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0
Q

Why did people not believe Charles Darwin’s theory at first?

A

Darwin’s theory conflicted with religious views that God had made all the animals and plants on Earth
Darwin did not have enough evidence at the time to convince many scientists
it took 50 years after Darwin’s theory was published to discover how inheritance and variation worked.

1
Q

What is the major flaw of Lamarck’s theory?

A

Lamarck’s theory cannot account for all the observations made about life on Earth. For instance, his theory implies that all organisms would gradually become complex, and simple organisms disappear. On the other hand, Darwin’s theory can account for the continued presence of simple organisms.

2
Q

Who was Charles Darwin?

A

Charles Darwin was an English naturalist. He studied variation in plants and animals during a five-year voyage around the world in the 19th century. He explained his ideas about evolution in a book called On the Origin of Species, which was published in 1859.

3
Q

What do evolutionary trees show?

A

Evolutionary trees are used to represent the relationships between organisms.

4
Q

What are Lamarck’s theory?

A

A characteristic which is used more and more by an organism becomes bigger and stronger, and one that is not used eventually disappears
Any feature of an organism that is improved through use is passed to its offspring.

5
Q

What happens if a mutation occurs?

A

Mutations cause changes in genes. When new forms of a gene appear because of mutation, a rapid change in a species may happen if the environment changes.

6
Q

What is the theory of evolution?

A

different species have developed over time from simple life forms through natural selection. These simple life forms first developed more than three billion years ago (as the Earth is believed to be about 4.5 billion years old).

7
Q

Who was Jean-Baptiste Lamarck?

A

Jean-Baptiste Lamarck was a French scientist who developed an alternative theory of evolution at the beginning of the 19th century.

8
Q

What are mutations?

A

A random change in the DNA of an organism due to an error in DNA replication.

9
Q

How do antibiotic-resistant bacterium support the theory of evolution?

A

Microorganisms such as bacteria and viruses reproduce very rapidly. They can evolve in a relatively short time. One example is the bacterium E. coli. Its DNA can be damaged or changed when it reproduces. Most of the time this causes the death of the bacterial cell.
Occasionally, the mutation is beneficial for the bacterial cell. For example, it may allow resistance to an antibiotic. When that antibiotic is present, the resistant bacteria have an advantage over bacteria that are not resistant.

10
Q

How do peppered moths support the theory of evolution?

A

Before the industrial revolution in Britain, most peppered moths were of the pale variety, meaning that they were camouflaged against the pale birch trees that they rest on. Moths with a mutant black colouring were easily spotted and eaten by birds. This gave the white variety an advantage and they were more likely to survive to reproduce.
Airborne pollution in industrial areas then blackened the birch tree bark with soot. This meant that the mutant black moths were now camouflaged, while the white variety became more vulnerable to predators. The black variety now had the advantage and were more likely to survive and reproduce. Over time, black peppered moths have become far more numerous in urban areas.

11
Q

How does natural selection work?

A

individuals in a species show a wide range of variation
this variation is because of differences in their genes
individuals with characteristics most suited to the environment are more likely to survive and reproduce
the genes that allow these individuals to be successful are passed to their offspring.

Individuals that are poorly adapted to their environment are less likely to survive and reproduce. This means that their genes are less likely to be passed on to the next generation. Given enough time, a species will gradually evolve.

12
Q

How do we classify different organisms?

A

Different organisms can be classified by studying their similarities and differences. These studies also help us to understand the evolutionary relationships between different organisms.

13
Q

How does a tissue culture work?

A

A tissue sample is scraped from the parent plant, and then placed in agar growth medium containing nutrients and auxins. Samples grow into plantlets which are then transferred to compost.

14
Q

What is environmental variation and what are some examples?

A
Variation caused by the conditions is called environmental variation
    climate
    diet
    accidents
    culture
    lifestyle.
15
Q

Can asexual reproduction happen in animals?

A

Asexual reproduction in animals is less common than sexual reproduction but does happens in sea anemones and starfish, for example.

16
Q

How does embryo cloning work?

A

A developing embryo is removed from a pregnant animal at an early stage, before the embryo’s cells have had time to become specialised. The cells are separated from one another. They are then grown for a while in a laboratory and transplanted into host mothers.
When the offspring are born, they are identical to each other and genetically related to the original pregnant animal. They are not related to their host mothers because they contain different genetic information.

17
Q

What are the disadvantages of GM?

A

Some believe the process is unethical and should be banned. There are concerns about the effect of GM crops on wild flowers and insects, and whether eating GM food may harm human health.

18
Q

What are the advantages of cloning plants?

A

it allows a successful variety of a plant to be produced commercially and cheaply in a short space of time and on a massive scale.

19
Q

How does taking a cutting work?

A

A branch from the parent plant is cut off, its lower leaves removed and the stem planted in damp compost. Plant hormones are often used to encourage new roots to develop. The cutting is usually covered in a clear plastic bag at this stage to keep it moist and warm. After a few weeks, new roots develop and a new plant is produced. The method is easy enough for most gardeners to do successfully.

20
Q

How do chromosomes in a gamete work to produce an embryo?

A

In human beings, each gamete contains 23 chromosomes, half the number found in the other cells of the body. When the male and female gamete fuse, the new embryo contains the full 46 chromosomes – half from the father and half from the mother.

21
Q

Where are chromosomes found and what do they contain?

A

Chromosomes, found in the cell nucleus, contain many genes.

22
Q

What is the disadvantages of tissue cultures?

A

Sterile agar jelly with plant hormones and lots of nutrients is needed. This makes tissue culture more expensive and difficult to do than taking cuttings.

23
Q

What happens during sexual reproduction?

A

Male and female gametes fuse in a process called fertilisation. exual reproduction allows some of the genetic information from each parent to mix, producing offspring that resemble their parents but are not identical to them. In this way, sexual reproduction leads to variety in the offspring.

24
Q

How does adult cell cloning work?

A

the nucleus is removed from an unfertilised egg cell and discarded
the nucleus is removed from an adult body cell and injected into the egg cell
an electric shock is applied to fuse them together and make the egg cell begin to divide to form an embryo
while it is still a ball of cells, the embryo is inserted into the womb of an adult female
the embryo continues to grow and develop
The new individual is genetically identical to the animal that donated the nucleus from one of its body cells.

25
Q

How does asexual reproduction in plants work?

A

Many plants develop underground food storage organs that later develop into the following year’s plants: potato plants and daffodil plants are examples of this.Some plants produce side branches with plantlets on them. Busy Lizzy does this. Other plants, such as strawberries, produce runners with plantlets on them.

26
Q

What are the advantages of cloning an animal?

A

Just like the cloning of plants, the cloning of animals has many important commercial implications. It allows an individual animal with desirable features, such as a cow that produces a lot of milk, to be duplicated several times.

27
Q

What is inherited variation and what are some examples?

A

Variation due to genetic causes is inherited variation.
eye colour
hair colour
skin colour

28
Q

How does GM work?

A

Certain enzymes can cut pieces of DNA from one organism, and join them into a gap in the DNA of another organism. This means that the new organism with the inserted genes has the genetic information for one or more new characteristics. For example, the organism might produce a useful substance, or be able to carry out a new function. We say that the organism has been genetically modified.

29
Q

What are gametes?

A

sex cells

30
Q

What is asexual reproduction?

A

Asexual reproduction only needs one parent, unlike sexual reproduction, which needs two parents. Since there is only one parent, there is no fusion of gametes and no mixing of genetic information. As a result, the offspring are genetically identical to the parent and to each other: in other words, they are clones.

31
Q

What is the difference between cloning and genetic engineering (genetic modification or GM for short)?

A

Cloning produces exact copies, whilst GM produces a unique set of genes. Cloning only allows genes to be copied within the same species, but GM allows genes to be swapped across species.

32
Q

What is a gene?

A

A gene is a section of DNA, which carries coding for a particular protein. Different genes control the development of different characteristics of an organism. Many genes are needed to carry all the genetic information for a whole organism.

33
Q

What is variation caused by?

A

Some variation within a species is inherited, and some variation is due to the environment; some variation is due to a combination of both.

34
Q

What are the advantages of GM?

A

Can make insulin produces bacterium- medical properties. Can make crops resistant to herbicides and pests. GM crops generally have increased yields, useful for feeding a growing population. Tobacco plants that glow in the dark when they need watering have even been produced.

35
Q

What is a decomposer?

A

An organism that eats dead organisms or animal droppings, and breaks them down into simple materials.

36
Q

What does biomass mean?

A

Biomass means the mass of living material at a stage in a food chain. Biomass decreases from one stage to the next, just like the amount of energy.

37
Q

What is the third step of the carbon cycle?

A

Animals feed on the plants. Thus passing the carbon compounds along the food chain. Most of the carbon these animals consume however is exhaled as carbon dioxide. This is through the process of respiration. The animals and plants then eventually die.

38
Q

How do substances in an environment remain stable?

A

Some of the substances released during decay are needed by plants for healthy growth. In a stable community of living things, processes that return substances to the environment (such as decay) are balanced by the processes that remove and use substances. In this way, the substances are continuously recycled.

39
Q

How does the decay process work?

A

Decay is an essential life process that digests food or waste matter and recycles materials. Materials from living things decay because they are digested (broken down) by microorganisms. These microorganisms cause decay by releasing enzymes that break down compounds to be absorbed by their cells.Bacteria and fungi are the main groups of decomposer.

40
Q

What are scavengers?

A

feed on dead animals

for example, crows, vultures and hyenas are scavengers

41
Q

What factors affect the rate of decay?

A

moisture
temperature
amount of available oxygen.

42
Q

What are decomposers?

A

feed on dead and decaying organisms, and on the undigested parts of plant and animal matter in faeces

43
Q

What is the first step of the carbon cycle?

A

Carbon enters the atmosphere as carbon dioxide from respiration (from animals and PLANTS) and combustion (burning).

44
Q

Why do these factors affect the rate of decay?

A

Microorganisms are more active and digest materials faster when they are in moist, warm and aerobic conditions. They will digest materials more slowly in dry, cold and anaerobic conditions.

45
Q

What are prey?

A

the animals that predators feed on

46
Q

What are predators?

A

kill for food

they are either secondary or tertiary consumers

47
Q

What are pyramids of biomass?

A

Pyramids of biomass reveal the mass of living material at each stage in a chain. The amount of material and energy decreases from one stage to the next.

48
Q

What happens to the available energy absorbed in food chains?

A

Some of the available energy goes into growth and the production of offspring. This energy becomes available to the next stage, but most of the available energy is used up in other ways. For example:
energy released by respiration is used for movement and other life processes, and is eventually lost as heat to the surroundings
energy is lost in waste materials, such as faeces.
All of the energy used in these ways returns to the environment, and is not available to the next stage.

49
Q

What are producers?

A

green plants and algae

they make food by photosynthesis

50
Q

What are primary consumers?

A

usually eat plant material - they are herbivores

for example rabbits, caterpillars, cows and sheep

51
Q

Why are most food chains short?

A

There are rarely more than four stages, because a lot of energy is lost at each stage.

52
Q

How do you draw a pyramid of biomass?

A

A pyramid of biomass is a chart, drawn to scale, showing the biomass at each stage in a food chain. The bars become narrower as you reach the top. Note that you do not need to draw the organisms but you must draw your pyramid of biomass to scale. Each bar should be labelled with the name of the organism.

53
Q

What is the fourth step of the carbon cycle?

A

Picture
The dead organisms (dead animals and plants) are eaten by decomposers (who respire) in the ground. The carbon that was in their bodies is then returned to the atmosphere as carbon dioxide. In some circumstances the process of decomposition is prevented. The decomposed plants and animals may then be available as fossil fuel in the future for combustion.

54
Q

What are secondary consumers?

A

usually eat animal material - they are carnivores

for example cats, dogs and lions

55
Q

How does a food chain work?

A

Radiation from the Sun is the ultimate source of energy for most communities of living things. Green plants and algae absorb some of the Sun’s light energy and transfer this energy to chemical energy. This happens during photosynthesis, and the chemical energy is stored in the substances that make up the cells of the plants or algae. The other organisms in a food chain are consumers, because they all get their energy and biomass by consuming (eating) other organisms.

56
Q

What is the second step of the carbon cycle?

A

Carbon dioxide is absorbed by producers (life forms that make their own food e.g. plants) in photosynthesis . The carbon becomes part of complex molecules (known as carbon compounds) such as proteins, fats and carbohydrates in the plants and algae. These producers then put off oxygen.

57
Q

What sort of extreme conditions would you find extremophiles in?

A

high temperatures
high concentrations of salt in water
high pressures.

58
Q

How are cacti adapted?

A

stems that can store water
widespread root systems that can collect water from a large area.
spines instead of leaves. These minimise the surface area and so reduce water loss by transpiration. The spines also protect the cacti from animals that might eat them.

59
Q

What are lichens and how can they be used?

A

Lichens are plants that grow in exposed places such as rocks or tree bark. They need to be very good at absorbing water and nutrients to grow there. Rainwater contains just enough nutrients to keep them alive. Air pollutants dissolved in rainwater, especially sulfur dioxide, can damage lichens, and prevent them from growing. This makes lichens natural indicators of air pollution

60
Q

How do you use aquatic invertebrates as natural indicators?

A

level of water pollution indicator species
clean mayfly larva
low freshwater shrimp
high water louse
very high rat-tailed maggot,
sludgeworm

61
Q

What is the effect of environmental change?

A

Changes in the environment affect the distribution and behaviour of living organisms.

62
Q

How are camels adapted?

A

large, flat feet to spread their weight on the sand
thick fur on the top of the body for shade, and thin fur elsewhere to allow easy heat loss
a large surface-area-to-volume ratio to maximise heat loss
the ability to go for a long time without water - they don’t store water in their humps, but they lose very little water through urination and perspiration
the ability to tolerate body temperatures up to 42ºC
slit-like nostrils and two rows of eyelashes to help keep out sand.

63
Q

How can you use lichens as natural indicators?

A

bushy lichens need really clean air
leafy lichens can survive a small amount of air pollution
crusty lichens can survive in more polluted air.

In places where no lichens are growing, it is often a sign that the air is heavily polluted with sulfur dioxide.

64
Q

What is the relationship between predator and prey?

A

If the prey population grows, predator numbers will respond to the increased food supply by increasing as well. Growing predator numbers will eventually reduce the food supply to the point where it can no longer sustain the predator population, and the number of predators will go down.

65
Q

What do non-living environmental factors include?

A

temperature or rainfall.

66
Q

How can rainfall be measured?

A

using a rain gauge. The depth of rain is usually measured daily. A simple rain gauge consists of a funnel that empties into bottle. The daily contents of the bottle are poured into a measuring cylinder. This is calibrated so that it reads the depth of rainfall in millimetres.

67
Q

What are extremophiles?

A

Extremophiles are organisms that live in very extreme environments and can survive conditions that would kill most other organisms.

68
Q

What is the cause of water pollution?

A

Water pollution is caused by the discharge of harmful substances into rivers, lakes and seas.

69
Q

How are plants in the arctic adapted?

A

Plants in the Arctic often grow very close to the ground and have small leaves. This helps to conserve water and to avoid damage by the wind.

70
Q

How are polar bears in the arctic adapted?

A

a white appearance as camouflage from prey on the snow and ice
thick layers of fat and fur for insulation against the cold
a small surface area to volume ratio, to minimise heat loss
a greasy coat that sheds water after swimming
large furry feet to distribute their load and increase grip on the ice.

71
Q

How is temperature measured?

A

An ordinary thermometer can be used to measure the temperature in an environment. Traditional maximum and minimum thermometers have a U-shaped tube. Each side contains a pin which moves inside with the liquid: one pin records the maximum temperature; and the other pin records the minimum temperature. After readings have been taken, the pins are reset using a magnet.

72
Q

What causes air pollution?

A

The most common source of air pollution is the combustion of fossil fuels. This usually happens in vehicle engines and power stations. Sulfur dioxide is released if the fuel contains sulfur compounds. This gas contributes to acid rain.

73
Q

What is the advantages of a digital thermometer?

A

A digital thermometer connected to a data logger allows an almost continuous measurement of temperature over time. It also has the advantage that no one needs to be there to take a reading.

74
Q

What do living environmental factors include?

A

a predator, a food source or a competitor.

75
Q

How is the snowshoe hare adapted?

A

The snowshoe hare has white fur in the winter and reddish-brown fur in the summer. This means that it is camouflaged from its predators for most of the year.

76
Q

What are the resources that animals compete for?

A

food
water
space.
(mates- same species)

77
Q

What are the resources that plants compete for?

A

water
space
mineral salts.

78
Q

How are aquatic invertebrates useful natural indicators?

A

Many aquatic invertebrate animals cannot survive in polluted water, so their presence or absence indicates the extent to which a body of water is polluted.

79
Q

What is the placebo effect?

A

people feeling better simply because they expect to feel better if they take a medicine.

80
Q

How do double blind trials work?

A

Some patients are given the drug while others are given a placebo. A placebo is designed to appear exactly the same as the drug itself, but it does not actually contain any of the drug. The doctors and patients are not told who have received the drug and who have received the placebo until the trial is over.

81
Q

What is nicotine?

A

Nicotine is the addictive substance in tobacco smoke. It reaches the brain within 20 seconds and creates a dependency so that smokers become addicted.

82
Q

What is the third stage in developing a drug?

A

Drugs that have passed animal tests are used in clinical trials. They are tested on healthy volunteers to check they are safe. Very low doses of the drug are given to begin with. If there are no problems, further clinical trials are done to find the optimum dose for the drug.

83
Q

What is the first stage in developing a drug?

A

The drugs are tested using computer models and human cells grown in the laboratory. Many substances fail this test because they damage cells or do not seem to work.

84
Q

What happened as a result of the Thalidomide disaster?

A

thalidomide was banned. Drug testing was also made more rigorous than before.

85
Q

What is the problem with performance enhancing drugs?

A

the use of performance enhancing drugs is widely seen as unfair. They may also damage the athlete’s body.

86
Q

What is alcohol?

A

The alcohol in alcoholic drinks such as wines, beer and spirits is ethanol, which is a depressant, meaning that it slows down signals in the nerves and brain.

87
Q

What is Thalidomide?

A

Thalidomide is a medical drug that caused unexpected and serious damage to unborn babies in the 1950s and 1960s. Thalidomide was developed as a sleeping pill, but it was also thought to be useful for easing morning sickness in pregnant women.

88
Q

What did a research report in 2006 do?

A

classified various drugs according to their health and social risks, without reference to whether they are legal or not. In the report, heroin and cocaine are the most dangerous two drugs, alcohol is the fifth most dangerous and tobacco is ninth.

89
Q

What are the downsides of drug development?

A

Clinical trials are not without risk. Sometimes severe and unexpected side effects occur. Most substances do not pass all of the tests and trials, so drug development is expensive and takes a long time.

90
Q

What does smoking increase the risk of?

A

heart disease and strokes
miscarriage, premature birth and low birth weight
lung cancer, mouth cancer and throat cancer.

91
Q

What are the health problems associated with illegal drugs?

A

Heroin and cocaine are very addictive. Like ecstasy, they can damage the heart and circulatory system. Cannabis smoke contains chemicals that cause mental illness in some people

92
Q

What is the second stage in developing a drug?

A

Drugs that pass the first stage are tested on animals. A typical test involves giving a known amount of the substance to the animals, then monitoring them carefully for any side-effects.

93
Q

What are the indirect effect of drugs on our health?

A

buying the drugs reduces the amount of money available to buy food, and may place users in dangerous situations. Injecting a drug using a needle and syringe that someone else has used may lead to a number of diseases from infected blood, including HIV and hepatitis. Users of illegal drugs may turn to crime to pay for their habit.

94
Q

What is Thaidomide used for today?

A

Thalidomide is now used as a treatment for leprosy and bone cancer. Its use is heavily regulated, however, to prevent a repeat of the problems it caused in the last century.

95
Q

Why do new medical drugs have to be tested?

A

to ensure that they work, and are safe

96
Q

What do illegal drugs include?

A

prescription drugs that have been dangerously modified and substances that are banned by law.

97
Q

What do performance enhancing drugs include?

A

stimulants – these boost heart rate and other body functions

anabolic steroids – these stimulate the growth of muscles.

98
Q

What effects did Thalidomide caused on unborn babies?

A

By 1960 thalidomide was found to damage the development of unborn babies, especially if it had been taken in the first four to eight weeks of pregnancy. The drug led to the arms or legs of the babies being very short or incompletely formed.

99
Q

What are the effects of alcohol?

A

Small amounts of alcohol help people to relax, but greater amounts lead to a lack of self-control.Alcohol is addictive. Long-term effects of alcohol include damage to the liver and brain, and it is often the cause of weight gain. Dangerous during pregnancy.

100
Q

How do the roots and shoots respond to light?

A

The shoot grows towards the light, and the root grows away from the light.

101
Q

How does rooting powder work?

A

Rooting powder contains growth hormones to make stem cuttings quickly develop roots.

102
Q

What do fertility drugs contain and what do they do?

A

Fertility drugs contain FSH and LH, which stimulate eggs to mature in the ovary.
Fertility treatments increase a woman’s chance of becoming pregnant,

103
Q

What are auxins?

A

Auxins are a family of hormones found in plants. They change the rate of elongation in plant cells, controlling how long they become.

104
Q

What are receptors?

A

Receptors are groups of specialised cells that can detect changes in the environment called stimuli.

105
Q

When is IVF used?

A

If a couple are having difficulty conceiving a child because the quantity or quality of the man’s sperm is poor then IVF can be used.

106
Q

What are auxins?

A

Auxins are a family of hormones found in plants. They change the rate of elongation in plant cells, controlling how long they become.

107
Q

What does the oral contraceptive (the pill) contain and how does it work?

A

It contains oestrogen or progesterone (another hormone). These hormones inhibit the production of FSH, which in turn stops eggs maturing in the ovaries.

108
Q

What does FSH do?

A

it causes an egg to mature in an ovary

it stimulates the ovaries to release the hormone oestrogen.

109
Q

Why do some women have difficulty becoming pregnant?

A

because they don’t produce enough FSH to allow their eggs to mature.

110
Q

What does oestrogen do?

A

it stops FSH being produced - so that only one egg matures in a cycle
it stimulates the pituitary gland to release luteinizing hormone (LH), which triggers ovulation (the release of the mature egg from the ovary).

111
Q

How is blood sugar level controlled?

A

Blood sugar level is controlled by the release and storage of glucose controlled by insulin.

112
Q

Where is FSH secreted?

A

The hormone FSH is secreted by the pituitary gland

113
Q

What are the two different types of tropism?

A

positive tropism – the plant grows towards the stimulus

negative tropism – the plant grows away from the stimulus.

114
Q

What is homeostatis?

A

The maintenance of a constant internal environment

115
Q

What do relay neurones do?

A

relay neurones carry messages from one part of the CNS to another

116
Q

What is a synapse?

A

A tiny gap where two neurones meet.

117
Q

What does LH do?

A

It causes ovulation (the release of the mature egg from the ovary)

118
Q

How do shoots and roots react to high concentrations of auxin?

A

cells in shoots grow more

cells in roots grow less.

119
Q

How do the roots and shoots respond to gravity?

A

The shoots grows against the force of gravity, and the root grows with (towards) the force of gravity.

120
Q

What is an effector?

A

An effector is any part of the body that produces the response. Here are some examples of effectors:
a muscle contracting
a gland releasing (secreting) a hormone or other chemical.

121
Q

How do weed killers work?

A

Selective weed killers work on some plants but not others. Selective weed killers contain growth hormone that cause the weeds to grow too quickly and then die. The weed killer is absorbed in larger quantities by the weeds than the beneficial plants, which stay healthy. This is because weeds have broader leaves.

122
Q

Why does temperature of the body need to be controlled?

A

This is controlled to maintain the temperature at which enzymes work best.

123
Q

Why does water content in the body need to be controlled?

A

Water in the body has to be controlled to protect cells from either too much water entering or too much water leaving them.

124
Q

What happens during a reflex action?

A

receptor detects a stimulus - a change in the environment
sensory neurone sends impulses to relay neurone
motor neurone sends impulses to effector
effector produces a response.

125
Q

What are the risks of the pill?

A

The first birth-control pills contained higher amounts of oestrogen than the pills taken today. This caused women to have significant side effects, such as changes in weight, mood and blood pressure. Modern birth-control pills contain much less oestrogen. Some only contain progesterone, which also leads to fewer side effects.

126
Q

Why does blood sugar level need to be controlled?

A

This is controlled to provide cells with a constant supply of energy.

127
Q

Where is LH secreted?

A

In the pituitary gland.

128
Q

What do sensory neurones do?

A

sensory neurones carry signals from receptors to the spinal cord and brain

129
Q

Where is oestrogen secreted?

A

The hormone oestrogen is secreted by the ovaries.

130
Q

How do signals pass the synapse?

A

Signals cross this gap using chemicals. One neurone releases the chemical into the gap. The chemical diffuses across the gap and makes the next neurone transmit an electrical signal.

131
Q

What do motor neurones do?

A

motor neurones carry signals from the CNS to effectors.

132
Q

How are hormones transported around the body?

A

Through the bloodstream

133
Q

What happens during IVF?

A

This is where the egg is fertilised outside the woman’s body and then implanted back into her uterus. As FSH can also be used to encourage the production of several mature eggs at once, it is used as part of IVF to increase the number of eggs available for fertilisation.

134
Q

What is phototropism?

A

Phototropism is a tropism where light is the stimulus

135
Q

What are reflex actions?

A

Reactions that rapid and happen without us thinking and bypass the brain.

136
Q

What are hormones?

A

Hormones are chemicals secreted by glands in the body. Different hormones affect different target organs and they regulate the functions of many cells and organs.

137
Q

What makes up the central nervous system and how does it work?

A

The human central nervous system (CNS) consists of the brain and spinal cord. When a receptor is stimulated it sends a signal along the nerve cells, also called neurones, to the brain. The brain then coordinates the response.

138
Q

How does phototropism work?

A

In a shoot, the shaded side contains more auxin. This means that the shaded side grows longer, causing the shoot to bend towards the light. Auxins have the opposite effect on root cells. In a root, the shaded side contains more auxin, but this time the shaded side grows less than the lit side. This causes the root to bend away from the light.

139
Q

What is auxin produced?

A

Auxins are mostly made in the tips of the shoots and roots, and can diffuse to other parts of the shoots or roots.

140
Q

How is water content in the body controlled?

A

Water content is controlled by water loss from:
the lungs - when we exhale
the skin - through sweating
passing urine - produced by the kidneys.

141
Q

How does rooting powder work?

A

Rooting powder contains growth hormones to make stem cuttings quickly develop roots.

142
Q

How is ion content in the body controlled?

A

Ion content is controlled by the loss of ions from:
the skin - through sweating
passing urine - produced by the kidneys.

143
Q

What are the risks of fertility drugs?

A

The treatment doesn’t always work. On the other hand, because the treatment boosts the production of mature eggs, multiple conceptions sometimes occur, with twins or triplets being expected. This increases the risk of complications in pregnancy and childbirth, and may lead to premature or underweight babies.

144
Q

What are Neurones?

A

Neurones are nerve cells that carry information as tiny electrical signals. There are three different types of neurones, each with a slightly different function

145
Q

How does gravitropism work?

A

In a root placed horizontally, the bottom side contains more auxin than the top side. This makes the bottom side grow less than the top side, causing the root to bend in the direction of the force of gravity.
In a shoot placed horizontally, the bottom side contains more auxin than the top side. This makes the bottom side grow more than the top side, causing the shoot to bend and grow against the force of gravity.

146
Q

How does gravitropism work?

A

In a root placed horizontally, the bottom side contains more auxin than the top side. This makes the bottom side grow less than the top side, causing the root to bend in the direction of the force of gravity.
In a shoot placed horizontally, the bottom side contains more auxin than the top side. This makes the bottom side grow more than the top side, causing the shoot to bend and grow against the force of gravity.

147
Q

How is body temperature controlled?

A

Body temperature is controlled by sweating, shivering, and controlling blood flow to the skin.

148
Q

What are the disadvantages of IVF?

A

Some people worry about the ethical implications of IVF. They are concerned that couples may want ‘designer babies’ with ‘desirable’ qualities, so may only want certain fertilised eggs.

149
Q

What is auxin produced?

A

Auxins are mostly made in the tips of the shoots and roots, and can diffuse to other parts of the shoots or roots.

150
Q

How does phototropism work?

A

In a shoot, the shaded side contains more auxin. This means that the shaded side grows longer, causing the shoot to bend towards the light. Auxins have the opposite effect on root cells. In a root, the shaded side contains more auxin, but this time the shaded side grows less than the lit side. This causes the root to bend away from the light.

151
Q

What are the benefits of the pill?

A

Oral contraceptives allow couples to choose the time they start a family, and choose the time they stop having children.

152
Q

What is gravitropism (also called a ‘geotropism’)

A

a tropism where gravity is the stimulus

153
Q

How do shoots and roots react to high concentrations of auxin?

A

cells in shoots grow more

cells in roots grow less.

154
Q

Why does ion content in the body need to be controlled?

A

Ion levels are controlled to protect cells from too much water entering or leaving them.

155
Q

How do weed killers work?

A

Selective weed killers work on some plants but not others. Selective weed killers contain growth hormone that cause the weeds to grow too quickly and then die. The weed killer is absorbed in larger quantities by the weeds than the beneficial plants, which stay healthy. This is because weeds have broader leaves.

156
Q

What did Ignaz Semmellweiss discover?

A

He thought that illness could be transferred by touch- noticed that doctors went from dead bodies to helping with child birth, spread childbed fever. Semmelweiss insisted that doctors should wash their hands before examining patients, something that was not common at the time. This policy greatly reduced the number of deaths from infectious diseases in his hospital.

157
Q

What are some of the diseases caused by viruses?

A
nfluenza (flu)
colds
measles
mumps
rubella
chicken pox
AIDs.
158
Q

Why are resistant strains of bacteria dangerous?

A

The appearance of resistant strains of bacteria means that vaccinations and antibiotics may no longer work. As people are not immune to it, and there is no effective treatment, a resistant strain will spread rapidly. New antibiotics must be developed as a result.

159
Q

How does vaccination work?

A

Vaccination involves putting a small amount of an inactive form of a pathogen, or dead pathogen, into the body.When injected into the body, they stimulate white blood cells to produce antibodies against the pathogen. If the person does get infected by the pathogen later, their body can respond in the same way as if they had had the disease before. If a large proportion of the population is immune to a particular pathogen, the spread of that pathogen is greatly reduced.

160
Q

Why was Semmellweiss ideas ignored at the time?

A

although his ideas were successful, they were ignored at the time because people did not know that diseases were caused by pathogens that could be killed.

161
Q

What do white blood cells do?

A

ingest pathogens and destroy them
produce antibodies to destroy particular pathogens
produce antitoxins that counteract the toxins released by pathogens.

162
Q

What does an imbalanced diet lead to?

A

An imbalanced diet causes a person to become malnourished. For example:

too little food may lead to a person being underweight
too much food may lead to a person being overweight.

A poor diet may also lead to deficiency diseases.

163
Q

What temperature should you incubate a culture of bacteria at?

A

It would be dangerous to incubate (keep and grow) cultures at temperatures close to body temperature (37°C) because doing so might allow the growth of pathogens harmful to health. So the maximum temperature used in school and college labs is 25°C. However, higher temperatures can be used industrially, and these produce faster growth.

164
Q

What factors affect the metabolic rate?

A

age, gender and inherited factors, proportion of muscle to fat in the body, amount of exercise and other physical activity. The metabolic rate increases as we exercise and stays high for a while afterwards. People who exercise regularly are usually healthier than people who don’t.

165
Q

What is a balanced diet?

A

A balanced diet contains the different nutrients in the correct amounts to keep us healthy.

166
Q

What do antibiotics do?

A

Antibiotics are substances that kill bacteria or stop their growth. They do not work against viruses because they live and reproduce inside cells. It is difficult to develop drugs that kill viruses without also damaging the body’s tissues.

167
Q

What is the metabolism?

A

The metabolic rate is the speed at which such chemical reactions take place in the body

168
Q

How do you slow down or stop the development of resistive strains of bacteria?

A

avoid the unnecessary use of antibiotics

complete the full course.

169
Q

What is protein found in and why is it needed?

A

meat, fish, eggs and cheese. They are needed for growth and repair - building cells

170
Q

How do you grow a culture of bacteria?

A

the Petri dishes, nutrient agar jelly and other culture media must be sterilised
the inoculating loops used to transfer microorganisms must be sterilised (usually by passing the metal loop through a Bunsen burner flame)
the lid of the Petri dish is sealed with sticky tape to stop microorganisms from the air getting in and contaminating the culture.

171
Q

What are fats found in and why are they needed?

A

cheese, butter, margarine and oils. They are a source of energy for life processes: fats are also needed to make cell membranes and to insulate our bodies

172
Q

What is MRSA?

A

MRSA is the acronym for ‘methicillin-resistant Staphylococcus aureus’. It’s very dangerous because it’s a strain of bacterium that is resistant to most antibiotics.

173
Q

What does bacteria do?

A

Bacteria are living cells and, in favourable conditions, can multiply rapidly. Once inside the body, they release poisons or toxins that make us feel ill. Diseases caused by bacteria include:

food poisoning
cholera
typhoid
whooping cough.
174
Q

How does bacteria become resistant?

A

antibiotics kill individual pathogens of the non-resistant strain
resistant individual pathogens survive and reproduce
the population of the resistant pathogens increases.

175
Q

What did Robert koch discover?

A

In 1878 Robert Koch discovered how to grow bacteria in a Petri dish (named after his assistant Julius Petri). He was able to discover which bacteria caused certain diseases, including TB and cholera. Scientists still grow microorganisms in the lab so that they can be investigated.

176
Q

What are vitamins and minerals needed for?

A

They are needed in small amounts for healthy functioning of the body.

177
Q

How do antibodies work?

A

bind to pathogens and damage or destroy them

coat pathogens, clumping them together so that they are easily ingested by white blood cells called phagocytes.

178
Q

What are carbohydrates found in and why are they needed?

A

potatoes, pasta, bread, bananas, sugar and rice. They are a source of energy for life processes

179
Q

How are antibodies produced?

A

Pathogens contain certain chemicals that are foreign to the body. These chemicals are called antigens. Certain white blood cells, called lymphocytes, can produce specific antibodies to kill a particular pathogen- - a protein that has a chemical ‘fit’ to a certain antigen. When a lymphocyte with the appropriate antibody meets the antigen, the lymphocyte reproduces quickly and makes many copies of the antibody to kill the pathogen.

180
Q

What do viruses do?

A

Viruses can only reproduce inside host cells and they damage the cell when they do this. A virus can get inside a cell and, once there, take over and make hundreds of thousands of copies of itself. Eventually the virus copies fill the whole host cell and burst it open. The viruses are then passed out in the bloodstream, the airways, or by other routes.

181
Q

What do painkillers do?

A

Painkillers helps to relieve the symptoms of an infectious disease, but they do not kill the pathogens involved.

182
Q

What did Alexander Fleming discover and how?

A

Penicillin. He noticed that some bacteria he had left in a Petri dish had been killed by naturally occurring penicillium mould. Since the discovery of penicillin, many other antibiotics have been discovered and developed.

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