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Biology > Chapter 2: Cells, Viruses and Reproduction of Living Things > Flashcards

Chapter 2: Cells, Viruses and Reproduction of Living Things Flashcards

1
Q

2.1 Eukaryotic and prokaryotic cell structure and function

Describe the cell theory

A

Cell theory is a unifying concept that states that cells are the fundamental unit of structure, function, and organization in all living organisms.

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2
Q

2.1 Eukaryotic and prokaryotic cell structure and function

How can magnification and resolution be achieved in microscopy?

A

Magnification and resolution can be achieved using light and electron microscopy techniques.

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3
Q

2.1 Eukaryotic and prokaryotic cell structure and function

Discuss the importance of staining specimens in microscopy.

A

Staining specimens in microscopy is important as it enhances contrast, allowing for better visualization of cellular structures.

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4
Q

2.1 Eukaryotic and prokaryotic cell structure and function

Explain the organization of cells in complex organisms.

A

In complex organisms, cells are organized into tissues, organs, and organ systems.

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5
Q

2.1 Eukaryotic and prokaryotic cell structure and function

Identify the key components of prokaryotic cells.

A

Prokaryotic cells have ultrastructural components such as nucleoid, plasmids, 70S ribosomes, and a cell wall.

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6
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What are the features of bacterial cell walls?

A
  • Prevent water entry by osmosis, maintaining cell shape.
  • Made of peptidoglycan, a polymer of sugar and peptide chains.
  • Some have a capsule/slime layer for nutrient storage and immune protection.
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7
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What is the function of pili and flagella in bacteria?

A
  • Pili (fimbriae): Aid attachment and reproduction in bacteria like E. coli.
  • Flagella: Enable movement via rapid rotation (100 revolutions per second), made of flagellin protein.
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8
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What is the function of the bacterial cell surface membrane?

A
  • Controls the exchange of substances like in eukaryotic cells.
  • Can replace mitochondria for respiration in some bacteria.
  • Contains mesosomes, possibly aiding in DNA separation and respiration.
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9
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What are plasmids and their function in bacteria?

A
  • Small, circular DNA molecules separate from the main bacterial chromosome.
  • Often contain genes for antibiotic resistance or toxin production.
  • Can be transferred between bacteria via pili.
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10
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What is the nucleoid in bacterial cells?

A
  • Contains bacterial DNA, usually a single, circular molecule.
  • Not enclosed in a membrane.
  • Occupies a significant area of the cell.
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11
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What are 70S ribosomes in bacteria and their function?

A

Smaller than eukaryotic 80S ribosomes.
Responsible for protein synthesis.
Consist of two subunits and function similarly to eukaryotic ribosomes.

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12
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What is Gram staining, and how does it differentiate bacterial cell walls?

A

Differentiates bacteria based on cell wall composition.
Gram-positive bacteria: Thick peptidoglycan layer with teichoic acid, retains crystal violet stain (blue/purple).
Gram-negative bacteria: Thin peptidoglycan layer, outer membrane with lipopolysaccharides, stains red with safranin.

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13
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What are examples of the gram positive and gram negative bacteria?

A

Gram-Positive: Staphylococcus aureus, Streptococcus pneumoniae.
Gram-Negative: Escherichia coli, Salmonella spp.

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14
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What do all typical animal cells contain?

A

Contains structures common to all eukaryotic cells, including plants and fungi.
Cell surface membrane:
Cytoplasm.
Nucleus
- all together forming the protoplasm.
Cytoplasm: Houses essential components for cell functions and survival.

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15
Q

2.1 Eukaryotic and prokaryotic cell structure and function

Describe the membrane of a eukaryotic cell

A
  • Act as an outer boundary to the cell.
  • Internal (intracellular) membranes compartmentalize the cell.
  • Functions:
  • Control movement of substances.
  • House enzymes for reactions (e.g., respiration, photosynthesis).
  • Form compartments (e.g., lysosomes for hydrolytic enzymes).
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16
Q

2.1 Eukaryotic and prokaryotic cell structure and function

Describe what the protoplasm is

A

Initially thought to be structureless but contains many organelles.
Revealed by the electron microscope to be full of sub-cellular structures.

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17
Q

2.1 Eukaryotic and prokaryotic cell structure and function

Describe the nucleus of eukaryotic cells

A
  • Largest organelle, size: 1–20 µm.
  • Visible under light microscopy; electron microscopy reveals:
  • Spherical shape surrounded by double nuclear membrane.
  • Nuclear membrane contains pores for material exchange.
    Contains:
  • Nucleic acids (DNA and RNA) and proteins.
  • DNA binds to proteins to form chromatin when not dividing.
  • Nucleolus, which produces ribosomes and plays a role in cell growth/division.
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18
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What is the function, structure, and theory of the mitochondria?

A
  • They are the site of cellular respiration, producing ATP to meet energy demands.
  • A double membrane with the inner membrane folded into cristae to increase surface area, and a matrix where reactions occur.
  • It allows mitochondria to replicate independently within the cell.
  • They evolved from bacteria that were incorporated into early eukaryotic cells.
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19
Q

2.1 Eukaryotic and prokaryotic cell structure and function

Describe centrioles in terms of structure, location and function.

A
  • Near the nucleus, usually in pairs.
  • Centrioles are bundles of nine microtubules, measuring about 0.5 µm long and 0.2 µm wide.
  • They are involved in cell division by forming a spindle of microtubules to move chromosomes.
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20
Q

2.1 Eukaryotic and prokaryotic cell structure and function

Describe the cytoskeleton in terms of structure, components, functions

A
  • It is a dynamic, 3D web-like structure filling the cytoplasm in eukaryotic cells.
  • Microfilaments (protein fibers) and microtubules (tiny tubes about 20 nm in diameter).
  • It provides structure to the cytoplasm, keeps organelles in place, and assists with cell movement and transport.
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21
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What proteins are microtubules related to in muscle cells?

A

Actin and Myosin

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22
Q

2.1 Eukaryotic and prokaryotic cell structure and function

Can prokaryotic cells have a cytoskeleton?

A

Some prokaryotic cells also have a cytoskeleton

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23
Q

2.1 Eukaryotic and prokaryotic cell structure and function

Describe vaculoes in terms of the structure, function and if animal cells have them.

A
  • They form and dissolve as needed.
  • They act as food vacuoles or help control water content (contractile vacuoles).
  • Permanent vacuoles are never seen in higher animal cell
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24
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What are the differences between 80S and 70S ribosomes?

A
  • 80S ribosomes: Found in eukaryotic cells; made of a 40S small subunit and 60S large subunit (1:1 RNA:protein ratio).
  • 70S ribosomes: Found in mitochondria, chloroplasts, and prokaryotes; made of a 30S small subunit and 50S large subunit (2:1 RNA:protein ratio).
  • 70S ribosomes are evidence of endosymbiosis, showing mitochondria and chloroplasts evolved from bacteria.
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25
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What is the function of the Golgi apparatus?

A
  • Stacked, flattened membranes (cisternae) modify, sort, and package proteins and lipids.
  • Proteins from RER are processed and sent to their destinations via vesicles.
  • Adds carbohydrates to proteins (forming glycoproteins) and produces lysosomes.
  • Orientation: Cis face receives proteins; Trans face releases finished products.
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26
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What are the structues and differences between the rER and sER?

A
  • Rough ER (RER): Studded with ribosomes; synthesizes proteins for secretion and membranes.
  • Smooth ER (SER): No ribosomes; synthesizes lipids and steroids, detoxifies chemicals, and stores calcium.
  • Structure: RER has ribosomes attached, SER is tubular.
  • Cells involved in secretion (e.g., digestive enzymes) have more RER, while those in lipid metabolism (e.g., liver) have more SER.
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27
Q

2.1 Eukaryotic and prokaryotic cell structure and function

If a cell needs to be destroyed which organelle is used?

A

Lysosomes. It can release its enzymes to rupture the cells and can self destruct.

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28
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What is the plant cell wall made of, and what are its key characteristics?

A
  • Composed of cellulose microfibrils held together by hydrogen bonds.
  • Freely permeable to water and solutes unless impregnated with suberin or lignin (e.g., in cork or wood).
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29
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What is the middle lamella, and what is its function?

A
  • First layer formed during cell division.
  • Made of pectin, which acts as a glue to bind neighboring cells together.
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30
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What is the primary cell wall, and what are its properties?

A
  • Flexible and composed of cellulose microfibrils.
  • Microfibrils are oriented in the same direction to allow the wall to stretch as the cell grows.
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31
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What is the secondary cell wall, and how does it differ from the primary cell wall?

A
  • Forms as the cell matures and becomes more rigid.
  • Contains additional cellulose layers and lignin, providing extra strength and rigidity.
  • Found in structures like plant fibers, making them durable for uses like rope and paper.
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32
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What are plasmodesmata, and why are they important?

A
  • Cytoplasmic bridges between plant cells, enabling communication and substance exchange.
  • Lined by the cell membrane and allow cytoplasm to pass through, forming the symplast (shared cytoplasmic system).
  • Essential for coordinated cell activity, growth, and tissue development (e.g., plant grafts).
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33
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What is the permanent vacuole, and what surrounds it?

A

The permanent vacuole is a large, fluid-filled space in plant cells, surrounded by a membrane called the tonoplast.

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34
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What are the main functions of the permanent vacuole?

A
  • Maintains cell shape and turgor pressure by filling with cell sap.
  • Stores pigments, waste products, chemicals, and proteins.
  • Plays a role similar to lysosomes in animal cells, containing enzymes for digestion.
  • Regulates water potential and stores secondary metabolites.
  • Ensures rigidity through osmosis, keeping the cytoplasm pressed against the cell wall.
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35
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What is the structure of the chloroplast?

A

Surrounded by a double membrane with an inner membrane forming thylakoids (stacked into grana).
Contains stroma, chlorophyll, ribosomes, starch grains, and DNA for semi-autonomous function.

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36
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What is the function of the chloroplast?

A

Chloroplasts are the site of photosynthesis, converting light energy into glucose and oxygen.
Chlorophyll captures light energy for the light-dependent and light-independent reactions.

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37
Q

2.1 Eukaryotic and prokaryotic cell structure and function

What are amyloplasts, where are they found, and function?

A
  • Amyloplasts are colorless plastids derived from leucoplasts, specialized for starch storage.
  • Found in high-starch areas like potato tubers and storage tissues.
  • Store starch as an energy reserve.
  • Convert starch into glucose when energy is needed.
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38
Q

2.2 Viruses

What type of virus is each of the following:
human immunodeficiency virus,λ (lambda) phage,tobacco mosaic virus,Ebola

A

λ (lambda) phage-DNA
tobacco mosaic virus and Ebola-RNA
human immunodeficiency virus-RNA retrovirus

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39
Q

2.2 Viruses

What are viruses, and why are they not considered living organisms?

A

Viruses are obligate intracellular parasites that can only survive and reproduce inside host cells. They are not considered living because they lack cellular structure and cannot perform metabolic processes independently.

40
Q

2.2 Viruses

What are the basic components of a virus?

A

Viruses have a capsid (protein coat made of capsomeres) that protects their genetic material, which can be DNA or RNA. Some viruses also have a lipid envelope derived from the host cell.

41
Q

2.2 Viruses

What makes enveloped viruses more vulnerable?

A

The lipid envelope, derived from the host cell membrane, makes enveloped viruses more susceptible to detergents and disinfectants.

42
Q

2.2 Viruses

What are RNA viruses, and how do they differ?

A

RNA viruses contain RNA as their genetic material.
Positive-sense RNA viruses: Can be directly translated into proteins.
Negative-sense RNA viruses: Require transcription into positive-sense RNA before translation.

43
Q

2.2 Viruses

What are retroviruses, and how do they replicate?

A

Retroviruses are RNA viruses, like HIV, that use reverse transcriptase to synthesize DNA from RNA, which is then integrated into the host genome.

44
Q

2.2 Viruses

How do viruses reproduce?(general)

A

Viruses infect by attaching to host cells using virus attachment particles (VAPs) on their surface.
Host specificity depends on compatibility with host cell receptors.
Virus injects genetic material into the host cell, hijacking its machinery for replication.
Plant viruses often use vectors (e.g., aphids) to penetrate cell walls.

45
Q

2.2 Viruses

What is latency in the lysogenic pathway of DNA viruses?

A
  • The viral DNA integrates into the host’s genome as a provirus and replicates with the host DNA during cell division.
  • A repressor protein prevents the expression of viral genes, stopping the production of viral components.
  • The virus does not harm the host cell or cause illness during this phase.
  • This latent phase, called lysogeny, allows the virus to remain dormant as part of the host’s reproducing cells.
46
Q

2.2 Viruses

What is the lytic cycle in a virus?

A

The lytic cycle is a viral replication process where the virus infects a host cell, uses the host’s machinery to produce new viral particles, and eventually causes the host cell to burst (lyse), releasing new viruses.

47
Q

2.2 Viruses

What are the key steps of the lytic cycle?

A

The key steps of the lytic cycle are:

Attachment: The virus binds to the host cell surface.
Entry: The viral genetic material enters the host cell.
Replication: The virus uses the host’s machinery to replicate its genetic material and produce viral proteins.
Assembly: New viral particles are assembled inside the host cell.
Lysis: The host cell bursts, releasing the new viruses to infect other cells.

48
Q

2.2 Viruses

How does the lytic cycle affect the host organism?

A

The lytic cycle damages the host cell by causing it to burst, which can lead to tissue damage and symptoms of illness in the host organism.

49
Q

2.2 Viruses

Describe the lysogenic cycle. Identify all periods including what cycle it may shift into.

A

Attachment and Entry:
* The virus attaches to the host cell and injects its genetic material (DNA or RNA) into the host.
* Integration:
* The viral genetic material is incorporated into the host cell’s DNA. Once integrated, the viral DNA is called a provirus.
Dormancy (Lysogeny):
* The provirus remains dormant within the host’s DNA. During this time:
* The viral genes are not expressed.
* The host cell’s normal functions continue unaffected.
* The provirus is copied along with the host DNA during cell division.
Reactivation:
* Under certain conditions (e.g., stress, UV radiation, or chemical triggers), the dormant provirus is activated and enters the lytic cycle.
Switch to Lytic Cycle:
* The viral genetic material is expressed, producing new viruses.
* The host cell eventually lyses, releasing new viral particles.

50
Q

2.2 Viruses

Draw the lysogenic and lytic cycle

A
51
Q

2.2 Viruses

What are positive ssRNA viruses?

A

Viruses with a single sense strand of RNA that is used directly as mRNA for protein translation, producing viral structural proteins and RNA polymerase to replicate viral RNA.

52
Q

2.2 Viruses

What are negative ssRNA viruses?

A

Viruses with a single antisense strand of RNA, transcribed into a sense strand by RNA replicase to act as mRNA for protein translation, producing RNA replicase for viral RNA replication and new virus formation.

53
Q

2.2 Viruses

How do antivirals work?

A

Antivirals work by inhibiting virus replication within the host cells.

54
Q

2.2 Viruses

What is an RNA retrovirus, and how does it replicate?

A

Retroviruses, like HIV, use RNA as their genetic material.
RNA is converted into DNA by reverse transcriptase after entering the host cell.
The DNA integrates into the host genome as a provirus.
The provirus directs the synthesis of new viral RNA, mRNA, and proteins.
New viral particles are assembled and released, continuing the infection cycle.

55
Q

2.2 Viruses

Draw the process of the RNA retrovirus lifecycle

A
56
Q

2.2 Viruses

What are vaccinations and how do they work?

A

Vaccinations introduce a weakened or inactive form of a virus into the body. This triggers the immune system to produce antibodies against the virus, providing immunity if you are later exposed to the actual virus.

57
Q

2.2 Viruses

What can be learned from the 2014 Ebola outbreak about disease control?

A

The outbreak showed that early prevention and containment efforts are essential to manage and stop the spread of highly contagious viruses.

58
Q

2.2 Viruses

What are some key measures for controlling the spread of viral diseases?

A

Handwashing and hygiene
Isolation of infected individuals
Sterilizing equipment and bedding
Identifying and monitoring contacts of infected individuals
Vaccination (when available)

59
Q

2.2 Viruses

What are some challenges in controlling viral diseases in developing countries?

A

Limited access to healthcare infrastructure (e.g., isolation units)
Lack of resources for rapid disease identification and testing
Cultural practices that may facilitate disease transmission (e.g., funeral rituals)

60
Q

2.2 Viruses

How do antiviral drugs work?

A

Antiviral drugs target specific stages of the viral replication cycle, such as:

Binding to viral receptors
Inhibiting viral enzymes
Preventing the release of new virus particles

61
Q

2.2 Viruses

What are some key features of the Ebola virus and its transmission?

A

Severe viral illness with high mortality rates.
Transmitted through contact with infected bodily fluids (blood, feces, secretions).
Can spread from person to person through direct contact or contaminated surfaces.

62
Q

2.2 Viruses

What is an epidemic?

A

An epidemic occurs when the number of cases of a disease in a population is significantly higher than expected over a given period.

63
Q

2.2 Viruses

What are some ethical considerations in using untested drugs during epidemics?

A

Balancing the potential benefits of the drug with the risks to human safety.
Ensuring informed consent from patients participating in clinical trials.
Prioritizing access to experimental treatments for those most in need

64
Q

2.3 Eukaryotic cell cycle and division

A
65
Q

2.3 Eukaryotic cell cycle and division

A
66
Q

2.3 Eukaryotic cell cycle and division

A
67
Q

2.3 Eukaryotic cell cycle and division

A
68
Q

2.3 Eukaryotic cell cycle and division

A
69
Q

2.3 Eukaryotic cell cycle and division

A
70
Q

2.3 Eukaryotic cell cycle and division

A
71
Q

2.5 Sexual reproduction in plants

What are the 2 life cycle phases of plant gametogenesis?

A
  1. sporophyte generation
  2. gametophyte generation
72
Q

2.5 Sexual reproduction in plants

What occurs in gametophyte generation?

A

Haploid gametes are formed via mitosis.
The diploid spores become gametophytes via mitosis and then the gametes become a zygote by 2 fusing together.

73
Q

2.5 Sexual reproduction in plants

What occurs in sporophyte generation?

A

Diploid spores are formed via meiosis.
The zygote undergoes mitosis becoming a sporphyte and then via meiosis becoming diploid spores.

74
Q

2.5 Sexual reproduction in plants

The phases of gametogenesis are combined in…

A

flowering plants

75
Q

2.5 Sexual reproduction in plants

In terms of the products of gametogenesis:
The main plant boyd is ….(1)
Parts of the anther and ovary are…(2)

A
  1. Diploid sporophytes
  2. Haploid gametophytes
76
Q

2.5 Sexual reproduction in plants

Draw the process of alternation of generation

A
77
Q

2.5 Sexual reproduction in plants

Draw a labelled diagram of a plant

A
78
Q

2.5 Sexual reproduction in plants

What makes up the stamen?

A

Anther and filament

79
Q

2.5 Sexual reproduction in plants

What makes up the carpel?

A

stigma, style and ovary

80
Q

2.5 Sexual reproduction in plants

How is pollen formed?

A

Meiosis occurs at the anther creating many pollen grain which contain male gametes

81
Q

2.5 Sexual reproduction in plants

How many pollen sacs does each anther contain?

A

4-Each have many microspore mother cells (diploid)

82
Q

2.5 Sexual reproduction in plants

Diploid microspores (mother cells) divide by…

A

meiosis creative haploid microspores, which are the gametophyte generation. The gametes themselves are formed from the gametophyte generation.

83
Q

2.5 Sexual reproduction in plants

Gametes are formed from microspores via…

A

mitosis.

84
Q

2.5 Sexual reproduction in plants

What does each microspore contain?

A

Two nuclei. One is the generative nuclei which fuses with the ovule nuclei. The other is the tube nuclei which produces the pollen tube.

85
Q

2.5 Sexual reproduction in plants

What produces ovules in an ovary?

A

Meosis produces ovules in ovaries

86
Q

2.5 Sexual reproduction in plants

How is an ovule attached to the ovary?

A

Via placenta which is then covered in a nucellus in a centre of this emryo sac where the gametophyte generation forms.

87
Q

2.5 Sexual reproduction in plants

How does the diploid megaspore form?

A

It divides to form 4 haploid megaspores. Three of these are degenerate and form the antipodal cells, while one undergoes 3 mitotic divisions leaving an embryo sac containing an egg cell, two polar nuclei, 3 antipodal cells and 2 synergids

88
Q

2.5 Sexual reproduction in plants

What is a synergid?

A

direct pollen tube growth downwards (toward female gametophyte) and facilitate entrance of tube to embryo sac.

89
Q

2.5 Sexual reproduction in plants

What is an antipodal cell?

A

provide nutrients to support developing embryo

90
Q

2.5 Sexual reproduction in plants

What is pollination?

A
  • Pollination is the process of transferring pollen from the anthers of one plant to the stigma of another (of the same species).
  • After this, a pollen tube grows down the stigma carrying the male gamete to the ovary where it fuses with an ova (fertilisation).
  • This will then develop into a fruit.
91
Q

2.5 Sexual reproduction in plants

Draw a diagram describing the formation of an egg cell in plants

A
92
Q

2.5 Sexual reproduction in plants

What is a pollinator?

A

Pollinators can be insects (particularly bees), or other animals that can move pollen around (or have the pollen stick to them as they move around).

93
Q

2.5 Sexual reproduction in plants

What is external fertilisation?

A
  • Takes place outside the plant
  • Relies on chance
  • Male and femail gametes fuse in the environment (usually aquatic)
94
Q

2.5 Sexual reproduction in plants

What is the process of plant fertilisation until germination?

A
  1. Male gamete is contained in pollen grain, while the female gamete is deep in the ovarian tissue.
  2. Pollen lands on the surgace of the stigma of the flower during pollination
  3. Molecules on the surface of stigma and pollen grain interact.
  4. If same species, grain grows (germinates)
95
Q

2.5 Sexual reproduction in plants

What is internal fertilisation?

A
  • Higher chance of fertilisation than external
  • Involves males releasing sperm into the females body, in some instances males can deposit a package of sperm for the females to pick up
  • More common in land animals
96
Q

2.5 Sexual reproduction in plants

What is the process of plant fertilisation after germination?

A
  1. Pollen tube grows out of tube cell through the stigma and style
  2. Tip produces hydrolytic enzymes digesting the style tissue so pollen tube makes it way down the cell
  3. Digested tissue acts as a nutrient source for the tube as it grows
  4. Generative nucleus travels down pollen tube in the generative cell
  5. Nucleus divides to form 2 male nuclei
  6. Eventually tip of pollen tube passes through micropule of ovule
  7. 2 male nuclei pass through micropyle
  8. Double fertilisation occurs
  9. One male nuclei fuses with two polar nuclei to form endosperm
  10. Endosperm is involved in supplying the embryo plant food
  11. Other male nucleus fuses with egg cell to form zygote
  12. Seed and embryo development begins
97
Q

2.5 Sexual reproduction in plants

Draw the process of fertilisation as a labelled diagram

A

Biology (8 decks)

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