what does cell metabolism lead to?
the build up of waste products in the blood, including carbon dioxide and urea
1 of 209
what is carbon dioxide?
a waste product of respiration
2 of 209
what is urea?
the product of excess amino acids in the liver
3 of 209
how is urea removed?
by the kidneys
4 of 209
what are the parts of the urinary system?
renal artery, renal vein, kidneys, ureters, bladder, urethra
5 of 209
what do the renal arteries do?
carry blood from the body to the kidneys
6 of 209
what do the renal veins do?
carry clean blood back to the body
7 of 209
what do the kidneys do?
remove substances including urea from the blood and make urine
8 of 209
what do the ureters do?
carry urine from the kidneys to the bladder
9 of 209
what does the bladder do?
10 of 209
what is the urethra?
urine flows through the urethra to the outside of the body
11 of 209
what are sphincter muscles?
a muscle that keeps the exit from the bladder closed until we decide to urinate
12 of 209
what is kidney failure?
when both kidneys stop working causing toxic urea to build up in the blood
13 of 209
how can kidney failure be treated?
organ donation and kidney dialysis
14 of 209
how does kidney dialysis work?
blood is passed through a dialysis machine to remove waste urea and excess substances before the blood is returned to the blood
15 of 209
how does organ donation work?
a healthy kidney from another person is placed in the body and connected to the blood system, so that waste substances are removed from the blood
16 of 209
what are nephrons?
millions of tiny tubules that lie in the kidney, they are responsible for making urine
17 of 209
what are the structures inside of a nephron?
renal artery, glomerulus, bowman's capsule, convoluted tubules, loop of Henlé, collecting duct
18 of 209
what are the processes that take place inside of the nephron?
filtration, selective reabsorption, osmoregulation
19 of 209
how does filtration take place?
filtration in the nephron is of small molecules from blood into tubule,including water, glucose, salts and urea
20 of 209
how does selective reabsorption take place?
selective reabsorption of glucose from the tubule back into blood by active transport
21 of 209
how does osmoregulation take place?
reabsorption of water that the body NEEDS from the tubule goes back into the blood
22 of 209
how are the structures of the glomerulus and the bowman's capsule related to their function?
high blood pressure. leaky walls (small molecules filter from the blood into the capsule), large surface area (filtration happens as quickly as possible
23 of 209
how are the structures of the loop of henlé and the convoluted tubules related to their functions?
they lie close to the capillary (glucose and water can be reabsorbed into the blood from the tubule)
24 of 209
what is the role of ADH?
regulates the water content of the blood
25 of 209
where is ADH produced?
the pituitary gland
26 of 209
how is ADH production controlled?
by a negative feedback mechanism
27 of 209
what is the menstrual cycle controlled by?
the hormomes oestrogen and progesterone
28 of 209
what are the main stages of the menstrual cycle?
menstruation, changes to uterus lining and ovulation
29 of 209
what is menstruation?
the breakdown of the uterus lining. it begins on day 1 of the cycle and usually lasts between 4 and 7 days
30 of 209
what happens to the uterus lining?
during the second week, the lining of the uterus is gradually built up
31 of 209
what happens during ovulation?
an egg is released from an ovary. This usually takes place around day 14
32 of 209
when is fertilisation most likely to occur?
33 of 209
what happens in weeks 3 and 4?
the lining of the uterus continues to build up
34 of 209
what happens if fertilisation does occur?
the uterus lining is maintained and menstruation does not happen
35 of 209
why is the uterus lining maintained if fertilisation does occur?
the embryo that develops from a fertilised egg needs to embed in thick uterus lining, so that it can get nutrients from the mother
36 of 209
what is the role of oestrogen in the menstrual cycle?
stimulates the release of LH and causes thickening of uterus wall, when levels fall, it triggers menstruation
37 of 209
what is the role of F.S.H ?
follicle stimulating hormone - causes maturation and growth of follicles, this stimulates oestrogen production
38 of 209
what is the role of LH?
triggers ovulation, which releases progesterone
39 of 209
what is the role of progesterone?
it inhibits FSH and LH release, when it falls it triggers menstruation
40 of 209
how is the control of the menstrual cycle a negative feedback mechanism?
changes caused by the release of one hormone inhibit the secretion of other hormones. for example, progesterone inhibits FSH and LH
41 of 209
how is the structure of an egg adapted to its function?
cytoplasm (provides nutrients), haploid nucleus (one set of genetic material), cell membrane (blocks entry of other sperm after fertilisation)
42 of 209
how is the structure of a sperm cell related to its function?
acrosome (contains enzymes), haploid nucleus (one set of genetic material), mitochondria (in middle section to release energy from respiration to power tail), tail (for motility)
43 of 209
what is IVF?
in vitro fertilisation - egg cells taken from the woman's ovaries are mixed with sperm cells from the man in a dish. one or two healthy embryos are implanted to develop
44 of 209
what is an advantage of IVF?
it is useful if a man produces only a few healthy sperm
45 of 209
what is a disadvantage of IVF?
IVF babies may be born early, which can cause problems at birth or later in life
46 of 209
what is egg donation?
eggs from another woman are fertilised by the man's sperm using IVF. one or two are implanted in the uterus of the woman in the couple to develop
47 of 209
what is an advantage of egg donation?
it can be used when the woman of the couple has no eggs in her ovaries
48 of 209
what is a disadvantage of egg donation?
hormones used to collect eggs may cause a bad reaction. the egg donor may want access to the child
49 of 209
what is a surrogate mother?
eggs and sperm from the couple are mixed in a petri dish. A healthy embryo is placed in the uterus of another woman - the surrogate - to develop
50 of 209
what is an advantage of a surrogate mother?
it can be used when the woman of a couple cannot grow an embryo in her uterus
51 of 209
what is a disadvantage of a surrogate mother?
some surrogate mothers find it hard to hand over the baby to the couple
52 of 209
what are hormones (as an infertility treatment)?
the woman is given extra hormones to help her ovaries release eggs
53 of 209
what is an advantage of hormones?
they can be used when the woman's hormones are not enough to cause ovulation
54 of 209
what is a disadvantage of hormones?
there is a greater risk of having several babies at the same time. these babies tend to be born earlier than normal, which can cause problems at birth or later in life
55 of 209
what is the sex of a person controlled by?
one pair of chromosomes, x,x, in a female, x,y, in a male
56 of 209
when is the sex of offspring determined?
57 of 209
how can you show how it is determined?
genetic diagram or punnett square
58 of 209
how can you show how sex -linked genetic disorders are inherited?
genetic diagrams, punnett squares
59 of 209
what are two examples of sex-linked genetic disorders?
haemophillia and colour blindness
60 of 209
what scientist contributed to the development of vaccines?
61 of 209
what was the first step of the process?
he gave a boy a pathogen that causes cowpox, the boy developed the cowpox and recovered
62 of 209
what is the second step of the process?
he gave the same boy the pathogen with smallpox, the boy did not develop smallpox
63 of 209
what had he discovered?
the cowpox vaccine made him immune to smallpox
64 of 209
what can immunisation do?
can protect you from infection
65 of 209
what are antigens?
surface proteins that identify a cell
66 of 209
what are antibodys?
chemicals made by lymphocytes
67 of 209
what is step 1 in the process of immunisation?
a vaccine containing a dead or weakened pathogen is injected
68 of 209
what is step 2 in the process of immunisation?
a type of white blood cell (lymphocyte), with an antibody that perfectly fits the antigen is activated
69 of 209
what is step 3 of immunisation?
this lymphocyte divides over and over again to produce clones of identical lymphocytes
70 of 209
what is step 4 of immunisation?
some of the lymphocytes secrete large amounts of antibodies, this stick to the antigens and destroy the pathogen. other lymphocytes remain in the blood as memory lymphocytes, ready to respond immediately if the same antigen ever turns up again
71 of 209
what are some risks of immunisation?
some people get a mild reaction or mild form of the disease,very rarely but sometimes, a person has a major harmful reaction
72 of 209
what are some advantages of immunisation?
immunity is produced without being ill, it lasts a long time, often for life, if most people are immune, then the few who aren't are also less likely to catch the disease.
73 of 209
what is the role of a memory lymphocyte?
a secondary response to an antigen
74 of 209
what are monoclonal antibodies?
antibodies that carry useful chemicals markers or treatments. a set of monoclonal antibodies are identical because they are produced in large quantities from the same hybridoma cells
75 of 209
how can B lymphocytes by produced?
by mice, it makes particular antibodies continuously but they do not divide
76 of 209
what are the beneficial properties of a cancer cell?
it divides continuously, but does not make antibodies
77 of 209
how can hybridoma cells be produced?
by fusing a B lymphocyte cell and a cancer cell, the hybridoma cell divides and produces antibodies all at the same time
78 of 209
what are the uses of monoclonal antibodies?
in pregnancy tests, in blood clots, in radiotherapy treatments
79 of 209
how are monoclonal antibodies used in pregnancy tests?
to identify if the pregnancy hormone is present in urine
80 of 209
how are monoclonal antibodies used in blood clots?
they stick to blood clots or cancer cells so they can be detected and treated
81 of 209
how are monoclonal antibodies used in radiotherapy?
used to deliver drugs to the target cells, only the target cells are affected and smaller amounts of drugs are used
82 of 209
what can growth of a population of bacteria lead to?
exponential growth of a population of bacteria can lead to rapid development of an infection
83 of 209
what did Louis Pasteur do?
he carried out experiments showing that once micro-organisms are destroyed- they don't suddenly appear again
84 of 209
how can micro-organisms be transferred?
micro-organisms can only be transferred from something that already contains them, e.g. the air
85 of 209
what was his experiment?
he used two different sized beakers to show that if micro organisms are not present in a solution, it can stay fresh for much longer
86 of 209
why did he boil his experiments?
because boiling (for one hour) kills any microorganisms already in a broth
87 of 209
why did he use broth?
because broth is a liquid containing nutrients
88 of 209
what did Pasteur's work lead to?
the development of aseptic techniques that are used to destroy microorganisms
89 of 209
how are these 'aseptic techniques' used?
to prevent spoilage of food and in surgery (operations) to prevent infections of wounds
90 of 209
what are plant defences?
plans protect themselves from attack by producing chemicals
91 of 209
what do they make?
poisons that deter pests and chemicals that kill pathogens which infect them and cause disease
92 of 209
what do we use plant chemicals for?
we use some of the defence chemicals found in plants as medicines
93 of 209
what are some examples of plant chemicals?
quinine (from cinchona tree) to treat human disease (e.g. malaria), digoxin (from foxglove) to treat human disorders ( e.g. heart), aspirin (willow tree and other plants), to relieve symptoms (e.g. pain and fever)
94 of 209
what is the impact of pests on food supply?
pathogens and pests that attack crop plants cause damage, this reduces the yield of the crop.
95 of 209
why does this impact our food supply?
because most of the food we eat comes from plants
96 of 209
what is photoperiodicity?
the response of a plant that changes as day length changes
97 of 209
where is it most noticeable?
in places where day length varies significantly throughout the year
98 of 209
what are some examples of photoperiodism?
germination, growth and reproduction (flowering)
99 of 209
how does germination show photoperiodicity?
seeds are not affected by light as they grow underground but they germinate in spring hen conditions for growth are getting better (e.g. lettuce)
100 of 209
how does growth show photoperiodicity?
plants stop growing over winter, some trees lose their leaves
101 of 209
how does reproduction show photoperiodicity?
plants in seasonal areas produce flowers at a particular time of year. some produce flowers in response to days getting longer (spring/summer) other plants flower when day length gets shorter (autumn)
102 of 209
what is a circadian rhythm?
a pattern of behaviour that changes over a 24 hour period, controlled by an internal biological clock and external factors such as day or night help to match this clock to changes in the environment
103 of 209
what does sexual reproduction require?
finding and selecting a suitable mate, this can involve courtship behaviour
104 of 209
how do some animals have different mating strategies?
some animals mater for life and only choose another if their mate dies, some have several mates over their lifetime, some have one mate for a breeding season, some have several mates for a breeding season
105 of 209
what is an example of courtship behaviour?
roaring of an animal - demonstrates its strength, males that roar the longest will mate with more females
106 of 209
what is the role of a female in courtship?
selecting between males, so that their offspring inherit the best genes possible
107 of 209
what are parenting behaviours?
some animals, particularly birds and mammals, have special behaviours for rearing young, these are parenting behaviours
108 of 209
what are some examples of parenting behaviours?
protecting the youth from danger, helping the young to find food, sheltering the young from cold and wet, teaching the young new skills, such as hunting
109 of 209
why can parental care be a successful evolutionary strategy?
because there is an increased chance of survival and the offspring also inherits the genes for good parenting and are more likely themselves to have young that survive
110 of 209
how may parental care involve risks to the parents?
parents may try so hard to deter predators away from their offspring that they are killed themselves and their offspring are now in more danger than before
111 of 209
what is innate behaviour?
a behaviour that an animal does not have to learn
112 of 209
what is imprinting?
a simple learned behaviour, e.g. a gosling learning to recognise its mother after hatching. imrpinting only happens at a particular time but may last throughout life without change
113 of 209
what is habituation?
a simple form of learned behaviour. it happens when an animal "switches off" its response to a repeated harmless stimulus. this helps the animal to concentrate on changes in the environment that are important
114 of 209
what is classical conditioning?
it occurs when an innate behaviour is changed through associating a new stimulus with the old response
115 of 209
what is operant conditioning?
a chance behaviour is strengthened by receiving a reward. At first, the behaviour is chance, but the animal learns to associate the reward with the behaviour and so carry out the behaviour more often
116 of 209
how are sniffer dogs trained with use of behaviours?
in operant conditioning - they are trained with a toy that they enjoy playing with. the first time in training that they find drugs they are given the toy to play with - this happens again and again until the dog will look for the drugs.
117 of 209
how are dolphins trained with use of behaviours?
in operant conditioning - they are trained with a reward , e.g. food, that they enjoy. the first time they do a trick they are given the food - this happens again and again until the dolphin will do the trick alone.
118 of 209
how are police horses trained with use of behaviours?
police horses are exposed to crowds during their training so that they learn to become used to the noise - this is habituation
119 of 209
what is an example of classical conditioning?
salivating when food is present, bell rung when food is presented, bell associated with food being presented, salivating when a bell is rung, even with no food
120 of 209
what are choice chambers?
a choice chamber can be used to investigate innate behaviour in small animals
121 of 209
what is ethology?
the study of animal behaviour. Niko Tinbergen was an ethologist who studied the innate behaviour of gull chicks
122 of 209
what was his experiment with gull chicks?
he noticed that gull chicks peck at their parent's beak to ask for food, he tested different models of adult gull beaks to see which model the chicks would innately respond to and peck at the most frequently
123 of 209
what did Konrad Lorenz show?
that newly hatched goslings could imprint on an object rather than their mother goose if they saw the object first
124 of 209
why is this an example of learning and not innate behaviour?
if recognising the mother was innate, then the goslings would not become attatched to the object. Imprinting is a learned behaviour because the goslings learn to recognise what they see first as their parent, and this can be different
125 of 209
what does some animal behaviour require?
126 of 209
what are the different types of signals in animal communication?
sound, chemical and visual
127 of 209
what are some examples of sound communication?
birds sing to establish and maintain territory, cats hiss to frighten other cats, deer stags roar to challenge other stags and attract females
128 of 209
what are some examples of chemical communication?
animals release hormone like chemicals called pheremones into the air, e.g. female moths release them to attract male moths
129 of 209
what are some examples of visual communication?
gestures - such as head nodding or hand waving, body language - the position of the body can express feelings and emotion, facial expressions - such as showing teeth
130 of 209
what is social behaviour?
social behaviour occurs between individuals in a group. it includes the use of different types of signal. social behaviour can increase the change of survival of individuals and all of the group
131 of 209
what are examples of social behaviour?
defending a larger territory, some individuals watching for danger while others feed, fighting off predators as a group, working as a group to hunt for food
132 of 209
Who was Dian Fossey?
an ethologist who studied the social behaviour of gorillas by watching them in the wild. Fossey learned the meaning of many gorilla calls and found that gorillas had complex social relationships. She also showed that gorillas were not violent
133 of 209
how has the work of Jane Goodall contributed to our understanding of chimpanzee behaviour?
she watched chimpanzee groups for many years and recorded what she saw. her work shows that chimpanzees live in complex family groups that communicate using many different calls, she was first to record chimpanzees using tools and hunting as a group
134 of 209
how do plants communicate?
using chemicals with animals and with other plants
135 of 209
how do plants communicate with animals?
flowering plants produce scents to attract particular animals, such as some insects. as the animal feeds on nectar, the pollen attatches to the animal and is transported to the next. mutualistic relationship
136 of 209
how do plants communicate with other plants?
they produce chemicals from their roots tat damage the roots of other plants, reduces competition for resources (water and mineral ions), release chemicals into the air when they are attacked by herbivores, surrounding plants produce poisons
137 of 209
what is co-evolution?
is evolution that is caused in one species by a change in another species.
138 of 209
how have plants and animals co-evolved?
plants have co-evolved the shape of their flowers with animal pollinators so that only one or a few species of animal can feed at the flower
139 of 209
how does this benefit both the plant and animal?
pollen from the plant's flowers is more likely to be taken to a flower of the same species, the animal is less likely to have to compete to get the nectar in the flower
140 of 209
what will happen if the relationship becomes too specialised?
the populations can become too dependent on each other. if one population crashes, the other can be affected
141 of 209
why do plants growing in areas of herbivores produce more poison than areas with fewer herbivores?
this is an example of co-evolution because where there are many herbivores, the plants that survive and reproduce have large amounts of poison. so the neext generation inherit the genes for producing lots of poison
142 of 209
where does the evidence we have for evolution come from?
fossils, of bones and teeth
143 of 209
when did 'ardi' exist?
ardipithecus ramidus existed 4.4 million years ago
144 of 209
when did 'lucy' exist?
australopithecus afarensis existed 3.2 million years ago
145 of 209
when did "handy man" exist?
**** habilis existed 2.4 -1.4 million years ago
146 of 209
when did "upright man" exist?
**** erectus existed 1.8- 0.5 million years ago
147 of 209
when did 'modern man' exist?
since c.200 000 years ago
148 of 209
what species are known as part of the 'Leakey family'?
**** habilis and **** erectus
149 of 209
how has height changed over time?
went down from ramidus to afarensis but has increased since then
150 of 209
how has brain size changed over time?
it has increased
151 of 209
what are some major changes over time?
use of tools, walking upright, build
152 of 209
how do stone tools also give us evidence for evolution?
the earliest stone tools are around 2.4 million years old. Over time more complex tools were made, and a greater range of tool types
153 of 209
what are some examples of how tools have changed?
2 million years ago - a large stone that has had some chips flaked off it (simple hand axe), 40 000 years ago fine flake split from larger stones (arrow head, spear head, scraper, knife)
154 of 209
how can stone tools be dated from their environment?
the amount of radiation in samples of sediment just above and below the layer in which the tools are found can be used to date the sediment and so give a range of dates when the tools were left there
155 of 209
why can the stone not be used to date when the tool was made?
because the stone used to make the tools is much older than the tools, so cannot be used to date when the tool was made
156 of 209
what is the African Eve theory?
all people today can trace their inheritance back to one female who lived in Africa between 130,000 and 200,000 years ago
157 of 209
how does mitochondrial DNA provide evidence for the African Eve theory?
Mitochondrial DNA is passed from mother to child, differences in mitochondrial DNA are caused by mutations. Analysis of these mutations suggest that all people are related to one female who is referred to as 'African Eve' because she lived in africa
158 of 209
why is mitochondrial DNA more useful than nuclear DNA?
it is easier to extract as it is more abundant, it is only passed from mother to child, it is less likely to degrade in fossils, it has a higher mutation rate, so there are more differences between people
159 of 209
what impact did climate change have on human behaviour?
the ice age - more water was frozen, sea levels were lower, humans could walk between places separated by water today (e.g. Africa to Asia ), low sea levels (25,000 years ago) humans could walk from Siberia across into north America
160 of 209
what happened at the end of the ice age?
humans migrated north as the land became habitable
161 of 209
what is biotechnology?
the alteration of natural biomolecules using science and engineering to provide goods and services
162 of 209
what is a fermenter?
a vessel used to cultivate micro-organisms for the production of biomolecules on a large scale
163 of 209
what are the suitable conditions needed inside of a fermenter?
aseptic precautions( stops competing microorganisms getting in), nutrients (for growth), optimum temperature, optimum pH (for growth), oxygenation (for aerobic respiration) and agitation (stirrer to keep everything mixed)
164 of 209
what is biotechnology used to provide?
useful substances (e.g. foods such as cheese and bread, and chemicals such as insulin), services (e.g. tests for chemical pollutants)
165 of 209
what are the examples of food from microorganims?
bread (yeast), yogurt (Lactobacillus bacteria), mycoprotein (Fusarium fungus) and beer/wine (yeast)
166 of 209
what are the factors of using micro-organisms for food production?
rapid population growth, ease of manipulation, production independent of climate, use of waste products from other industrial processes
167 of 209
what is the advantage of rapid population growth?
microorganisms grow and reproduce much more quickly than animals or plants
168 of 209
what is the advantage of ease of manipulation?
microorganisms are easier to handle than whole plants and animals
169 of 209
what is the advantage of production independent of climate?
fermenters need a relatively small area and can be built almost anywhere, while plants and animals need large areas of particular environmental conditions
170 of 209
what is the advantage of the use of waste products?
waste products from other processes, such as from making flour, can be used as nutrients for growing microorganisms - this is cheaper and reduces the amount of waste disposal needed
171 of 209
how is mycoprotein manufactured?
using the fungus Fusarium sp. The fungus is grown in large fermenters.
172 of 209
what is the role of Fusarium sp?
the fungus makes long thread-like hyphae, which gives mycoprotein a fibrous texture.The broth in the fermenter isn't stirred as this would damage the hyphae
173 of 209
how is mycoprotein fermented?
ammonia and air pumped in, excess gases removed, glucose syrup and minerals are added to supply energy and nutrients for growth, heat kills cells and removes bitter taste, drying and pressing removes water, mycoprotein is ready for packaging
174 of 209
why is mycoprotein a healthier protein than red meat?
no saturated fat, which is a risk factor for heart disease, high fibre content, many healthy effects, can reduce rate of glucose absorption and so reduce gluose and insulin surges, also moves food through the intestines faster (carcinogens removed)
175 of 209
what is the process of making yoghurt from milk?
fresh milk is warmed to about 40°C a culture of bacteria (Lactobacillus bulgaricus) is added to the milk, the bacteria convert lactose in the milk to lactic acid, the lactic acid makes the mixture taste more sour and causes it to thicken
176 of 209
what are the different factors in yoghurt making?
type of bacteria used, type of milk used, temerature of the mixture, pH of the mixture all can change the speed at which and type of yoghurt produced
177 of 209
what are the uses of enzyme technology?
vegetarian cheese, sweets and washing powder
178 of 209
What is Chymosin?
an enzyme that affects proteins in milk, making it separate into solid curds and whey. The curds are then used to make cheese. Natural chymosin is extracted from calves' stomachs, but it can also be made using GM bacteria and used to make vegetarian
179 of 209
what is Invertase?
a.k.a sucrase is the enzyme that converts the sugar sucrose into glucose and fructose. Sucrase is commercially produced by Saccharomyces cerevisiae (yeast). It is used to make sweets taste sweeter and for making soft centres of some sweets
180 of 209
What are the two types of enzymes used in biological washing powders?
protease enzymes digest proteins and lipases digest fats and oils. Proteins, fats and oils are often found as food stains on clothes. Washing powders with these enzymes work more quickly at lower temperatures than washing powders without enzymes
181 of 209
how can you investigate enzymes?
lactase is an enzyme that breaks down lactose sugar, it can be immobilised in alginate beads before it is used to produce lactose-free milk.Immobilising enzymes mean that the enzymes can be easily separated from the product so they can be reused.
182 of 209
what is Recombinant DNA technology?
the use of technology to make genetically modified organisms
183 of 209
what is step 1 in making human insulin?
DNA from the human cell is cut into piece using enzymes called restriction enzymes. These make staggered cuts across the double- stranded DNA, leaving a few unpaired bases at each end, called sticky ends
184 of 209
what is step 2 in making human insulin?
bacteria cells contain small circles of DNA called plasmids. the same restriction enzymes are used to cut plasmids open, leaving sticky ends with matching sets of unpaired bases
185 of 209
what is step 3 in making human insulin?
the pieces of DNA containing the insulin gee are mixed with the plasmids. The bases at the sticky ends 'pair up'. an enzyme called DNA ligase is added, linking the DNA back into a continuous circle
186 of 209
what is step 4 in making human insulin?
the recombiant plasmids are inserted into bacteria, the bacteria can now be grown in huge fermenters where they make human insulin.
187 of 209
what is the role of enzymes in the formation of genetically modified bacteria?
restriction enzymes cut the required gene out of the human DNA. They leave 'sticky ends' on the gene. The same restriction enzymes cut open the plasmid, creating matching sticky ends. The DNA ligase enzyme joins the matching sticky ends.
188 of 209
what is global food security?
the ability to provide enough food for all the people on Earth. As the human population grows, we need to grow more food so there is enough for everyone
189 of 209
how has food production increased?
conventional plant-breeding programmes can develop new varieties of plants that have higher yields
190 of 209
how do these programmes work?
plants with good features are crossed, plants grown from seeds of these crosses are selected for their good features and crosses with eachother, selection and crossing is repeated many times until a high-yielding variety is produced
191 of 209
how have pest management strategies increased food production?
by killing the pests that damage crop plants
192 of 209
what do these strategies include?
pheremone traps to attract/kill pests, crop varieties that are less attractive, attracting natural predators, using pesticides, rotating crops between different fields
193 of 209
what is a biofuel?
a fuel that is produced from living organisms, such as oil palm trees
194 of 209
what are the advantages of biofuels?
they are renewable, fossil fuels are not. crop growth also takes carbon dioxide from the air
195 of 209
what are the disadvantages of biofuels?
biofuel crops need land to grow on, and this may take land needed for growing food crops
196 of 209
what is a 'vector'?
something that carries a gene into another cell and inserts it into the DNA of that cell
197 of 209
how can plants be genetically modified?
using a bacterium called Agrobacterium tumefaciens as the vector
198 of 209
what is an example of this?
the gene for making flavonoid can be inserted into tomato cells to make purple tomatoes
199 of 209
what are the benefits of flavonoid?
tests have shown that mice with cancer live longer if they eat flavonoids
200 of 209
what is a transgenic plant?
a plant that has genes from another species
201 of 209
how can genetic modification be used to increase food production?
a gene that helps a plant grow faster or cope better with difficult conditions and produce more seeds could be inserted into a crop plant such as wheat. Growing these GM plants would increase the yield of the crop in an area
202 of 209
what are the benefits of GM of crop plants?
eating purple tomatoes that contain flavonoids might help anyone with cancer live longer, but they cost more to buy
203 of 209
what are the costs of GM crop plants?
GM crop seeds may be too expensive for poor farmers to buy
204 of 209
what is Bacillus thuringiensis?
a bacterium that naturally produces a chemical that is poisonus to insect pests such as caterpillars. This chemical is caalled Bt toxin
205 of 209
what can you do with Bt toxin?
the gene can be cut out of the bacterial DNA and inserted into the DNA of a plant cell using Agrobacterium tumefaciens. Plants grown from these cells produce the Bt toxin. when an insect tries to eat them, the poison kills the insect pest
206 of 209
what are the advantages of using Bt plants?
crop damage is reduced so crop yield should increase, less chemical insecticide is needed so other, harmless and useful insects are less likely to be harmed
207 of 209
what are the disadvantages of using Bt plants?
seed is more expensive, insect pests may become resistant to Bt toxin, Bt gene may transfer to closely related wild plants by pollination, which would make those plants resistant to pests too
208 of 209
how can GM with the Bt toxin gene increase food production?
damage to a plant's leaves by an insect pest will reduce food production by photosynthesis. This will reduce the rate of plant growth, including growth of the parts of the plant that we eat. Bt toxin kills insect pests that eat the leaves
209 of 209
Other cards in this set
what is carbon dioxide?
a waste product of respiration
what is urea?
how is urea removed?
what are the parts of the urinary system?