
Q

when was the behaviour of chromosomes observed

A

late 19th century

331
Q

what were the hereditary units in mendels discovery

A

genes

332
Q

when was the structure of DNA determined and mexhanism of gene function

A

mid 20th century

333
Q

why was mendels discovery not recognised until after his death

A

-no knowledge of genes, DNA, chromosomes

334
Q

what was discorvered in the early 20th century

A

similarities in how chromosomes and mendels ‘units’ behaved

335
Q

what is evidence for natural selection by evolution

A

-fossils -antibiotic resistance in bacteria

336
Q

why is the theory of evolution now accepted

A

-evidence available to show that characteristics are passed on to offspring in genes

337
Q

define a fossil

A

remains of organisms from millions of years ago found in rocks

338
Q

how are fossils formed

A

-bones, teeth, shells which do not decay easily are buried -replaced with minedals overtime forming hard rock like substance in same shape -soft tissues and organs of organisms decay -fossil remains in rock and is dug up

339
Q

3 examples of fossils

A

-gradual replacement by minerals -casts and impressions -preservation

340
Q

how are fossils formed from preservation

A

-no oxygen or moisture so decay microbes cant survive in amber -glaciers is too cold for decay microbes to function -peat bogs too acidic for decay microbes to survive

341
Q

what do fossils show

A

how much or little different organisms have changed as life developed on Earth

342
Q

why is the fossil record incomplete

A

-many earlier forms of life were soft bodies, decayed completely and didnt form fossils and left few traces -traces destroyed by geological activity

343
Q

why are scientists uncertain about how life began on earth

A

fossil record in incomplete

344
Q

how can fossils be dated

A

-radioactive dating rocks surrounding the fossils

345
Q

why can bacteria evolve rapidly

A

-reproduce at fast rate -binary fission occurs every 20 minutes

346
Q

process of antibiotic resistance

A

-mutations cause new strains of antibiotic resistant bacteria to arise -some strains are resistant and are not killed in bacteria population whilst non-resistant are killed -resistant bacteria survive and reproduce rapidly, population of resistant strain increases -resistant strain spreads as people not immune, no effective treatment

347
Q

what is an example of an antibiotic resistant bacteria

A

MRSA in hospitals

348
Q

what can be done to reduce rate if antibiotic resistance

A

-doctors not prescribe antibiotics inappropriately (for viral or non serious infections for eg) -patients should complete full course of antibiotics so none survive and mutate to form resistant strains -agricultural use of antibiotics restricted

349
Q

how can the development of new antibiotics be described

A

-costly -slow

350
Q

what have living things been classified into groups by

A

-structure -characteristics

351
Q

what are organisms named by

A

-binomial system of genus and species

352
Q

who classified species into the linnaean system

A

Carl linnaeus

353
Q

what is the linnaean system organised into

A

-Kingdom -Phylum -Class -Order -Family -Genus -Species

354
Q

why did classification systems change over time

A

-evidenxe of internal structures more developed due to microscope improvements -more understanding of biochemical processes -new models of classification proposed

355
Q

what did carl wowse propose

A

three-domain system

356
Q

which scientists came up with models of classification

A

-Carl Linnaeus -Carl Woese

357
Q

what did carl woese use evidence from

A

-new chemical analysis techniques

358
Q

what is the three domain system divided into

A

-archaea -bacteria -eukaryota

359
Q

what are archaea

A

primitive bacteria usually living in extreme environments

360
Q

what are bacteria

A

true bacteria

361
Q

what do eukaryota include

A

-protists -fungi -plants -animals

362
Q

example of binomial naming system

A

Homo sapiens

363
Q

what do evolutionary trees show

A

how organisms are believed to be related

364
Q

what do evolutionary trees use as evidence

A

-current classification data for living organisms -fossil data for extinct organisms

365
Q

what specifically do evolutionary trees exhibit and how is this helpful

A

-common ancestors between species (more recent common ancestor= more closely relates species= more characteristics likely to be shared)

366
Q

define a habitat

A

place where organisms live

367
Q

define population

A

all organisms of one species living in a habitat

368
Q

define community

A

populations of different species living in one habitat

369
Q

what are abiotic factors

A

non living factors of environment

370
Q

define biotic favtors

A

living factors of environment

371
Q

define ecosystem

A

interaction of community of living organisms interacting with non living parts of environment

372
Q

what do organisms need resources for

A

to survive and reproduce

373
Q

what do plants compete with each other for

A

-light -space -water -mineral ions from soil

374
Q

what do animals compete with each other for

A

-food -mates -territory

375
Q

what do species depend on others for

A

-food -shelter -pollination -seed dispersal

376
Q

what does interdependence mean

A

any major change can have far reaching effects

377
Q

what happens if one species is removed

A

affects the whole community

378
Q

what is a stable community

A

one where all species and environmental factors in balance, population size remains constant

379
Q

examples of abiotic factors x7

A

-moisture level -light intensity -temperature -carbon dioxide level -wind intensity -oxygen level -soil pH and minerals

380
Q

what could a decrease in mineral content cause

A

nutrient deficiencies

381
Q

what could a decrease in light intensity, temperature or level of carbon dioxide cause

A

decreased rate of photosynthesis, less plant growth, population size decrease

382
Q

examples of biotic factors x 4

A

-new predators -competition -new pathogens -availibility of food

383
Q

define interdependence

A

when all species in a community depend on one another for survival and any change affects many diff species

384
Q

why does competition lead to population decrease

A

species is outcompeted for resources needed to survive and develop, so numbers are insufficient to breed

385
Q

types of adaptations

A

-structural -behavioural -functional

386
Q

example of structural adaptation

A

camel having large surface area to volume ratio to lose heat

387
Q

example of behavioural adaptation

A

migrating during the winter

388
Q

example of functional adaptation

A

-bears hibernating in winter, lower metabolism, conserve energy -camel humps store fat to metabolise later when there is lack of food in desert

389
Q

example of extremophiles

A

-bacteria living in deep sea vents

390
Q

aspects of extreme environments

A

-high temperatures -high salt concentration -high pressure

391
Q

what are extremophiles

A

microorganism like bacteria that are adapted to live in very extreme conditions

392
Q

examples of plant adaptations

A

-cacti having spines and thick stems, wide shallow roots -sunken stomata to limit transpiration (loss of water) -space, some seeds have propellers to distribute, produce fruit to be eaten and defecated elsewhere

393
Q

why can’t most living things live in very hot conditions

A

temperature too high, denatures enzymes

394
Q

why are extremely salty environments bad for organisms

A

-upset osmotic balance

395
Q

what are producers and why

A

-photosynthetic organisms (plants) that produce their own food (glucose) -producers of biomass for rest of life on earth

396
Q

what is transferred when organisms are eaten

A

energy

397
Q

what is used to measure abundance of organisms

A

quadrats

398
Q

what is used to measure distribution of organisms along a line

A

transects

399
Q

what are predators

A

consumers that kill and eat other animals

400
Q

what is prey

A

animals that are killed and consumed by other animals (predators)

401
Q

what materials are cycled in an ecosystem

A

-water -carbon

402
Q

what do environmental changes affect

A

distribution of organisms ( where they live)

403
Q

what can affect change in distribution of organisms

A

-change in water availability -change in temperature -change in composition of atmospheric gases

404
Q

what are different materials cycled through

A

abiotic and biotic components of ecosystem

405
Q

explain the steps of the water cycle

A

-energy from sun cause water evaporation from land and sea, turn to vapour+ water evaporate from plants (transpiration) -warm water vapour rises, cools and condense form clouds -water fall as precipitation onto land, fresh water provided for plants and animals -drain into sea, repeats

406
Q

two types of decay organisms

A

-detritus feeders -fungi

407
Q

what does cycling of materials provide

A

building blocks for future organisms

408
Q

what do plants turn elements into and examples of these elements (from where)

A

-complex compounds -carbon, hydrogen oxygen, nitrogen -from soil and air

409
Q

factors that affect decay

A

-warmer temperature -aerobic conditions -moist

410
Q

where does CO2 enter in the leaves

A

stomata

411
Q

three main processes in carbon cycle

A

-photosynthesis -respiration -combustion

412
Q

steps of carbon cycle

A

-CO2 from air taken in by plants through stomata for photosynthesis -carbon used to make carbon compounds like glucose, turned into carbs, fats, proteins etc (-plants respire, return carbon to atmosphere as CO2) -eaten by animals, glucose used as fuel, some carbon is part of proteins and fats in body, animals respire (release CO2 back into atmosphere) -plants, algae, animals die (provided conditions for decay are optimal), detritus feeders and bacteria and fungi can feed on remains, respire to break down (release CO2) -animals produce waste (feces, urine) also broken down, return nutrients back to soil -no decay= fossils= fossil fuels (coal, natural gas etc), burned = combustion in power stations (release CO2 in air)

413
Q

what is a human activity affecting the carbon cycle

A

combustion of fossil fuels in power stations

414
Q

what happens when aquatic animals respire

A

carbon dissolved in oceans

415
Q

what are examples of carbon sink

A

-fossils containing carbon trapped in sedimentary rock -carbon dissolved in oceans

416
Q

define carbon sink

A

large amounts of carbon locked up

417
Q

how can nitrates be recycled

A

-dead plant/ animal decomposes -by decomposerssuch as detritus feeders and bacteria and fungi -releases mineral ions into soil -mineral ions taken in by plants through roots

418
Q

examples of decomposers

A

-detritus feeders -bacteria -fungi

419
Q

conditions affecting rate of decay and why

A

-warmer temperatures for optimum enzyme activity, not too much that denatures -oxygen availibility for respiration (aerobic conditions) -water availability for biological processes -number of decay organisms for faster decomposition

420
Q

how is biogas made

A

-anaerobic decay of waste material

421
Q

what is compost used by farmers as

A

natural fertiliser for growing garden plants or crops

422
Q

what is biogas mainly made up of

A

methane

423
Q

why is biogas produced

A

to be burned as a fuel to release energy

424
Q

where is biogas (methane gas) produced

A

in biogas generators

425
Q

how are optimum conditions provided for decay by farmers

A

-compost bins -decaying materials (food, grass) -opening for oxygen (aerobic decay) and bacteria, detritus feeders added -water added -temperature increases due to aerobic activity of feeders producing heat (may be insulated in winter) -circulated by stirring, distribute oxygen and feeders -produces sludge used as fertiliser

426
Q

aspects of simple biogas generator

A

-inlet for waste materials -food and waste material digested by decomposes -made air tight for anaerobic decay -methane gas produced, collected from biogas outlet -outlet for digested material

427
Q

negative of biogas generation

A

-cant be stored as liquid -must be used instantly -generator need to be kept at constant temp

428
Q

what three things can environmental changes be

A

-seasonal -geographic -caused by human interaction

429
Q

define biodiversity

A

variety of all different species of organisms on earth or in ecosystem

430
Q

what does great biodiversity ensure

A

-stability of ecosystems -reduce dependence of one species on another for food, shelter and maintenance of physical environment

431
Q

examples of geographic environmental changes

A

-water availability -salinity -altitude

432
Q

examples of seasonal environmental changes

A

-species migrate or hibernate -different regions (tropical, temperate ) with different seasons

433
Q

examples of human caused environmental changes x4

A

-air pollution -acid rain -global warming -industry and farming cause water pollution

434
Q

indicator species for air pollution and what this shows

A

-bushy lichen= clean air -leafy/ crusty lichen= polluted air

435
Q

indicator species for water and what they show

A

-stonefly nymph/ fresh water shrimp= clean -sludge worm/ red tailed maggot= high pollution

436
Q

environmental impacts of human population growth due to pollution

A

-water pollution=from sewage, fertiliser, toxic chemicals -air pollution from smoke and acidic gases -land= from landfill and toxic chemicals

437
Q

what does pollution do

A

kills plants and animals, reduces biodiversity

438
Q

why is consumption of resources increasing

A

-standard of living increases -more resources used due to increase in demand, more finite materials used to generate energy for manufacturing

439
Q

what contributes to global warming

A

-increasing levels of carbon dioxide and methane in the atmosphere, thickens green house gas layer= less of suns trapped energy radiated back into space

440
Q

consequences of global warming

A

-ice to melt and seawater expands= sea level rise, flood low level land (lose habitats) -distribution of animals change as temp increase -change in migration patterns -reduction in biodiversity

441
Q

why is the human population increasing rapidly

A

-modern better medicine -improved farming methods (less hunger and people dying from disease)

442
Q

define eutrophication

A

-pesticides and herbicides wash into water -increased nutrient fertilisers means algae form bloom over water surface -less sunlight reach other water plants -plants die and they cannot carry out enough photosynthesis without light -bacteria etc increase and decompose dead plants, using up and reducing oxygen in water during respiration -low oxygen levels cause insects and fish to suffocate (die)

443
Q

what is it called when nitrate fertilisers are washed into waterways

A

leaching

444
Q

what do humans use land for

A

-farming -dumping waste -building -quarrying

445
Q

examples of human land use with bad environmental effects

A

-deforestation -destruction of peat bogs

446
Q

what is deforestation

A

large scale clearing of trees

447
Q

why does deforestation take place

A

-clear land for farming cattle -grow crops for biofuels

448
Q

effects of deforestation

A

-less carbon sink as trees removed -more CO2 into atmosphere as trees burned to clear land + decomposes respire when feed on dead wood -less biodiversity as less habitats, species extinct

449
Q

what are peat bogs

A

-areas of land that are acidic and waterlogged -plants don’t fully decay due to lack oxygen, partly rotted plant build up form peat -carbon stored

450
Q

what happens when peat bogs are drained

A

-peat contact with air, microorganisms decompose it, release CO2

451
Q

negatives of destroying peat bogs

A

-habitats destroyed -peat burned as fuel= release CO2

452
Q

why are peat bogs cleared

A

-use peat as fuel -farmland -compost

453
Q

define bioaccumulation

A

toxins from fertilisers and pesticides build up in food chain and affect organisms

454
Q

programmes to reduce negative effects of humans on ecosystems x5

A

-breeding programmes endangered species -protection of rare habitats -reintroduce field margins and hedgerows in agricultural areas where one type crop grown ( habitats) -reduce deforestation and co2 emissions policies -recycle resources, less waste dump in landfill

455
Q

difficulties in maintaining biodiversity x 3

A

-costs money -some people can lose jobs (tree chopping, logging) -some organisms seen as pest by farmers

456
Q

tropic level 1

A

producers (plants and algae) that make own food

457
Q

tropic level 2

A

herbivores, primary consumers

458
Q

tropic level 3

A

carnivores that eat herbivores (secondary consumers)

459
Q

trophic level 4

A

carnivores eat other carnivores (tertiary consumers)

460
Q

define apex predators

A

carnivores with no predators

461
Q

how do decomposers break down waste

A

-bacteria and fungi decompose dead matter -secrete enzymes into environment -break down into small soluble food molecules, diffuse into microorganism

462
Q

what happens when you move up a tropic level

A

-less energy -less biomass -fewer organisms

463
Q

what is lost between each tropic level

A

biomass

464
Q

how much energy is transferred from light from the sun for photosynthesis by producers

A

0.01

465
Q

how much biomass is transferred to each tropic level

A

0.1

466
Q

why is biomass lost between trophic levels

A

-not all ingested material absorbed, some egested as faeces -not all of organism eaten (e.g bones, some plant material) -biomass converted to other substances lost as waste e.g glucose in respiration

467
Q

how to calculate efficiency of biomass transfer

A

(biomass transferred to next / biomass available at previous) x 100

468
Q

define food security

A

having enough food to feed a population

469
Q

biological factors affecting food security x6

A

-birth rate increase -changing diets developed countries (scarce food made more scarce) -new pests and pathogens affect farming -conflict affect water and food availability -cost of agricultural input like machinery -environment changes cause famine if less rain

470
Q

what decreases fish stocks

A

overfishing

471
Q

sustainable ways to maintain fish stocks

A

-fishing quotas -net size

472
Q

why is it important to maintain fish stocks

A

some species might disappear due to less breeding

473
Q

what are fishing quotas

A

limits on number and size fish caught in certain areas prevent overfishing

474
Q

how do net sizes help in sustainable fisheries

A

bigger mesh size means younger fish slip through, reach breeding age ,maintain population

475
Q

how can food production be made more efficient

A

-limit movement ( chickens kept in small pens) less energy used moving and fish farmed in cages -kept in temperature controlled environment, less transfer of energy to control body temp -more energy available for growth -animals fed high protein food

476
Q

objections against factory farming

A

-disease spread easily -ethical = unnatural, uncomfortable -use of antibiotics in cattle cause antibiotic resistance

477
Q

why is efficient farming helpful

A

means more energy available for growth in organisms

478
Q

example of biotechnology for food

A

-fungus Fusarium produce mycoprotein -grown in aerobic conditions on glucose syrup -biomass harvested and purified to produce mycoprotein

479
Q

what is mycoprotein used for

A

produce high protein meat substitute for vegetarians

480
Q

why are modern biotechnological techniques beneficial for food

A

large amounts of microorganisms can be cultured for food under controlled conditions

481
Q

process of genetic engineering of bacteria to produce insulin

A

-plasmid removed -insulin gene cut out human chromosome using restriction enzymes leaving with ‘sticky ends’ -bacterial plasmid cut open using same enzyme, leaving the same sticky ends -plasmid and human insulin gene joined together by DNA ligase enzyme -ends joined to form molecule of DNA -recombinant plasmid inserted into bacterial cell -bacteria reproduce, plasmids are copied, all express human insulin gene and produce human insulin protein -grown in vat under controlled conditions -insulin harvested and purified, treat diabetics

482
Q

example of GM crop

A

golden rice

483
Q

benefits of GM crops

A

-resistance to pests=increase crop yield -more nutritional value eg golden rice= vitamin a= aid eyesight

AQA Biology (27 decks)

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