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GCSE Biology Revision > B5-7 Spec > Flashcards

B5-7 Spec Flashcards

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1
Q

what kind of cells are formed as a result of meiosis

A

non identical cells

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2
Q

what kind of cells are formed as a result of mitosis

A

identical cells

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3
Q

what is sexual reproduction in terms of cells

A

fusion of male and female gametes

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4
Q

what are the two gametes in animals

A

sperm and egg

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5
Q

what are the two gametes in plants

A

pollen and egg cells

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6
Q

how are gametes formed

A

meiosis

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7
Q

in sexual reproduction there is a ___of genetic information which leads to ____in the offspring

A

mixing
variety

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8
Q

asexual reproduction has how many parents and how much fusion of gametes and how much mixing of genetic information leading to genetically____offspring and only___is involved

A

1 parent
no fusion of gametes
no mixing of genetic information
identical
mitosis

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9
Q

describe meiosis and where does it happen and what does it produce

A

reproductive organs
gametes
normal cell makes copies of genetic information
cell divides twice to form 4 gametes - each with a single set of chromosomes
all gametes are genetically different from each other

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10
Q

when meiosis forms gametes are they the same genetically or different?

A

all are different

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11
Q

gametes join at ___to restore the __number of chromosomes

A

fertilisation
normal

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12
Q

after fertilisation cells divide by ___. as the embryo develops cells ____

A

mitosis - differentiate

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13
Q

homeostasis definition

A

regulations of the internal condition of a cell or organism to maintain conditions for function in response to internal and external changes

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14
Q

give 2 reasons homeostasis is important

A

to maintain optimum conditions for enzyme activity
and cell function

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15
Q

what does homeostasis maintain levels of

A

glucose
water
temperature

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16
Q

what things are involved in automatic control systems (two ways of responding to internal or external conditions)

A

nervous responses or chemical responses

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17
Q

what is a receptor for

A

to detect stimuli

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18
Q

what are coordination centres for

A

receive and process information from receptors

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19
Q

what are 3 coordination centres

A

spinal chord
brain
pancreas

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20
Q

what are effectors for

A

bring about a response to restore optimum conditions

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21
Q

what 2 things could effectors be

A

muscle or gland

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22
Q

what does the nervous system allow humans to do

A

react to surroundings and coordinate behaviours

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23
Q

reflex arc of touching something hot

A

stimulus of hot thing
receptor of skin
sensory neurone detects it
information passes along the neurones as electrical impulses
CNS (using relay neurones) coordinates the response of the effectors (spinal chord)
motor neurones causes muscles to contract and pull away

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24
Q

why are reflexes important

A

to keep us safe from harm and prevent injury

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25
Q

how is information transferred between neurones

A

it passes along neurones as electrical impulses

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26
Q

what are reflex actions

A

do not involve the conscious part of the brain
they are automatic and rapid

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27
Q

ruler drop experiment control variables

A

caffeine intake
sleep
age
eyesight/disabilities
(ensure hand at bottom of ruler)

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28
Q

what is a risk of the ruler drop experiment

A

risk of drinking too much caffeine which could cause unpleasant side effects

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29
Q

what is another variation of the ruler drop experiment

A

use computer software to find reaction time - reaction to a stimulus

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30
Q

why are computers more accurate

A

remove possibility of human error

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31
Q

why are computers more precise

A

computer can record reaction time in milliseconds - kind of interchangeable with the accuracy one

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32
Q

3 advantages of sexual reproduction

A

produces variation
variation gives a survival advantage by natural selection if the environment changes
natural selection can be sped up by humans in selective breeding to increase food production

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33
Q

advantages of asexual reproduction

A

only 1 parent needed
more time and energy efficient (as don’t need to find mate)
faster
many identical offspring can be produced - when conditions are favourable

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34
Q

how do malarial parasites reproduce in the human host

A

asexually - as can’t get any gals in the human

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35
Q

how do malarial parasites reproduce in the mosquito

A

sexually

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36
Q

how do fungi do asexual reproduction

A

by spores - but they can also reproduce sexually!!

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37
Q

give 3 examples of things that can reproduce both sexually and asexually

A

plants
fungi
malaria

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38
Q

how do plants reproduce sexually

A

using seeds

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39
Q

give 2 examples of plants that reproduce asexually - and the process of their asexual reproduction

A

bulb division such as daffodils
runners such as strawberry plants

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40
Q
A
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41
Q

define genome

A

entire genetic material of an organism

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42
Q

what is the structure of DNA

A

double helix - two strands

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43
Q

what type of thing is DNA

A

polymer

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44
Q

what is DNA contained in

A

the nucleus
chromosomes

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45
Q

what is a gene

A

small section of DNA on a chromosome

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46
Q

each gene codes for what

A

a particular sequence of amino acids to make a specific protein

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47
Q

the whole human genome has been what and what is this greatly important for

A

studied
medicine in the future

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48
Q

give 3 reasons it is important to understand the human genome

A

search for genes linked to different types of disease
understand and treat inherit disorders
trace human migration patterns from the past

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49
Q

why is understanding the human genome linked to tracing past migration patterns

A

understanding common ancestor in Africa
tracing how new populations split off leading to tiny differences in genomes

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50
Q

what is DNA made from

A

4 different nucleotides

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51
Q

what is a nucleotide comprised of

A

sugar - pentagon
phosphate group -cirlce
1 base - square

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52
Q

what are the 4 bases

A

ACTG

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53
Q

How many bases in one amino acid

A

3

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54
Q

how do bases control production of a protein

A

the order controls the order of
amino acids being assembled

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55
Q

DNA consists of alternating what

A

sugar and phosphate sections

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56
Q

what is C linked to and what is A

A

C=G
A=T

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57
Q

where are proteins synthesised

A

ribsomomes

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58
Q

how are proteins synthesised

A

carriers molecules
bring specific amino acids
in the correct order to form a
protein chain

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59
Q

when the protein chain is complete what happens

A

it folds to form a unique shape

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60
Q

why is it important that proteins have a unique shape

A

this enables the proteins to do their job (as enzymes, hormones or structure forming proteins like collagen)

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61
Q

give 3 examples of proteins

A

hormones, enzymes and collagen

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62
Q

how often do mutations occur

A

continuously

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63
Q

what do most mutations do

A

either don’t alter protein
or alter so slightly that appearance or function doesn’t change

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64
Q

give 2 thing that could happen if a mutation changes the shape of a proetin

A

an enzyme might not fit with the substrate binding site
and the structural protein could lose its strength

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65
Q

give an example of a piece of DNA which doesn’t code for proteins - what does it do?

A

non coding DNA - switches genes on and off

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66
Q

non coding genes (switching them on and off)could affect what

A

how the genes are expressed

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67
Q

what 2 things could a mutation do

A

change a coding gene
change a non coding gene - how expressed
could change phenotype or lead to genetic disease like cystic fibrosis

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68
Q

what is a gamete

A

sex cell

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69
Q

what is a chromosome

A

carries the DNA (genetic information)

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70
Q

what is an allele

A

a different version of the same gene

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71
Q

what does dominant mean

A

an allele that is always expressed even if only one copy is present

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72
Q

what is a recessive allele

A

only expressed if the individual has 2 copies of a gene

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73
Q

what does homozygous mean

A

alleles are identical

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74
Q

what is a phenotype

A

the observable physical characteristics of an organism

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75
Q

give 2 examples of characteristics controlled by a single gene

A

fur colour in mice and red green colour blindness in humans

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76
Q

what is the genotype

A

the alleles present

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77
Q

most characteristics are from one/many genes interacting

A

many

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78
Q

what is polydactly and what is it caused by

A

having extra fingers or toes
dominant

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79
Q

what is cystic fibrosis and what is it caused by

A

disorder of cell membranes
recessive

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80
Q

give 3 advantages and 3 disadvantages of embryonic screening

A

3 +
prevents suffering
financial benefits as don’t have to pay for long term treatment NHS
embryos in IVF need to be screened to check they are healthy
3 -
ethical concerns with destroying the embryos not used
designer babies
discrimination against characteristics or non designed people
expensive in the short term

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81
Q

how many pairs of chromosomes do human body cells have ordinarily

A

23

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82
Q

how many pairs determine sex

A

1

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83
Q

what is sex chromosomes for females

A

XX

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84
Q

sex chromosomes for males

A

XY

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85
Q

give 3 reasons for variations in characteristics of a population

A

genes
environment
combination of the two

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86
Q

how many genes roughly determine phenotype, how many influence it and what do most do

A

very few
some
no effect

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87
Q

what is the theory of evolution

A

all species evolved from simple life forms (that first developed more than 3 billion years ago)

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88
Q

when did simple life forms first develop

A

3 billion years ago

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89
Q

why does a new species happen

A

two populations of one species become so different in phenotype
that they can no longer interbreed to form fertile offspring

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90
Q

stages of evolution answer

A

mutation
variation (say what the variation is of)
competition
survival and reproduction as __is better suited to its environment!!
the allele is inherited over generations
evolution over time

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91
Q

what is selective breeding

A

when humans breed plants and animals for particular genetic charactertistics

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92
Q

when did humans first do selective breeding and give 2 examples

A

thousands of years ago
food crop breeding from wild plants
and domestication of animals

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93
Q

describe the process of selective breeding

A

choose parents with desired characteristic from a mixed population
breed them together
breed offspring with desired charactertistic together
continues over generations until all offspring show the desired charactertistic

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94
Q

give 4 examples of selective breeding for characteristics

A

disease resistance in food crops
animals producing more meat/milk
domestic dogs with gentle nature
large or unusual flowers

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95
Q

what bad thing can selective breeding lead to

A

inbreeding - where breeds are prone to disease or inherited defects

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96
Q

give 2 examples of genetic engineering in plants

A

engineered for disease resistance
and to produce bigger/better fruits

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97
Q

give an example of genetic engineering not in plants

A

bacterial cells engineered to produce useful substances like human insulin to treat diabetes

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98
Q

give 3 characteristics of GM crops

A

resistance to insect attack
resistance to herbicides
increased yeilds

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99
Q

give 2 concerns about GM crops

A

effects on wild flowers and insects as pollen could be toxic
effects of eating GM crops on human health haven’t been fully explored

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100
Q

what is modern medical research exploring with regards to genetic modification

A

exploring its usage to overcome genetic inherited disorders

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101
Q

give the 3 steps of genetic engineering

A

enzymes used to isolate gene
gene inserted into vector
vector inserts gene into cells
genes transferred to cells of organism at an early stage of the organisms development

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102
Q

what is used to isolate the required gene

A

enzymes

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103
Q

what is the gene inserted into in genetic engineering and what is this usually

A

vector - plasmid or virus

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104
Q

what is a tissue culture

A

using small groups of cells from the plant to grow identical new plants

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105
Q

give 2 uses of tissue cultures

A

preserving rare plant species
commercially in nurseries

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106
Q

cuttings is a new/old method and who is it used by and what for

A

old and simple
gardeners
producing many identical new plants from a parent plant

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107
Q

what are embryo transplants for cloning

A

split apart cells from developing animal embryo before specialised
transplant the identical embryos into host mothers

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108
Q

give the 5 stages of adult cell cloning

A

nucleus removed form unfertilised egg cell (enucleated)
nucleus from adult body cell(such as skin cell) inserted into egg cell
electric chock stimulates egg cell to divide into embryo
embryo has same genetic information as adult skin cell
when it has developed into ball it is inserted into womb of adult female to continue development

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109
Q

what is used to stimulate a clump of cels to divide into an embryo in adult cell cloning

A

electric shock

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110
Q

give 3 things that led Charles Darwin to his theory of evolution

A

observations on a round the world expedition
years of experimentation and discussion
linked to developing knowledge of geology and fossils

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111
Q

what did Darwin publish his ideas in and when

A

on the origin of species 1859

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112
Q

give 3 reasons there was controversy over evolution theory and it took a while for ideas to be accepted

A

challenged the idea that god created all animals and plants on earth
insufficient evidence at the time of publishing to convince many scientists
mechanism of inheritance and variation wasn’t known until 50 years after theory published

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113
Q

how many years after the theory of evolution was published was the mechanism of inheritance and evolution discovered

A

50

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114
Q

what is the theory of another guy around the time of Darwin and what was his name

A

Jean-Baptiste Lamarck
changes that occur in an organism during its lifetime can be inherited

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115
Q

why do we know Lamarck is wrong

A

for the vast majority of cases his type of inheritance of characteristics acquired in a lifetime cannot occur

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116
Q

who independent also proposed evolution by natural selection

A

Alfred Russel Wallace

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117
Q

who proposed joint writings with Darwin and when which promoted Darwin to do what

A

Alfred russel Wallace
1858
publish on the origin of species the following year

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118
Q

what is Alfred Russel Wallace best known for

A

warning colouration in animals
and speciation

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Perfectly
119
Q

what did Alfred Russel Wallace do

A

worked worldwide gathering evidence for evolutionary theory

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120
Q

who pioneered our understanding of speciation

A

Alfred russel Wallace

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121
Q

how does speciation happen

A

two populations separated
different mutations take place
natural selection makes them evolve differently
interbreeding can’t happen as phenotypes are too difference

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122
Q

what was Gregor Mendel up to until the mid 1850s

A

carrying out breeding experiments on plants

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123
Q

what was one observation from Gregor mendel

A

inheritance of characteristics is determined by ‘units’ that are passed on to descendants unchanged

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124
Q

when was the behaviour of chromosomes during cell division observed

A

the late 1800s

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125
Q

when was it observed that Mendel’s units and chromosomes behaved in similar ways and what did this lead to

A

early 1900s
units (genes)were located on chromosomes

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126
Q

when was the structure of DNA determined

A

mid 1900s

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127
Q

when was the mechanism of the gene function worked out

A

mid 20th century

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128
Q

give a timeline of gene theory

A

mendel units - 1850s
chromosomes - late 1800s
units are on chromosomes - early 1900s
mid 1900s - structure of DNA and gene function worked out

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129
Q

give 3 pieces of evidence for evolution

A

anti biotic resistant bacteria evolve
fossil records - show simple life
characteristics of parents are passed onto offspring in genes

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130
Q

what are fossils

A

the remains of organisms from millions of years ago found in rocks

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131
Q

give 3 ways fossils could be formed

A

parts of the organism haven’t decayed (as the conditions needed for decay are absent: no oxygen, no water, too cold)
parts of the organism replaced by minerals as they decay
preserved traces of organisms

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132
Q

give 3 examples of preserved traces of organisms

A

footprints,
burrows
rootlet traces

133
Q

why have many early life forms left few traces

A

soft bodied
traces destroyed by geological activity

134
Q

why can scientists not be certain how life began on earth

A

few traces of early life forms (as soft bodied and remains destroyed geologically)

135
Q

what can we learn from fossils

A

how much/little organisms have changed as life developed on earth

136
Q

what is extinction

A

when there are no remaining indivdiduals of a species alive

137
Q

give 5 reasons for extinction

A

new disease
new predator
new, more successful competitor
climate change (changes to environment)
single catastrophic event (such as asteroid collision or volcanic eruption)

138
Q

why do bacteria evolve rapidly

A

they reproduce at a fast rate

139
Q

what do mutations of bacterial pathogens produce

A

new strains

140
Q

describe the production of anti biotic resistant strains of bacteria

A

mutations produce new strains
some strains are resistant and not killed
survive and reproducing increasing strain population
resistant strain spread as lack of immunity and treatment

141
Q

give an example of a anti biotic resistant strain of bacteria

A

MRSA

142
Q

give 3 ways to reduce the rate of development of anti biotic resistant strains of bacteria

A

don’t prescribe antibiotics inappropriately
complete course so all bacteria are killed and none survive and mutate to form resistant strains
agricultural usage of antibiotics restricted

143
Q

give 2 examples of inappropriately prescribing antibiotics

A

for non serious things
or viral infection

144
Q

the development of new antibiotics is__-and ___and so unlikely to keep up with what

A

costly and slow
the emergence of new strains

145
Q

what are living things classified into groups based on

A

structure and characteristics

146
Q

who developed the classification system traditionally used

A

carl Linnaeus

147
Q

what are the 7 groups of Linnaeus’s system of classificantion

A

kingdom
phylum
class
order
family
genus
species

148
Q

what system are organisms named by

A

binomial system of genus and species

149
Q

how do developments in biology impact classification systems

A

internal structures understanding is more developed due to improvements in microscopes
understanding of biochemical processes progressed
new improved models of classification

150
Q

what is the new model for classification due to new ___analysis

A

chemical
three domain

151
Q

who developed the 3 domain system

A

Charles Woese

152
Q

what are the 3 groups in the 3 domain system

A

Achaea
bacteria
eukayota

153
Q

what are archaea

A

primitive bacteria living in extreme environments

154
Q

what are bacteria

A

true bacteria

155
Q

what does eukaryota include

A

fungi protists animals and plants

156
Q

what is an ecosystem

A

the interaction of a community of living (biotic)and non living(abiotic) parts of the environment

157
Q

give 3 things animals compete for

A

food, mates, territory

158
Q

give 4 things plants compete for

A

light, space, water and mineral ions in soil

159
Q

if one species in a community of organisms is removed what happens and what is this called

A

interdependence it can affect the whole community

160
Q

what is a stable community

A

all species and environmental factors are in balance so the population size remains fairly constant

161
Q

give 3 examples of interdependence

A

relying on another species for food, shelter, seed dispersal, pollination

162
Q

how does temperature affect a community

A

plants grow healthily at optimum temp

163
Q

how can soil pH affect a community

A

some plants like heathers grow best in acidic soils but some don’t like it and are sensitive to that so won’t grow as well

164
Q

how can wind intensity and direction affect a community

A

affects CO2 supply to plants
increases rate of plant transpiration
can mechanically damage plants

165
Q

how can Co2 levels affect plants

A

more CO2 increases growth and yield as needed for photosynthesis
CO2 is acidic so may not raise yields of all plants as some are sensitive to pH

166
Q

how do oxygen levels affect aquatic animals

A

oxygen needed for respiration
stagnant and polluted waters have low levels of oxygen
moving lakes have high levels

167
Q

give 4 biotic factors affecting a community

A

new predators
new pathogens
food availability
competition - outcompeted

168
Q

give 3 types of adaption

A

structural
behavioural
functional

169
Q

what are extremophiles and give an example

A

organisms adapted to live in extreme environments
bacteria living in deep sea vents

170
Q

give 3 examples of extreme environments for extremophiles

A

high temp, pressure or salt conc

171
Q

who are the producers of biomass for life on earth

A

photosynthetic organisms

172
Q

what do food chains begin with

A

a producer which synthesises molecules

173
Q

give an example of a typical producer

A

green plant or alga that makes glucose with photosynthesis

174
Q

what are producers eaten by

A

primary consumers

175
Q

what are primary consumers eaten by

A

secondary consumers (then tertiary etc)

176
Q

in a stable community what happens to the levels of predator and prey

A

they rise and fall in cycles

177
Q

describe a method for measuring population of a species

A

choose plants or slow moving creatures
image space as a grid
use random numbers to generate a set of coordinates for first quadrant
count number of species in quadrat
repeat 14 times
do this in another area with contrasting environment

or use a transect line running from are with one environment to another one with a contrasting environment. take samples every 1m or so

178
Q

give 2 examples of experimental methods used to measure abundance and distribution of a species

A

transects and quadrats

179
Q

what is the carbon cycle

A

returns carbon from organisms to atmosphere where used by plants in photosynthesis

180
Q

what does the water cycle do

A

provides freshwater for plants and animals on land before draining to seas

181
Q

what are 3 factors affecting rate of decomposition

A

temp
water
oxygen

182
Q

explain how temp affects decomposition

A

colder = decomposers less active
rate = low
at too high decomposers killed and it stops
as the decomposers secrete enzymes then absorb the molecules

183
Q

explain how water affects decomposition

A

too dry = die
as volume of water increases rate increases

184
Q

what is oxygen used for by decomposers

A

respiring to grow and multiply

185
Q

what is compost used for

A

a natural fertiliser for growing garden plants or crops

186
Q

what does anaeorobic decay produce

A

methane gas

187
Q

what is used to make methane into a fuel

A

biogas generators

188
Q

describe the practical investigating effect of temp on rate of decay of fresh milk by measuring pH change

A

20 cm cubed of fresh milk into 3 beakers
do 5 degrees, 20, and 35
use Universal indicator solution to check pH
cover with cling film and incubate at appropriate temp
revisit after 24, 48, 72 hours
repeat

189
Q

why does the pH of milk reduce as it decomposes

A

bacteria in milk carries out a process converting lactose milk to lactic acid

190
Q

4.7.2.4 okay?

A
191
Q

what is biodiversity

A

variety of species of organisms in an ecosystem or on earth

192
Q

what is a positive impact of biodiversity

A

reduces dependence of one species on another for food, shelter and maintenance of physical environment

193
Q

the future of what relies on a good level of biodiversity

A

THE HUMAN SPECIES ON EARTH

194
Q

give 2 reasons more resources are used and more waste is produced

A

rapid growth of human population
increase in standard of living

195
Q

Give 3 areas of pollution

A

water
air
land

196
Q

give 3 causes of water pollution

A

sewage(pollution is shit) fertiliser and toxic chemicals

197
Q

give 2 causes of air pollution

A

smoke and acidic gases

198
Q

give 2 causes of land pollution

A

landfill and toxic chemicals

199
Q

what can pollution reduce

A

biodiversity as kills plants and animals

200
Q

give 4 ways humans reduce land available to other animals and plants

A

farming, quarrying, building, dumping waste

201
Q

how can peat bogs release. greenhouses gases and which one

A

decay or burning
CO2

202
Q

what does the destruction of peat bogs do

A

reduces area of habitat and hence biodiversity

203
Q

give 2 reasons for large scale deforestation in tropical areas

A

land for cattle and rice fields provision
growing crops for biofuels

204
Q

why is there consensus around climate change

A

based on systematic reviews of thousands of peer reviewed publications

205
Q

give 5 programs to reduce negative effects on ecosystems and biodiversity from humans

A

breeding programmes for endangered species
protection and regeneration of rare habitats
reintroduction of field margins and hedgerows in monocultures
reduction of deforestation and CO2 emissions
recycling

206
Q

what is trophic level 1

A

plants and algae - producers as make own food

207
Q

what is trophic level 2

A

primary consumers
herbivores eat plants and algae

208
Q

what is level 3 trophic

A

carnivores eat herbivores - secondary consumers

209
Q

what is trophic level 4

A

carnivores eat other carnivores - tertiary consumers

210
Q

what are apex predators

A

carnivores with no predators

211
Q

how do decomposers break down dead plant and animal matter

A

secreting enzymes into the environment
small soluble food molecules diffuse into the organism

212
Q

producers transfer ___% of light energy from photosynthesis

A

1

213
Q

only __% of biomass from each level is transferred to the one above

A

10

214
Q

give 2 reasons for loss of biomass between levels

A

lots of glucose used for respiration
not all ingested material is absorbed - some tested as faeces
some is lost as waste water, CO2 or urea

215
Q

what is food security

A

having enough food to feed a population

216
Q

give 6 biological factors affecting food security

A

increasing birth rate
changing diet = scarce food resources transported around the world
new pests and pathogens affect farming
if rains fail = widespread famine
cost of agricultural inputs
conflicts

217
Q

what needs to be done to feed people on earth

A

sustainable methods must be found

218
Q

how can the efficiency of food production be increased

A

restricting energy transfer from food animals to environment - limiting movement and controlling temperature

219
Q

what are some animals fe dot increase growth

A

high protein foods

220
Q

evaluate the advantages and disadvantages of modern farming techniques

A

higher yield
more efficient land use
ethical objections
can increase risk of antibiotic resistance
CONCLUDE

221
Q

what in oceans is declining

A

fish stocks

222
Q

why is it important to maintain fish stocks at a particular level

A

a level where breeding continues is important
or some may disappear in some areas

223
Q

give 2 ways to keep fish stocks at a sustainable level;

A

fishing quotas
control of net size

224
Q

what fungus is used to make food suitable for vegetarians and what is it called

A

fusarian
mycoprotein

225
Q

how is mycroprotein grown

A

fungus grown on glucose syrup
in anaerobic conditions
biomass harvested and purified

226
Q

what produces insulin

A

a genetically modified bacterium

227
Q

what could GM products provide and give an example

A

more food
food with an improved nutritional value
golden rice

228
Q

what does the brain do

A

control complex behaviour

229
Q

what is the brain made up of

A

billions of interconnected neurones
has different regions that carry out different functions

230
Q

identify cerebellum, cerebral cortex and medulla on Brain diagram

A
231
Q

give 3 ways neuroscientists have mapped regions of the brain to particular functions

A

studying patients with brain damage
electrical stimulation of different parts of the brain
using MRI scanning

232
Q

give 2 reasons that investigating and treating brain disorders is very difficult

A

delicacy and complexity of the brain

233
Q

the eye is a __organ

A

sense

234
Q

give 2 things receptors in the eye are sensitive to

A

light intensity and colour

235
Q

can you label the eye?

A
236
Q

what does the retina do

A

contains receptor cells sensitive to brightness and colour of light

237
Q

what is the optic nerve

A

carries impulses between the eye and brain

238
Q

what does the cornea do

A

refracts light as it enters the ey

239
Q

what is the iris doing

A

controls how much light let into pupil

240
Q

what does the lens do

A

further refracts light to focus it on the retina

241
Q

what does the sclera do

A

tough white outer layer
helps protect the eye from injury

242
Q

what is accomodation

A

the process of changing the shape of a lens to focus on near or distant objects

243
Q

explain what happens to focus on a near object

A

ciliary muscles contract
suspensory ligaments relax
lens is thicker and refracts light rays more strongly

244
Q

explain what happens to focus on a far object

A

ciliary muscles relax
suspensory ligaments contract
the lens is pulled thin and only slightly refracts light rays

245
Q

what are 4 ways to correct myopia or hyperopia

A

spectacle lenses
hard and soft contact lenses
laser surgery to change the shape of the cornea
replacement lenses

246
Q

how do you correct for myopia
hyperopia?

A

with concave lenses -
convex lenses - as there is an e in hyperopia

247
Q

what is body. temperature monitored by

A

thermoregulatory centre

248
Q

what is body temperature controlled by

A

thermoregulatory centre

249
Q

give 2 mechanisms for finding temperature of the body

A

thermoregulatory centre contains receptors sensitive to the temperature of blood
skin contains temperature receptors and sends nervous impulses to the thermoregulatory centre

250
Q

is body temp is too high what happens

A

blood vessels dilate - vasodilation
sweat is produced from the sweat glands
causing a transfer of energy from the skin to the environment

251
Q

what 3 things happen if too cold

A

blood vessels constrict - vasoconstriction
sweating stops
shivering - skeletal muscles contract

252
Q

what muscles contract in shivering

A

skeletal muscles contract

253
Q

what is the endocrine system composed of and what does it do

A

glands
secretes chemicals called hormones into the bloodstream

254
Q

describe the process of hormones being released to having an effect

A

glands secrete hormones into bloodstream
blood carries hormone to a target organ
where it produces and effect

255
Q

how to the effects of the endocrine system compare to the nervous system

A

the effects are slower but act for longer

256
Q

what is the master gland

A

the pituitary gland

257
Q

what does the pituitary gland do

A

secretes several hormones into the blood in response to body conditions
these hormones act on other glands to stimulate other hormones to be released to bring about effects

258
Q

label a diagram of hormonal glands of the body

A
259
Q

what is blood glucose concentration monitored and controlled by

A

the pancreas

260
Q

if blood glucose is too high what happens

A

pancreas produces insulin hormone
that moves glucose from blood to liver and muscle cells where excess glucose is converted to glycogen for storage

261
Q

where is glucose stored in and as what

A

glycogen - liver and muscle cells

262
Q

what is type 1 diabetes

A

pancreas fails to produce sufficient insulin

263
Q

what is type 1 diabetes characterised by

A

uncontrolled high blood glucose levels

264
Q

what is type 1 diabetes treated with

A

insulin injections

265
Q

what is type 2 diabetes

A

body cells no longer respond to insulin produced by the pancreas

266
Q

give 2 common treatments for type 2 diabetes

A

Carbohydrate controlled diet and exercise regime

267
Q

what is a risk factor for type 2 diabetes

A

obesity

268
Q

is blood glucose is too low what happens

A

pancreas produces glucagon
which converts glycogen back into glucose
and releases it into blood

269
Q

how does water leave the body

A

via lungs during exhalation

270
Q

what 3 things are lost from the skin in sweat

A

water, ions and urea

271
Q

is there any control over water, ion or urea loss by sweat or lungs?

A

no

272
Q

what 3 things are removed by the kidneys and via what

A

water, ions and urea
urine

273
Q

what 3 things are in urine

A

water, ions and urea

274
Q

If body cells gain or lose water too much by osmosis what happens

A

they don’t function effectively

275
Q

how are excess amino acids from the digestion of proteins excreted safely and where

A

liver
amino acids deaminated to make ammonia
ammonia is toxic
so immediately converted to urea for safe excretion

276
Q

ammonia is____

A

toxic

277
Q

how do kidneys produce urine

A

filtration of the blood
selective reabsorption of useful substances such as glucose, some ions and water

278
Q

what is water level in the body controlled by

A

the hormone ADH acting on kidney tubules

279
Q

what is ADH released by

A

the pituitary gland - as A is the master

280
Q

describe what happens when there is not enough water in the blood - negative feedback loop

A

ADH released by pituitary gland
more water reabsorbed back into the blood from the kidney tubules

281
Q

give 2 ways to treat kidney failure

A

organ transplant
kidney dialysis

282
Q

how does dialysis work

A

unfiltered blood high in urea
mixed with anti coagulants (blood thinners)
blood and dialysis fluid separated by partially permeable membrane
flowing in opposite directions
exchange over concentration gradient
glucose and ions similar conc in dialysis
but no urea
so urea passes out

283
Q

what does the dialysis fluid have the same conc of

A

glucose

284
Q

+/- of transplants

A

+transplants
lead more normal life
cheaper for NHS overall
-transplants
immunosuppressant drugs
shortage of donors
only last 8-9 years
operational risks

285
Q

+/- of dialysis

A

available to all - no shortage
no need for immunosuppressants
must limit salt and protein intake between dialysis sessions
expensive for NHS
regular sessions impact lifestyle

286
Q

during puberty what causes secondary sex characteristics to develop

A

reproductive hormones

287
Q

what is oestrogen produced in

A

the ovary

288
Q

one egg is released every ___days

A

28

289
Q

what is ovulation

A

the release of an egg

290
Q

what does testosterone do

A

stimulate sperm production

291
Q

What does FSH do

A

matures egg in ovary

292
Q

what does LH do

A

stimulates the release of an egg
as L - lets it go

293
Q

what do oestrogen and progesterone do

A

maintain uterus lining

294
Q

what is the start of the cycle

A

period

295
Q

what does FSH stimulate the release of

A

oestrogen

296
Q

what stops FSH production

A

oestrogen

297
Q

what does oestrogen stimulate the pituitary glands to release

A

LH

298
Q

what is progesterone produced by

A

follicle - and released by ovaries

299
Q

how do oral contraceptives work

A

inhibit FSH so eggs c=don’t mature

300
Q

what does injection, implant or skin patch of slow release progesterone do to be contraception

A

inhibits maturation and release of eggs

301
Q

how do barrier methods work

A

prevent sperm reaching the egg

302
Q

what are 2 ways intrauterine devices can work

A

prevent implantation of embryo
or release a hromone

303
Q

what do spermicidal agents do

A

kill or disable sperm

304
Q

when do you abstain from intercourse

A

when egg might be in the oviduct

305
Q

the progesterone pill - evaluate

A

free
at least 99% effective
have to take same time each day
no STD protection
some medicines make it less effective

306
Q

evaluate spermicide

A

short term
non invasive
only 70-80% effective
no STI protection

307
Q

abstinence is very/not very effective

A

not very

308
Q

condoms are __% effective and have __side effects but give 2 costs

A

98%
no
costs money
can tear
latex allergies

309
Q

how effective is diaphragm

A

92%

310
Q

the implant is free/not free NHS

A

free

311
Q

give costs of the contraceptive implant

A

disrupted periods
pain on insertion

312
Q

what hormones are in fertility drugs for women

A

FSH and LH

313
Q

give the 4 stages of IVF

A

give mother FSH and LH to stimulate the maturation of several eggs
eggs collected and fertilised with father’s sperm in lab
fertilised eggs develop into embryos
when tiny balls of cells one or two inserted into uterus (womb)

314
Q

give 3 costs of IVF

A

very emotionally and physically stressful
success rates low
can lead ti multiple births - risk to baby and mother

315
Q

what is adrenaline produced by and when

A

adrenal glands
times of fear or stress

316
Q

give 3 things adrenaline does

A

increases heart rate
boosts delivery of oxygen and glucose to brain and muscles
preparing for fight or flight

317
Q

what is thyroxine from and what does I tdo

A

thyroid gland
stimulates basal metabolic rate

318
Q

what does basal metabolic rate do

A

plays a role in growth and development

319
Q

describe what happens when thyroxine conc in blood is too low

A

production of TSH increases
stimulates thyroxine secretion by thyroid

320
Q

what controls phototropism and gravitropism

A

plant hormones - unequal distributions of auxin causing unequal growth rates in roots and shoots

321
Q

what hormones are important for seed germination

A

gibberellins - G G

322
Q

what controls cell division and fruit ripening

A

ethene

323
Q

give 3 things auxins are used for

A

weed killers
rooting powers
promoting growth in tissue cultures

324
Q

what is ethene used for

A

controlling ripening of fruit during storage and transport in the food industry

325
Q

what 3 things can gibberellins be used for

A

ending seed dormancy
promote flowering
increase fruit size

326
Q

describe the auxins practical method

A

cotton wool on 3 Petri dishes with same amount of water for each dish
10 seeds per dish and placed somewhere warm
allow to germinate
one in dark, one in light and measure heights

327
Q

which side does auxin gather on for phototropism

A

shaded side as promotes growth there

328
Q

what do auxins do in gravitropism (negative)

A

inhibit growth and make root curve down - for positive stimulates growth to serve upwards

GCSE Biology Revision (10 decks)

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