topic 2 cells/immunity

Question 1

Explain why its not possible to determine identity of structure
‘X’ using optical microscope {2}

Answer 1

. resolution too low
. wavelength of light too long;

Question 2

Describe role of 1 named organelle digesting bacteria in cytoplasm {3}

Answer 2

. lysosomes
. fuse with vesicle/phagosome
. Releases hydrolytic enzymes

Question 3

Give 2 structures in all prokaryotic and eukaryotic cells {2}

Answer 3

. cell membrane
. ribosomes
. Cytoplasm
. DNA

Question 4

function of golgi apparatus

Answer 4

.makes lysosomes
.transporting lipids and protiens

Question 5

function of RER

Answer 5

large SA for protien synthesis

Question 6

function of SER

Answer 6

synthesise lipids and carbohydrates

Question 7

Suggest 1 explanation for the faster rate of plasmid replication in cells growing in a culture with a high amino acid concentration. {2}

Answer 7

. Amino acid used for protien synthesis
.so more enzymes for plasmid replication

Question 8

Describe how sample of chloroplasts could be isolated from leaves {4}

Answer 8

1. Grind/blend leaves AND filter
2. In cold, isotonic buffered solution
3. Centrifuge low speed and remove nuclei/cell debris;
   4.spin at higher speed, chloroplasts settle out;

Question 9

Give 1 feature of chloroplast that allows protein to be synthesised
inside chloroplast and desc 1 diff between this feature in chloroplast and similar features in rest of the cell {2}

Answer 9

1. DNA
2. in chloroplast its circular but in nucleus its linear

Question 10

contrast the structure of prokaryotic cell and animal {5}

Answer 10

. animal has dna in nucleus
prokaryote has free floating DNA
. animal has mitochondria
prokaryote doesn’t
. animal has no slime capsule
prokaryote does
. animal has no cell wall
prokaryote has murien cell wall
. animal DNA bound to histones
prokaryote not bound to histones
. animal has endoplasmic retic
prokaryote doesnt

Question 11

Outline role of organelles in production, transport & release of
proteins from eukaryotic cells.
Dont include details of transcription/ translation in answer {4}

Answer 11

. mitochondria- produce ATP for protien synthesis
. ribosomes-produce proteins
.nucleus- contains DNA which codes for protien
. golgi apparatus- modifies proteins
. vesicle- transports protein by fusing with cell membrne

Question 12

Suggest why nucleus is not visible in the plant cell image {1}

Answer 12

. nucleus isnt stained
. not in the section

Question 13

The detail shown in diagram above wouldnt be seen using optical microscope. Explain why {2}

Answer 13

1. Light has longer wavelength
2. So lower resolution

Question 14

Describe 3 properties of solution and explain how each property prevented damage to the organelles before centrifuge. {3}

Answer 14

. COLD- prevent enzyme activity;
. BUFFERED pH- prevent denaturing of enzyme
. SAME WATER POTENTIAL isotonic-to prevent bursting

Question 15

what is cell membrane made out of [1]

Answer 15

. phospholipid

Question 16

which microscope pruduces 3D images {1}

Answer 16

.SEM scanning electron microscope

Question 17

Contrast how optical & transmission electron microscope work and contrast limitations of their use {6}

Answer 17

1. TEM use electrons
   optical use light;
2. TEM greater resolution;
3. TEM smaller organelles observed
4. TEM view only dead / dehydrated specimens
   optical can view live specimens
5. TEM does not show colour
   optical can
6. TEM requires thinner specimens;
7. TEM requires a more complex/time consuming preparation;
8. TEM focuses using magnets and optical uses glasses lenses

Question 18

Suggest explanation for appearance of the cell-surface membraneas two dark lines {3}

Answer 18

1.Membrane has phospholipid bilayer
2. Stain binds to phosphate / glycerol
3. On inside and outside of membrane

Question 19

Describe binary fission in bacteria{3}

Answer 19

. Replication of (circular) DNA
. Replication of plasmids
. Division of cytoplasm to produce daughter cells

Question 20

Describe and explain two features you would expect to find in a cell
specialised for absorption. {2}

Answer 20

. Folded membrane/microvilli SO large sa for absorption
. Large number of cotransport/carrier proteins for active transport
.Large number of mitochondria so energy for active transport

Question 21

define antigen

Answer 21

protien on surface of cell that trigger immune response

Question 22

Describe how HIV is replicated {6}

Answer 22

. Attachment proteins attach to helper T cell receptor
. RNA enters cell
. Reverse transcriptase convert RNA to DNA
DNA/chromosome/genome/nucleus;
. DNA transcribed into mRNA;
. mRNA translated into (HIV/viral proteins.
. Viral protein/capsid produced;
. Virus particles assembled and released

Question 23

Give two types of cells, other than pathogens, that can stimulate an immune response. {2}

Answer 23

. Cells from other organisms /transplants
. Abnormal/cancer/tumour (cells);
. Cells infected by virus;

Question 24

Explain how HIV affects the production of antibodies when AIDS develops in a person. {3}

Answer 24

. Less antibody produced;
. cos destroys helper T cells;
. so less B cells stimulated to divide to plasma to antibody

Question 25

Previously, the viruses infected only one species of frog. Suggest and explain how the viruses started to infect other species of frog. {3}

Answer 25

. Mutation in the viral genetic material . changes tertiary structure of attachment protein . Allows virus to bind to receptors of other species

Question 26

Determining genome of viruses could allow scientists develop a vaccine. Explain how. {2}

Answer 26

. identify proteins that derive from the genetic code . then identify potential antigens to use in the vaccine

Question 27

What is a monoclonal antibody? {1}

Answer 27

.1 type of antibody with the same tertiary structure

Question 28

Give 1 example of using monoclonal antibodies in a medical treatment. {1}

Answer 28

.carries drug to specific antigens/receptors

Question 29

When a vaccine is given to a person, it leads to the production of antibodies against a disease-causing organism. Describe how. {5}

Answer 29

1. Vaccine contains antigen from pathogen 2. phagocyte presents antigen on its surface 3. T cell with complementary receptor protein binds to antigen 4. T cell stimulates B cell 5. With complementary antibody on its surface 6. B cell secretes large amounts of antibody 7. B cell divides to form clone all secreting / producing same antibody.

Question 30

Describe the difference between active and passive immunity. {5}

Answer 30

. Active involves memory cells, -passive does not; . Active involves production of antibody by plasma cells / memory cells; . Passive involves antibody introduced into body from outside . Active long term, cos antibody produced in response to antigen . Passive short term, because antibody (given) is broken down; . Active take time to work, -passive fast acting

Question 31

example of natural and artificial active immunity each

Answer 31

. natural - catching disease . artificial - vaccination

Question 32

example of natural and artificial passive immunity each

Answer 32

. natural - antibodies from breast milk . artificial - injected antibodies e.g antivneom