Biology Paper 2 Topics Flashcards

1
Q

What is homeostasis?

A

Homeostasis is the regulation of the conditions inside your body and cells in order to maintain a stable internal environment

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2
Q

What is the role of receptors in the body?

A

Receptors detect stimuli ( a change in the environment)

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3
Q

What is the role of coordination centres in the body?

A

Coordination centres are responsible for receiving information and coordinating a response

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4
Q

What is the role of effectors in the body?

A

Effectors bring about a change

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5
Q

What three things does the control systems control?

A

The control systems control body temperatures, blood glucose levels and water content

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6
Q

What are neurones?

A

Neurones are cells that carry information as electrical impulses

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7
Q

What is the order by which the nervous system undergoes to bring about homeostasis?

A

Stimulus > Receptor > Sensory Neurone > CNS > Motor Neurone > Effector > Response

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8
Q

What does the CNS consist of?

A

The CNS consists of the brain and spinal cord

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9
Q

How are the parts of the CNS connected?

A

The CNS is connected by neurones

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10
Q

What are the two main types of effectors?

A

The two main types of effectors include:

  • Muscles = Contracts
  • Glands = Secretes hormones
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11
Q

What does homeostasis maintain?

A

Homeostasis maintains optimal conditions for enzyme action

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12
Q

What is phototropism?

A

Phototropism is when shoots of plants grows towards the light

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13
Q

What is auxin?

A

Auxin is a plant hormone which is used to stimulate growth in plants

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14
Q

Describe the response of a shoot to sunlight

A

Phototropism

  • Shoot is exposed to sunlight
  • Auxin accumulates on shaded side
  • Cells grow faster on the shaded side
  • Shoot bends towards the light
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15
Q

What is gravitropism/geotropism?

A

Gravitropism/Geotropism is when roots of plants grow towards gravity

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16
Q

Describe the root of the plant during geotropism

A

Geotropism:

  • Auxin accumulates on lower side of root
  • Auxin inhibits growth on lower side
  • Root bends downwards
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17
Q

What are the commercial uses of auxin?

A

The commercial uses of auxin include:

  • Added to rooting powders to stimulate growth for plant cuttings
  • Kills weeds whilst leaving other crops untouched
  • Stimulates cell division in tissue culture, promoting cloning of plants
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18
Q

What are the commercial uses of giberellin?

A

The commercial uses of gibberellin include:

  • Promotes seed germination at any time of the year
  • Flowering where no specific conditions are needed
  • Makes fruits grow larger
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19
Q

What are the commercial uses of ethene?

A

The commercial uses of ethene include:

  • Speeds up fruit ripening
  • Effects can be blocked to delay ripening in storage
  • Controls cell division
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20
Q

Which receptors detect the change in the body’s core temperature?

A

Temperature receptors detect the change in the body’s temperature

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21
Q

How does the body respond when the body’s temperature is too high?

A

When the body’s temperature is too high, blood vessels dilate and blood flows closer to the skin. Sweat glands also produce sweat to transfer out energy

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22
Q

What is Vasodilation?

A

Vasodilation is when the blood vessels dilate and blood flows closer to the skin in order to transfer heat into the environment

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23
Q

How does the body respond when the body’s temperature is too low?

A

When the body’s temperature is too low, the blood vessels constrict so less blood flows close to the skin, there is no sweat produced, and the body shivers due to the skeletal muscles contracting

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24
Q

What is Vasoconstriction?

A

Vasoconstriction is when the blood vessels constrict so less blood flows close to the skin

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25
Q

What is the endocrine system?

A

The endocrine system is a system made up of glands that secret hormones

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26
Q

What is the role of the pituitary gland?

A

The pituitary gland, also known as the master gland, stimulates other glands

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27
Q

Which hormone does the thyroid produce?

A

Thyroid produces thyroxine

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28
Q

Which gland does adrenaline come from?

A

Adrenaline comes from the adrenal gland

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29
Q

Which gland does insulin come from?

A

Insulin comes from the pancreas

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30
Q

Which hormone do ovaries produce?

A

Ovaries produce oestrogen

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31
Q

Which hormone do the testes produce?

A

Testes produce testosterone

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32
Q

What comparisons can be made between hormones and nerves?

A

Hormones are slower than nerves but hormones last longer

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33
Q

How many parents are involved in asexual reproduction?

A

Asexual reproduction involves one parent

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34
Q

Which cell division is involved in asexual reproduction?

A

Cells in asexual reproduction divide by mitosis

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35
Q

What offspring are produced in asexual reproduction?

A

Genetically identical offspring is produced in asexual reproduction

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36
Q

What are the advantages of asexual reproduction?

A

The advantages of asexual reproduction include;

  • Faster than sexual reproduction = means many identical offspring can be produced in favourable conditions
  • Only one parent is needed = no energy is wasted finding a mate
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37
Q

How many parents are involved in sexual reproduction?

A

Two parents are involved in sexual reproduction

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38
Q

How do the cells divide in sexual reproduction?

A

The cells divide by meiosis and mitosis in sexual reproduction

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39
Q

What are the advantages of sexual reproduction?

A

The advantages of sexual reproduction include:

  • Variation increases the chance of individuals surviving a change in the environment
  • Selective breeding can be used to increase variation and increase food production
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40
Q

How are gametes formed?

A

Gametes are formed by meiosis in the reproductive organs

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41
Q

What happens at the end of fertilisation?

A

At the end of fertilisation, after gametes have fused, the normal number of chromosomes is restored. The fertilised cell will then continue to divide by mitosis to form an embryo.

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42
Q

What is the process of meiosis?

A

The process of meiosis:

1) . The cell duplicates its genetic information
2) . The cell divides and each new cell has one copy of each chromosome
3) . Both cells divide again to make four gametes
4) . Each gamete has a single set of chromosomes

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43
Q

How many chromosomes do cells contain in meiosis?

A

In meiosis, the cells contain half the normal number of chromosomes, 23.

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44
Q

What is a population?

A

A Population is all the organisms of one species living in a habitat

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45
Q

What is a community?

A

A community is the populations of different species living in a habitat

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46
Q

What is a stable community?

A

A stable community is a community in which all species and environmental factors are in balance

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47
Q

What is an ecosystem?

A

An ecosystem is the interaction of a community of organisms and the parts of their environment that are non-living

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48
Q

What is an adaptation?

A

An adaptation is a feature that enables an organism to survive in the conditions of its normal habitat

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49
Q

What is interdependence?

A

Interdependence is each species in a community depending upon other species for things eg pollination and seed dispersal

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50
Q

Name examples of biotic factors

A

Examples of biotic factors include new predators, food availability, competition and new pathogens

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51
Q

Name examples of abiotic factors

A

Examples of abiotic factors include wind intensity and direction, CO2 levels (for plants), soil pH and mineral content, temperature

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52
Q

What do plants compete for in an ecosystem?

A

Plants compete for light, space, minerals and water

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53
Q

What do animals compete for in an ecosystem?

A

Animals compete for food, mates and territory in an ecosystem

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54
Q

What are the three types of adaptation?

A

The three types of adaptation include structural, behavioural and functional

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55
Q

What is an example of a structural adaptation?

A

An example of a structural adaptation is white fur in arctic areas, allowing for camouflage

56
Q

What is an example of a behavioural adaptation?

A

An example of a behavioural adaptation is migration, eg moving away from harsh cold conditions into warmer areas

57
Q

What is an example of a functional adaptation?

A

An example of a functional adaptation is bears slowing their metabolism during hibernation so they require less energy

58
Q

What are extremophiles?

A

Extremophiles are organisms adapted to live in extreme conditions

59
Q

What is the order of the food chain?

A

Consumer > Primary consumer > Secondary consumer > Tertiary consumer > Apex predator

60
Q

What is biomass?

A

Biomass is the mass of living material

61
Q

How does energy move across a food chain?

A

Energy thats stored in biomass is transferred along food chains and used by other organisms to build biomass. However, not all energy is transferred as lots are lots through heat, sound etc

62
Q

Why are predator-prey cycles always out of phase with each other?

A

Predator-prey cycles are always out of phase with each other as it takes a while for one population to respond to changes in another population

63
Q

What are three examples of environmental changes that can affect the distribution of organisms?

A

Three examples of environmental changes that can affect the distribution of organisms include water availability, temperature, atmospheric gases

64
Q

What can environmental changes that affect organism distribution be caused by?

A

Changes can be caused by seasonal factors, geographical factors and human interaction

65
Q

Why are organisms with the most suitable characteristics more likely to survive?

A

Organisms with more suitable characteristics are more likely to survive a change in the environment, as they can adapt and breed so that the offsprings also have the beneficial characteristics

66
Q

How do limited resources affect an ecosystem?

A

Limited resources in an ecosystem results in more competition

67
Q

What is speciation?

A

Speciation is the development of a new species by natural selection

68
Q

What does it mean by reaction time?

A

Reaction time is the time it takes to react to a stimulus

69
Q

Describe a practical that can be used to measure human reaction time

A

Measuring human reaction time:

  • Hold a ruler between the thumb and forefinger of the person being tested
  • Drop the ruler without warning and record the distance it falls before it is caught
  • Repeat the test several times then calculate the mean distance that the ruler fell
  • Repeat the experiment to investigate the effect of a factor on reaction time - eg caffeine or background noise
70
Q

What are the independent, dependent and control variables of the effect of light or gravity on the growth of seedlings practical?

A

Independant variable = Direction of light
Dependant variable = direction of growth
Control variables = number + type of seeds, water, temperature, light intensity

71
Q

How do you estimate populations of organisms using quadrats?

A

Estimating populations using quadrats:

1) . Place 1m squared quadrat at random in a field
2) . Count all the daisies within it
3) . Repeat several times and work out the mean number of daisies per quadrant ( total number of organisms divided by the number of quadrats)
4) . Multiply the size of the entire area by the number of organisms per metre squared

72
Q

How do you estimate populations of organisms using transects?

A

Estimating populations using transects:

1) . Mark out a line using a tape measure
2) . Count the daisies in quadrates placed at regular intervals along the line
3) . Draw a graph to show how the daises are distributed

73
Q

What are the disadvantages of sexual reproduction?

A

The disadvantages of sexual reproduction is that time and energy is needed to find a mate and its not possible for an isolated individual

74
Q

What are the disadvantages of asexual reproduction?

A

The disadvantages of asexual reproduction is that there is no variation, offspring are only suited to one habitat and disease may affect all the individuals of a population due to lack of variation

75
Q

What five processes occur during the water cycle?

A

The processes that occur during water cycle are evaporation, condensation, precipitation, transpiration and percolation

76
Q

Describe what happens during the water cycle

A

1) . Heat energy from the sun causes the water from oceans and lakes to evaporate. The warm air rises and carries water vapour with it
2) . Water vapour condenses back into liquid to form clouds
3) . Water droplets become too heavy for clouds to hold and precipitates
4) . Water travels through the soil (percolation) and enters back into rivers, lakes and oceans
5) . Plants undergo transpiration where they release water vapour into the air and the cycle continues

77
Q

How is carbon dioxide released in the carbon cycle?

A

In the carbon cycle, when animals and microorganisms respirate they release carbon dioxide into the atmosphere. This can be done when microorganisms decompose matter and respire. The combustion of fossil fuels that comes from decaying matter also releases carbon dioxide into the atmosphere.

78
Q

How is carbon dioxide taken away from the atmosphere in the carbon cycle?

A

Carbon dioxide is removed in the carbon cycle when plants photosynthesise

79
Q

What are the different ways our body loses water?

A

Our body loses water via the lungs when we exhale, through sweat and via kidneys in urine

80
Q

How does blood filter through the kidneys?

A

Arteries contain the blood which contains urea, water and ions, which are sent through the kidneys. The kidneys convert this into urine which is stored in the bladder. The filtered blood leaves the kidneys via the veins

81
Q

What is selective reabsorption?

A

Selective reabsorption is when some molecules are absorbed back into the blood

82
Q

What happens to excess amino acids? What is this process called?

A

Deamination - the process by which excess amino acids are broken down into ammonia. Ammonia is toxic so it is converted into urea to be safely excreted by the kidneys

83
Q

How does the body respond when water levels fall/the concentration of blood becomes to high?

A

When water levels fall, the pituitary gland releases the hormone ADH. ADH travels to kidneys and causes kidney tubules to become more permeable to water (more water can pass out and be reabsorbed). This means less urine is produced so water levels will increase. ADH production will stop at this point.

84
Q

How does the body respond when the water levels rise/concentration of blood becomes too low?

A

When water levels rise, no ADH is produced so the kidneys will reabsorb less water and more urine can be produced so water levels will decrease

85
Q

What happens in kidney dialysis?

A

In kidney dialysis:
Water/urea/ions pass through as blood passes over a semi-permeable membrane (large molecules eg proteins and body cells cannot pass through) > another side of the fluid will contain normal levels of water and ions (no urea) > provides a concentration gradient for urea to diffuse from blood to fluid. Some ions and water also diffuse into fluid > normal levels restored

86
Q

Why is the dialysis fluid regularly refreshed?

A

The dialysis fluid is regularly refreshed so to maintain a large concentration gradient

87
Q

What is the advantage of kidney dialysis?

A

The advantage of kidney dialysis is that there is no shortage of dialysis machines

88
Q

What are the disadvantages of kidney dialysis?

A

The disadvantages of kidney dialysis are that frequent hospital visits are required, patients have to follow a controlled diet, can be expensive long-term

89
Q

What are the advantages of kidney transplants?

A

The advantages of kidney transplants are that the patients can lead a normal life and that they are only initially expensive

90
Q

What are the disadvantages of kidney transplants?

A

The disadvantages of kidney transplants are that they can be rejected, so anti-rejection drugs are needed for the rest of their lives and there is a shortage of kidney donors

91
Q

What allele is cystic fibrosis caused by?

A

Cystic fibrosis is caused by a recessive allele, meaning two lower case letters represent having the disorder, a capital letter with a lower case letter shows that they are a carrier and two upper case letters show that they are unaffected

92
Q

What allele is polydactyly caused by?

A

Polydactyly is caused by a dominant allele, meaning if on a genetic diagram it is shown as having at least one or two upper case letters, this means they have it. If someone is represented as having two lower case letters, this means they do not have polydactyly

93
Q

What types of genetic embryonic screening are there?

A

Types of genetic embryonic screening includes:

  • Antenatal testing
  • Neonatal testing
  • Pre-implantation genetic diagnosis (PGD)
  • Amniocentesis
94
Q

What is amniocentesis in embryonic screening?

A

Amniocentesis in embryonic screening is where a needle is inserted into the amniotic fluid that surrounds the foetus and fluid is withdrawn.

Foetal cells in the fluid are then examined for the presence of genetic abnormalities such as Down syndrome and cystic fibrosis.

95
Q

What is gene therapy?

A

Gene therapy involves inserting copies of a normal allele into the chromosomes of an individual who carries a faulty allele

96
Q

What are the steps for gene therapy?

A

Steps of gene therapy:

  1. identify the gene involved in the genetic disorder
  2. restriction enzymes cut out the normal allele
  3. many copies of the allele are made
  4. copies of the normal working allele are put into the cells of a person who has the genetic disorder due to a mutated or faulty copy of an allele
97
Q

What are chromosomes?

A

Chromosomes are long threads of DNA, which are made up of many genes

98
Q

What is a gene?

A

A gene is a small section of DNA in a chromosome

99
Q

What is the genome?

A

Genome is the entire set of genetic material of an organism

100
Q

What are the benefits of fully understanding the human genome?

A

The benefits of fully understanding the human genome is being able to treat and understand inherited disorders, searching for genes linked to different types of disease, tracing past human migration patterns

101
Q

What is the peripheral nervous system?

A

The peripheral nervous system is made up of nerve cells that carry information to or from the CNS

102
Q

What are the adaptations of neurones?

A

Neurone adaptations:

  • Long axons which is insulated by a fatty sheath
  • Tiny branches (dendrons) which branch further as dendrites at each end
103
Q

What is a reflex arc?

A

Reflex arc is an automatic response to a stimulus

104
Q

What happens in a reflex arc?

A

In a reflex arc, receptor detects stimulus > sensory neurone sends impulse to relay neurone > motor neurone sends impulse to effector > effector produces response

105
Q

Why do muscles work in antagonistic pairs?

A

Muscles work in antagonistic pairs to ensure a part of the body can move back to its original position after being moved eg biceps and triceps

106
Q

What happens in a synapse?

A

In a synapse, neurotransmitters diffuse across a gap, stimulates other neurone to transmit an electrical impulse

107
Q

What is the role of ADH?

A

ADH is released by the pituitary gland and into the kidneys, and it controls water content of blood by increasing reabsorption by the collecting ducts

108
Q

What is the response of the body when it is too hot?

A

When the body is too hot, sweat is produced which evaporates off the skin and removes heat energy from the skin, blood vessels dilate to allow more blood to flow

109
Q

What is the response of the body when it is too cold?

A

When the body is too cold, the muscles contract so the body shivers which needs energy from respiration which comes as heat, blood vessels constrict so less blood flows close to the skin and heat is conserved

110
Q

What part of the body monitors body temperature?

A

The hypothalamus monitors the body temperature

111
Q

How does the body respond when thyroxine levels are too low?

A

When thyroxine levels are too low, the hypothalamus releases TRH, which causes the pituitary gland to release TSH so thyroid releases more thyroxine

112
Q

How does the body respond when thyroxine levels are normal?

A

When thyroxine levels are normal, production of TRH and TSH are inhibited

113
Q

How does adrenaline prepare the body for the flight or fight response?

A

Adrenaline increases breathing rate, increases heart rate, increases the conversion of glycogen into glucose so more energy is released in the muscles, diverts blood away from areas such as digestive system to muscles

114
Q

What happens when there is a high concentration of plasma?

A

When there is a high concentration of plasma, this means too little water is in the blood, so ADH increases, more water is reabsorbed by nephrones, urine becomes more concentrated

115
Q

What happens when there is a low concentration of plasma?

A

When there is a low concentration of plasma, this means there is too much water in the blood, so ADH decreases, less water is reabsorbed by nephrons, and the urine becomes more dilute

116
Q

What is the role of testosterone?

A

Testosterone controls the development of male secondary sexual characteristics

117
Q

What is the role of oestrogen?

A

Oestrogen controls the development of female secondary sexual characteristics

118
Q

Where are auxins made?

A

Auxins are made in the tips of shoots and roots (the apical meristems) + can diffuse. This promotes growth through cell division and elongation

119
Q

What happens as a result of a high concentration of auxins?

A

If there is a high concentration of auxins, cells in stems grow more and cells in rocks grow less

120
Q

How do you find the affect of light intensity on plants?

A

1) add equal volumes of water to three dishes
2) add seeds and place in warm place
3) allow seeds to germinate
4) one in full light, one in partial light, one in no light
5) measure height once a week

121
Q

What is the process of meisosis?

A

In meosis:

1) genetic info duplicated, chromsomes pair up
2) 1 st division - chromosomes pairs line up at centre of cell, pairs pulled apart so each new cell only has 1 copy of each chromosome, chromosomes swapped around
3) 2nd division - chromosomes line at centr eagain, arms of chromosomes pulled apart
4) 4 gametes produced

122
Q

What happens during fertilisation?

A

During fertilisation, gametes fuse and the new cell divides by mitosis. Eventually cells differentiatte as embryo develops

123
Q

What is an allele?

A

Allele is a version of a gene

124
Q

What is a genotype?

A

Genotype is combination of alleles you have

125
Q

What is a phenotype?

A

Phenotype is alleles that determine your characteristics

126
Q

What is cystic fibrosis?

A

Cystic fibrosis is the buildup of mucus in the air passages. It is caused by a recessive allele.

127
Q

Why does selective breeding reduce variation?

A

Selective breeding reduces variation because there are less different alleles

128
Q

What is the process of selective breeding?

A

Animals with desirable characteristics breed together, produce offspring, offspring reproduce with eachother

129
Q

What is genetic engineering?

A

Genetic engineering is when a gene is isolated using an enzyme, and is inserted into vector eg bacteria

130
Q

What are the pros and cons of GM crops?

A

Pros - increases yield, less malnourishment in poor areas

Cons - reduces farmland biodiversity, effects not fully understood

131
Q

How are plants cloned?

A

Tissue culture (plant cells are put in growth medium with hormones) and cuttings

132
Q

How are animals cloned?

A

Animals are cloned through embryo transplants

133
Q

What happens in adult cell cloning?

A

In adult cell cloning, the nucleus of an egg cell is removed and replaced by a nucleus of an adult body cell, it is then stimulated by an electric shock and is implanted into a womb

134
Q

What are the three ways fossils are formed?

A

Fossils are formed by:

  • Gradual replacement by minerals
  • -from casts and impressions
  • from preservation in places where no decay happens
135
Q

What is speciation?

A

Speciation is the development of new species, which occurs when populations of same species can no longer breed

136
Q

What happens as a result of overusing antibiotics?

A

Overusing antibiotics > antibiotic resistant bacteria > made worse by rapid reproduction

137
Q

What is biogas?

A

Biogas is made by anaerobic decay of waste material