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A level Biology AQA > Unit 2: Cells > Flashcards

Unit 2: Cells Flashcards

(78 cards)

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1
Q

Eukaryotic- Describe role of Golgi apparatus in lipid absorption (3)

A

1) Modifies/ processes triglycerides
2) Combines triglycerides with proteins
3) Packages for release/exocytosis/forms vesicle

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2
Q

Eukaryotic- Compared to Prokaryotic (7)

A

1) Bacterial cell much smaller than human
2) Bacterial cell has a cell wall, human cell doesn’t
3) Bacterial cell lacks a nucleus, human cell has nucleus
4) Bacterial cell lacks membrane-bound organelles, human cells has them
5) Bacteria has 70s ribosomes whereas humans has 80s
6) Bacteria DNA is circular, human DNA linear
7) Bacterial DNA ‘naked’ whereas human DNA is bound to histones

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3
Q

Homogenisation and Ultracentrifugation- How to separate mitochondria? (4)

A

1) Break open cells/ homogenise cells
2) Remove debris by filtration
3) Centrifuge highest density organelle nuclei obtained as pellet at slowest speed
4) Mitochondria in 2nd pellet as less dense than nucleus/organelles in first pellet

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4
Q

Microscopes- Resolution of image obtained by using electron microscope is higher than resolution of image obtained by optical microscope. Why?

A

Shorter wavelengths between electrons

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5
Q

Microscopes- Advantage of electron microscope over optical microscope (2)

A

1) High resolution
2) Can see internal structure of organelles

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6
Q

Microscopes- Advantages and limitation of Transmission Electron Microscope (TEM) (6)

A

Advantages: 1) Small objects can be seen
2) TEM has high resolution as wavelengths of electron shorter
Limitations:
3) Cannot look at living cell as cells be in vacuum
4) Must be thin specimen
5) Preparation may create artefact
6) Doesn’t produce colour image

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7
Q

Prokaryotic- Name the biological molecule in bacterial cell wall?

A

Murein

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8
Q

Eukaryotic- Describe role of mitochondria in secreting protein?

A

Many mitochondria releases ATP for movements of vesicles/protein-synthesis/Active Transport

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9
Q

Eukaryotic- Name main biological molecule in cell membrane (1)

A

Phospholipids

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10
Q

Eukaryotic, Give one feature of chloroplast that allows protein to be synthesised inside and describe on difference between this feature in chloroplast and eukaryotic cell? (2)

A

1) DNA
2) Circular but nuclear DNA is linear

3) Ribosomes
4) Are smaller than cytoplasmic ribosomes

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11
Q

Homogenisation- Conditions required for cell homogenisation (3)

A

1) Ice cold- Slows/stops enzyme activity to prevent digestion of organelles
2) Buffered- Maintains pH so enzymes/proteins not denatured
3) Isotonic- Prevents osmosis so no shrinkage of organelles

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12
Q

Eukaryotic- State three difference between DNA in nucleus of plant cell and DNA is prokaryotic cell (3)

A

(plant v prokaryote)
1) Histones v no histones
2) Linear v circular
3) No plasmids v plasmids
4) Introns v no introns
5) Longer v shorter

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13
Q

Eukaryotic- Eukaryotic cells produce and release proteins. Outline role of organelles in production, transport and release of proteins from eukaryotic cells? (4)

A

1) DNA in nucleus is code for protein
2) Ribosomes/RER produce protein
3) Mitochondria produce ATP for proteinsynthesis
4) Golgi apparatus package/modifiy
5) Vesicles/RER transports
6) Vesicles fuse will cell membrane

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14
Q

Eukaryotic- Identify two organelles in cells that enable production of glycoproteins?

A

Rough endoplasmic reticulum ribosomes and Golgi apparatus

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15
Q

Eukaryotic- Name the main polymer that forms the following cell walls- plant and fungal cells?

A

Cellulose (plant)
Chitin (fungi)

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16
Q

Prokaryotic- Give two features of all prokaryotic cells that aren’t features of eukaryotic cells? (5)

A

1) Cytoplasm with no membrane bound organelles
2) Single, circular DNA
3) DNA free in cytoplasm
4) DNA that not associated with histones
5) Cell wall that contains murein

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17
Q

Eukaryotic- Describe role of Golgi body secreting protein?

A

Many Golgi vesicles transport protein to cell membrane

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18
Q

Microscopes- Comparison of TEM and optical microscope? (8)

A

1) TEM uses electrons, optical uses light
2) TEM allows greater resolution
3) TEM see smaller organelles
4) TEM view only dead specimen, optical view live specimen
5) TEM doesn’t show colour, optical can
6) TEM requires thinner specimens
7) TEM requires complex preparation
8) TEM focus using magnets and optical uses glass lenses

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19
Q

Suggest why scientists can use detergent to break open cells instead of homogenisation? (2)

A

1) Cell membranes made from phospholipid
2) Detergent dissolves membranes/ phospholipid bilayer

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20
Q

Microscopes- Describe and explain one difference between TEM and SEM? (2)

A

1)- 3D image with SEM, not 2D
- Lower resolution with SEM
2) Because electrons deflected/ bounce off using SEM

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21
Q

Why are viruses classed as non-living?

A

-Have no metabolism
-Cannot independently move/respire
-No nutrition

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22
Q

Viruses- Give 2 features of all viruses? (3)

A

1) Attachement Proteins
2) Capsid
3) Nucleic Acid

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23
Q

Eukaryotic- Give two structures found in all prokaryotic cells and in all eukaryotic cells? (4)

A

1) Cell surface membrane
2) Ribosomes
3) Cytoplasm
4) DNA

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24
Q

Eukaryotic- Describe the role of one named organelle in digesting bacteria? (3)

A

1) Lysosomes
2) Fuses with vesicle
3) Releases hydrolytic enzymes

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25
Eukaryotic- Describe structure and function of the nucleus? (4)
1) Nuclear envelope- holds/stores genetic information for production of proteins 2) Nuclear pores- DNA replication 3) Chromosomes- Production of mRNA 4) Nucleolus- Production of rRNA/ribosomes
26
Eukaryotic division- During the cell cycle, the amount of DNA in a cell changes...
Increases
27
Eukaryotic division- State name given to the division of cytoplasm during the cell cycle?
Cytokinesis
28
Bacteria- Describe binary fission in bacteria? (3)
1) Replication of circular DNA 2) Replication of plasmids 3) Division of cytoplasm to produce daughter cells
29
Eukaryotic Division- Suggest why preventing the formation of a spindle fibres stopped the cell cycle (4)
1) Chromosomes/chromatids cant attach to spindle 2) So, no metaphase 3) Chromatids cannot separate on spindle 4) So, no anaphase
30
Eukaryotic Division- Describe the role of the spindle fibres and the behaviour of the chromosomes during mitosis (6)
1) In prophase, chromosomes condense 2) In prophase/metaphase, centromeres attach to spindle fibres 3) In metaphase, chromosomes/ sister chromatids line up at equator of the cell 4) In anaphase, centromeres divide 5) In anaphase, chromatids from each pair pulled to opposite ends of cell 6) In prophase/metaphase/anaphase, spindle fibres shorten
31
Eukaryotic Division- Chromosomes behaviour in all stages (8)
1+2) In prophase, chromosomes coil/condense, chromosomes appears as two sister chromatids joined at centromere 3,4+5) During metaphase, chromosomes line up at equator, centre of cell, chromosomes attach to spindle fibres, by their centromere 6+7) centromere splits and divides and sister chromatids/chromosomes pulled apart to opposite poles and separate 8) Chromatids/chromosomes uncoil/unwind
32
Eukaryotic Division- What is a tumour? (2)
1) Mass of cells 2) Many cells in mitosis/uncontrolled division
33
Eukaryotic Division- Describe and explain arrangement of genetic material in prophase? (2)
1) Chromosomes becoming visible/distinct 2) Because they still condensing 3) Chromosomes arranged at random/not lined up 4) Because no spindle activity
34
Viruses- Describe viral replication (5)
1) Attachment proteins attach to receptors 2) Virus injects nucleic acid into host cell 3) Host cell replicates viral nucleic acid 4) Host cell produces protein/capsid/enzyme 5) Virus assembled and released
35
Bacteria- Describe now bacteria divide (4)
1) Binary Fission 2) Replication of circular DNA 3) Division of cytoplasm to produce 2 daughter cells 4) Each with single copy of circular DNA
36
Eukaryotic division- Describe the appearance of chromosomes in anaphase
Chromatids are being pulled to opposite poles/ends by spindle fibres
37
Eukaryotic Division- Evidence for a cell in anaphase (2)
1) Chromosomes/chromatids are at poles of spindle/ends of spindle 2) V-shape shows sister chromatids have been pulled apart at their centromeres
38
Explain how the behaviour of chromosomes causes these changes in the amount of DNA per cell
1) Chromosomes/DNA replicates 2) Homologous chromosomes separate 3) Sister Chromatids separate
39
Eukaryotic Division- Suggest and explain how two environmental variables could be changed to increase growth rate of cells (10)
1) Increased concentration of glucose 2) Increased respiration 3) Increased concentration of oxygen 4) Increased respiration 5) Increased temperature 6) Increased enzyme activity 7) Increased concentration of phosphate 8) Increased ATP/DNA/RNA
40
Why are viruses classed as acellular?
- No cell surface membrane -Not made of cells -No cytoplasm
41
Eukaryotic Division- Scientists measured percentage change in tumour volume. Suggest why they recorded both
Percentage change: 1) To allow comparison as tumors may differ in volume/size Tumor Volume: 2) Tumors may differ in length/width/shape
42
Eukaryotic Division- Give two pieces of evidence that the cell was undergoing mitosis?
- Chromosomes are visible because they have condensed - Chromosomes made up of chromatids because DNA has replicated -Chromosomes not arranged in homologous pairsM
43
Membrane Structure- Describe how proteins arrange themselves in the membrane (2)
1) Hydrophobic parts of helix sit within the hydrophobic fatty acid tails of phospholipids 2) hydrophilic parts of helix to the inside as ions are charged/polar
44
Transport methods- Name and describe 5 ways substances can move across the cell surface membrane into cells (5)
1) Simple diffusion of small, non-polar molecules down a diffusion gradient 2) Facilitated diffusion of larger/charged molecules down a concentration gradient via protein carrier/channel 3) Osmosis of water down a water potential gradient 4) Active transport of molecules against concentration gradient via protein carrier using ATP 5) Co-Transport of 2 different substances using a carrier protein
45
Transport Methods- What two factors affected rate of facilitated diffusion? (2)
1) External concentration 2) Number of channel/carriers proteins
46
Transport Methods- Suggests and explain two ways the cell-surface membranes may be adapted to allow transport of nutrients (4)
1) Membrane filed/large SA 2) Large number of protein channels/carriers for facilitated diffusion 3) Large number of protein carriers for active transport 4) Large number of protein for co-transport
47
Transport Methods- Movements of substances across cell membranes is affected by membrane structure. Describe how (8)
1) Phospholipid bilayer allows diffusion of non-polar/lipid soluble substances 2) Phospholipid bilayer prevents diffusion of polar/lipid insoluble molecules 3) Carrier proteins allow active transport 4) Channel/carrier proteins allow facilitated diffusion/ co-transport 5) Shape/charge of channel/carrier determines which substances move 6) Number of channels/carriers determines how much movement 7) Membrane surface area determines how much diffusion/movement 8) Cholesterol affects fluidity
48
Transport Methods- Give two similarities in movement of substances by diffusion and by osmosis (2)
1) Movement down a gradient 2) Passive/ no active process
49
Transport Methods- Describe how substances move across cell surface membrane by facilitated diffusion (3)
1) Carrier/ channel protein 2) Protein specific / complementary to substance 3) Substances move down concentration gradient
50
Transport Methods- Contrast the processes of facilitated diffusion and active transport (3)
1) Facilitated diffusion involves channel or carrier proteins whereas active transport only involves carrier proteins 2) Facilitated diffusion does not use ATP whereas active transport use ATP 3) Facilitated down concentration gradient whereas active transport is against concentration gradient
51
Transport Methods- Why does inhibiting respiration/ using cyanide prevent active transport? (4)
1) Oxygen required for aerobic respiration which releases ATP 2) ATP needed to change shape of protein carrier 3) Which would cause release of transported molecule 4) No ATP, no active transport
52
Membrane Structure- Describe the role of cholesterol
Cholesterol stabilises the membrane restricts movement of molecules/phospholipids
53
Non-Specific- Describe how a phagocyte destroys pathogen present in blood (3)
1) Engulfs pathogen 2) Forming phagosome and fuses with lysosome 3) Enzymes hydrolyses pathogen
54
Non-Specific- Phagocytosis (3)
1) Phagosome fuses with lysosome 2) Pathogen destroyed by lysozymes/ hydrolytic enzymes 3) Antigen from pathogen displayed on cell membrane of phagocyte
55
Vaccines- Explain why giving children more than one vaccine develops good immunity (2)
1) Production of more memory cells 2) So higher concentration of antibodies in blood/ So rapid production of antibodies on further infection
56
HIV- Explain how HIV affects the production of antibodies when AIDs develops in a person (3)
1) Less/no antibody produced 2) Because HIV destroys helper T cells 3) So few/no B-cells activated
57
Specific- What is an antibody? (2)
1) A protein specific to an antigen 2) Produced by B cells/ secreted by plasma cells
58
Specific- Give two types of cell, other than pathogens that can stimulate an immune response (4)
1) Cells from other organisms 2) Cancer/ tumour cells 3) Cells infected by virus 4) Antigen presenting cell
59
Specific- What is an antigen? (2)
1) Foreign protein 2) That stimulates an immune response of antibody
60
MABs- Suggest how one antibody can bind two different molecules (2)
1) Have a similar structure 2) Antigen is complementary to both
61
MABs- Describe role of antibodies in producing a positive in an Elisa test (4)
1) First antibody complementary in shape to antigen 2) Second antibody with enzyme attached is added 3) Second antibody attaches to antigen 4) Substrate added and colour changes
62
HIV- Describe how HIV is replicated (5)
1) Attachment proteins attach by receptors on helper T cell/lymphocyte 2) Nucleic acid/ RNA enters cell 3) Reverse transcriptase converts RNA to DNA 4) Viral proteins/ enzyme produced 5) Virus particles assembled and released from cell
63
Specific- Antigen-Antibody complex formation (4)
1) Antibody has 4 polypeptide chains and has a quaternary structure 2) Antibody has a variable region which has a specific amino acid sequence 3) Shape of binding site is complementary to antigen 4) Forming an antigen-antibody complex
64
MAB- Explain why antibody will only bind to target cell (4)
1) Antibody has specific tertiary structure 2) Has binding site that complementary to one antigen 3) Antigen to this antibody only found on these nerve cells 4) So, antibody only binds to/ forms antigen- antibody complex with these cells
65
Vaccine- Immunity- Compare and Secondary response (4)
1) Before vaccination, no antibody released cause patients not yet encountered vaccine 2) Primary response is activation of specific B cells in to plasma cells 3) Plasma cells releases antibodies 4) Secondary response is when memory cells produce more antibodies more quickly
66
Specific- Humoral Response (6)
1) Antigen surface of bacterium binds to surface protein on specific B cell 2) Activated B cells divides by mitosis 3) Division stimulated by T-cells 4) B cells/ Plasma cells release antibodies 5) Some B cells become memory cells 6) Memory cells produce plasma/ antibodies faster
67
MAB- Suggest how monoclonal antibodies help scientists to identify target cells (4)
1) Antigen in cell surface membrane 2) Antibody is complementary 3) So binds to protein 4) Cells identified with dye marker linked to antibody
68
Vaccines- Immunity- Compare active and passive immunity (6)
1) Active involves memory cells, passive doesn't 2) Active involves production of antibody by plasma cella/memory cells 3) Passive involves antibody introduced into body from outside source 4) Active is long term because antibody is produced in response to antigen 5) Passive is short term because antibody given is broken down 6) Active can take time to develop/work, passive is fast acting
69
Vaccines- Determining the genome of the virus could allow scientists to develop vaccine. Explain How (2)
1) The scientist could identify proteins that derive from genetic code 2) They could then identify potential antigens to use in vaccines
70
Vaccines- Describe how B lymphocytes would respond to vaccination (4)
1) Specific B cell antibody binds to specific antigen 2) B cell divides by mitosis 3) Plasma cells release monoclonal antibodies against virus 4) Specific B cells produce memory cells
71
HIV- HIV treatment against anti-retroviral drug AZT (6)
1) Person infected by HIV has HIV DNA 2) New HIV particles still made 3) AZT inhibits reverse transcriptase 4) AZT stops replication of HIV 5) Stops destruction of more/newly infected T cells 6) So immune system continues to work and AIDs doesn't develop
72
Specific- Describe how presentation of a virus antigen leads to a secretion of an antibody against this virus (4)
1) Helper T cell binds to specific antigen on phagocyte 2) This helper T cell stimulates specific B cell 3) B cell divides by mitosis 4) Forms specific plasma cells that releases specific antibodies
73
Specific- Describe and explain the role of antibodies in stimulating phagocytosis (2)
1) Bind to antigen 2) Antibodies cause agglutination
74
Specific- Antibody Specificity? (4)
1) Antibody has specific tertiary structure 2) Has binding site/variable region which only binds to one antigen 3) Antigen is only found on this particular pathogen 4) So antibody only binds to antigen
75
Vaccine- How a vaccine produces an immune response (7)?
1) Vaccine contains antigen from pathogen 2) Macrophage presents antigen on its surface 3) Specific T cell with complementary receptor protein binds to antigen 4) T cell stimulates specific B cell 5) With complementary antibody on its surface 6) Plasma cell secretes large amounts of antibody 7) B cell divides by mitosis to form clone all secreting same antibody
76
HIV- Describe how human immunodeficiency virus (HIV) is replicated once inside helper T cell (4)
1) RNA converted into DNA using reverse transcriptase 2) DNA incorporated/inserted into helper T cell DNA 3) DNA transcripts into HIV mRNA 4) HIV mRNA translated into new HIV viral proteins
77
HIV- Describe the structure of human immunodeficiency virus (HIV) (5)
1) RNA as genetic material 2) Reverse transcriptase 3) Protein capsule/capsid 4) Phospholipid viral envelope 5) Attachment proteins
78
MABs- What is a monoclonal antibody? (3)
1) Antibody specific to one antigen only 2) Antibodies all same and from one original plasma cell 3) Derived from a hybridoma cell/ fused B lymphocyte and cancer cell

A level Biology AQA (8 decks)

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