Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology - Module 2 > Chapter 6 - Cell Division > Flashcards

Chapter 6 - Cell Division Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Stages of the cell cycle

A

o interphase
o nuclear division (mitosis)
o cell division (cytokinesis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Length of the cell cycle

A

variable depending on environmental conditions, the cell type and the organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the movement from one phase to another triggered by

A

Chemical signals = cyclins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

First phase

A

Interphase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What makes up interphase

A

o G1 phase
o S phase
o G2 phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What happens in G1

A

o In this phase, at some point a signal is received telling the cell to divide again
o The gap between the previous cell division and the S phase is called the G1 phase
o Cells make the RNA, enzymes and other proteins required for growth during the G1 phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What happens in S phase

A

o The S phase is relatively short
o The DNA in the nucleus replicates = resulting in each chromosome consisting of two identical sister chromatids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens in G2 phase

A

o the cell continues to grow and the new DNA is checked and any errors are usually repaired
o Other preparations for cell division are made = production of tubulin protein, which is used to make microtubules for the mitotic spindle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Where does cell growth stop

A

Mitosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is cytokineses

A

• Once the nucleus has divided, the whole cell divides + one nucleus moves into each cell to create two genetically identical daughter cells
• Animal cells = involves constriction of the cytoplasm between two nucleus
• Plant cells = new cell wall is formed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How is the cell cycle regulated

A

Checkpoints = • Specific proof-reading enzymes + repair enzymes are involved in this checking process

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What happens if an error is identifies

A

enzymes will repair the error but in some cases the cell may destroy itself to prevent passing on harmful mutations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How many checkpoints

A

4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Where are the main checkpoints = detailed

A
  1. G1 phase - chromosomes are checked for damage.
    o If damage is detected then the cell does not advance into the S phase until repairs have been made
  2. S phase - chromosomes are checked to ensure they have been replicated.
    o If all the chromosomes haven’t been successfully replicated then the cell cycle stops
  3. G2 phase - an additional check for DNA damage occurs after the DNA has been replicated.
    o The cell cycle will be delayed until any necessary repairs are made
  4. During metaphase - the final check determines whether the chromosomes are correctly attached to the spindle fibres prior to anaphase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Where are the main checkpoints = numbers

A

G1

S

G2

Metaphase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Stages of mitosis

A

prophase + metaphase + anaphase + telophase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Define mitosis

A

• process of nuclear division by which two genetically identical daughter nuclei are produced that are also genetically identical to the parent cell nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What happens in prophase

A

• Chromosomes condense and are now visible when stained
• chromosomes consist of two identical chromatids = sister chromatids (each containing one DNA molecule) that are joined together at the centromere
• The two centrosomes (replicated in the G2 phase just before prophase) move towards opposite poles (opposite ends of the nucleus)
• Spindle fibres (protein microtubules) begin to emerge from the centrosomes (consists of two centrioles in animal cells)
• The nuclear envelope (nuclear membrane) breaks down into small vesicles
• The nucleolus disappears

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens in metaphase

A

• Centrosomes reach opposite poles
• Spindle fibres (protein microtubules) continue to extend from centrosomes
• Chromosomes line up at the equator of the spindle (the metaphase plate) so they are equidistant to the two centrosome poles
• Spindle fibres reach the chromosomes and attach to the centromeres
o attachment involves specific proteins = kinetochores
• Each sister chromatid is attached to a spindle fibre originating from opposite poles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What happens in anaphase

A

• The sister chromatids separate at the centromere = the centromere divides in two
• Spindle fibres begin to shorten
• The separated sister chromatids (now called chromosomes) are pulled to opposite poles by the spindle fibres (protein microtubules)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What happens in telophase

A

• Chromosomes arrive at opposite poles and begin to decondense
• Nuclear envelopes begin to reform around each set of chromosomes
• spindle fibres break down
• New nucleoli form within each nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Where does growth in plant occur

A

Meristems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Where are meristems found

A

just behind the protective root cap

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How can root tip meristems be studies for mitosis

A

using the squash technique (root tips are stained and then gently squashed, spreading the cells out into a thin sheet and allowing individual cells undergoing mitosis to be clearly seen)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Method to view mitosis in plants

A

Method
• Garlic or onion (Allium cepa) root tips are most commonly used (the bulbs can be encouraged to grow roots by suspending them over water for a week or two)
• Remove the tips of the roots (about 1cm) and place in a suitable stain (eg. warm, acidified acetic orcein, which stains chromosomes a deep purple)
• The stained root tip is gently squashed on a glass slideusing a blunt instrument (eg. the handle of a mounting needle)
• Cells undergoing mitosis are seen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What does prophase look like

A
  • big blob mess
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What does metaphase and anaphase look like

A

Metaphase = kinda see the chromosome lines
Anaphase = pulling apart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Limitations of method

A

• It can be very difficult to distinguish between prophase and telophase in cells
• The size of cells or structures of tissues may appear inconsistent in different specimen slides
• Optical microscopes do not have the same magnification power as other types of microscopes and so there are some structures that can not be seen
• The treatment of specimens when preparing slides could alter the structure of cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

If there are multiple nuclei in one cell what stage is it in

A

Telophase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Significance of mitosis

A
  • growth
  • replacement of damaged cells and repair of tissue
  • asexual reproduction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

How is mitosis important in growth

A

• The two daughter cells produced are genetically identical to one another (clones) and have the same number of chromosomes as the parent cell
• This enables unicellular zygotes (as the zygote divides by mitosis) to grow into multicellular organisms
• Growth may occur across the whole body of the organism or be confined to certain regions, such as in the meristems (growing points) of plants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

How is mitosis important in replacement of cells and repair of tissue

A

• Damaged tissues can be repaired by mitosis followed by cell division
• As cells are constantly dying they need to be continually replaced by genetically identical cells
• In humans, for example, cell replacement occurs particularly rapidly in the skin and the lining of the gut
• Some animals can regenerate body parts, for example, zebrafish can regenerate fins and axolotls regenerate legs and their tail amongst other parts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

How is mitosis important in asexual reproduction

A

• For unicellular organisms such as Amoeba, cell division results in the reproduction of a genetically identical offspring
• For multicellular organisms, new individuals grow from the parent organism (by cell division) and then detach (‘bud off’) from the parent in different ways

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Define asexual reproduction

A

the production of new individuals of a species by a single parent organism – the offspring are genetically identical to the parent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Examples of organisms with asexual reproduction

A

Hydra and yeast and runners from strawberries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

In S phase how is DNA copied

A

DNA sequences of high importance (genes that are active in all cells) are replicated first

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Why is the S phase fast

A

Because DNA bases are exposed during replication thus more susceptible to mutagens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

The quicker the s phase…

A

The lower chance of mutations occurring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Graph for mass of DNA at each stage

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q
A

D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q
A

A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q
A

A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q
A

No DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q
A

224

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q
A

17

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

Define meiosis

A

orm of nuclear division that results in the production of haploid cells from diploid cells - It produces gametes in plants and animals that are used in sexual reproduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

What happens in prophase 1

A

• DNA condenses = visible as chromosomes

• The chromosomes are arranged side by side in homologous pairs

• As the homologous chromosomes are very close together = crossing over of non sister chromatic = chiasma (chiasmata; plural)

• centrioles migrate to opposite poles

  • spindle is formed

• nuclear envelope breaks down + nucleolus disintegrates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

What does DNA look like in prophase 1

A

• DNA replication has already occurred so each chromosome consists of two sister chromatids joined together by a centromere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

What is a bivalent

A

o A pair of homologous chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

What happens in metaphase 1

A

bivalents line up along the equator of the spindle = spindle fibres attached to the centromeres

The maternal and paternal chromosomes in each pair position themselves independently of the others = independent assortment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

What is independent assortment

A

maternal and paternal chromosomes in each pair position themselves independently of the others

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

What does independent assortment mean

A

that the proportion of paternal or maternal chromosomes that end up on each side of the equator is due to chance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

What happens in anaphase 1

A

homologous pairs of chromosomes are separated = microtubules pull whole chromosomes to opposite ends of the spindle

• The centromeres do not divide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

What happens in telophase 1

A

chromosomes arrive at opposite poles

• Spindle fibres start to break down

• Nuclear envelopes form around the two groups of chromosomes + nucleoli reform

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

What do some plant cells do that’s different to normal cels

A

• Some plant cells go straight into meiosis II without reformation of the nucleus in telophase I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

What are the sites where crossing over happens called

A

Chiasmata

68
Q

What is independent assortment aided by

A

protein structure called the synaptonemal complex

69
Q

What happens in cytokinesis 1

A

• division of the cytoplasm

• Cell organelles =. distributed between two developing cells

• The end product of cytokinesis in meiosis I is two haploid cells

70
Q

What happens in cytokinesis 1 in animals

A

cell surface membrane pinches inwards creating a cleavage furrow in the middle of the cell which contracts, dividing the cytoplasm in half

71
Q

What happens in cytokinesis 1 in plant cells

A

vesicles from the Golgi apparatus gather along the equator of the spindle (the cell plate).

  • vesicles merge with each other to form the new cell surface membrane + secrete a layer of calcium pectate which becomes the middle lamella.
  • Layers of cellulose are laid upon the middle lamella to form the primary and secondary walls of the cell
72
Q

What is the end product of meiosis 1

A

two haploid cells

73
Q

In plant cells, what do vesicles secrete

A

layer of calcium pectate

74
Q

What does the layer of calcium pectate become

A

The middle lamella

75
Q

What is difference between the second division of meiosis - before prophase 11

A

no interphase between meiosis I and meiosis II

76
Q

What does having no interphase between meiosis I and meiosis II mean

A

DNA is not replicated

77
Q

What happens in prophase II

A

o The nuclear envelope breaks down and chromosomes condense
o A spindle forms at a right angle to the old one

78
Q

What happens in metaphase II

A

o Chromosomes line up in a single file along the equator of the spindle

79
Q

What happens in anaphase II

A

o Centromeres divide and individual chromatids are pulled to opposite poles

o This creates four groups of chromosomes that have half the number of chromosomes compared to the original parent cell

80
Q

What happens in telophase II

A

o Nuclear membranes form around each group of chromosomes

81
Q

What happens in cytokinesis II

A

o Cytoplasm divides as new cell surface membranes are formed creating four haploid cells

82
Q

Draw a flow chart summarising meiosis

A
83
Q

Significant of meiosis

A

increase the genetic diversity of gametes produced

84
Q

Genetic diversity in meiosis

A
  • crossing over
  • independent assortment
  • random fusion of gametes
  • mutations ( not strictly meiosis)
85
Q

What is crossing over

A

• process by which non-sister chromatids exchange alleles

86
Q

Process of crossing over

A

o During meiosis I homologous chromosomes pair up and are in very close proximity to each other

o The non-sister chromatids can cross over and get entangled

o These crossing points are called chiasmata

o The entanglement places stress on the DNA molecules

o As a result of this a section of chromatid from one chromosome may break and rejoin with the chromatid from the other chromosome

FORMS recombinant chromatids

87
Q

Why is this swapping of alleles in crossing over significant

A

can result in a new combination of alleles on the two chromosomes

FORMS recombinant chromatids

88
Q

How many chiasmata are there in each bivalent

A

At least 1

89
Q

Where is crossing over most likely to happen

A

more likely to occur further down the chromosome away from the centromere

90
Q

What is independent assortment

A

the production of different combinations of alleles in daughter cells due to the random alignment of homologous pairs along the equator of the spindle during metaphase I

91
Q

When does independent assortment happen

A

metaphase I

92
Q

Process of independent assortment

A

o Each pair can be arranged with either chromosome on top, this is completely random

• The homologous chromosomes are then separated and pulled apart to different poles

• The combination of alleles that end up in each daughter cell depends on how the pairs of homologous chromosomes were lined up

93
Q

How to work out the number of different possible chromosome combinations = independent assortment

A

2n can be used, where n corresponds to the number of chromosomes in a haploid cell

94
Q

How does random fusion of gametes create genetic diversity

A

random fusion of gametes at fertilization creates genetic variation between zygotes as each will have a unique combination of alleles

95
Q

How do mutations increase genetic diversity

A

• random mutation that takes place during DNA replication can lead to the production of new alleles and increased genetic variation.

96
Q

Function of erythrocytes

A

transport oxygen around the body and carbon dioxide to the lungs

97
Q

Adaptations of erythrocytes (4)

A

o biconcave in shape which increases the surface area over which oxygen can be absorbed

o cytoplasm contains high amounts of the pigment haemoglobin which can readily bind to oxygen

o No nucleus = makes more space inside the cell for haemoglobin molecules for maximum oxygen-carrying capacity

o Elastic membrane allows cell to be flexible and change shape as it squeezes through narrow capillaries

98
Q

Function of neutrophils

A

destroy pathogens by phagocytosis and the secretion of enzymes

99
Q

Adaptations of neutrophils

A

o very flexible shape = allows them to squeeze through cell junctions in the capillary wall

o flexibility = form pseudopodia (cytoplasmic projections) that engulf microorganisms

o large number of lysosomes = digestive enzymes help to digest and destroy invading cells

o A flexible nuclear membrane = helps the cell to penetrate cell junctions.

100
Q

Function of squamous epithelial cells

A

provide a surface covering or outer layer

aids rapid diffusion

Found on a variety of organs and structures e.g. blood vessels and alveoli

101
Q

Adaptations of squamous epithelial cells

A

consists of a single layer of flattened cells on a basement membrane

one cell thick

o layer forms a thin cross-section which reduces the distance that substances have to move to pass through - it shortens the diffusion pathway

o It is permeable, allowing for the easy diffusion of gases

102
Q

Function of ciliated epithelial cells

A

moving substances across the surface of a tissue

103
Q

Adaptations of ciliated epithelial cells

A

o Have cilia = beat in a coordinated way to shift material along the surface of the epithelium tissue

o Goblet cells secrete mucus = trap dust, dirt and microorganisms - preventing them from entering vital organs where they may cause infection

104
Q

Function of sperm cells

A

reproduction - to fuse with an egg, initiate the development of an embryo and pass on fathers genes

105
Q

Adaptations of sperm cell

A

head contains a nucleus that contains half the normal number of chromosomes (haploid, no chromosome pairs)

o The acrosome in the head contains digestive enzymes that can break down the outer layer of an egg cell so that the haploid nucleus can enter to fuse with the egg’s nucleus

o The mid-piece is packed with mitochondria to release energy for the tail movement

o The tail rotates, propelling the sperm cell forwards and allowing it to move towards the egg

106
Q

Function of palisade cell

A

carry out photosynthesis to produce glucose and oxygen

107
Q

Adaptations of palisade cell

A

arge number of chloroplasts (the site of photosynthesis) are present in the cytoplasm to maximise the absorption of light for photosynthesis

o tall + thin shape of the cells allows light to penetrate deeper before encountering another cell wall (cell walls absorb/reflect light) and for many cells to be densely packed together

108
Q

Function of root hair cell

A

absorption of water and mineral ions from soil

109
Q

Adaptations of root hair cells

A

o Root hair = increase SA = rate of water uptake by osmosis is greater

o Thinner walls = water can move through easily (due to shorter diffusion distance)

o Permanent vacuole contains cell sap which is more concentrated than soil water, maintaining a water potential gradient

o Mitochondria for active transport of mineral ions

110
Q

Function of guard cells

A

control the opening of the stomata to regulate water loss and gas exchange

111
Q

Adaptations of guard cells

A

o Inner cell walls are thicker (those facing the air outside the leaf) while the outer cell walls are thinner (those facing adjacent epidermal cells).

difference in the thickness of the cell walls allows the cell to bend when turgid

o The cytoplasm has a high density of chloroplasts and mitochondria.

112
Q

Tissues

A

group of cells that work together to perform a particular function

113
Q

What forms the epithelial tissue

A

Epithelial cells = function = absorb food in small intestine

114
Q

Organs

A

Made up of different tissue

115
Q

Heart as an organ is made up of what

A

cardiac muscle tissue, blood vessel tissues and connective tissue

116
Q

Organ systems

A

Different organs working together

117
Q

Tissue / organ / organ system of epithelial cells

A
118
Q

Tissue / organ / organ system of muscle cells

A
119
Q

Tissue / organ / organ system of neurones

A
120
Q

Tissue / organ / organ system of rod and cone cells

A
121
Q

Function of xylem cells

A

transport water for tissue and dissolved ions

122
Q

Adaptations of xylem cells

A

o No top and bottom walls between cells to form continuous hollow tubes through which water is drawn upwards towards the leaves by transpiration

o Cells are essentially dead, without organelles or cytoplasm, to allow free movement of water

o Outer walls are thickened with a substance called lignin, strengthening the tubes, which helps support the plant

123
Q

Function of phloem cells

A

transport of dissolved sugars and amino acids

124
Q

Adaptations of phloem cells

A

o Made of living cells which are supported by companion cells

o joined end-to-end and contain holes in the end cell walls (sieve plates) forming tubes that allow sugars and amino acids to flow easily through (by translocation)

o have very few subcellular structures to aid the flow of materials

125
Q

Function of muscle cells

A

contraction for movement

126
Q

Adaptations of muscle cells

A

have layers of protein filaments in them, these layers can slide over each other causing muscle contraction

o have a high density of mitochondria to provide sufficient energy (via respiration) for muscle contraction

o Skeletal muscle cells fuse together during development to form multinucleated cells that contract in unison

127
Q

Three types of muscle in animals

A

skeletal, smooth and cardiac

128
Q

Function of cartilage

A

provide support

prevents the ends of bones rubbing together

129
Q

What is cartilage

A

strong and flexible connective tissue

130
Q

Where is cartilage found

A

One place is in rings along the trachea, called Tracheal rings

found outer ear / nose / between bones

131
Q

Stem cells

A

cell that can divide (by mitosis) an unlimited number of times

132
Q

Potency

A

ability of stem cells to differentiate into more specialised cell types

133
Q

Three types of potency

A

Totipotency

Pluripotent

Multipotency

134
Q

o Totipotency

A

stem cells that can differentiate into any cell type found in an embryo, as well as extra-embryonic cells (the cells that make up the placenta).

135
Q

o Pluripotency

A

embryonic stem cells that can differentiate into any cell type found in an embryo but are not able to differentiate into extra-embryonic cells (the cells that make up the placenta)

136
Q

o Multipotency

A

adult stem cells that have lost some of the potency associated with embryonic stem cells and are no longer pluripotent

137
Q

What are adult stem cells

A

small numbers of stem cells remain to produce new cells for the essential processes of growth, cell replacement and tissue repair

138
Q

What are adult stem cells

A

Multi potent

139
Q

Stem cells in bone marrow

A

Multi potent - only differentiate into blood cells (red blood cells, monocytes, neutrophils and lymphocytes)

140
Q

Summary diagram - types of stem cells

A
141
Q

erythropoiesis

A

• As red blood cells lack a nucleus, they cannot divide, meaning that new erythrocytes are constantly being formed from bone marrow stem cells in order to maintain the red blood cell count in the blood

142
Q

Stages of erythropoiesis

A
143
Q

Changes that occur when stem cells differentiate into neutrophils

A

o Indentations form in the nucleus, giving it a lobed structure

o Granules accumulate (these are lysosomes that contain hydrolytic enzymes)

144
Q

Cambium

A

• xylem and phloem are formed from stem cells that are found in the tissue between them = tissue = cambium

145
Q

What is cambium

A

A meristem

146
Q

Meristem

A

any undifferentiated tissue in a plant that has the ability to give rise to new cells

147
Q

Where in the cambium do the cells differentiate into xylem + where phloe,

A

stem cells at the inner edge of the cambium differentiate into xylem cells and the stem cells at the outer edge of the cambium differentiate into phloem cells

148
Q

Changes that occur when differentiating into xylem

A

lose their cytoplasm, deposit lignin in their cell walls and lose their end cell walls

149
Q

Changes that occur when differentiating into phloem

A

lose some of their cytoplasm and organelles, and develop sieve plates

150
Q

What is cell differentiation from cambium triggered by

A

Hormones

151
Q

Where are meristems found

A

Tips of roots / shoots

152
Q

When are embryonic stem cells totipotent

A

if taken in the first 3-4 days after fertilisation

153
Q

When are embryonic stem cells pluripotent

A

if taken on day 5

154
Q

Uses of stem cells

A

used for research are often the waste (fertilised) embryos from in vitro fertilisation treatment

155
Q

Why is there ethical objections to using embryonic stem cells as research

A

embryos have the potential to develop into human beings

156
Q

Uses of multi potent adult stem cells

A

Transplant

157
Q

Why is using multi potent stem cells not great

A
158
Q

Problem caused by Alzheimer’s

A
  • most common cause of dementia

+ memory loss + loss of other cognitive abilities

159
Q

Treatment using stem cells - Alzheimer’s

A

Stem cells - grown into nerve cells = repair

160
Q

Why is using stem cells in Alzheimer’s difficult

A

Damage to brain is widespread rather than localised

161
Q

Problem caused by Parkinson’s

A
  • shaking /stiffness / slowness of movement
162
Q

What is Parkinson’s disease caused by

A

Death of dopamine

163
Q

Treatment using stem cells - Parkinson’s

A

Stem cells can replace dopamine producing cells

164
Q

Problem caused by age related muscular degeneration

A
  • damage to macula of retina = cause loss of vision
165
Q
A

Biology - Module 2 (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions