biology paper 2 advanced information Flashcards
need to do: 4.7.2 organisation of an ecosystem, 4.7.3 Biodiversity and the effect of human interaction on an ecosystem, required practical) (110 cards)
1
Q
what do food chains always start with?
A
a producer - producers make their own food using energy from the Sun. Producers are usually green plants or algae - they make glucose by photosynthesis
2
Q
what is the biomass of the plant?
A
the mass of living material - biomass can be thought of as energy stored in a plant
3
Q
what is glucose used for after a green plant produces it?
A
some of it is used to make other biological molecules in the plant. These biological molecules are the plant’s biomass - the mass of living material
4
Q
what will happen in a stable community containing prey and predators?
A
- the population of any species is usually limited by the amount of food available
- if the population of the prey increases, then so will the population of the predators
- however as the population of predators increases, the number of prey will decrease, which therefore eventually causes the population of the predator to decrease
- However this allows the population of the prey to increase, and the cycle starts again
- Predator-prey cycles are always out of phase with each other. This is because it takes a while for one population to respond to changes in other populations. E.g. when the number of rabbits goes up, the number of foxes doesn’t increase immediately because it takes time for them to reproduce
5
Q
how is energy transferred through living organisms?
A
energy is transferred through living organisms in an ecosystem when organisms eat other organisms. Producers are eaten by primary consumers. Primary consumers are then eaten by secondary consumers and secondary consumers are eaten by tertiary consumers
6
Q
what is the distribution of an organism? What is it affected by?
A
where an organism is found - this is affected by environmental factors. An organism might be more common in one area than another due to differences in environmental factors between the two areas
7
Q
give two ways to study the distribution of an organism. What kind of data do these methods give?
A
- by measuring how common an organism is in two sample areas (e.g. using quadrats) and compare them
- by studying how the distribution changes across an area, e.g. by placing quadrats along a transect
both of these methods give quantitative data (numbers) about the distribution
8
Q
what is a quadrat?
A
a square frame enclosing a known area, e.g. 1m^2
9
Q
what are 2 ways to study the distribution of an organism?
A
- measuring how common an organism is in two sample areas (e.g. using quadrats) and compare them
- study how the distribution changes across an area, e.g. by placing quadrats along a transect
10
Q
what type of data do quadrats give about the distribution of organisms?
A
quantative data (numbers)
11
Q
what is a quadrat?
A
a square frame enclosing a known area, e.g. 1 m^2
12
Q
how would you use quadrats to compare how common an organism is in two sample areas (e.g. shady and sunny spots in a playing field)
A
- place a 1m^2 quadrat on the ground at a random point within the first sample area. E.g. divide the area into a grid and use a random number generator to pick coordinates
- count all the organisms within the quadrat
- repeat steps 1 and 2 as many times as you can
- work out the mean number of organisms per quadrat within the first sample area
- repeat steps 1 to 4 in the second sample area
- finally compare the two means.
13
Q
what does “abundance” mean?
A
the population size of an organism
14
Q
how can you work out the population size of an organism in one area?
A
- work out the mean number of organisms per m^2
2. multiply the mean by the total area (in m^2) of the habitat
15
Q
what can we use transects for?
A
to help find out how organisms (like plants) are distributed across an area - e.g. if an organism becomes more or less common as you move from a hedge towards the middle of a field
16
Q
how can we use transects to help find out how organisms (like plants) are distributed across an area?
A
- mark out a line in the area you want to study using a tape measure
- then collect data along this line
- you can do this by just counting all the organisms you’re interested in that touch the line
- or, you can collect data by using quadrats. These can be placed next to each other along the line or at intervals, e.g. every 2 m
17
Q
why might you want to work out the percentage cover of an organism in a quadrat?
A
if it’s difficult to count all the individual organisms in the quadrat (e.g. if they’re grass) it might be easier to work out the percentage cover
18
Q
what does it mean to calculate the percentage cover?
A
estimating the percentage area of the quadrat covered by a particular type of organism, e.g. by counting the number of little squares covered by the organisms
19
Q
how do you work out the percentage cover of an organism?
A
- count the number of small squares in a quadrat covered by the organism
- make this into a percentage - divide the number of squares covered by the organism by the total number of squares in the quadrat, and then multiply the result by 100
20
Q
what is a transect?
A
a line used to help find out how organisms are distributed across an area
21
Q
how could you estimate the number of organisms in a quadrat, if they are difficult to count?
A
by working out the percentage cover
22
Q
what are the 8 stages of the water cycle?
A
- energy from the Sun makes water evaporate from the land and sea, turning it into water vapour
- water also evaporates from plants - this is known as transpiration
- the warm water vapour is carried upwards (as warm air rises). when it gets higher up it cools and condenses to form clouds.
- water falls from the clouds as precipitation (usually rain, but sometimes snow or hail) onto land, where it provides fresh water for plants and animals
- some of this water is absorbed by the soil and is taken up by plant roots. This provides plants with fresh water for things like photosynthesis. Some of the water taken up by plants becomes part of the plants’ tissues and is passed along to animals in food chains
- like plants, animals need water for the chemical reactions that happen in their bodies. Animals return water to the soil and atmosphere through excretion (processes that get rid of the waste products of chemical reactions, e.g. sweating, urination and breathing out)
- water that doesn’t get absorbed by the soil will runoff into streams and rivers
- from here, the water then drains back into the sea, before it evaporates all over again
23
Q
how are elements cycled back to the start of the food chain by decay?
A
- living things are made of materials they take from the world around them. E.g. plants turn elements like carbon, oxygen, hydrogen and nitrogen from the soil and the air into the complex compounds (carbohydrates, proteins and fats) that make up living organisms. These get passed up the food chain
- these materials are returned to the environment in waste products, or when the organisms die and decay
- materials decay because they’re broken down (digested) by microorganisms. This happens faster in warm, moist, aerobic (oxygen rich) conditions because microorganisms are more active in these conditions
- decay puts the stuff that plants need to grow (e.g. mineral ions) back into the soil
- in a stable community, the materials that are taken out of the soil and used by plants etc. are balanced by those that are put back in. There’s a constant cycle happening
24
Q
what is the constant cycling of carbon called?
A
the carbon cycle
25
what are the 8 stages of the carbon cycle?
1. CO2 is removed from the atmosphere by green plants and algae during photosynthesis. The carbon is used to make glucose, which can be turned into carbohydrates, fats and proteins that make up the bodies of the plants and algae
2. when plants and algae respire, some carbon is returned to the atmosphere as CO2
3. when the plants and algae are eaten by animals, some carbon becomes part of the fats and proteins in their bodies. The carbon then moves up the food chain
4. when the animals respire, some carbon is returned to the atmosphere as CO2
5. when plants, algae and animals die, other animals (called detritus feeders) and microorganisms feed on their remains. When these organisms respire, CO2 is returned to the atmosphere
6. animals also produce waste that is broken down by detritus feeders and microorganisms
7. the combustion of wood and fossil fuels releases CO2 back into the air
8. so the carbon (and energy) is constantly being cycled - from the air, through food chains (via plants, algae and animals, and detritus feeders and microorganisms) and eventually back out into the air again
26
what happens to the energy that green plants and algae get from photosynthesis?
it is transferred up the food chain
27
what is biodiversity?
the variety of different species of organisms on Earth, or within an ecosystem
28
why is high biodiversity important?
it makes sure that ecosystems are stable because different species depend on each other for things like shelter and food. Different species can also help to maintain the right physical environment for each other (e.g. the acidity of the soil). For the human species to survive, it's important that a good level of biodiversity is maintained
29
name three human actions that are reducing biodiversity
1. deforestation
2. global warming
3. waste production
30
why is the global population rising?
mostly because of modern medicine and farming methods, which have reduced the number of people dying from disease and hunger
31
why are our actions having a far more widespread effect in modern times?
1. our increasing population puts pressure on the environment, as we take resources we need to survive
2. but people around the world are also demanding a higher standard of living (and so demand luxuries to make life more comfortable - cars, computers, etc.). So we use more raw materials (e.g. oil to make plastics), but we also use more energy for the manufacturing processes. This all means we're taking more and more resources from the environment more and more quickly
3. unfortunately, many raw materials are being used up quicker than they're being replaced. So if we carry on like we are, one day we're going to run out
4. we're also producing more waste
32
what effect does our increasing population have on waste production? why is this important?
as we make more and more things we produce more and more waste, including waste chemicals. And unless this waste is properly handled, more harmful pollution will be caused. Pollution affects water, land and air and kills plants and animals, reducing biodiversity
33
how is water affected by our waste?
sewage and toxic chemicals from industry can pollute lakes, rivers and oceans, affecting the plants and animals that rely on them for survival (including humans). And the chemicals used on land (e.g. fertilisers, pesticides and herbicides) can be washed into water
34
how does our waste pollute the land?
we use toxic chemicals for farming (e.g. pesticides and herbicides). We also bury nuclear waste underground, and we dump a lot of household waste in landfill sites
35
how does our waste affect the air?
smoke and acidic gases released into the atmosphere can pollute the air, e.g. sulfur dioxide can cause acid rain
36
what is the temperature of the Earth a balance between? How is this balance maintained?
- the temperature of the Earth is a balance between the energy it gets from the Sun and the energy it radiates back out into space.
- gases in the atmosphere naturally act like an insulating layer. They absorb most of the energy that would normally be radiated out into space, and re-radiate it in all directions (including back towards the Earth). This increases the temperature of the planet.
- if this didn't happen, then at night there'd be nothing to keep any energy in, and the earth would quickly get too cold.
37
which two gases are causing the main problems for global warming? Why do we have to worry about these gases in particular?
the main greenhouse gases we have cause for concern over are carbon dioxide (CO2) and methane - because the levels of these two gases are rising sharply
38
what is global warming?
global warming is a type of climate change in which the Earth is gradually heating up because of the increasing levels of greenhouse gases. Global warming can cause other types of climate change, e.g. changing rainfall patterns
39
what could be some of the consequences of climate change?
1. Higher temperatures cause seawater to expand and ice to melt, causing the sea level to rise. It has risen a small amount over the last 100 years. If it keeps rising it will cause many problems for people and animals living in low-lying places. It will lead to flooding, resulting in the loss of habitats (where organisms live)
2. The distribution of many wild animal and plant species may change as temperatures increase and the amount of rainfall changes in different areas. Some species may become more widely distributed, e.g. species that need warmer temperatures may become less widely distributed, e.g. species the need warmer temperatures may spread further as the conditions they thrive in exist over a wider area. Other species may become less widely distributed, e.g. species that need cooler temperatures may have smaller ranges as the conditions they thrive in exist over a smaller area.
3. there could be changes in migration patterns, e.g. some birds may migrate further north, as more northern areas are getting warmer
4. Biodiversity could be reduced if some species are unable to survive a change in the climate, so become extinct.
40
why might programmes be set up to protect ecosystems and biodiversity?
it's important that biodiversity is maintained at a high enough level to make sure that ecosystems are stable - in some areas, programmes have been set up by concerned citizens and scientists to minimise damage by human activites to ecosystems and biodiversity
41
give some examples of programmes that have been set up to minimise damage by human activities
1. Breeding programmes have been set up to help prevent endangered species from becoming extinct. These are where animals are bred in captivity to make sure the species survives if it dies out in the wild. Individuals can sometimes be released into the wild to boost or re-establish a population.
2. programmes to protect and regenerate rare habitats like mangroves, heathland and coral reefs have been started. Protecting these habitats helps to protect the species that live there - preserving the ecosystem and biodiversity in the area
3. there are programmes to reintroduce hedgerows and field margins around fields on farms where only a single type of crop is grown. Field margins are areas of land around the edges of fields where wild flowers and grasses are left to grow. Hedgerows and field margins provide a habitat for a wider variety of organisms than could survive in a single crop habitat
4. some governments have introduced regulations and programmes to reduce the level of deforestation taking place and the amount of carbon dioxide being released into the atmosphere by businesses. This could reduce the increase of global warming
5. people are encouraged to recycle to reduce the amount of waste that gets dumped in landfill sites. This could reduce the amount of land taken over for landfill, leaving ecosystems in place/
42
give some conflicting pressures that have to be taken into account when trying to maintain biodiversity
1. protecting biodiversity costs money. For example, governments sometimes pay farmers a subsidy to reintroduce hedgerows and field margins to their land. It can also cost money to keep a watch on whether the programmes and regulations designed to maintain biodiversity are being followed. There can be conflict between protecting biodiversity and saving money - money may be prioritised for other things
2. Protecting biodiversity may come at a cost to local people's livelihood. For example, reducing the amount of deforestation is great for biodiversity, but the people who were previously employed in the tree-felling industry could be left unemployed. This could affect the local economy if people move away with their family to find work
3. there can be conflict between protecting biodiversity and protecting our food security. Sometimes certain organisms are seen as pests by farmers (e.g. locusts and foxes) and are killed to protect crops and livestock so that more food can be produced. As a result, however, the food chain and biodiversity can be affected
4. Development is important, but it can affect the environment. Many people want to protect biodiversity in the face of development, but sometimes land is in such high demand that previously untouched land with high biodiversity has to be used for development, e.g. for housing developments on the edge of towns, or for new agricultural land in developing countries
43
what are hormones?
chemical molecules released directly into the blood - they are chemical messengers sent in the blood
44
where are hormones carried to in the blood, and what do they effect?
they are carried in the blood to other parts of the body, but only affect particular cells in particular organs (called target organs)
45
what do hormones control?
things in organs and cells that need constant adjustment
46
where are hormones produced and secreted from?
endocrine glands
47
what do your endocrine glands make up?
your endocrine system
48
how long do the effects of hormones last?
a long time
49
name 6 endocrine glands
1. the pituitary gland
2. ovaries
3. testes
4. thyroid
5. adrenal gland
6. the pancreas
50
what does the pituitary gland do?
it produces many hormones that regulate body conditions. It is sometimes called the 'master gland' because these hormones act on other glands, directing them to release hormones that bring about change
51
what do ovaries produce?
oestrogen, which is involved in the menstrual cycle
52
what do testes produce?
testosterone, which controls puberty and sperm production in males
53
what does the thyroid gland produce?
thyroxine, which is involved in regulating things like the rate of metabolism, heart rate and temperature
54
what does the adrenal gland produce?
adrenaline, which is used to prepare the body for a 'fight or flight' response
55
what does the pancreas produce?
insulin, which is used to regulate the blood glucose level
56
what are 3 differences between nerves and hormones
1. nerves have a very fast action, whereas hormones have a slower action
2. nerves act for a very short time whereas hormones act for a long time
3. nerves act on a very precise area, whereas hormones act in a more general way
57
what happens at puberty (hormone wise)?
at puberty, your body starts releasing sex hormones that trigger secondary sexual characteristics (such as the development of facial hair in men and breasts in women) and cause eggs to mature in women
58
what is the reproductive hormone in men? where is it produced? what does it do?
the main male reproductive hormone is testosterone. It's produced by the testes and stimulated sperm production
59
what is the main reproductive hormone in women? where is it produced? what does it do?
in women, the main reproductive hormone is oestrogen. It's produced by the ovaries. As well as bringing about physical changes, oestrogen is also involved in the menstrual cycle
60
how many stages does the menstrual cycle have?
four
61
what happens in stage 1 of the menstrual cycle?
Day 1 - menstruation starts. The uterus lining breaks down for about 4 days
62
what happens in stage 2 of the menstrual cycle?
the uterus lining builds up again, from day 4 to day 14, into a thick spongy layer full of blood vessels, ready to receive a fertilised egg
63
what happens in stage 3 of the menstrual cycle?
an egg develops and is released from the ovary at day 14 - this is called ovulation
64
what happens in stage 4 of the menstrual cycle?
the wall is then maintained for about 14 days until day 28. If no fertilised egg has landed on the uterus wall by day 28, the spongy lining starts to break down and the whole cycle starts again
65
what are the 4 hormones that control the menstrual cycle?
1. FSH (follicle-stimulating hormone)
2. LH (luteinising hormone)
3. oestrogen
4. progesterone
66
where is FSH produced?
in the pituitary gland
67
what does FSH cause/stimulate
it causes an egg to mature in one of the ovaries, in a structure called a follicle. It also stimulates the ovaries to produce oestrogen
68
where is oestrogen produced?
the ovaries
69
what does oestrogen cause/stimulate/inhibit?
it causes the lining of the uterus to grow. It also stimulates the release of LH and inhibits release of FSH
70
where is LH produced?
the pituitary gland
71
what does LH do?
it stimulates the release of an egg at day 14 (ovulation)
72
where is progesterone produced?
in the ovaries by the remains of the follicle after ovulation
73
what does progesterone do?
it maintains the lining of the uterus during the second half of the cycle. When the level of progesterone falls, the lining breaks down. It also inhibits the release of LH and FSH
74
what happens if a woman has too low levels of FSH?
their eggs don't mature, which means that no eggs are released and the woman can't get pregnant
75
which hormones can be given to women in a fertility drug? how do they work?
the hormones FSH and LH can be given to women in a fertility drug to stimulate ovulation
76
what are the cons of fertility drugs?
- it doesn't always work - some women may have to do it many times, which can be expensive
- too many eggs could be stimulated, resulting in unexpected multiple pregnancies (twins, triplets, etc.)
77
what does IVF stand for?
in vitro fertilisation
78
what does IVF involve?
- collecting eggs from the woman's ovaries and fertilising them in a lab using the man's sperm
- it can also involve a technique called intra-cytoplasmic sperm injection (ICSI), where the sperm is injected directly into an egg
79
what is intra-cytoplasmic sperm injection (ICSI)? when is it useful?
it's a form of IVF where the sperm is injected directly into an egg. It's useful if the man has a very low sperm count
80
what are the 4 stages of IVF?
1. collecting eggs from the woman's ovaries and fertilising them in a lab using the man's sperm
2. The fertilised eggs are then grown into embryos in a laboratory incubator
3. once the embryos are tiny balls of cells, one or two of them are transferred to the woman's uterus to improve the chance of pregnancy
4. FSH and LH are given before egg collection to stimulate several eggs to mature (so more than one egg can be collected)
81
what are the cons of IVF?
- multiple births can happen if more than one embryo grows into a baby - these are risky for the mother and babies (there's a higher risk of miscarriage, stillbirth...)
- the success rate of IVF is low - the average success rate in the UK is about 26%. This makes the process incredibly stressful and oftwn upsetting, especially if it ends in multiple failures
- as well as being emotionally stressful, the process is also physically stressful for the woman. Some women have a strong reaction to the hormones - e.g. abdominal pain, vomiting, dehydration
82
how have advances in microscopic techniques helped to improve the techniques (and therefore success rate) of IVF?
specialised micro-tools have been developed to use on the eggs and sperm under the microscope. They're also used to remove single cells from the embryo for genetic testing. More recently, the development of time-lapse imaging (using a microscope and camera built into the incubator) means that the growth of the embryos can be continuously monitored to help identify those that are more likely to result in a successful pregnancy
83
why are some people against IVF?
- the process of IVF often results in unused embryos that are eventually destroyed. Because of this, some people think it is unethical because each embryo is a potential human life
- the genetic testing of embryos before implantation also raises ethical issues as some people think it could lead to the selection of preferred characteristics, such as gender or eye colour
84
what do insulin and glucagon control?
blood glucose level
85
describe how your blood glucose level fluctuates, and how the body reacts to these changes
1. eating foods containing carbohydrate puts glucose into the blood from the gut
2. the normal metabolism of cells removes glucose from the blood
3. vigorous exercise removes much more glucose from the blood
4. excess glucose can be stored as glycogen in the liver and the muscles
5. the level of glucose in the blood must be kept steady. Changes are monitored and controlled by the pancreas, using the hormones insulin and glucagon, in a negative feedback cycle
86
which hormone is released when the blood glucose level is too high?
insulin
87
which hormone is added when the blood glucose level is too low?
glucagon
88
how does insulin work?
1. when the blood glucose level is too high, insulin is secreted by the pancreas
2. insulin moves the glucose from the blood into the muscle cells and liver (insulin makes the liver turn glucose into glycogen so it can be stored)
3. the blood glucose level is reduced
89
how does the hormone glucagon work?
1. when the blood glucose levels are too low, glucagon is secreted by the pancreas
2. glucagon makes the liver turn glycogen into glucose, which is released into the blood
3. the blood glucose increases
90
what does insulin do?
remove glucose from the blood
91
is glucagon a hormone or a store of glucose?
a hormone
92
is glycogen a hormone or a store of glucose?
a store of glucose
93
what is diabetes?
a condition that affects your ability to control your blood sugar level
94
what is type 1 diabetes?
type 1 diabetes is where the pancreas produces little or no insulin. This means that a person's blood glucose level can rise to a level that can kill them. People with Type 1 diabetes need insulin therapy - this usually involves several injections of insulin throughout the day, most likely at mealtimes. This makes sure that glucose is removed from the blood quickly once food has been digested, stopping the level getting too high. It's a very effective treatment. The amount of insulin that needs to be injected depends on the person's diet and how active they are. As well as insulin therapy, people with Type 1 diabetes need to think about limiting the intake of food rich in simple carbohydrates, e.g. sugars (which cause the blood glucose to rise rapidly) and taking regular exercise (which helps to remove excess glucose from the blood)
95
what is Type 2 diabetes?
where a person becomes resistant to their own insulin. This can also cause a person's blood sugar level to rise to a dangerous level. Being overweight can increase your chance of developing Type 2 diabetes, as obesity is a major risk factor in the development of the disease. Type 2 diabetes can be controlled by eating a carbohydrate-controlled diet and getting regular exercis
96
what are non-hormonal forms of contraception designed to do?
to stop the sperm from getting to the egg
97
what is the only form of contraception that will protect against sexually transmitted diseases?
condoms
98
what is a diaphragm (in contraception)?
a shallow plastic cup that fits over the cervix (the entrance to the uterus) to form a barrier. It has to be used with spermicide (a substance that disables or kills the sperm)
99
what is spermicide?
a substance that disables or kills sperm
100
can spermicide be used alone as a form of contraception? If it were to be used alone, how effective would it be?
Spermicide can be used alone as a form of contraception, but it is not as effective (only about 70-18%)
101
give 3 more drastic ways to avoid pregnancy
1. sterilisation
2. 'natural' methods
3. abstinence
102
what does sterilisation involve?
sterilisation involves cutting or tying the fallopian tubes (which connect the ovaries to the uterus) in a female, or the sperm duct (the tube between the testes and penis) in a male. This is a permanent procedure. However, there is a very small chance that the tubes can rejoin
103
what are 'natural' methods of avoiding pregnancy? who are these methods popular with?
pregnancy may be avoided by finding out when in the menstrual cycle the woman is most fertile and avoiding sexual intercourse on those days. It's popular with people who think that hormonal and barrier methods are unnatural, but it's not very effective
104
what is adrenaline?
a hormone released by the adrenal glands, which are just above the kidneys
105
what is adrenaline released in response to?
stressful or scary situations - your brain detects fear or stress and sends nervous impulses to the adrenal glands, which respond by secreting adrenaline
106
what does adrenaline do?
it gets the body ready for 'fight or flight' by triggering mechanisms that increase the supply of oxygen and glucose to cells in the brain and muscles. For example, adrenaline increases heart rate.
107
give an example of a negative feedback system
thyroxine regulating metabolism
108
where is thyroxine made? what is it made from?
thyroxine is made in the thyroid gland from iodine and amino acids
109
how does thyroxine regulate metabolism?
1. thyroxine is a hormone released by the thyroid gland, which is in the neck
2. it plays an important role in regulating the basal metabolic rate - the speed at which chemical reactions in the body occur while the body is at rest. Thyroxine is also important for lots of processes in the body, such as simulating protein synthesis for growth and development
3. Thyroxine is released in response to thyroid stimulating hormone (TSH), which is released from the pituitary gland
4. a negative feedback system keeps the amount of thyroxine in the blood at the right level - when the level of thyroxine in the blood is higher than normal, the secretion of TSH from the pituitary gland is inhibited. This reduces the amount of thyroxine released from the thyroid gland, so the level in the blood falls back towards normal
110
where is the thyroid gland?
in the neck
