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Biology Paper 2 Flashcards

1
Q

Define homeostasis.

A

Homeostasis is the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes.

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2
Q

Name 3 things that homeostasis controls.

A

1) Blood glucose concentration
2) Body temperature
3) Water levels

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3
Q

Are homeostatic control systems automatic or manual?

A

Automatic.

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4
Q

Name the three things that all control systems include.

A

1) Receptor cells
2) Coordination centres
3) Effectors

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5
Q

What do receptor cells do?

A

They detect stimuli.

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6
Q

What are stimuli?

A

Changes in the environment.

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7
Q

What do coordination centres do?

A

They receive and process information from receptors.

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8
Q

What do effectors do?

A

They bring about a response.

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9
Q

Give 3 examples of coordination centres in the body.

A

1) Brain
2) Pancreas
3) Spinal cord

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10
Q

Give 2 examples of effectors in the body.

A

1) Muscles

2) Glands

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11
Q

What does the nervous system enables human to do?

A

It allows them to react to their surroundings and coordinate their behaviour.

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12
Q

What does CNS stand for?

A

Central nervous system.

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13
Q

Name the three parts of the nervous system.

A

1) The brain
2) The spinal cord
3) nerves

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14
Q

Name the two parts of the CNS.

A

1) The brain

2) The spinal cord

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15
Q

What type of impulses pass ACROSS neurones, chemical or electrical?

A

Electrical.

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16
Q

What type of impulses pass BETWEEN neurones?

A

Chemical.

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17
Q

The CNS coordinates the response of effectors which may cause muscles to…

A

Contract.

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18
Q

The CNS coordinates the response of effectors which may cause glands to…

A

Secrete hormones.

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19
Q

Put the following in the following order starting with stimulus: coordinator, stimulus, effector, receptor, response

A

Stimulus -> receptor -> coordinator -> effector -> response

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20
Q

What is a reflex action?

A

It is an automatic and rapid action that does not involve the conscious parts of the brain.

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21
Q

Why are reflex actions important?

A

They reduce the chances of being injured.

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22
Q

What is a synapse?

A

The connection (gap) between two neurones.

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23
Q

The human endocrine consists of glands that secrete what?

A

Hormones.

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24
Q

What are hormones?

A

Chemical messengers.

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25
Q

Where are hormones released into?

A

The bloodstream

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26
Q

What do hormones act upon?

A

Target organs.

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27
Q

Describe the differences in the effects caused by nerves and hormones.

A

1) Nerves have a faster action / Hormones have a slower action
2) Nerves act for a short time / Hormones act for a longer time
3) Nerves act on a precise area / Hormones act in a more general way

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28
Q

Name the ‘master gland’ in the body

A

The pituitary gland.

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29
Q

Where is the pituitary gland located?

A

In the brain.

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30
Q

Name the gland which produces many digestive enzymes.

A

Pancreas

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31
Q

Name the gland which produces testosterone.

A

Testes

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32
Q

Name the gland which produces thyroxine.

A

Thyroid

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33
Q

Name the gland which produced adrenaline.

A

Adrenal gland

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34
Q

Name the gland which produces hormones such as oestrogen and progesterone.

A

Ovary

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35
Q

Which gland is located in the neck?

A

Thyroid.

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36
Q

What is monitored for changes in glucose concentration?

A

The blood.

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37
Q

Which gland controls the response to changes in blood glucose concentration?

A

The pancreas.

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38
Q

What does the pancreas produce if the blood glucose concentration is too high?

A

The hormone insulin.

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39
Q

What does insulin do?

A

Causes glucose to move from the blood into cells, lowering the blood glucose concentration.

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40
Q

What is excess glucose in the liver and muscle cells stored as?

A

Glycogen.

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41
Q

What happens in type 1 diabetes?

A

The pancreas fails to produce sufficient insulin.

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42
Q

Describe the blood glucose concentration of a person suffering from type 1 diabetes.

A

Expect them to have a high blood glucose concentration.

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43
Q

How is someone with type 1 diabetes treated?

A

They are normally treated with insulin injections.

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44
Q

What happens in type 2 diabetes?

A

The body cells no longer respond to insulin produced by the pancreas.

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45
Q

Name a risk factor for type 2 diabetes.

A

Obesity.

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46
Q

What treatment is recommended to a person suffering from type 2 diabetes?

A

1) A carbohydrate controlled diet.

2) An exercise regime

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47
Q

What does the pancreas produce if the blood glucose concentration is too low?

A

Glucagon.

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48
Q

What does glucagon do?

A

It causes glycogen to be converted into glucose and released into the blood.

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49
Q

Describe the effect increased levels of glucagon will have on blood glucose concentration.

A

Cause blood glucose concentration to rise.

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50
Q

Briefly describe how insulin interacts with glucagon in a negative feedback mechanism to control blood glucose levels.

A

1) If blood glucose levels are too high insulin is released by the pancreas causing glucose to move into cells and so lower blood glucose levels.
2) If blood glucose levels are too low, glucagon is released by the pancreas causing glycogen to be converted into glucose and released into he blood, increasing blood glucose levels.

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51
Q

Name the main female hormone involved in development and reproduction.

A

Oestrogen.

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52
Q

Name the main male hormone involved in development and reproduction.

A

Testosterone.

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53
Q

During puberty reproductive hormones cause secondary characteristics to develop. Give examples of those that happen in men.

A

Develop facial hair, voice deepens, underarm and pubic hair growth

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54
Q

During puberty reproductive hormones cause secondary characteristics to develop. Give examples of those that happen in women.

A

Breasts develop, eggs mature, underarm and pubic hair growth, hips widen

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55
Q

Approximately how often is an egg released in a woman?

A

Every 28 days.

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56
Q

What is ovulation?

A

When an egg is released from an ovary.

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57
Q

Where is testosterone produced and released form?

A

The testes.

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58
Q

Testosterone stimulates the production of what?

A

Sperm.

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59
Q

Describe the role of FSH in the menstrual cycle.

A

Causes an egg to develop in one of the ovaries.

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60
Q

Describe the role of LH in the menstrual cycle.

A

Stimulates the release of an egg - ovulation

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61
Q

Which hormones are involved in the maintenance of the uterus lining?

A

Oestrogen and progesterone.

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62
Q

What stimulates the production of oestrogen in the ovaries?

A

FSH.

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63
Q

What stimulates the release of LH and inhibits the release of FSH?

A

Oestrogen.

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64
Q

What inhibits the release of FSH and LH?

A

Progesterone.

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65
Q

How do oral contraceptives containing hormones prevent pregnancy?

A

Inhibits FSH production so no eggs mature

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66
Q

How does an injection, implant or skin patch containing slow-release progesterone prevent pregnancy?

A

Inhibits the maturation of eggs

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67
Q

How do barrier methods, such as condoms and diaphragms, prevent pregnancy?

A

Prevents the sperm reaching the egg

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68
Q

How do intrauterine devices prevent pregnancy?

A

Prevents the implantation of an embryo AND/OR release hormones

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69
Q

How do spermicidal agents prevent pregnancy?

A

Kills or disable sperm

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70
Q

How does abstaining from sexual intercourse prevent pregnancy?

A

Reduces the chance of sperm meeting an egg in the oviduct

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71
Q

How does surgical sterilisation prevent pregnancy?

A

Prevents sperm or eggs being release by the male or female

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72
Q

Name the two hormones given to women to increase fertility.

A

FSH and LH.

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73
Q

State three drawbacks to IVF treatment.

A

1) It is very emotionally and physically stressful
2) The success rates are not high
3) It can lead to multiple births which are a risk to both the babies and the mother

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74
Q

State one positive of IVF treatment.

A

It allows pregnancy when previously not possible.

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75
Q

Detail the four steps in IVF treatment.

A
  1. The mother is given FSH and LH to stimulate the maturation of several eggs
  2. The eggs are collected from the mother and fertilised by sperm from the father in the laboratory
  3. The fertilised eggs develop into embryos.
  4. At the stage when they are tiny balls of cells, one or two embryos are inserted into the mother’s uterus (womb).
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76
Q

Why are some people against IVF?

A

IVF results in the unused embryos being destroyed.

They say this is unethical because each embryo is a potential human life.

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77
Q

Name the hormone which controls the “fight or flight” reaction in humans.

A

Adrenaline

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78
Q

Describe the effect adrenaline has in the body.

A

It increases heart rate and boosts the delivery of oxygen and glucose to the brain and muscles.

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79
Q

Name the glands that produces adrenaline.

A

Adrenal glands.

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80
Q

Which gland produces the hormone thyroxine?

A

The thyroid.

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81
Q

What does thyroxine regulate?

A

Basal metabolic rate.

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82
Q

What two things does thyroxine play an important role in?

A

Growth and development.

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83
Q

What is TSH and what does it do?

A

Thyroid stimulating hormone. It stimulates the thyroid to release thyroxine.

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84
Q

Where is TSH produced and released from?

A

The pituitary gland.

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85
Q

What are gametes?

A

Sex cells.

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86
Q

Name the gametes in animals.

A

Sperm and egg.

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87
Q

Name the gametes in plants.

A

Pollen and egg.

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88
Q

Complete the sentence: “Sexual reproduction leads to …… in the offspring.”

A

Variation.

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89
Q

Does mitosis or meiosis lead to identical cells?

A

Mitosis

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90
Q

What process leads to the formation of gametes?

A

Meiosis.

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91
Q

What is meant by cells being clones?

A

They are identical and have exactly the same genes.

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92
Q

Describe the 4 main differences between sexual and asexual reproduction.

A

1) Sexual involves the fusion of gametes asexual does not
2) Sexual involves two parents asexual involves one
3) Sexual involves the mixing of genetic material, asexual does not
5) Sexual leads to variation, asexual does not (asexual produces clones)

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93
Q

What process leads to the formation of gametes?

A

Meiosis.

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94
Q

What effect does meiosis have on the number of chromosomes in a cell?

A

Halves it.

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95
Q

In animals, where are the gametes formed?

A

Ovaries and testes.

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96
Q

When a new cell is formed through fertilisation, how does it divide?

A

Mitosis.

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97
Q

If 80 chromosomes are present in an animal cell. How many chromosomes will be present in a gamete?

A

40 chromosomes.

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98
Q

What must first happen before the cell starts to divide in meiosis?

A

The genetic information must be copied.

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99
Q

How may divisions occur during meiosis?

A

Two

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100
Q

How many gametes are formed from one parent cell?

A

Four

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101
Q

When an embryo is formed, by what process to the cells become specialised?

A

Differentiation.

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102
Q

How can you genetically describe the gametes that are formed in meiosis?

A

They are genetically different. There is variation.

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103
Q

The genetic material in the nucleus of a cell is made up of which molecule?

A

DNA

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104
Q

DNA is found in structures called?

A

Chromosomes

105
Q

What is DNA?

A

A polymer made up of two strands forming a double helix.

106
Q

What is a gene?

A

A small section of DNA on a chromosome.

107
Q

What does each gene code for?

A

A particular sequence of amino acids, to make a specific protein.

108
Q

What is the genome of an organism?

A

It is the entire genetic material of that organism.

109
Q

State 3 ways in which understanding of the human genome will be important.

A
  1. To search for genes linked to different types of disease
  2. To understand and treat inherited disorders
  3. To trace early human migration patterns
110
Q

Do chromosomes normally come in pairs or triplets?

A

Pairs

111
Q

Describe the structure of DNA.

A

Double helix.

112
Q

What is a gamete?

A

A sex cell (egg or sperm; egg or pollen).

113
Q

What is a gene?

A

A small section of DNA on a chromosome that codes for a specific protein.

114
Q

What is an allele?

A

A different version/form of a gene.

115
Q

What does the term “dominant” mean?

A

The individual only needs one copy of this allele for its phenotype to be seen.

116
Q

What does the term “recessive” mean?

A

The individual needs two copies of this allele for its phenotype to be seen.

117
Q

What does the term “homozygous” mean?

A

The individual has two identical alleles for this gene.

118
Q

What does the term “heterozygous” mean?

A

The individual has two different alleles for this gene.

119
Q

What is meant by genotype?

A

The combination of alleles for a specific gene.

120
Q

What is meant by phenotype?

A

The displayed characteristics of the genotype.

121
Q

All characteristics are controlled by a single gene. True or False?

A

False.

122
Q

How many copies of each gene do we inherit from each parent?

A

One from each parent.

123
Q

Some diseases disorders are inherited? True or False?

A

True.

124
Q

What are inherited disorders caused by?

A

By inheriting faulty alleles.

125
Q

What is polydactyly?

A

A condition that causes a person to have extra fingers or toes.

126
Q

What is cystic fibrosis.

A

A disorder of cell membranes that leads to excess mucus production in the lungs and digestive system.

127
Q

Is cystic fibrosis caused by a dominant or recessive allele?

A

Recessive.

128
Q

Is polydactyly caused by a dominant or recessive allele?

A

Dominant.

129
Q

State one argument for aborting embryos with faulty alleles discovered by embryonic screening.

A

1) Stop people suffering

2) Save government money through not needed to treat people

130
Q

State one argument against aborting embryos with faulty alleles discovered by embryonic screening.

A

It implies people with genetic problems are undesirable, this could lead to prejudice.

131
Q

How many pairs of chromosomes does an ordinary human body cell have?

A

23

132
Q

How many pairs of chromosomes determine the sex of the individual?

A

1

133
Q

What is the genotype of a female?

A

XX

134
Q

What is the genotype of a male?

A

XY

135
Q

Which chromosome X or Y causes male characteristics?

A

Y

136
Q

Would an egg cell ever possess a Y chromosome?

A

No.

137
Q

Define variation.

A

Differences in the characteristics of individuals in a population.

138
Q

Only genes determine the phenotype of an organism – true or false?

A

False – the environment also plays a role.

139
Q

State three causes of variation in a population.

A
  1. Genes
  2. The environment
  3. A combination of both
140
Q

Within a population, there is normally very little genetic variation – true or false?

A

False.

141
Q

What causes variation within a population?

A

Mutations.

142
Q

How often does a mutation result in a new phenotype?

A

Very rarely.

143
Q

What is a mutation?

A

A rare and random change in an organism’s DNA.

144
Q

Do mutations occur continuously?

A

Yes.

145
Q

Mutations are always bad. True or False?

A

False.

146
Q

Why can mutations cause changes in phenotype?

A

Changes in the DNA can produce a different form of a gene. Genes code for the sequence of amino acids that make up a protein. Could lead to changes in the protein being made.

147
Q

True or false – does the theory of evolution by natural selection state that all living things evolved from simple life forms more than three billion years ago?

A

True.

148
Q

Would the best organism within a species to survive and reproduce be:

a) the strongest?
b) the one which reproduces the fastest?
c) the best adapted to the environment?

A

c)

149
Q

What is the definition of a species?

A

Organisms that can interbreed to produce fertile offspring.

150
Q

What is evolution?

A

A change in the inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species.

151
Q

How do we know when two populations of a species have formed two new species?

A

When they can no longer interbreed to produce fertile offspring.

152
Q

Animals that are not adapted to their environment are more likely to survive. True or False?

A

False.

153
Q

Are animals that are suited to their environment more likely to pass on their characteristics, why?

A

Yes, because they are more likely to survive and reproduce.

154
Q

What is selective breeding?

A

The process by which humans breed plants and animals for particular genetic characteristics.

155
Q

Name two historic examples of selective breeding.

A
  1. Breeding food crops from wild plants

2. Domesticating animals

156
Q

State four modern examples of selective breeding.

A
  1. Disease resistance in food crops
  2. Animals which produce more meat or milk
  3. Domestic dogs with a gentle nature
  4. Large or unusual flowers
157
Q

State a drawback to selective breeding.

A

Inbreeding – some breeds are prone to disease or inherited defects because of a reduction in the gene pool.

158
Q

Describe the four steps involved in selective breeding.

A

1) Select parents with the desired characteristics from a mixed population.
2) The parents are bred together.
3) From the offspring those with the desired characteristics are bred together.
4) This continues over many generations until all the offspring show the desired characteristic.

159
Q

What is genetic engineering?

A

The process which involves modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic.

160
Q

State two ways plants might be genetically engineered.

A
  1. Resistant to insect attack
  2. Resistant to herbicides
  3. Increased yields
161
Q

Give one example of how bacterial cells have been genetically engineered.

A

To produce useful substances such as human insulin to treat diabetes.

162
Q

How is a gene “cut out” from the genome of one species and inserted the genome of another?

A

Using enzymes.

163
Q

Into what is the gene inserted before it is introduced to an organism?

A

A vector

164
Q

Give two examples of vectors used in genetic engineering

A

A bacterial plasmid, a virus

165
Q

Why should a gene be transferred between organisms at an early stage of development?

A

So that they develop with desired characteristics.

166
Q

What is the name given to crops that have had their genes modified?

A

Genetically modified crops (GM crops)

167
Q

State two concerns about GM crops.

A

1) They can have a negative impact on the number of wildflowers and insects
2) Some people feel the effects of eating GM crops on human health have not been fully explored.

168
Q

State three discoveries that supported the theory of evolution by natural selection.

A

1) The discovery of genetics. Characteristic are passed on as genes.
2) Fossils and how changes in organisms developed slowly over time.
3) Bacteria developing antibiotic resistance.

169
Q

How did the discovery of genetics support the theory of evolution by natural selection?

A

It showed that characteristics are passed on to offspring in genes.

170
Q

How did the discovery of fossils support the theory of evolution by natural selection?

A

By looking at fossils of different ages it allows you to see how changes in organisms developed slowly over time.

171
Q

How has observing bacteria supported the theory of evolution by natural selection?

A

By observing how resistance to antibiotics evolves in bacteria.

172
Q

Who came up with the theory of evolution by natural selection?

A

Charles Darwin.

173
Q

What are fossils?

A

The remains of organisms from millions of years ago, which are found in rocks.

174
Q

What are the three ways fossils may be formed?

A
  1. From parts of organisms that have not decayed as one (or more) of the conditions needed for decay is absent.
  2. Parts of the organisms have been replaced with minerals as they decay.
  3. Preserved traces of organisms such as footprints, burrows and rootlet traces.
175
Q

Why are few fossils of early life found?

A

Most early life were soft-bodied and so left little trace behind.

176
Q

What does the lack of fossils of early life on Earth mean about the theories scientists have on the beginning of life on Earth?

A

We can’t be certain about them as there is little evidence.

177
Q

Why are fossils useful?

A

Can be used to determine how much or how little organisms have changed as life developed on Earth.

178
Q

In evolutionary diagrams, what do junctions between the lines represent?

A

A common ancestor of two species

179
Q

When is a species said to be extinct?

A

When there are no remaining individuals of that species alive.

180
Q

State two of the 5 ways a species can become extinct.

A

1) The environment changes to quickly
2) A new predator kills them off
3) A new diseases kills them off
4) They can’t compete with another species for food
5) A catastrophic event kills them off

181
Q

Why do bacteria evolve so rapidly?

A

They have a very fast reproduction rate.

182
Q

New strains of bacteria are caused by…..

A

Mutation of their DNA.

183
Q

State the 4 steps leading to the development of antibiotic resistance in a population of bacteria.

A
  1. The population is exposed to an antibiotic, some of the population are resistant to the antibiotic.
  2. The resistant bacteria are not killed, so survive the treatment.
  3. These resistant bacteria reproduce and pass on the resistance genes to the next generation.
  4. The new resistant strain spreads quickly as hosts are not immune to it and there is no effective treatment.
184
Q

State three ways we can reduce the rate of antibiotic resistance development.

A
  1. Stop prescribing antibiotics inappropriately, such as for viral infections.
  2. Patients should complete their course of antibiotics so all bacteria are killed.
  3. Use of antibiotics in agriculture should be restricted or banned.
185
Q

Why aren’t many new antibiotics being developed?

A

The development of new antibiotics is very costly and very slow.

186
Q

Which is quicker, the development of new antibiotics or the development of antibiotic resistance in bacteria?

A

The development of antibiotic resistance in bacteria (currently).

187
Q

Traditionally, how have we classified living things into groups?

A

Based on their structure and characteristics.

188
Q

Who developed the first true classification system of living organisms?

A

Carl Linnaeus.

189
Q

What are the titles of each classification level?

A

Kingdom, Phylum, Class, Order, Family, Genus, Species

190
Q

Escherichia coli and homo sapiens are examples of the naming of organisms by the binomial system. Which two classification groups are used in these names?

A

Genus (Escherichia and homo) and species (coli and sapiens)

191
Q

Name two developments which led to new classification systems being invented.

A

Developments in microscopes and development in the understanding of biochemical processes in cells.

192
Q

Carl Woese proposed the “three-domain system” for living organisms. What are these three domains?

A

Archaea, Bacteria and Eukaryota

193
Q

What are “Archaea”?

A

Primitive (old) bacteria often living in extreme environments.

194
Q

Give an example of a type of cell in the Bacteria domain.

A

True bacteria.

195
Q

Give an example of a type of cell in the Eukaryota domain.

A

Protists, fungi, plants and/or animals

196
Q

What is an ecosystem?

A

An ecosystem is the interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment.

197
Q

What do organisms require from their surroundings in order to survive and reproduce?

A

A supply of materials from their surroundings

198
Q

State four factors plants compete with each other for.

A

Space, light, mineral ions, water

199
Q

State three factors animals compete with each other for.

A

Food, mates, territory

200
Q

What is interdependence?

A

Each species within a community depend on others for food, shelter, pollination, seed dispersal, etc. If one species is removed, this will affect the whole community.

201
Q

In a stable community, what should be a common trend in the populations of all the different species?

A

All of the species and environmental factors will be in balance so that population sizes remain fairly constant.

202
Q

Name the 7 abiotic factors

A

Light intensity, temperature, moisture levels, soil pH and mineral content, wind intensity (and direction), carbon dioxide concentration (for plants), oxygen concentration (for aquatic animals)

203
Q

What is an abiotic factor?

A

A non-living factor which can affect a community.

204
Q

How could a decrease in light intensity affect plant numbers?

A

Decrease in light intensity could decrease the rate of photosynthesis. This could affect plant growth and cause a decrease in the population size.

205
Q

What is a biotic factor?

A

A living factor which may affect a community.

206
Q

State all 4 possible biotic factors which may affect a community.

A

Availability of food, new predators, new pathogens, one species outcompeting another

207
Q

How could a new predator cause population numbers to change?

A

A new predator could hunt and kill a species as prey. The prey population would decrease.

208
Q

Organisms have adaptations to enable them to survive in their usual conditions. What 3 categories do these adaptations fall under?

A

Structural, behavioural, functional (cellular reactions)

209
Q

What is an extremophile?

A

An organism that lives in an extreme environment, such as at high temperature, pressure or salt concentration.

210
Q

Give an example of an extremophile.

A

Bacteria living in deep sea vents/Organisms living in water with a high salt concentration.

211
Q

Arctic fox have white fur to help them camouflage, what type of adaptation is this?

A

Structural.

212
Q

Animals that live in hot places have a large surface area to volume ratio, what type of adaptation is this?

A

Structural.

213
Q

Many species migrate to warmer climates during the winter, what type of adaptation is this?

A

Behavioural.

214
Q

Desert animals conserve water by producing very little sweat and small amounts of concentrated urine. What type of adaptation is this?

A

Functional.

215
Q

Brown bears hibernate over winter. What type of adaptation is this?

A

Functional.

216
Q

What type of organisms are the producers of biomass for life on Earth?

A

Photosynthetic organisms.

217
Q

How can we represent feeding relationships within a community?

A

Food chains and food webs.

218
Q

What do all food chains begin with?

A

A producer?

219
Q

What is a producer?

A

An organism that makes its own food.

220
Q

Give an example of a producer.

A

Green plants or algae

221
Q

What are producers eaten by?

A

Primary consumers.

222
Q

What are primary consumers eaten by?

A

Secondary consumers.

223
Q

What are secondary consumers eaten by?

A

Tertiary consumers.

224
Q

What name is given to consumers that kill and eat their prey?

A

Predators.

225
Q

How would you describe the change in predator and prey numbers in a stable community?

A

The numbers of predators and prey rise and fall in cycles.

226
Q

Calculate the mean of the following numbers: 12, 25, 64, 34, 97.

A

46.4

227
Q

Calculate the median of the following numbers: 12, 25, 64, 34, 97.

A

34

228
Q

Calculate the mode of the following numbers: 12, 25, 64, 34, 97, 12, 25, 54, 12, 84, 76.

A

12

229
Q

What is a quadrat?

A

A square frame enclosing a known area, e.g. 1m2

230
Q

Why are all materials in the living world recycled?

A

To provide the building blocks for future organisms.

231
Q

Name the process by which carbon dioxide is removed from the atmosphere.

A

Photosynthesis.

232
Q

State three processes which return carbon from organisms to atmospheric carbon dioxide.

A
  1. Respiration – releases carbon dioxide.
  2. Release (carbon containing) waste – microorganisms decompose this and respire – releases carbon dioxide.
  3. Death – microorganisms decompose the body and respire – release carbon dioxide.
233
Q

Whys is the water cycle important for life?

A

It provides fresh water for plants and animals.

234
Q

What does water fall from clouds as?

A

Precipitation.

235
Q

Water evaporates from the land and sea. How else is water vapour formed?

A

Evaporates from plants - Transpiration

Animals release water vapour into the air when they breathe

236
Q

When precipitation falls, what happens to the water that doesn’t get absorbed by the soil?

A

It will run off into streams and rivers.

237
Q

How does carbon move from plants to animals?

A

Animals eat plants.

238
Q

How is carbon release from plants back into the atmosphere, other than plant respiration.

A

The burning of products made from plants produces carbon dioxide.

239
Q

Define biodiversity

A

Biodiversity is the variety of all the different species of organisms on Earth, or within an ecosystem.

240
Q

Why does a high level of biodiversity ensure the stability of ecosystems?

A

It reduces the dependence of one species on another for food, shelter, and the maintenance of the physical environment.

241
Q

What is human activity reducing, which may be an issue for the future of the human species on Earth?

A

Biodiversity.

242
Q

How is water polluted?

A

Sewage, fertilisers or toxic chemicals.

243
Q

How is air polluted?

A

Smoke and acidic gases.

244
Q

How is land polluted?

A

Landfill and toxic chemicals.

245
Q

Why does pollution reduce biodiversity?

A

It kills plant and animals.

246
Q

What two things are causing more resources to be used and more waste to be produced?

A

The rapid growth in the human population and an increase in the standard of living.

247
Q

What is the increased release of waste and chemical materials causing?

A

(More) pollution.

248
Q

How do humans reduce the amount of land available for other animals and plants?

A

By building, quarrying, farming and dumping waste

249
Q

Why are peat bogs being destroyed?

A

To produce garden compost.

250
Q

What effect does destruction of peat bogs have on an area?

A

Reduces biodiversity.

251
Q

What happens as a result of decay or burning of peat?

A

Release of carbon dioxide into the atmosphere.

252
Q

State the two main reasons for large-scale deforestation in tropical areas.

A

1) Provide land for cattle and rice fields

2) Grow crops for biofuels

253
Q

What affect does large scale deforestation have on biodiversity?

A

Reduces biodiversity.

254
Q

Why does cutting more trees down mean less carbon dioxide being removed from the atmosphere.

A

Trees take-in carbon dioxide for photosynthesis. Less trees mean less photosynthesis, so less carbon dioxide needed.

255
Q

Which 2 gases are increasing in the atmosphere and contributing to global warming?

A
  1. Carbon dioxide

2. Methane

256
Q

What are the four main biological consequences of global warming?

A
  1. Affecting migration patterns of animals
  2. Melting of polar ice caps, causing flooding
  3. Reduced habitats in polar regions
  4. Reduced biodiversity
257
Q

State three positive human interactions to reduce the negative effects of humans on ecosystems and biodiversity.

A
  1. Breeding programmes for endangered species
  2. Protection and regeneration of rare habitats
  3. Reintroduction of field margins and hedgerows in agricultural areas where farmers grow only one type of crop
  4. Reduction of deforestation and carbon dioxide emissions by some governments
  5. Recycling resources rather than dumping waste in landfill
258
Q

State two negative human interactions in an ecosystem.

A
  1. Clearing of land for agriculture, buildings and/or transport
  2. Hunting of rare species
  3. Mining from the land

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