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GCSE > Biology 1a-b > Flashcards

Biology 1a-b Flashcards

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1
Q

Why are vaccinations helpful?

A

Because it takes white blood cells a few days to learn how to fight new microorganisms, you can become very ill though in that time

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2
Q

What are vaccinations?

A

When someone is injected with small amounts of dead of inactive microorganisms that carry antigens, forcing the body to produce antibodies

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3
Q

What happens if someone gets an illness they have been vaccinated from

A

The white blood cells can rapidly produce lots oft he necessary antibodies to fight the pathogen

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4
Q

What are booster injections?

A

Some vaccinations wear off so booster injections increase the levels of antibodies again

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5
Q

What is a pro of vaccinations?

A

They help control lots of infectious diseases that were once common in the uk e.g. small pox no longer occurs at and polio infections infections have fallen by 99%

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6
Q

What is another pro of vaccinations?

A

Big outbreaks-epidemics- can be prevented if a lot of the population is vaccinated from it. Even then if some people aren’t vaccinated, its unlikely they will get the illness.

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7
Q

What are cons of vaccinations?

A

They don’t always work and sometimes people can have bad reactions to the vaccination

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8
Q

What do painkillers do?

A

They relieve pain but don’t cure the actual disease, they just reduce the symptoms

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9
Q

What do antibiotics do?

A

They prevent the growth of the bacteria causing the problem without killing body cells. There are different antibiotics for different types of bacteria

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10
Q

Why can’t antibiotics be used to treat viruses?

A

Because viruses reproduce by using your own body cells so it is hard to make drugs that destroy the virus without harming your body cells

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11
Q

What can bacteria do that causes resistance to antibiotics?

A

They can mutate to become resistant

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12
Q

What happens if you treat an infection but have some resistant bacteria?

A

Only the non resistant strains will be destroyed, the resistant ones will survive and reproduce, creating more non resistant bacteria - natural selection

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13
Q

What is methicillin-resistant staphylococcus aureus?

A

MRSA causes serious wound infections and is resistant to the powerful antibiotic, Methicillin. It is very serious and can’t be treated with antibiotics

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14
Q

How can you slow down the rate of development of resistant strains?

A

Doctors need to avoid over-prescribing antibiotics, you only get them for something serious

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15
Q

How can you investigate antibiotics?

A

By growing microorganisms in the lab

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16
Q

How are microorganisms grown?

A

in a culture medium, usually agar jelly containing carbohydrates, minerals, proteins and vitamins needed for growth

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17
Q

What did Semmelweis do?

A

He cut deaths by using antiseptics. Starting in hospitals when he noticed lots of women died after childbirth

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18
Q

What are dangers of bacteria?

A

They can mutate, become resistant to antibiotics, create new strains we don’t know how to treat and no one would be immune to it so it could spread quick and cause an epidemic

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19
Q

What are the dangers of viruses?

A

Viruses mutate often , hard to develop vaccines to treat them, if a fatal one developed it would be hard to stop. I the worst case scenario, a flu pandemic could kill billions of people all over the world

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20
Q

What do sense organs detect?

A

Stimuli

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21
Q

What is a stimulus?

A

A change in your environment which causes you to react§

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22
Q

What is an example of stimuli?

A

Light, sound, pressure, pain, change in temperature etc

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23
Q

What are the five different sense organs?

A

eyes, ears, nose, tongue, skin

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24
Q

What receptor do eyes contain?

A

light receptors, sensitive to light

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25
Q

What receptor do ears contain?

A

Sound receptors, sensitive to sound and balance receptors, sensitive to change in position

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26
Q

What receptor do noses contain?

A

Smell receptors, sensitive to chemical stimuli

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27
Q

What receptor do tongues contain?

A

Taste receptors, sensitive to chemical stimuli

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28
Q

What receptor does skin contain?

A

sensitive to touch, pressure, pain and temperature changes

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29
Q

What does the central nervous system do?

A

It coordinates a response

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30
Q

What does the central nervous system consist of?

A

The brain and spine

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31
Q

What are synapses?

A

Gaps that connect neutrons, they are how nerves communicate and pass impulses to one another

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32
Q

What do reflexes prevent?

A

Injury

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33
Q

Where is the reflex arc?

A

It goes through the central nervous system

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34
Q

How do reflexes happen?

A

Impulses travel along through these in order Stimuli-receptor-sensory neurone-relay neurone-motor neurone- effector- response (reflex)

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35
Q

What are hormones?

A

Chemical messengers sent in the blood that only affect certain cells, target cells

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36
Q

What do hormones do?

A

Control things in organs and cells that need constant adjustment

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37
Q

Where are hormones produced?

A

They are produced and secreted by various glands and travel at the same speed as blood

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38
Q

What glands produce each hormone?

A 
Pituitary gland=ADH, FSH, LH
Thyroid-throat=Thyroxine
Adrenal gland=Adrenaline
Pancreas=Insulin
Ovary=Oestrogen
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39
Q

Hormones and nerves do similar things, but what are the differences?

A

Nerves=very fast action while hormones are slower. Nerves act for a very short time while hormones act for a long time, Nerves act on a very precise area while hormones act in a more general way

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40
Q

How many stages are there in the menstrual cycle?

A

Four

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41
Q

What happens at the first stage?

A

Bleeding starts, the uterus lining breaks down for about 4 days

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42
Q

What happens at stage two?

A

The lining of the uterus builds up again, up to day 14 it build into a thick spongey layer full of blood vessels ready for a fertilised egg

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43
Q

Stage three?

A

An egg is released from the ovaries at day 14

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44
Q

What happens at the final stage, stage four?

A

The wall is maintained for another fourteen days, if there is no fertilised egg, it goes back to stage one and repeats, hence the name menstrual CYCLE

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45
Q

What are the four hormones involved in the menstrual cycle?

A

FSH, Oestrogen, progesterone and LH

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46
Q

What does FSH do?

A

Causes the egg to mature in one the ovaries and stimulates ovaries to produce oestrogen, it is produced by the pituitary gland

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47
Q

What does oestrogen do?

A

Causes the pituitary gland to produce LH and inhibits further release of FSH, produced in the ovaries

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48
Q

What does LH do?

A

Stimulated the release of an egg at around the middle of the menstrual cycle, produced by that pituitary gland

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49
Q

What can hormones also do?

A

Artificially change fertility

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50
Q

How can oestrogen be used as contraception?

A

If it is taken every day it inhibits FSH and egg development and production stop. Also it is in the pill

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51
Q

Pros of the pill?

A

over 99% effective at preventing pregnancy and reduces the risk of some types of cancer

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52
Q

Cons of the pill?

A

It isn’t 100% effective, can cause side effects such as headaches, nausea, irregular menstrual bleeding and fluid retention. Also it doesn’t prevent STDs

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53
Q

What does it mean if you have low levels of FSH

A

You cant become pregnant

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54
Q

What are the pros of injecting FSH and LH to stimulate egg release and become pregnant?

A

It can help women get pregnant when they previously couldn’t

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55
Q

What are the cons of injecting FSH and LH to stimulate egg release and become pregnant?

A

It doesn’t always work and can be expensive also too many eggs could be stimulated resulting in unexpected multiple pregnancies (twins, triplets etc.)

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56
Q

What is IVF?

A

You collect eggs from the woman’s ovaries and fertilise them in a lab using the mans sperm, they then grow into embryos. Once the embryos are tiny balls of cells, one or two of them are transferred to the woman’s uterus to increase the chance of pregnancy

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57
Q

What is the woman given before IVF starts?

A

She is given FSH and LH to stimulate egg production

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58
Q

What are the pros of IVF?

A

Fertility treatment can give an infertile couple a child where they previously couldn’t instead of having to adopt

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59
Q

What are the cons of IVF?

A

Some women can have bad reactions to the hormones. There have been reports of increased risk of cancer due to the hormones although others say it doesn’t increase the risk. Multiple births can happen if more than one embryo grows into a baby, this adds more risk to the mother and child (miscarriage/stillbirth)

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60
Q

What is a plant growth hormone that controls growth near the tips of shoots and roots?

A

Auxin

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61
Q

Auxin control the growth of a plant in response to…?

A

Light (phototropism) Gravity (geotropism) and moisture

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62
Q

Where is auxin produced?

A

In the tips and moves backwards to stimulate the cell elongation (enlargement) process which occurs in the cells behind the tips

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63
Q

What happens if the tip of a shoot is produced?

A

No auxin is available and the shoot may stop growing

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64
Q

Where do shoots grow towards?

A

Towards light, when it is exposed to light, more auxin is made on the sids thats in the shade making the cells grow faster on the shaded side so the shoot bends towards the light

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65
Q

Where do shoots grow away from?

A

Away from gravity . When a shoot is growing sideways, gravity produces an unequal distribution of auxin in the tip with more auxin on the lower side causing the lower side to grow faster bending the shoot upwards

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66
Q

Where do roots grow towards?

A

Towards gravity, a root growing sideways will have more auxin on its lower side but in a root the extra auxin inhibits growth so the cells on top grow faster and the root bends downwards

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67
Q

What else do roots grow towards?

A

Moisture, if the amount of moisture is uneven, more auxin is produced on the side with the most auxin which inhibits growth on that side, meaning that the root bends in the direction towards the moisture

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68
Q

What does tropism mean?

A

When a plant responds to its environment

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69
Q

What are two different ways that plant hormones are used in agriculture?

A

Rooting powder (containing auxin) produces roots for plant cuttings making it quicker and easier to clone plants. Also some weedkillers are made of plant hormones and can kill the weeds but leaf the crops alone…see what I did there, leaf it alone…cus its a plant…get it…no…never mind

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70
Q

What does homeostasis mean?

A

It means all the functions of your body which try to maintain a constant internal environment

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71
Q

To keep your body working properly, what bodily levels need to be controlled?

A

Iron content, Water content, Sugar content and Temperature

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72
Q

What is ion content regulated by?

A

The kidneys

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73
Q

How does ion enter the body?

A

It enters in food and is then absorbed into the blood

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74
Q

What happens if food contains too much ion?

A

The excess ions need to be removed

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75
Q

How is ion removed?

A

Some is lost in sweat while the rest, the kidneys will remove excess from the blood, then is gotten rid of in urine

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76
Q

What are some different ways that water is lost?

A

Through skin as sweat, via the lungs in breath and via the kidneys as urine

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77
Q

How is water lost on a cold day?

A

If its cold or your not exercising, you won’t sweat much so you’ll produce more urine- pale as it carries the waste which is more diluted

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78
Q

How is water lost on a hot day?

A

If its hot or your exercising, you set a lot and will produce less urine, it would be more concentrated and you will lose more water through your breath-breathing faster

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79
Q

What controls body temperature?

A

The brain

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80
Q

What temperature do enzymes work best at?

A

around 37 degrees C, so this is the temperature your body tries to maintain

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81
Q

What happens when you eat foods containing carbohydrates?

A

It puts glucose into the blood from the gut.

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82
Q

How is glucose removed?

A

The normal metabolism of cells remove glucose from blood, but if you do a lot more exercise, much more glucose is removed

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83
Q

What does insulin do?

A

Helps to maintain the right level of glucose in your blood so your cells get a constant supply of energy

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84
Q

What do drugs change in your body?

A

Your body chemistry

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85
Q

What do these chemical changes lead to?

A

Addiction

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86
Q

What drugs are particularly addictive?

A

Heroin, Cocaine, Nicotine and Caffeine

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87
Q

What are medical drugs?

A

Things like antibiotics, some you don’t need a prescription (paracetamol) but other you do need a prescription (morphine) because they can be dangerous if misused

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88
Q

What are recreational drugs?

A

They are used for fun, these can be either legal or illegal

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89
Q

What are performance enhancing drugs?

A

These improve someones performance in sport

90
Q

What are some different types of performance enhancing drugs?

A

Antibiotic steroids (increase muscle size) and stimulants (increase heart rate)

91
Q

Why are people against the use of performance enhancing drugs?

A

It is unfair as the person taking them have an advantage by taking the drugs instead of just training and also athletes may not be fully informed of the serious health risks of these drugs

92
Q

Why are people for the use performance enhancing drugs?

A

Athletes have the right to make their own decision about whether taking the drugs is worth the risk or not and drug-free sport isn’t fair either as athletes have access to different training facilities, coaches, equipment ect

93
Q

Are performance enhancing drugs legal?

A

Some are banned by law, some are prescription only but all are banned for sporting competitions and events

94
Q

What are statins?

A

Prescribed drugs used to lower the risk of heart and circulatory diseases and lower blood cholesterol

95
Q

Why do claims about drugs need to be carefully looked at?

A

Drugs affect people differently, sometimes you may not know how many people have been tested on and some don’t have any or little scientific evidence

96
Q

What is the first stage of drug testing?

A

Drugs are tested on human cells and tissue in a lab but you cant test drugs that affect whole or multiple body systems e.g. blood pressure, on cells and tissue

97
Q

What is the second stage of drug testing?

A

Testing on live animals to see if the drug works, to test its toxicity and what dosage is the best. In Britain, the law is that a drug must be tested on two different live mammals. Some people believe it is cruel and pointless as animals are different to humans while others believe it is the safest way to test the drugs before giving it to humans

98
Q

What is the third stage of drug testing?

A

Tested in a clinical trial on healthy, human volunteers to test for side effects, starting with a low dosage, if results are good, they are tested on people suffering with the illness and the optimum dosage is found. Usually it is a double blind trial so that you can tell how much the drug actually works in case of the placebo effect

99
Q

What is a double blind trial?

A

When the volunteers and scientists both don’t know who is taking the real drug and who is taking a fake version

100
Q

What is a placebo?

A

When something isn’t medicine but make a person feel the effect as they think they have taken medicine

101
Q

What are the effects of smoking?

A

Heart disease, blood vessel disease, lung disease, cancer, and it is addicting

102
Q

What are the effects of alcohol?

A

Affects nervous system, slows down the body’s reactions, impaired judgement, poor coordination, unconsciousness, liver disease, brain damage and it is addictive

103
Q

What have desert animals adapted to do?

A

Save water and keep cool

104
Q

Why do desert animals have a large surface area compared to volume?

A

To lose more body heat to stop them overheating

105
Q

How are desert animals more efficient with water?

A

They lose less water by producing concentrated urine and make very little sweat. Camels can tolerate big changed in body temperatures while kangaroo rats live in cooler underground burrows

106
Q

How are desert animals good in hot conditions?

A

They have thin layers of body fat and a thin coat to lose body heat e.g. camels keep almost all their fat in their humps

107
Q

Why are desert animals camouflaged?

A

They are a sandy colour to avoid predators and can sneak up on prey easier

108
Q

What have arctic animals adapted to do?

A

Reduce heat loss

109
Q

Why do arctic animals have a small surface area compared to volume?

A

They are more compact (round) to keep their surface area minimal which reduces heat loss

110
Q

How are arctic animals well insulated?

A

They have a thick layer of fat called blubber for insulation and also acts as an energy store when food is scarce. Thick furry coats also keep body heat in and greasy fur sheds water to prevent cooling due to evaporation

111
Q

Why are arctic animals camouflaged?

A

White fur to help avoid predators and can sneak up on prey easier

112
Q

What are desert plants adapted for?

A

Having little water

113
Q

How are desert plants adapted to having little water?

A

Small surface area compared to volume (reduces water loss), water storage tissues (stores water in its thick stem) and they’re good at maximising water absorption

114
Q

How do cacti’s spines reduce water loss?

A

Plants lose water vapour from the surface of their leave, cacti have spines instead which reduces water loss

115
Q

How do cacti maximise water absorption?

A

Some have shallow but extensive roots to absorb water quickly over a large area, others have deep roots to access underground water

116
Q

How are some plants and animals adapted to deter predators?

A

Some have armour like roses have thorns, cacti have spines and tortoises have shells, others produce poisons like bees and poisons ivy, and others have warning colours like wasps to scare off predators

117
Q

Some microorganisms such as bacteria are known as extremophiles, what does this mean?

A

They’re adapted to live in seriously extreme conditions like really hot volcanic bents or in salty lakes or at high pressure on the sea bed

118
Q

What do plants need/what are they in competition for?

A

Light, space, water and minerals/nutrients from the soil

119
Q

What do animals need/what are they in competition for?

A

Space/territory, food, water and mates

120
Q

What is an example of competition?

A

Red and grey squirrels live in the same habitat and eat the same food. Competition with the grey squirrels for these resources means theres not enough food for the red squirrels so the population decreases

121
Q

Who can competition occur between?

A

Organisms compete with other species and also members of their own species

122
Q

What are living factors of environmental change?

A

A change in the occurrence of infectious diseases, number of predators, number of prey/availability of for sources and a change in the number of types of competitors

123
Q

What are non living factors of environmental change?

A

A change in average temperature, rainfall and level of air or water pollution

124
Q

What are three different ways that environmental changes affect populations?

A

Population size increases, population size decreases or population distribution changes

125
Q

How can population size increase?

A

Eg if the number of prey increases then theres more food available for the predators, so more predators service and reproduce and so the population increases

126
Q

How can the population size decrease?

A

Eg the number of bees in the US is falling rapidly, possibly because some pesticides are having a negative affect on them, theres less food available as there aren’t as many nectar rich plants around any more or because theres more diseases as there are new pathogens and parasites that are killing the bees

127
Q

How can the population distribution change?

A

A change in distribution is a change in where an ordains lives, for example the distribution of bird species in Germany is changing because of a rise in average temperature. Also there are mediterranean species like the European Bee-Eater, which now lives in Germany

128
Q

How can environmental changes be measured?

A

Using living indicators

129
Q

What are living indicators?

A

Organisms thats are very sensitive to change in their environment so they can be studied to see the effect of human activities, these are known as indicator species

130
Q

How can air pollution be monitored?

A

By looking at particular types of lichen that are very sensitive to the concentration of sulfur dioxide in the atmosphere and so give a good idea about the level of pollution from car exhausts and power stations. The number and type of lichen show how clean the air is

131
Q

What does it show if an area has lots of lichen?

A

The air is clean

132
Q

How can water pollution be monitored?

A

By looking at some invertebrate animals like mayfly larvae as they’re very sensitive to the concentration of dissolved oxygen in the water. If raw sewage is released into a river, the bacterial population in the water increases and uses up the oxygen

133
Q

What does it show if there are mayfly larvae in the river?

A

The water is clean

134
Q

How else can you tell if there is water pollution?

A

Some species have adapted to live in polluted conditions such as rat-tailed maggots and sludge worm so they indicate high levels of water pollution

135
Q

What are four different non-living indicators?

A

Satellites, automatic weather stations, rain gauges and dissolved oxygen meters

136
Q

What do satellites do?

A

Measure the temperature of the sea surface and the amount of snow and ice cover, they’re modern accurate instruments and give us global coverage

137
Q

What do automatic weather stations do?

A

Tell us the atmospheric temperatures at various locations, they contain thermometers that are sensitive and accurate and measure to very small fractions of a degree

138
Q

What do rain gauges do?

A

They measure rainfall to find out how much the average rainfall changes each year

139
Q

What do dissolved oxygen meters do?

A

Measure the concentration of dissolved oxygen in water to discover how the level of water pollution is changing

140
Q

How does the energy and biomass change every time you move up a trophic level?

A

Theres less energy and less biomass, usually fewer organisms too

141
Q

What is an example of this?

A

100 dandelions feed 10 rabbits which feed one fox

142
Q

What does biomass mean?

A

The mass of living material

143
Q

What is an example where the amount of organisms doesn’t decrease at each trophic level?

A

There could then be 500 fleas feeding on the fox

144
Q

What is a better way to look at food chains instead of by the amount of each organism?

A

Looking at pyramids of biomass

145
Q

What does each bar on a pyramid of biomass show?

A

The mass of living material, basically how much all the organisms at each level would weigh if you put them all together

146
Q

What shape are biomass pyramids?

A

Usually always pyramid shaped unlike pyramids of numbers

147
Q

What does a pyramid of biomass look like?

A

The big bar on the bottom is the producer e.g. dandelions, the next bar is the primary consumer e.g. the rabbits, the next bar is the secondary consumer e.g. the fox and then the top bar is the tertiary consumer e.g. the fleas

148
Q

What is the source of energy for nearly all life on Earth?

A

Energy from the sun

149
Q

Where does the energy go from green plants and algae that use the suns energy to make food during photosynthesis?

A

This energy’s stored in the substances which make up the cells of plants and algae, and then works its way through the food chain as animals eat them and each other

150
Q

What supplies most of the energy for all life processes, including movement?

A

Respiration

151
Q

What happens to the energy supplied from respiration?

A

Most is eventually lost to the surroundings as heat. This is especially true for mammals and birds, whose bodies must be kept at a constant temperature which is normally higher than their surroundings

152
Q

Why doesn’t some parts of plants and animals pass to the next stage of the food chain?

A

Because some parts are inedible e.g. bone, material and and energy are also lost from the food chain in the organisms’ waste materials

153
Q

How does this explain biomass pyramids?

A

Most of the biomass is lost and so does not become biomass in the next level. It also explains why you hardly ever get food chains with more than about five-trophic levels, so much energy is lost at each stage that theres not enough left to support more organisms after four or five stages

154
Q

What are living things made up of?

A

Materials they take form the world around them

155
Q

What sort of elements do plants take in and why?

A

Carbon, oxygen, hydrogen and nitrogen from the soil or the air, they turn these elements into the complex compounds (carbohydrates, proteins and fats) that make up living organisms, and these then pass through the food chain

156
Q

What happens to these elements?

A

They’re returned to the environment in waste products produced by the organisms, or when the organisms die. These materials decay because they’re broken down (digested) by microorganisms-thats how the elements get put back into the soil

157
Q

Where do microorganisms work best?

A

In warm, moist conditions. Many also break down material faster when theres plenty of oxygen available. Compost bins recreate these ideal conditions.

158
Q

What happens in compost bins?

A

All the important elements are recycled and return back to the soil, ready to be used by new plants and put back into the food chain again

159
Q

What happens in a stable community?

A

The materials taken out of the soil and used are balanced by those that are put back in. Theres a constant cycle happening

160
Q

What is compost?

A

Decayed remains of animal and plant matter that can be used as fertiliser. It recycles nutrients back into the soil

161
Q

What are the components of a compost bin?

A

Warmth is generated by decomposition and helps the process move along, mesh side let the air in, extra decomposers are added (compost maker), finely shredded waste is best

162
Q

In the carbon cycle, what is the only arrow going down from the atmosphere?

A

Photosynthesis, the whole cycle is powered by photosynthesis. CO2 is removed from the atmosphere by green plants and algae, and the carbon is used to make carbohydrates, fats and proteins in the plants and algae

163
Q

What is some of the carbon returned to the atmosphere?

A

As CO2 when the plants and algae respire, some of the carbon becomes part of the fats and proteins in animals when the plants and algae are eaten. The carbon then moves through the food chain

164
Q

How else can carbon be returned to the atmosphere?

A

By animals respiring

165
Q

What happens when plants, algae and animals die?

A

Other animals called detritus feeders and microorganisms feed on their remains. When these organisms respire, CO2 is returned to the atmosphere

166
Q

What happens when animals produce waste?

A

This too is broken down by detritus feeders and microorganisms. Compounds in the waste are taken up from the soil by plants as nutrients-there put above into the food chain again

167
Q

What happens when fossil fuels are burnt?

A

Some useful plat and animal products e.g. wood and fossil fuels, are burnt (combustion). This also releases CO2 back into the air

168
Q

What happens to the carbon in the carbon cycle?

A

Its constantly being cycled from the air, through food chains and eventually back out into the air again

169
Q

What are differences within species called?

A

Variations

170
Q

What are the two types of variation?

A

Genetic variation and environmental variation

171
Q

What are an organisms characteristics determined by?

A

The genes inherited from their parents. These genes are passed on in gametes which the offspring develop from. Most animals get some genes from the mother and some from the father

172
Q

What are genes?

A

The codes inside your cells that control how you’re made

173
Q

What does the combining of genes from two parents cause?

A

Genetic variation-no two of the species are genetically identical, except for identical twins

174
Q

What are examples of characteristics that are only determined by genes?

A

Eye colour, blood group and inherited disorders like cystic fibrosis

175
Q

What is an example of how sun light on a plant causes environmental variation?

A

A plant grown in sunlight will grow luscious and green whereas the same plant grown in darkness would grow tall and spindly with yellow leaves

176
Q

How can characteristics be due to a mixture of genetic and environmental factors?

A

How tall a plant can grow is due to genetics but whether it grows depends on environmental factors like sun

177
Q

What is the nucleus?

A

Most cells have a nucleus which contains genetic material in the form of chromosomes

178
Q

How many chromosomes do human cell nuclei contain?

A

23 pairs of chromosomes, they’re always in pairs, one from each parent

179
Q

What do chromosomes carry?

A

Genes, different genes control the development of different characteristics e.g. hair colour

180
Q

What is a gene?

A

A short length of the chromosome which is quite a long length of DNA

181
Q

What is DNA?

A

The DNA is coiled up to form the arms of the chromosomes

182
Q

What are alleles?

A

Different versions of the same gene which give different versions of a characteristic like blue or brown eyes

183
Q

What is s***** reproduction?

A

Where genetic information from two organisms (mother and father) is combined to produce offspring which are genetically different to either parent

184
Q

How many chromosomes do each gamete contain?

A

23, half the number of chromosomes in a normal cell, so when the gametes fuse together, they form a cell with the full number of chromosomes (half from the mother half from the father)

185
Q

What is the full definition of s** reproduction?

A

Involves the fusion of male and female gametes. Because there are two parents, the offspring contain a mixture of their parents’ genes.

186
Q

How can an ordinary cell make a new cell?

A

By dividing in two. The new cell has exactly the same genetic information as the parent cell-asexual reproduction

187
Q

What is the definition of asexual reproduction?

A

Theres only one parent. Theres no fusion of gametes, no mixing of chromosomes and no genetic variation between parent and offspring. The offspring are genetically identical to the parent-theyre clones

188
Q

What is the process of this?

A

X-shaped chromosomes have two identical halves, so each chromosome splits down the middle to for two identical sets of half chromosomes. A membrane forms around each set and the DNA replicates itself to form two identical cells with complete sets of X-shaped chromosomes

189
Q

When is asexual reproduction used?

A

Its how plants and animals grow and produce replacement cells. Some organisms also produce offspring using this e.g. bacteria and certain plants

190
Q

What are the two ways that plants can be cloned?

A

Cuttings and tissue culture

191
Q

How can plants be cloned by cuttings?

A

Gardeners take cuttings from good parent plants and then plan them to produce genetically identical copied of the parent plant. These plants can be produced quickly and cheaply

192
Q

How can plants be cloned by tissue culture?

A

A few plant cells are put in a growth medium with hormones, and they grow into new plants-clones of the parent plant. These plays can be made very quickly in very little space, and be grown all year

193
Q

What are the different ways of animal cloning?

A

Embryo transplants and adult cell cloning

194
Q

How can farmers produce cloned offspring from their best animal using embryo transplants?

A

S** cells are taken from prize bull and egg cells taken from prize cow. They artificially fertilise and the embryo develops and is then split many to form clones times before any cells become specialised. These cloned embryos are then implanted into lots of other cows where they grow into baby claves, genetically identical to each other. Hundreds of ideal offspring can be produced every year from the best bull and cow

195
Q

How can adult cell cloning be used to make a clone?

A

Involves taking an unfertilised egg cell and removing its genetic material (nucleus). A complete set of chromosomes from an adult body cell e.g. skin cell is inserted into the empty egg cell. The egg cell is stimulated by an electric shock to make it divide like a normal embryo. When its a ball of cells its implanted into the surrogate mother to grow into a genetically identical copy of the original adult body cell. This technique made Dolly the cloned sheep

196
Q

What are the issues surrounding cloning

A

You get a reduced gene pool as there are fewer different alleles in a population, new diseases can then occur and they can be wiped out as no allele in the population is resistant to the disease.However study of animal clones can lead to greater understanding of the development of embryos and of ageing/age related disorders. Cloning could help preserve endangered species. However clones may not be as healthy as normal animals e.g. Dolly had arthritis. Some people worry that humans may be cloned in future which could be very unsuccessful and cause severely disabled children

197
Q

What is the basic idea of genetic engineering?

A

To copy a useful gene from one organisms chromosome into the cells of another

198
Q

What is the process of genetic engineering?

A

A useful gene is cut form one organisms chromosomes using enzymes, enzymes are then used to cut another organisms chromosomes an then to insert the useful gene. Scientists use this method to do things such as the human insulin gene can be inserted into bacteria to produce human insulin

199
Q

What are GM crops?

A

Genetically modified crops have had their genes modified e.g. to make them resistant to viruses, insects or herbicides

200
Q

How can animals be genetically engineered?

A

Sheep have been genetically engineered to produce substances like drugs in their milk that can be used to treat human diseases

201
Q

How can human disorders be cured via genetic engineering?

A

Genetic disorders like cystic fibrosis are caused by faulty genes. Scientists are trying to treat these disorders by inserting working genes into sufferers. They call this gene therapy

202
Q

What are the worries for genetic engineering?

A

The long term effects are unclear. Chasing a persons genes might accidentally create unplanned problems which could get passed onto future generations

203
Q

What are the pros of GM crops?

A

They can increase yield of a crop, making more food. People in developing nations often lack nutrients but GM crops could be engineered to give the missing nutrients e.g. golden rice contains beta-carotene as lack of this causes blindness.

204
Q

What are the cons of GM crops?

A

It will affect the number of weeds and flows (so also insects) that live around the crop, reducing farmland biodiversity. Not everyone is convinced they are safe, they think they may develop allergies to the food although there is probably no more risk than with normal foods. Also the transplanted genes may get out into the natural environment e.g. herbicide resistance gene may be picked up by weeds creating a supersede variety

205
Q

How can differences between organisms be used to separate them into fixed groups?

A

Plants make their own food by photosynthesis and are fixed in the ground. Animals move about and cant make their own food. Microorganisms are different to platens and animals e.g. bacteria are single celled

206
Q

What are evolutionary relationships?

A

Species with similar characteristics often have similar genes, share a common ancestor so closely related. Often look alike and ten to live in similar types of habitats e.g. whales and dolphins. Occasionally genetically different species look alike e.g. dolphins and sharks, because they’re both adapted to the same habitat but they’re evolved from different ancestors. Evolutionary trees show the more recent common ancestors, the more closely related the two species

207
Q

What are ecological relationships?

A

If we see organisms in the same environment with sillier characteristics e.g. dolphins and sharks it suggests they might be in competition e.g. for the same food. Differences between organisms in the same environment e.g. dolphins swim in small groups but herring seem in giant shoals, can show predator-prey relationships, dolphins hunt herring

208
Q

Who came up with the idea of natural selection?

A

Charles Darwin

209
Q

How does natural selection explain how evolution occurs?

A

Individuals within a species show variation because of the difference in their genes. Individuals with characteristics that make them better adapted to their environment have a better chance of survival and successfully breed, passing on their genes, while the others die.The useful gene is passed down until they all have it-evolution

210
Q

How can evolution occur due to mutations?

A

A mutation is a change in an organisms DNA. Most of the time mutations have no effect but occasionally they can be beneficial by producing a useful characteristic which may give a better change of survival and then reproduction. It can then be passed down through generations by natural selection. Over time the beneficial mutation will accumulate in a population e.g. some bacteria are resistant to antibiotics due to mutation

211
Q

Why did some people disagree with Darwin?

A

It went against religious beliefs about how life on Earth developed, Darwin couldn’t give a good explanation for why these new useful characteristics appeared or exactly how individual organisms passed on their e=beneficial characteristics to their offspring as genes and mutations weren’t discovered for another 50 years. Also there wasn’t much evidence to convince many scientists because not many other studies had been done for this subject

212
Q

What was Lamarcks theory?

A

He argued that if a characteristic was used a lot by an organism the it would become more developed during its lifetime e.g. if a rabbit used its legs to run a lot then its legs would get longer. He believed that these acquired characteristics would be passed on to the next generation

213
Q

What are carbohydrates for?

A

To release energy

214
Q

What are fats for?

A

To keep warm and release energy

215
Q

What are proteins for?

A

Growth, cell repair and cell replacement

216
Q

What is fibre for?

A

To keep everything moving smoothly through your digestive system

217
Q

What are various vitamins and mineral ions for?

A

To keep your skin, bones, blood and everything else generally healthy

218
Q

What do you need energy for?

A

To fuel the chemical reactions in the body that keep you alive, these reactions are called your metabolism and the speed at which they occur is your metabolic rate

219
Q

Why is there variation in different peoples resting metabolic rate?

A

Muscle needs more energy than fatty tissue meaning people with a higher proportion of muscle to gay will have a higher metabolic rate

220
Q

Why are physically bigger people likely to have a higher metabolic than smaller people?

A

The bigger you are, the more energy your body needs as you have more cells

GCSE (26 decks)

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