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biology 2022 paper 1 > Paper 1: Topic 1 Cell Biology - Cell division (LV) > Flashcards

Paper 1: Topic 1 Cell Biology - Cell division (LV) Flashcards

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1
Q

Name the genetic material found in all living cells

A

DNA

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2
Q

State where the genetic material is located in eukaryotic cells

A

Contained inside the nucleus

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3
Q

State where the genetic material is located in prokaryotic cells

A

Free in the cytoplasm

Exists as a nucleoid and some bacteria can also have additional small loops of DNA called plasmids

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4
Q

Describe how DNA is arranged in eukaryotic cells

A

As a linear chromosomes

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5
Q

Explain the term chromosome

A

A coiled length of DNA

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6
Q

State how many chromosomes are found in human somatic (body) cells

A

46

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7
Q

State how many chromosomes are found in human gametes

A

23

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8
Q

Explain the term diploid

A

A full set of chromosomes

This is represented as ‘2n’

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9
Q

Explain the term haploid

A

Half a set of chromosomes

This is represented as ‘n’

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10
Q

Explain the term ‘cell cycle’

A

A series of events in which a cell grows, replicates its DNA and then divides to form daughter cells

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11
Q

How do human somatic cells divide?

A

Mitosis

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12
Q

What is the function of mitosis?

A

To produce two GENETICALLY identical daughter cells

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13
Q

Why do multicellular organisms use mitosis?

A

To produce new cells:

a) For growth of tissues and organs
b) To repair damaged tissues and organs
* Remember do not just say “growth and repair” you must say ‘of tissues and organs’ as well*

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14
Q

Describe what happens to the chromosome number when a cell undergoes mitosis

A

It is maintained/kept constant

i.e. remains as 2n (diploid)

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15
Q

State the 3 main events during mitosis

A

DNA replication

Division of DNA

Splitting of the cell into 2

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16
Q

Explain what events occur inside a human somatic (body) cell BEFORE it takes part in mitosis

A

The cell increases in size

The sub-cellular structures (organelles) are replicated

The DNA is replicated (copied) so that there is double the quantity of DNA inside the cell

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17
Q

Describe the shape of a chromosome after it has replicated

A

It will appear as a cross

The 2 strands of DNA are held together by a centromere

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18
Q

Describe the relationship between the 2 arms of a chromosome after it has replicated

A

They are genetically identical

This means they carry the same genes and alleles

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19
Q

Describe the main events that take place during mitosis Hint: 6 key events

A
  1. The chromosomes line up in the middle of the cell along the equator
  2. Special protein fibres pull the chromosomes apart
  3. Half of each chromosome is pulled to the opposite pole of the cell
  4. Membranes form around the outside of each set of chromosomes (to form 2 nuclei inside the one cell)
  5. The cell splits equally into 2
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20
Q

Describe how prokaryotic cells divide

A

Binary fission

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21
Q

Explain the key events that occur during binary fission Hint: 4 events

A
  1. The circular DNA (nucleoid) and plasmids replicate
  2. The cell increases in size and the circular DNA moves to the poles of the cell
  3. The cytoplasm divides and new cell walls are formed
  4. 2 daughter cells are formed each has a circular DNA but they can have variable numbers of plasmids
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22
Q

Describe the main features of cell division in bacteria

A

Occurs by binary fission

Occurs very quickly (~once every 20 minutes)

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23
Q

How can you calculate the number of bacteria present after a given period of time?

A

Calculate the number of minutes in the time period

Divide the number of minutes by 20 (to calculate the number of divisions the bacteria will undertake).

Call this answer ‘x’

Calculate 2 to the power ‘x’ i.e. 2x

This will be the number of cells present after the specified time period.

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24
Q

Define the term stem cell

A

An unspecialised cell that can replicate to produce more unspecialised cells

All these cells can then differentiate to become specialised cells

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25
Q

Explain the term differentiation

A

The process of an unspecialised cell changing its shape, chemical content and organelle content to become a specialised cell

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26
Q

What controls differentiation?

A

The switching on and off of certain genes inside the unspecialised cell

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27
Q

State 2 sources of stem cell

A

Early embryos

Umbilical cord (after birth)

Adult bone marrow

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28
Q

What is special about early embryo stem cells?

A

They can differentiate into ANY type of specialised cell

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29
Q

How are adult stem cells different from embryo stem cells?

A

Embryo stem cells can differentiate into any type of specialised cell but adult stem cells can only differentiate into certain types of specialised cells e.g. red blood cells

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30
Q

How can stem cells be used in medical research

A

Either type of stem cell can be grown in science laboratories to produce clones

These clones can then be stimulated to differentiate into specific specialised cells

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31
Q

Explain what is meant by the term ‘specialised cell’

A

A cell that has changed its shape, chemical content and/or the organelle content of itself to become suited for a specific function

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32
Q

Describe what changes occur in stem cell when it differentiates into a red blood cell

A

Change in shape = it changes from spherical to biconcave

Change in chemical content = it produces a lot of haemoglobin

Change in organelle content = it breaks down its mitochondria and nucleus

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33
Q

State 3 examples of how stem cells can be use to cure disease

A
  1. Adult stem cells taken from the bone marrow of a healthy person can be used to replace faulty blood cells in a patient
  2. Embryonic stem cells can be used to replace faulty cells e.g. insulin producing cells can be used to treat people with diabetes nerve cells can be used to treat people with spinal cord injuries (paralysis)
  3. Stem cells can be used for therapeutic cloning – they are taken from the patient stimulated to differentiate into the required specialised cells and then returned to the same patient.
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34
Q

What is the advantage of using a patient’s own stem cells in therapeutic cloning?

A

The specialised cells formed from the patient’s stem cells are genetically identical to the patient’s cells and are therefore not rejected

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35
Q

What are carried on each chromosome?

A

Each chromosome carries a large number of genes.

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36
Q

What is a gene?

A

A section of DNA that codes for the production of one specific protein

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37
Q

Describe how chromosomes are normally found in somatic (body) cells

A

In body cells the chromosomes are normally found in pairs.

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38
Q

Where are stem cells found in plants?

A

In the meristematic tissue i.e. root tips and shoot tips

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39
Q

What is special about meristematic tissue in plants?

A

Meristem tissue in plants can differentiate into ANY type of plant cell, THROUGHOUT the life of the plant.

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40
Q

State two concerns people have with stem cell treatments

A

The use of stem cells has potential risks such as transfer of viral infection

Some people have ethical or religious objections.

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41
Q

State an advantage for horticulturists who using plant stem cells

A

Stem cells from meristems in plants can be used to produce clones of plants quickly and economically.

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42
Q

State 2 benefits of the use of plant stem cells in research and treatments

A

Rare species can be cloned to protect from extinction.

Crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers.

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43
Q
  1. Asexual reproduction
  2. Sexual reproduction
A

Name the two types of reproduction

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44
Q
  • Asexual reproduction involves only one parent and no fusion of gametes
  • There is no mixing of genetic information
  • This leads to genetically identical offspring (clones)
  • Only mitosis is involved
A

Define asexual reproduction

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45
Q
  • Reproduction that involves two parents
  • It involves the mixing of genetic information
  • This leads to variety in the offspring
  • The formation of gametes involves meiosis
  • It involves the fusing of gametes
A

Define sexual reproduction

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46
Q
  1. sperm
  2. ova (egg cells)
A

State the 2 types of gametes that are involved in sexual rep

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47
Q
  1. pollen
  2. ova (egg cells)
A

State the 2 types of gametes that are involved in sexual rep

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48
Q
  1. Produces variation in the offspring
  2. If the environment changes variation gives a survival advantage by natural selection
  3. Natural selection can be speeded up by humans in selective breeding to increase food production
A

Give 3 advantages of sexual reproduction

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49
Q
  1. Only one parent needed
  2. More time and energy efficient as do not need to find a mate
  3. Faster than sexual reproduction
  4. Many identical offspring can be produced when conditions are favourable
A

Give 4 advantages of asexual reproduction

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50
Q
  • Malarial parasites
  • Fungi
  • Plants e.g. strawberry plants
A

Name 3 organisms that reproduce by both asexual and sexual r

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51
Q

Malarial parasites reproduce asexually in the human host, but sexually in the mosquito

A

State how malarial parasites demonstrate both sexual and ase

52
Q
  • Many fungi reproduce asexually by spores
  • They also reproduce sexually by spores to give variation

Remember: fungal spores can be produced asexually and sexually

A

State how fungi demonstrate both sexual and asexual reproduc

53
Q
  • When conditions are favourable the fungi can produce spores asexually to make many identical spores in a short period of time
  • When conditions are unfavourable fungi can produce spores sexually to make genetically different spores to increase the chances of surviving the environmental conditions
A

Explain why it is an advantage for fungi to be able to produ

54
Q
  • Flowering plants produce seeds sexually
  • They also reproduce asexually by runners such as strawberry plants, or bulb division such as daffodils
A

State how some plants demonstrate both sexual and asexual re

55
Q

Mitosis

A

State the type of cell division involved in asexual reproduc

56
Q

Meiosis

A

State the type of cell division involved in sexual reproduct

57
Q

Meiosis

A

Which type of reproduction involves the production of haploi

58
Q

Fertilisation

A

State the term that describes the fusing of two gametes to f

59
Q
  • Half the full number i.e. haploid (n)
  • For human cells this is 23
A

How many chromosomes are found in a gamete?

60
Q
  • A full set of chromosomes i.e. diploid (2n)
  • For human cells this is 46
A

How many chromosomes are found in a somatic (body) cell?

61
Q
  • Sexual reproduction involves the fusing of two gametes
  • Each gamete contains genetic material from each parent
  • The zygote will have half the DNA from the mother and half from the father
  • This mixture of genetic information produces variation
A

Explain why sexual reproduction causes greater genetic varia

62
Q
  1. It increases genetic variation
  2. Genetic variation increases the chances of survival of the species if there is a change in the environment
  3. Genetic variation will mean some individuals will be better adapted to the environment and therefore more likely to survive and breed and pass the successful alleles on to the next generation (called natural selection)
  4. Scientists can use selective breeding to speed up natural selection
A

State the 4 advantages of sexual reproduction

63
Q
  1. Only one parent is required (so there is no need to find a mate)
  2. This means asexual reproduction uses less energy (no energy used in finding a mate, producing gametes)
  3. It is also faster (as no time is used in finding a mate)
  4. Many genetically identical offspring can be produced when conditions are favourable
  5. It maintains genetic stability by producing genetically identical cells
A

State the 5 advantages of asexual reproduction

64
Q
  • Gametes must contain half the chromosomes number so that when 2 gametes fuse during fertilisation the chromosome number is restored
  • If the gametes had a full set of chromosomes (2n) then the chromosome number would double at each generation
A

Explain the importance of producing haploid gametes

65
Q

2

A

How many daughter cells are produced in mitosis?

66
Q

4

A

How many daughter cells are produced in meiosis?

67
Q
  1. Copies of the genetic information are made
  2. The cell divides once to form two daughter cells, each with a full set of chromosomes(2n)
  3. All gametes are genetically identical to each other.
A

State the 3 main stages of mitosis

68
Q
  1. Copies of the genetic information are made
  2. The cell divides twice to form four gametes, each with a single set of chromosomes
  3. All gametes are genetically different from each other
A

State the 3 main stages of meiosis

69
Q

In the reproductive organs

  • testes
  • ovaries
A

State where meiosis occurs

70
Q

Mitosis

A

State the type of cell division that occurs in an embryo to

71
Q

The number of cells increases The number of cells doubles after each division

A

How does the cell number change as the embryo forms a fetus?

72
Q

Differentiation

A

As the embryo develops the cells become specialised. Name t

73
Q

Gamete → zygote → embryo → fetus → organism

A

Put these structures in order of increasing complexity:Gamet

74
Q
  • Runners e.g. strawberry plants
  • Bulbs e.g. daffodils
A

Give an example of asexual reproduction in plants

75
Q

23

Please note the questions asked you for the number of PAIRS

A

How many pairs of chromosomes are found in a somatic (body)

76
Q

Sex chromosomes

A

What is the name for the pair of chromosomes that determines

77
Q

XX

A

What 2 sex chromosomes are found in all somatic (body) cells

78
Q

XY

A

What 2 sex chromosomes are found in all somatic (body) cells

79
Q

100%

A

What percentage of female ova will carry an X chromosome?

80
Q

50%

A

What percentage of male sperm will carry an X chromosome?

81
Q

50%

A

What percentage of male sperm will carry a Y chromosome?

82
Q
  • Male
  • If the ovum is fertilised by a sperm carrying an X chromosome the individual will be female.
  • If the ovum is fertilised by a sperm carrying a Y chromosome the individual will be male.
A

State gamete will determine the sex of a human at fertilisat

83
Q

XY

A

State the genotype of a human male

84
Q

XX

A

State the genotype of a human female

85
Q
  1. Asexual reproduction
  2. Sexual reproduction
A

Name the two types of reproduction

86
Q
  • Asexual reproduction involves only one parent and no fusion of gametes
  • There is no mixing of genetic information
  • This leads to genetically identical offspring (clones)
  • Only mitosis is involved
A

Define asexual reproduction

87
Q
  • Reproduction that involves two parents
  • It involves the mixing of genetic information
  • This leads to variety in the offspring
  • The formation of gametes involves meiosis
  • It involves the fusing of gametes
A

Define sexual reproduction

88
Q
  1. sperm
  2. ova (egg cells)
A

State the 2 types of gametes that are involved in sexual rep

89
Q
  1. pollen
  2. ova (egg cells)
A

State the 2 types of gametes that are involved in sexual rep

90
Q
  1. Produces variation in the offspring
  2. If the environment changes variation gives a survival advantage by natural selection
  3. Natural selection can be speeded up by humans in selective breeding to increase food production
A

Give 3 advantages of sexual reproduction

91
Q
  1. Only one parent needed
  2. More time and energy efficient as do not need to find a mate
  3. Faster than sexual reproduction
  4. Many identical offspring can be produced when conditions are favourable
A

Give 4 advantages of asexual reproduction

92
Q
  • Malarial parasites
  • Fungi
  • Plants e.g. strawberry plants
A

Name 3 organisms that reproduce by both asexual and sexual r

93
Q

Malarial parasites reproduce asexually in the human host, but sexually in the mosquito

A

State how malarial parasites demonstrate both sexual and ase

94
Q
  • Many fungi reproduce asexually by spores
  • They also reproduce sexually by spores to give variation

Remember: fungal spores can be produced asexually and sexually

A

State how fungi demonstrate both sexual and asexual reproduc

95
Q
  • When conditions are favourable the fungi can produce spores asexually to make many identical spores in a short period of time
  • When conditions are unfavourable fungi can produce spores sexually to make genetically different spores to increase the chances of surviving the environmental conditions
A

Explain why it is an advantage for fungi to be able to produ

96
Q
  • Flowering plants produce seeds sexually
  • They also reproduce asexually by runners such as strawberry plants, or bulb division such as daffodils
A

State how some plants demonstrate both sexual and asexual re

97
Q

Mitosis

A

State the type of cell division involved in asexual reproduc

98
Q

Meiosis

A

State the type of cell division involved in sexual reproduct

99
Q

Meiosis

A

Which type of reproduction involves the production of haploi

100
Q

Fertilisation

A

State the term that describes the fusing of two gametes to f

101
Q
  • Half the full number i.e. haploid (n)
  • For human cells this is 23
A

How many chromosomes are found in a gamete?

102
Q
  • A full set of chromosomes i.e. diploid (2n)
  • For human cells this is 46
A

How many chromosomes are found in a somatic (body) cell?

103
Q
  • Sexual reproduction involves the fusing of two gametes
  • Each gamete contains genetic material from each parent
  • The zygote will have half the DNA from the mother and half from the father
  • This mixture of genetic information produces variation
A

Explain why sexual reproduction causes greater genetic varia

104
Q
  1. It increases genetic variation
  2. Genetic variation increases the chances of survival of the species if there is a change in the environment
  3. Genetic variation will mean some individuals will be better adapted to the environment and therefore more likely to survive and breed and pass the successful alleles on to the next generation (called natural selection)
  4. Scientists can use selective breeding to speed up natural selection
A

State the 4 advantages of sexual reproduction

105
Q
  1. Only one parent is required (so there is no need to find a mate)
  2. This means asexual reproduction uses less energy (no energy used in finding a mate, producing gametes)
  3. It is also faster (as no time is used in finding a mate)
  4. Many genetically identical offspring can be produced when conditions are favourable
  5. It maintains genetic stability by producing genetically identical cells
A

State the 5 advantages of asexual reproduction

106
Q
  • Gametes must contain half the chromosomes number so that when 2 gametes fuse during fertilisation the chromosome number is restored
  • If the gametes had a full set of chromosomes (2n) then the chromosome number would double at each generation
A

Explain the importance of producing haploid gametes

107
Q

2

A

How many daughter cells are produced in mitosis?

108
Q

4

A

How many daughter cells are produced in meiosis?

109
Q
  1. Copies of the genetic information are made
  2. The cell divides once to form two daughter cells, each with a full set of chromosomes(2n)
  3. All gametes are genetically identical to each other.
A

State the 3 main stages of mitosis

110
Q
  1. Copies of the genetic information are made
  2. The cell divides twice to form four gametes, each with a single set of chromosomes
  3. All gametes are genetically different from each other
A

State the 3 main stages of meiosis

111
Q

In the reproductive organs

  • testes
  • ovaries
A

State where meiosis occurs

112
Q

Mitosis

A

State the type of cell division that occurs in an embryo to

113
Q

The number of cells increases The number of cells doubles after each division

A

How does the cell number change as the embryo forms a fetus?

114
Q

Differentiation

A

As the embryo develops the cells become specialised. Name t

115
Q

Gamete → zygote → embryo → fetus → organism

A

Put these structures in order of increasing complexity:Gamet

116
Q
  • Runners e.g. strawberry plants
  • Bulbs e.g. daffodils
A

Give an example of asexual reproduction in plants

117
Q

23

Please note the questions asked you for the number of PAIRS

A

How many pairs of chromosomes are found in a somatic (body)

118
Q

Sex chromosomes

A

What is the name for the pair of chromosomes that determines

119
Q

XX

A

What 2 sex chromosomes are found in all somatic (body) cells

120
Q

XY

A

What 2 sex chromosomes are found in all somatic (body) cells

121
Q

100%

A

What percentage of female ova will carry an X chromosome?

122
Q

50%

A

What percentage of male sperm will carry an X chromosome?

123
Q

50%

A

What percentage of male sperm will carry a Y chromosome?

124
Q
  • Male
  • If the ovum is fertilised by a sperm carrying an X chromosome the individual will be female.
  • If the ovum is fertilised by a sperm carrying a Y chromosome the individual will be male.
A

State gamete will determine the sex of a human at fertilisat

125
Q

XY

A

State the genotype of a human male

126
Q

XX

A

State the genotype of a human female

biology 2022 paper 1 (11 decks)

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