1
Q
how are different breeds of dog produced
A
selective breeding
2
Q
what are the steps to select a particular feature in an organism
A
- choose individuals with the desired feature
- let only these individuals reproduce
- choose the offspring that have the desired feature
- let only these individuals reproduce
- repeat steps 3 and 4 until you have produced a variety in which all the individuals show the desired feature
3
Q
what is the key to success in selective breeding
A
identify the feature you want and only breed from the individuals that have that feature - do not allow individuals with undesirable features to breed
4
Q
what can selective breeding produce
A
- hens that lay big eggs of a particular colour
- cattle that produce lots of meat
- tomato plants that produce lots of tomatoes
- crops that are resistant to certain plant diseases
5
Q
why do farmers try to control the environement
A
to maximise the yield from crop plants and livestock
6
Q
what factors affect photosynthesis
A
- light intensity
- carbon dioxide concentration
- temperature
7
Q
what do farmers have in greenhouses
A
- artificial heating
- artificial lighting
- additional carbon dioxide in the air
- regular watering
8
Q
what do green houses and polythene tunnels provide
A
enhanced conditions for plants to grow in
9
Q
why do green houses and polythene tunnels provide enhanced conditions for plants to grow in
A
- the transparent material allows sufficient natural light in for photosynthesis during the summer. additional lighting gives a ‘longer day’ during the winter for valuable crops
- the greenhouse effect also raises temperature in the glasshouses
- burning fossil fuels or wood raises the temperature when the external temperature is too low + it also produces carbon dioxide and water vapour
- water vapour maintains a moist atmosphere and so reduces water loss by traspiration
10
Q
what do all of the factors that green houses and polythene tunnels increase
A
the rate of photosynthesis
the yield
11
Q
(what should the additional cost of providing these conditions be compared to)
A
they must be weighed against the extra profit provided from the increased yield
12
Q
what must the farmer find in the green houses and polythene tunnels
A
optimum conditions
13
Q
what do fertilisers do
A
they provide elements needed by plants to grow such as nitrates for proteins and magnesium for the production of chlorophyll
14
Q
what are the two types of fertilisers
A
organic and inorganic
15
Q
what is organic fertiliser
A
made from the faeces of a range of animals, sometimes mixed with straw. also compost from legumes such as clover
16
Q
what is inorganic fertiliser
A
inorganic compounds carefully formulated to yield a specific concentration of a particular ion when applied according to the manufacturer’s instructions
17
Q
what are the advantages of organic fertiliser
A
-improves soil structure
- greater range of minerals
-releases minerals over a longer period of time
- less cost to the farmer - already available on the farm
18
Q
what are the disadvantages of organic fertiliser
A
- slow acting - has to be decomposed first
- bulkier, so more difficult than inorganic fertilisers to apply
- may contain pests
19
Q
what are the advantages of inorganic fertiliser
A
- mineral ions release immediately so fast acting
- contents known
- easy to apply
20
Q
what are the disadvantages of inorganic fertiliser
A
- can lead to eutrophication as fertiliser is soluble
- requires regular reapplication
21
Q
what is another way to replace lost nitrates
A
grow a legume crop such as clover in a field (one year in four)
22
Q
why does growing a legume plant help replace lost nitrates
A
- these plants have nitrogen-fixing bacteria in nodules on their roots
- they convert nitrogen gas in air into ammonium ions
- some of this is passed to the plants, which use it to make proteins
- in the autumn the crop is ploughed in and when the protein in the crop and bacteria is broken down (decomposed) ammonium is released into the soil
- this ammonium is then converted to nitrate by nitrifying bacteria and is available to next year’s crops
23
Q
what are pests
A
organisms that reduce the yield of crop plants or stock animals
by doing this they cause economic damage to the farmer
24
Q
what types of organism can be a pest
A
any
25
what are the two key ways to control pests
- chemicals called Pesticides
- use another organism to reduce the numbers of a pest - biological control
26
what is the pesticide that kills plant pests
herbicides
27
what is the pesticide that kills insects
insecticides
28
what is the pesticide that kills fungi
fungicides
29
what is the pesticide that kills molluscs (slugs and snails)
molluscicides
30
what are pesticides used for
used to kill specific pests and so improve the yield from crops and livestock
31
why are pests a problem
- they are only a problem when they are present in sufficient numbers to cause economic damage; when or when not to use them is a financial decision, the increase in income must be set against the cost of the pesticide
-pesticides may also damage ecosystems as often the pesticide molecules are simply passed higher up the food chain, becoming concentrated in the tissues of top carnivores
32
what is biological control
uses a predator species rather than a toxic chemical, to reduce the numbers of a pest
33
what is an example of biological control
whiteflies in a greenhouse full of tomato plants can be controlled by introducing a tiny plastic wasp called Encarsia
these lay their eggs inside the larvae of the flies, which hatch and then eat the larvae so reduce the numbers of whitefly
34
what is a feature of biological control
it never eradicates a pest. if the organism killed off all the pests then it too would die from lack of food. the aim is to reduce pest numbers to a level where they no longer cause significant economic damage -- many can be mali-ordered, keeping their population high
35
what are six biological control agents
-introduce a natural predator
- introduce a herbivore
- introduce a parasite
- introduce a pathogenic microorganism
- introduce sterile males
- using pheromones
36
what is the effect/ example of introducing a natural predator
ladybirds can be used to control the population of aphids in orange groves
37
what is the effect/ example of introducing a herbivore
herbivore (e.g moth) eats pest plant such a prickly pear cactus in Australia
38
what is the effect/ example of introducing a parasite
wasp encarsia lays its eggs in whitefly eggs and reduces the population
39
what is the effect/ example of introducing a pathogenic microorganism
a fall in pest numbers - such as that caused by the myxomatosis virus on rabbit population in Australia
40
what is the effect/ example of introducing a sterile male
mate with females but produce no offspring, so pest numbers fall
41
what is the effect/ example of using pheromones
sex hormones released to attract males or females which are then collected and destroyed, reducing the reproductive potential of the population
42
what are the advantages of pesticides
- reduces pest population instantly
- can kill the whole population of pests
43
what are the disadvantages of pesticides
- cost (need for regular applications)
- not specific e.g will kill predaceous insects is pollinating insects in addition to the pest
- pest can become resistant to the chemical
- chemical can concentrate in all organisms higher up the food chain
44
what are the advantages of biological control
- organism only introduced once as it will reproduce
- only one cost for the initial introduction
- pest specific - only kills the pest
- pest will not become resistant
- no effect on other animals in the food chain
45
what are the disadvantages of biological control
- takes time to reduce pest population
- not all population killed
- expensive if re-populating is required
46
what things does anaerobic respiration happen in
plant cells
animals
some microorganisms - such as yeast
47
what is anaerobic respiration used for
bree brewing
bread-making
48
what is the word equation for anaerobic respiration
glucose --> ethanol + carbon dioxide
49
what is the chemical equation for anaerobic respiration (don't need)
C6H12O6 --> 2C2H5OH +2CO2
50
what is ethanol
is the alcohol found in alcoholic drinks like beer and wine
51
explain anaerobic respiration in bread making
bubbles of carbon dioxide gas expand through the dough and help the bread rise
the high temperature used in bread making mean that the ethanol does not remain in the bread after cooking has finished (it evaporated)
52
what is a way to investigate anaerobic respiration
study the production of carbon dioxide under different conditions
53
what happens to limewater in the presence of carbon dioxide
turns cloudy white/ milky
54
what happens to hydrogen carbonate indicator in the presence of carbon dioxide
changes from orange to yellow
55
what apparatus is needed to investigate anaerobic respiration in yeast
boiling tube (containing yeast in sugar solution and vegetable oil)
delivery tube
boiling tube with limewater
56
what are the steps of the production of carbon dioxide experiment
1. dissolve sugar in previously boiled solution
2. add yeast and mix to form a suspension, and pour into a boiling tube
3. add a layer of vegetable oil
4. connect a delivery tube to a second boiling tube, this time containing limewater or hydrogen carbonate indicator
57
what does the layer of vegetable oil do when studying the production of carbon dioxide
prevents oxygen entering the mixture, while allowing carbon dioxide to escape. this ensures its anaerobic respiration taking place
58
what do you measure when studying the production of carbon dioxide
number of bubbles over a set time can be counted, or the appearance of the indicator can be compared to a control containing boiled (dead) yeast.
the conditions that can be investigated include:
-- temperature
-- concentration of sugar
-- type of sugar
59
what do many micro-organisms produce
extremely useful chemicals that can be used in medicine
60
what are used to grow micro-organisms on an industrial scale
fermenters
61
what are components of fermenters
cooling jacket
air filter
stirrers
growth medium
super-heated steam
62
what does the cooling jacket do
removes heat energy, stopping the fermenter overheating and enzymes denaturing
63
what does the air filter do
filters air coming in, maintaining sterile conditions
64
what do the stirrers do
keep the broth well stirred to oxygenate all parts of the fermenter and prevent micro-organisms settling
65
what does the growth medium do
contains all necessary glucose and amino acids for micro-organism growth
66
what does the super-heated steam do
applied before the fermenter is used, killing unwanted, micro-organisms; leaves only water with no residue
67
what bacterium is yoghurt made with
Lactobacillus bulgaricus
68
explain how yoghurt was made (in detail)
- milk is initially pasteurised to kill bacteria
- after it has cooled, Lactobacillus is added and the mixture is maintained at 46 degrees C which ensures the bacteria's enzymes are not denatured
- Lactobacillus respires anaerobically producing lactic acid
this lowers the pH, acting as a preservative
the acid also coagulates the milk protein, as the acidic conditions change the shape of the proteins, giving yoghurt its texture and flavour
- finally the yoghurt is cooled to 5 degrees C to help preserve the yoghurt
69
why is milk pasteurised
to kill bacteria
70
why is the mixture maintained at 46 degrees C once Lactobacillus has been added
to ensure the bacteria's enzymes are not denatured
71
what does Lactobacillus respire anaerobically to produce
lactic acid
72
what does the lactic acid that Lactobacillus produces do
lowers the pH, acting as a preservative
it also coagulates the milk protein, as the acidic conditions change the shape of the proteins, giving yoghurt its texture and flavour
73
why is the yoghurt finally cooled to 5 degrees C
to preserve the yoghurt
74
explain yoghurt production simply
- equipment is sterilised
- milk is pasteurised by heating
- bacterial culture is added to the cooled milk and left at 46 degrees C for about 4 hrs
- samples are taken to see if the yoghurt is ready
- flavours and colours are added
- yoghurt is packaged
75
why is fish farming meeting a shortfall in fish
stocks in the wild have been depleted
76
what do farmers feed the fish
high lipid and protein food as well as regular feeding with small amounts so most gets eaten
77
why do farmers feed fish high lipid and protein food
to promote rapid growth
78
what are the problems if you put several species in one pond
1- interspecific competition: different species will compete for food and some species may be wiped out
2- predation: carnivorous species will prey on other fish
79
what is the solution to putting several species in one pond
place different species in different ponds, tanks, etc. use nets to separate species and wild/ farmed populations
80
how can predation from birds be reduced
by placing a cover over the ponds
81
what are the problems if you put too many individuals in one pond
1- intraspecific competition: larger individuals will out-compete smaller individuals for food or larger individuals may prey on smaller individuals
2- infectious diseases: parasites and pathogens spread quickly if the fish are close together
82
what is the solution to putting too many individuals in one pond
separate fish by age and size. remove dead or infected fish quickly and add antibiotics to the water to kill bacteria. add antifungals or chemicals to kill parasites
83
how do fish farms affect the environment
- fish may escape and out-compete or interbreed with local species reducing biodiversity and/or upsetting the local ecosystem
- parasites or pathogens can be introduced into ecosystems by farmed fish
- excess feed and waste from fish can cause eutrophication and a reduction in oxygen concentrations in the water (reduced by limiting feed, clearing {vacuuming out} waste and bubbling oxygen through water)
84
what is biodiversity
the measure of how many different species live in an ecosystem
85
what should be used to estimate the biodiversity of an area
quadrats and random sampling (random number generator to find coordinates to place multiple quadrats in the sample area)
86
what should be used within each individual quadrat
an identification key and record the number of each different species
87
what is an abiotic variable
non- living
88
what is an example of an abiotic variable
temperature or light intensity
89
what is a biotic variable
living
90
what is an example of a biotic variable
trampling or predation
91
what is the method to finding out the effect of abiotic or biotic variables on biodiversity -- look on one note
- select at least two areas where the variable is different
- measure/ describe the variable in each area
- estimate the biodiversity in each area by using random sampling to generate coordinates
- then place the corner of the quadrat where the two coordinates meet
-only count the species where the majority is within the quadrat
92
what does deforestation do
destroys the habitats of the organisms that live there which therefore causes extinctions and dramatically reduces biodiversity
93
what happens during the carbon cycle in global warming
-carbon dioxide is taken into plants and becomes part of the carbohydrates and other biological molecules
-the plant effectively becomes a 'carbon sink'
- if deforestation occurs there are less plants to store carbon, and carbon dioxide levels in the atmosphere will increase
- oxygen levels will decrease as there is less photosynthesis
-felled trees may also be burned as a source of energy which releases carbon dioxide back into the atmosphere, causing a further increase in atmospheric carbon dioxide
94
what is leaching
the process of loss of nutrients from soil, due to a run off and washing out of the soil
95
explain what happens to the soil due to leaching from deforestation
water is no longer taken up by plants and can begin to 'run off' from the soil into rivers and lakes
mineral ions (nitrates, phosphates and potassium in particular that occur in the soil and are dissolved into its water are removed from the soil in the water that runs off into the nearby rivers/ lakes
96
what does leaching cause
- mineral ions to be removed from the soil
-some of these nutrients (especially nitrates) can lead to further problems such as eutrophication
97
explain soil erosion
the water running off from deforested areas may carry some of the topsoil, causing erosion. Because of deforestation, there are no plants present in the soil and therefore there are no roots holding the soil in place. The topsoil contains the most fertile, mineral ion rich materials: when it is lost due to erosion the minerals are also lost, making the land very difficult to use for crop growth and reducing the chance of plats re-growing.
98
what is evapotranspiration
the process by which water is transferred from the land to the atmosphere bu evaporation from the soil and other surfaces and by transpiration from plants
99
explain evapotranspiration
transpiration is the evaporation and diffusion of water through the stomata of leaves.This evaporated water moves into the atmosphere and eventually (through the water cycle) makes rain in clouds. These rain clouds when they rain onto the plants, and the cycle will continue. When deforestation occurs, this cycle is broken. Transpiration stops, as no plants are present, thus meaning that water is not put into the atmosphere, and rain does not occur. This can lead to droughts
100
what does evapotranspiration cause
it can lead to droughts
101
what type of pH is acid rain
a low pH
102
explain how acid rain is formed
- sulphur dioxide, nitrogen monoxide and nitrogen dioxide are released into the atmosphere from cars and factories
- these gases then react with the atmospheric water vapour to form dilute acids (sulphuric and nitric acids)
103
what does acid rain cause - explain
- the dilute acid can dissolve limestone buildings and statues
- the rain when it falls can decrease the pH of rivers and lakes
- this can have a catastrophic effect on the enzymes of the organisms in the rivers and lakes, resulting in the death of fish and other animals
- acid rain can also kill trees and other plants
-it can increase dissolution of some metal ions in the soil including aluminium - these run off into rivers and lakes where they poison fish
104
how has in increase in human population led to an increase in pollution
- more fossil fuels being burnt for heat and power
- more movement and use of transport
- higher levels of industry for houses and goods
105
what happens when substances containing carbon are burned in a limited supply of oxygen
carbon monoxide is formed (CO)
106
what contains significant amounts of of carbon monoxide
vehicle exhausts
107
why is carbon monoxide a dangerous pollutant
- it binds more strongly with haemoglobin than oxygen
- if a person inhales carbon monoxide for a period of time, more and more haemoglobin becomes bound to CO and not 02 and the person will lose consciousness, and eventually die due to reduced aerobic respiration
107
why do farmers add fertilisers to the soil
increase the yield of their crops
108
what do fertilisers usually contain
nitrates and phosphates
109
what happens when a lot of fertiliser is present on farmland surrounding a river
it is washed out of the soil when it rains into the river - leaching
110
what are nitrates and phosphates very soluble in
water
111
explain the process caused by leached nitrates
- the nitrates are absorbed by the green algae in the water
- these multiply rapidly and may completely cover the water. this great growth is algae is called algae bloom
- this blocks out sunlight for other plants in the river or lake
- this means that they are unable to photosynthesise and die
- even the algae on the top eventually die
- the dead remains provide a good source of food for bacteria
- the bacteria multiply rapidly
- the large population of bacteria respire, increasing the biological oxygen demand, using up oxygen in the water
- this decreases the level of oxygen and results in the death of other organisms in the water
112
what is the process caused by leached nitrates
eutrophication
113
how could sewage enter water supplies
due to leaking pipes or run off from farm land
114
what is sewage
undigested food material
115
what does sewage contain
lots of biological molecules, including carbohydrates, proteins, nucleic acids and fats
116
explain pollution of water by sewage
- the sewage provide a good source of food for bacteria
- the bacteria therefore multiply rapidly
- the large population of bacteria respire, increasing the biological oxygen demand, using up oxygen in the water
- this decreases the level of oxygen and results in the death of other organisms in the water
117
how is pollution of water by sewage different from eutrophication
it does not involve and algal bloom
Biology - all note flashcards
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