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Biology Edexcel Sophie > Topic 3 Cells Specialization > Flashcards

Topic 3 Cells Specialization Flashcards

1
Q

What are the two types of cells?

A

Prokaryotic cells and Eukaryotic cells

Prokaryotic cells are typically single-celled organisms, while eukaryotic cells are found in multicellular organisms.

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2
Q

What are organelles?

A

Parts of cells, each with a specific function

Organelles are essential for the cell’s operation and can be found in both prokaryotic and eukaryotic cells.

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3
Q

What is a key feature of prokaryotic organisms?

A

They are made up of prokaryotic cells

Prokaryotic organisms are typically single-celled.

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4
Q

What type of cells are animal cells?

A

Eukaryotic cells

Eukaryotic cells are more complex than prokaryotic cells.

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5
Q

What distinguishes eukaryotic cells from prokaryotic cells?

A

Eukaryotic cells are larger and more complex

Eukaryotic cells include all animal and plant cells.

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6
Q

Name three organelles found in animal cells.

A
  • Nucleus
  • Mitochondrion
  • Ribosome

These organelles have specific functions vital for cell health and activity.

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7
Q

What is the function of the nucleus?

A

Controls cell activities and contains DNA

The nucleus is surrounded by a double membrane called the nuclear envelope.

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8
Q

What is the role of ribosomes?

A

Site where proteins are made

Ribosomes can be free in the cytoplasm or attached to the rough endoplasmic reticulum.

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9
Q

Fill in the blank: The _______ contains digestive enzymes.

A

Lysosome

Lysosomes digest invading cells or worn-out components of the cell.

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10
Q

What is the function of the mitochondrion?

A

Site of aerobic respiration where ATP is produced

Mitochondria are abundant in cells that require a lot of energy.

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11
Q

True or False: Organelles are whole cells.

A

False

Organelles are parts of cells, not complete cells.

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12
Q

What are the components of the rough endoplasmic reticulum (RER)?

A

Covered with ribosomes and involved in protein folding and processing

The RER synthesizes proteins that are to be exported from the cell.

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13
Q

What is the function of the Golgi apparatus?

A

Processes and packages lipids and proteins

The Golgi apparatus also makes lysosomes.

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14
Q

Fill in the blank: The _______ is involved with the separation of chromosomes during cell division.

A

Centriole

Centrioles are found in animal cells and some plant cells.

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15
Q

What is the structure of the mitochondrion?

A

Double membrane with inner folds called cristae

The matrix inside contains enzymes for respiration.

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16
Q

What is the function of smooth endoplasmic reticulum (SER)?

A

Synthesizes and processes lipids

The SER is involved in the production of hormones and other lipids.

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17
Q

Where are proteins made in a cell?

A

At the ribosomes

Ribosomes can be found on the rough endoplasmic reticulum or free in the cytoplasm.

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18
Q

What do ribosomes on the rough endoplasmic reticulum produce?

A

Proteins that are excreted or attached to the cell membrane

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19
Q

What is the role of free ribosomes in the cytoplasm?

A

Make proteins that stay in the cytoplasm

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20
Q

What happens to new proteins in the rough endoplasmic reticulum?

A

They are folded and processed

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21
Q

How are proteins transported from the rough endoplasmic reticulum?

A

In vesicles to the Golgi apparatus

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22
Q

What further processing can occur at the Golgi apparatus?

A

Sugar chains are trimmed or more are added

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23
Q

What do proteins enter after the Golgi apparatus for transport?

A

More vesicles

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24
Q

What is an example of a protein that moves to the cell surface?

A

Extracellular enzymes (like digestive enzymes)

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25
Q

How do prokaryotic cells compare in size to eukaryotic cells?

A

Prokaryotic cells are smaller

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26
Q

What is the main component of the plasma membrane in prokaryotic cells?

A

Lipids and proteins

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27
Q

What is the function of the cell wall in prokaryotic cells?

A

Supports the cell and prevents it from changing shape

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28
Q

What is murein?

A

A polymer that makes up the cell wall in prokaryotic cells

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29
Q

What type of ribosomes are found in prokaryotic cells?

A

Smaller ribosomes than those in eukaryotic cells

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30
Q

What are pili in prokaryotic cells?

A

Short hair-like structures that help stick to other cells

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31
Q

What is the function of a flagellum?

A

Rotates to make the prokaryotic cell move

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32
Q

True or False: All prokaryotes have a flagellum.

A

False

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33
Q

What is a capsule in prokaryotic cells?

A

A structure made of secreted slime that protects bacteria

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34
Q

What distinguishes the DNA in prokaryotic cells from that in eukaryotic cells?

A

It floats free in the cytoplasm and is circular

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35
Q

What are plasmids?

A

Small loops of DNA that aren’t part of the main circular DNA molecule

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36
Q

What genes do plasmids typically contain?

A

Genes for antibiotic resistance

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37
Q

Fill in the blank: Prokaryotic cells do not have a _______.

A

Nucleus

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38
Q

What are mesosomes?

A

Inward folds in the plasma membrane of prokaryotic cells

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39
Q

What is debated about the function of mesosomes?

A

Whether they play a role in cellular processes or are artefacts

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40
Q

Identify one structure that can only be found in prokaryotic cells.

A

Pili

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41
Q

Describe two ways in which DNA can be stored in a prokaryotic cell.

A
  1. Circular DNA as one long coiled-up strand. 2. Plasmids (small loops of DNA).
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42
Q

What is magnification?

A

Magnification is how much bigger the image is than the specimen.

It is calculated using the formula: size of image / size of real object.

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43
Q

What is the formula for calculating magnification?

A

Magnification = size of image / size of real object.

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44
Q

What is resolution in microscopy?

A

Resolution is how detailed the image is and how well a microscope distinguishes between two points that are close together.

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45
Q

What is an eyepiece graticule?

A

An eyepiece graticule is a transparent ruler fitted onto the eyepiece of a microscope, used to measure the size of a specimen.

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46
Q

What is a stage micrometer?

A

A stage micrometer is a microscope slide with an accurate scale used to measure the size of an object in micrometers.

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47
Q

What are the two main types of microscopes?

A
  • Light microscopes
  • Electron microscopes
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48
Q

What is the maximum resolution of light microscopes?

A

The maximum resolution of light microscopes is about 0.2 micrometres (um).

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49
Q

What is the maximum useful magnification of a light microscope?

A

The maximum useful magnification of a light microscope is about × 1500.

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50
Q

What is the maximum useful magnification of an electron microscope?

A

The maximum useful magnification of an electron microscope is about × 1,500,000.

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51
Q

What is the difference between transmission electron microscopes (TEMs) and scanning electron microscopes (SEMs)?

A
  • TEMs use electromagnets to focus a beam of electrons transmitted through the specimen.
  • SEMs scan a beam of electrons across the specimen, showing surface details.
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52
Q

What are the advantages of TEMs?

A
  • High resolution images
  • Can show internal structure of organelles
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53
Q

What are the disadvantages of TEMs?

A

TEMs can only be used on thin specimens.

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54
Q

What are the advantages of SEMs?

A
  • Can be used on thick specimens
  • Produce 3D images
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55
Q

What are the disadvantages of SEMs?

A

SEMs give lower resolution images than TEMs.

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56
Q

How do you convert micrometers (um) to millimeters (mm)?

A

To convert micrometers to millimeters, divide by 1000.

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57
Q

What is the maximum resolution of electron microscopes?

A

The maximum resolution of electron microscopes is about 0.0002 micrometres (um).

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58
Q

Calculate the size of 1 division on the eyepiece graticule if 1 division on the stage micrometer is 0.1 mm and equals 4.5 divisions on the eyepiece.

A

1 division on eyepiece graticule = 0.1 mm / 4.5 = 0.022 mm.

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59
Q

True or False: A light microscope can view organelles smaller than 0.2 um.

A

False.

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60
Q

How are the images produced by SEMs different from those produced by TEMs?

A

SEMs show surface details and can be 3D, while TEMs provide high resolution internal images.

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61
Q

What is the significance of calibrating the eyepiece graticule?

A

The eyepiece graticule needs to be re-calibrated at different magnifications.

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62
Q

What is squamous epithelium?

A

A single layer of flat cells lining a surface, found in places like the alveoli in the lungs.

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63
Q

What is ciliated epithelium?

A

A layer of cells with tiny hair-like structures (cilia) that move substances, found in the trachea.

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64
Q

What is the function of the basement membrane?

A

It supports the epithelium tissue by anchoring it to underlying tissues.

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65
Q

What are the two primary functions of xylem tissue?

A
  • Transporting water around the plant
  • Supporting the plant.
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66
Q

What types of cells are found in xylem tissue?

A
  • Xylem vessel cells
  • Xylem parenchyma cells.
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67
Q

What is cartilage?

A

A type of connective tissue found in joints, ears, nose, and windpipe.

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68
Q

What is an organ?

A

A group of different tissues that work together to perform a particular function.

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69
Q

Name the tissues that make up a plant leaf.

A
  • Lower epidermis
  • Spongy mesophyll
  • Palisade mesophyll
  • Xylem
  • Phloem
  • Upper epidermis.
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70
Q

What is the role of stomata in the lower epidermis of a leaf?

A

To allow air in and out for gas exchange.

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71
Q

Where does most photosynthesis occur in a leaf?

A

In the palisade mesophyll.

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72
Q

What tissues make up the lungs?

A
  • Squamous epithelium tissue
  • Fibrous connective tissue
  • Endothelium tissue.
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73
Q

What is the respiratory system?

A

A system made up of all organs, tissues, and cells involved in breathing.

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74
Q

Name the organs involved in the respiratory system.

A
  • Lungs
  • Trachea
  • Larynx
  • Nose
  • Mouth
  • Diaphragm.
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75
Q

What is the circulatory system?

A

A system made up of the organs involved in blood supply.

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76
Q

Name the parts of the circulatory system.

A
  • Heart
  • Arteries
  • Veins
  • Capillaries.
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77
Q

Fill in the blank: Tissues are organized into _______.

A

Organs.

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78
Q

True or False: Xylem tissue is made up of a group of organs that work together.

A

False.

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79
Q

True or False: The lungs are part of the respiratory system.

A

True.

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80
Q

Explain what is meant by the term organ system.

A

A group of organs working together to perform a particular function.

81
Q

Name one organ found in plants and one organ found in animals.

A
  • Plant organ: Leaf
  • Animal organ: Lungs.
82
Q

What is mitosis?

A

Mitosis is cell division that produces genetically identical daughter cells.

Mitosis is crucial for growth, repair, and asexual reproduction.

83
Q

What happens to a parent cell during mitosis?

A

A parent cell divides to produce two genetically identical daughter cells.

84
Q

What is the purpose of mitosis in multicellular organisms?

A

Mitosis is used for growth, repair, and asexual reproduction.

85
Q

What is interphase?

A

Interphase is the period of cell growth and DNA replication before mitosis.

86
Q

What are the three stages of interphase?

A

G1, S, and G2.

87
Q

What occurs during the S phase of interphase?

A

The cell replicates its DNA in preparation for division.

88
Q

What are the four stages of mitosis?

A

Prophase, Metaphase, Anaphase, and Telophase.

89
Q

What happens during prophase?

A

Chromosomes condense, centrioles move to opposite ends, and the nuclear envelope breaks down.

90
Q

What is the role of the spindle during mitosis?

A

The spindle helps separate the chromatids during mitosis.

91
Q

What occurs during metaphase?

A

Chromosomes line up along the middle of the cell and attach to the spindle by their centromeres.

92
Q

What happens during anaphase?

A

Centromeres divide, separating sister chromatids, which are pulled to opposite poles.

93
Q

What is telophase?

A

Chromatids reach opposite poles, uncoil, and a nuclear envelope forms around each group, resulting in two nuclei.

94
Q

What is cytokinesis?

A

Cytokinesis is the division of the cytoplasm, resulting in two daughter cells.

95
Q

Fill in the blank: The mitotic index is calculated using the formula: mitotic index = _______.

A

number of cells with visible chromosomes / total number of cells observed.

96
Q

Why is it important to squash the tissue when preparing a slide of plant root tip cells?

A

Squashing the tissue makes it thinner, allowing light to pass through for better observation under a microscope.

97
Q

What is the significance of a high mitotic index in plant root tips?

A

A high mitotic index indicates rapid tissue growth, as many cells are undergoing mitosis.

98
Q

True or False: All cells in multicellular organisms retain the ability to divide.

A

False.

99
Q

What increases in the cell during interphase to provide energy for cell division?

A

ATP content.

100
Q

What are chromatids?

A

The separate strands of a chromosome, joined at the centromere.

101
Q

What is the function of centrioles during mitosis?

A

Centrioles help form the spindle apparatus that separates chromatids.

102
Q

What is the role of the nuclear envelope during mitosis?

A

The nuclear envelope breaks down during prophase and reforms during telophase.

103
Q

What is the appearance of chromosomes during anaphase?

A

Chromatids appear V-shaped as they are pulled to opposite poles.

104
Q

What are the male and female gametes in animals?

A

Male gametes are sperm and female gametes are egg cells (ova).

105
Q

How many chromosomes do normal body cells contain in humans?

A

46 chromosomes.

106
Q

How many chromosomes do gametes contain?

A

Gametes contain 23 chromosomes.

107
Q

What is fertilisation?

A

The moment when the nuclei of the male and female gametes fuse.

108
Q

What is the result of fertilisation?

A

A zygote with the full number of chromosomes.

109
Q

What makes offspring genetically unique?

A

Combining genetic material from two individuals.

110
Q

Fill in the blank: In mammals, fertilisation occurs in the _______.

A

oviduct.

111
Q

What is the zona pellucida?

A

A protective glycoprotein layer that sperm have to penetrate.

112
Q

What happens during the acrosome reaction?

A

Digestive enzymes are released from the acrosome of the sperm.

113
Q

What is the function of the acrosome in sperm?

A

Contains digestive enzymes to break down the egg cell’s zona pellucida.

114
Q

What triggers the cortical reaction in the egg cell?

A

The fusion of the sperm head with the cell membrane of the egg cell.

115
Q

What happens to the zona pellucida after the cortical reaction?

A

It thickens and becomes impenetrable to other sperm.

116
Q

What occurs immediately after a zygote is formed?

A

It begins to divide by mitosis.

117
Q

True or False: Egg cells are smaller than sperm cells.

A

False.

118
Q

List two specialisations of sperm cells.

A
  • Flagellum for swimming
  • Lots of mitochondria for energy.
119
Q

List two specialisations of egg cells.

A
  • Larger size compared to sperm
  • Contains food reserves for the developing embryo.
120
Q

What is the role of mitochondria in sperm cells?

A

Releases energy in the form of ATP for swimming.

121
Q

What process produces gametes?

A

Meiosis

Meiosis is a type of cell division that reduces the chromosome number by half, producing gametes.

122
Q

How many chromosomes do cells that undergo meiosis have at the start?

A

Full set of chromosomes

Cells that divide by meiosis start with a full set of chromosomes.

123
Q

What is the chromosome number in cells formed from meiosis?

A

Half the number of chromosomes

The resulting cells from meiosis have half the chromosome number to maintain genetic stability during fertilization.

124
Q

What happens to chromosome number during the first division of meiosis?

A

Halved

The first division separates homologous pairs, halving the chromosome number.

125
Q

What is genetic variation?

A

Differences in individuals’ genetic material

Genetic variation is crucial for evolution and adaptation.

126
Q

What are the two main mechanisms by which meiosis creates genetic variation?

A
  • Crossing over of chromatids
  • Independent assortment of chromosomes
127
Q

What occurs during crossing over?

A

Chromatids twist and exchange genetic material

This recombination creates different combinations of alleles.

128
Q

What is independent assortment?

A

Random distribution of maternal and paternal chromosomes

This process ensures that gametes have different combinations of chromosomes.

129
Q

What is a locus?

A

The position of a gene on a chromosome

Loci are important for understanding gene linkage and inheritance.

130
Q

What does it mean when genes are linked?

A

They are located on the same chromosome and tend to be inherited together

Linked genes are less likely to be separated during meiosis unless crossing over occurs.

131
Q

What is a sex-linked characteristic?

A

A characteristic coded by an allele on a sex chromosome

Most sex-linked characteristics are found on the X chromosome.

132
Q

What are X-linked disorders?

A

Genetic disorders caused by faulty alleles on the X chromosome

Examples include color blindness and hemophilia.

133
Q

True or False: Males have two X chromosomes.

A

False

Males have one X and one Y chromosome, while females have two X chromosomes.

134
Q

Fill in the blank: The Y chromosome is ______ than the X chromosome.

A

smaller

135
Q

Why are males more likely to express recessive phenotypes for sex-linked genes?

A

They have only one allele for sex-linked genes

Because males have one X chromosome, they express the characteristic even if it’s recessive.

136
Q

What is produced at the end of meiosis?

A

Four genetically different gametes

Each gamete has a unique combination of alleles.

137
Q

What are stem cells?

A

Unspecialised cells that can develop into other types of cells.

Stem cells can differentiate into specialized cells through a process called differentiation.

138
Q

What is the process by which a cell becomes specialised?

A

Differentiation.

139
Q

What are the two types of potency in stem cells?

A
  • Totipotency
  • Pluripotency
140
Q

What does totipotency refer to?

A

The ability to produce all cell types, including extraembryonic cells.

141
Q

What does pluripotency refer to?

A

The ability of a stem cell to produce all specialized cells in an organism, excluding extraembryonic cells.

142
Q

When are totipotent stem cells present in mammals?

A

During the first few cell divisions of an embryo.

143
Q

Where are adult stem cells found?

A

In some adult tissues, such as the intestines.

144
Q

What determines the specialization of a cell?

A

Differential gene expression.

145
Q

What is transcription?

A

The process of copying DNA into mRNA.

146
Q

What is translation?

A

The process of producing proteins using the code in mRNA.

147
Q

What are transcription factors?

A

Proteins that bind to DNA and regulate gene expression.

148
Q

What is the role of activators in gene expression?

A

They increase the rate of transcription.

149
Q

What is the role of repressors in gene expression?

A

They decrease the rate of transcription.

150
Q

What is an operon?

A

A section of DNA that contains a cluster of structural genes and control elements.

151
Q

What is the lac operon?

A

An operon in E. coli that produces enzymes needed to respire lactose.

152
Q

What happens to the lac operon when lactose is present?

A

Lactose binds to the lac repressor, allowing transcription of the structural genes.

153
Q

Fill in the blank: The ability of stem cells to differentiate into specialised cells is called _______.

A

potency.

154
Q

True or False: All stem cells can differentiate into any type of cell.

A

False.

155
Q

What are the structural genes on the lac operon responsible for?

A

Producing proteins that help the bacteria digest lactose.

156
Q

What happens to embryonic stem cells after early development?

A

They become pluripotent and lose the ability to become extraembryonic cells.

157
Q

What is the significance of differential gene expression in stem cells?

A

It results in the activation of specific genes that lead to specialization.

158
Q

What occurs when RNA polymerase binds to the promoter in transcription?

A

It initiates the transcription of structural genes.

159
Q

What does the regulatory gene in an operon do?

A

Codes for an activator or repressor.

160
Q

What are stem cells?

A

Cells that can develop into any specialized cell type.

161
Q

Name a disease that stem cell therapy can potentially treat.

A

Leukemia.

162
Q

What type of stem cells are found in adult tissue?

A

Adult stem cells.

163
Q

What type of stem cells are obtained from early embryos?

A

Embryonic stem cells.

164
Q

List three conditions that scientists are researching stem cells to treat.

A
  • Spinal cord injuries
  • Heart disease
  • Damage caused by heart attacks
165
Q

Fill in the blank: Stem cells could be used to _______ damaged tissues in a range of diseases.

A

replace

166
Q

What is a potential benefit of stem cell therapies?

A

They could save many lives.

167
Q

True or False: Adult stem cells can develop into all types of specialized cells.

A

False.

168
Q

What procedure is used to create embryos for obtaining embryonic stem cells?

A

In vitro fertilization (IVF).

169
Q

What is the risk associated with using a patient’s own adult stem cells for a transplant?

A

Less risk of rejection.

170
Q

What ethical issue is raised by obtaining stem cells from embryos?

A

Destruction of a viable embryo.

171
Q

Some people believe that a genetically unique individual is formed at _______.

A

the moment of fertilization.

172
Q

What is one reason some people oppose using embryonic stem cells?

A

It destroys embryos.

173
Q

Name a benefit of using embryonic stem cells over adult stem cells.

A

They can develop into all types of specialized cells.

174
Q

List two ways regulatory authorities help manage stem cell research.

A
  • Licensing and monitoring research centers
  • Producing guidelines and codes of practice
175
Q

Fill in the blank: Regulatory authorities ensure that research involving embryos is carried out for a _______.

A

good reason.

176
Q

True or False: Adult stem cells are more flexible than embryonic stem cells.

A

False.

177
Q

What do regulatory authorities monitor in scientific research?

A

Developments and advances in the field.

178
Q

What is one potential application of stem cells for blind individuals?

A

Replace damaged cells in the eyes.

179
Q

What is one challenge that scientists face in stem cell research?

A

Ethical issues surrounding embryonic stem cells.

180
Q

Explain one reason why some people support using stem cells from unfertilized egg cells.

A

They can’t survive past a few days and wouldn’t produce a fetus.

181
Q

What is continuous variation?

A

Continuous variation is when individuals in a population vary within a range, with no distinct categories. Examples include height and skin color.

182
Q

What is discontinuous variation?

A

Discontinuous variation is when individuals fall into distinct categories, such as blood groups.

183
Q

Give an example of a characteristic that shows discontinuous variation.

A

Blood group

184
Q

What type of variation do most characteristics exhibit?

A

Polygenic variation

185
Q

What is a monogenic characteristic?

A

A characteristic controlled by only one gene, showing discontinuous variation.

186
Q

What is the significance of alleles in genotype variation?

A

Different genotypes arise from different combinations of alleles.

187
Q

How does genotype influence phenotype?

A

Variation in genotype results in variation in phenotype, the characteristics displayed by an organism.

188
Q

True or False: Some characteristics are influenced only by genotype.

A

True

189
Q

What environmental factor is known to affect height?

A

Nutrition

190
Q

How can cancer risk be influenced?

A

Cancer risk can be influenced by both genetic factors and environmental factors such as diet.

191
Q

What is methylation of DNA?

A

Methylation is the attachment of a methyl group to DNA, which can repress gene expression.

192
Q

What are histones?

A

Histones are proteins that DNA wraps around to form chromatin.

193
Q

What effect does histone acetylation have on chromatin?

A

Histone acetylation makes chromatin less condensed, allowing transcription proteins to bind and activate genes.

194
Q

Fill in the blank: Increased methylation of DNA ______ a gene.

A

represses

195
Q

What happens to epigenetic changes during cell division?

A

Epigenetic changes may be passed on to daughter cells.

196
Q

What is the role of environmental changes in gene expression?

A

Environmental changes can alter gene expression through mechanisms like epigenetic modifications.

197
Q

Give an example of a polygenic characteristic.

A

Height

198
Q

What are CpG sites in the context of DNA methylation?

A

CpG sites are where a methyl group attaches to DNA, specifically where cytosine and guanine bases are adjacent.

Biology Edexcel Sophie (8 decks)

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