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OCR AS-level Biology > 4.1.1 communicable diseases, prevention & immune system NOT ON MOCK > Flashcards

4.1.1 communicable diseases, prevention & immune system NOT ON MOCK Flashcards

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1
Q

what type of pathogen is malaria

A

parasite

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2
Q

How is malaria transmitted

A

spread by female anopheles mosquitoes

When an infected mosquito bites a human, it passes the parasite into the bloodstream

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3
Q

What are the symptoms of malaria

A

fever, sweats, chills, headaches, vomiting, diarrhoea

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4
Q

what organisms are affected by malaria

A

Humans

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5
Q

What is the prevention and treatment for malaria

A

Treatment: tablets, prevention: mosquito nets

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6
Q

What type of pathogen is potato/tomato blight

A

Protoctist

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7
Q

How is potato/tomato blight transmitted

A

Reproduces a sexually and sexually and spreads rapidly in the foliage of potatoes and tomatoes, causing collapse and decay. Rain can wash spores into the soil where they affect young tubes

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8
Q

What are the symptoms of potato/tomato blight

A

Potato: rapidly spreading, watery rot of leaves which collapse, shrivel and turn brown. Brown lesions on stem. Tomato: similar to potato and brown patches may appear on green fruit

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9
Q

What organisms are affected by potato/tomato blight

A

Potatoes and tomatoes

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10
Q

What is the prevention and treatment for potato blight

A

Good field hygiene and clean plant machinery

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11
Q

what is the type of pathogen for tuberculosis

A

bacterium

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12
Q

what is the transmission for tuberculosis

A

when a person with an active tuberculosis infection in their lungs coughs or sneezes and someone else inhaled droplets which contain tuberculosis bacteria. But would have to spend a long time to get ill

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13
Q

Symptoms of tuberculosis

A

lack of appetite, fever, persistent cough

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14
Q

What organisms are affected by tuberculosis

A

Humans

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15
Q

What prevention and treatments are there for tuberculosis

A

In most healthy people the immune system can destroy the bacteria

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16
Q

What type of pathogen is bacterial meningitis

A

Bacteria

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17
Q

How is bacterial meningitis transmission

A

Sneezing, coughing, kissing

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18
Q

Symptoms of bacterial meningitis

A

High fever with cold hands and feet, vomiting, drowsiness, pale blotchy skin

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19
Q

Organisms affected by bacterial meningitis

A

Humans

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20
Q

Prevention and treatment for bacterial meningitis

A

Intravenous antibiotics

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21
Q

What type of pathogen is ringrot

A

bacterium

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22
Q

how is Ring rot transmission

A

via infected seed potato tubets, Direct contact can spread it and can survive on machinery

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23
Q

symptoms of Ring rot

A

when tubers are cut across the heal, the vascular ring becomes discoloured and a soft cheese like rot develops

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24
Q

what organisms are affected by ring rot

A

Potato

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25
Q

Prevention and treatment for ring rot

A

Good field hygiene and clean plant machinery

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26
Q

What type of pathogen is HIV/AIDS

A

Virus

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27
Q

How is HIV and aids transmission

A

Having sex without a condom, contaminated needle and from HIV positive mother to her child during breastfeeding

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28
Q

Symptoms of HIV and aids

A

Fever, body rash, tiredness, joint pain, swollen glands

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29
Q

What organisms are affected by HIV and aids

A

Humans

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30
Q

Prevention and treatment for HIV and aids

A

No cure for HIV but treatment so they can live a long and healthy life and prevention is to use condoms

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31
Q

What type of pathogen is influenza

A

Virus

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32
Q

How is influenza transmission

A

Coughs and sneezes

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33
Q

Symptoms of influenza

A

High temperature, tiredness, dry and chesty coughs, sneezing

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34
Q

Organisms affected by influenza

A

Humans

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35
Q

Prevention and treatment for influenza

A

Most people naturally make a full recovery but elderly might develop a chest infection

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36
Q

Type of pathogen for tobacco mosaic virus

A

Virus

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37
Q

How is tobacco mosaic virus transmission

A

when an infected leaf rubs against a leaf of a healthy plant and by contaminated roots

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38
Q

Symptoms of tobacco mosaic virus

A

Can include Mosaic, modelling, leaf curling and yellowing of plant tissues

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39
Q

Organisms affected by tobacco mosaic virus

A

Can also infect tomatoes

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40
Q

Prevention and treatment of tobacco mosaic virus

A

Remove all weeds since they could harbour TMV and discard infected plants

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41
Q

type of pathogen for black sigatoka

A

Fungus

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42
Q

how is black sigatoka Transmission

A

Spread by the movement of infected plant material or by spores produced within dead/Dying leaves/spread through rain and wind

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43
Q

symptoms of black sigatoka

A

Premature ripening

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44
Q

which organisms are affected by black sigatoka

A

Fruits such as banana plants

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45
Q

prevention and treatment of black sigatoka

A

Prevention is fungicides and removal of affected leaves

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46
Q

Type of pathogen for ringworm

A

Fungal infection

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47
Q

How is ringworm transmission

A

Human to human contact and human to animal contact e.g. stroking cat and thrives in heat and moisture which means communal showers are also transmission point

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48
Q

Symptoms of ringworm

A

causes a red/silvery ring like rash on the skin

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49
Q

Which organisms are affected by ringworm

A

Humans mostly on the arms and legs but can be anywhere in the body

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50
Q

 Prevention and treatment of ringworm

A

Antifungal creams and don’t walk barefoot in communal showers

51
Q

Type of pathogen for athletes foot

A

Fungal infection

52
Q

Transmission for athletes foot

A

pass through contaminated towels, surfaces e.g. swimming pools

53
Q

Symptoms of athletes foot

A

Itchy red rash between toes

54
Q

Organisms affected by athletes foot

A

Humans

55
Q

Prevention and treatment of athletes foot

A

Antifungal medication

56
Q

What is a pathogen

A

A pathogen is a microorganism that causes disease, they can damage cells e.g. malarial parasites colon virus, protists and fungi and produce toxins: bacteria

57
Q

How are diseases transmitted

A

waterborne, airborne by droplet infection, transmission of bodily fluids e.g. saliva and blood, infected food, vector e.g. mosquito, fomites eg spoon Spores, faecal to oral transmission and direct contact

58
Q

Life-cycle of a pathogen

A

One spreading around transmitting, two enters a host, three reproduces, four leaves and destroyed by body

59
Q

Factors affecting transmission of disease in animals

A

Overcrowding, poor nutrition, compromised immune system e.g. suffering from aids, improper ways of disposal of waste, climate change E.g. hotter is more mosquitoes, culture E.g. use of traditional medicinesand socio-economic e.g. lack of health workers

60
Q

 Name four groups of pathogen that can cause communicable diseases

A

bacteria, fungi, protoctist and viruses

61
Q

How does tuberculosis cause disease

A
  1. Triggers inflammatory response by infecting phagocytes
    in lungs.
  2. Infected phagocytes are sealed in waxy-coated tubercles so bacteria remain dormant. First infection
    has no symptoms.
  3. If another factor weakens immune system, bacteria become active & destroy lung tissue
62
Q

How does HIV result in the symptoms of aids

A
  1. Attachment proteins bind to complementary CD4 receptor on Th cells
  2. HIV particles replicate inside Th cells, killing or damaging them.
  3. AIDS develops when there are too few Th cells for the immune system to function.

4 Individuals cannot destroy other pathogens & suffer from secondary diseases/ infections. May cause death.

63
Q

How does the tobacco mosaic virus cause disease

A

Affects plants. Mainly transmitted via infected sap.

Contains ssRNA, which is directly transcribed by host cell to assemble new virions.

Virions enter other cells via plasmodesmata then enter xylem & phloem.

Causes stunted growth & mottled leaves.

64
Q

How does the influenza virus cause disease

A

Transmitted via: droplet infection, contact with mucus containing virus, zoonotic infection, contact with fomites

Injects viral RNA into ciliated epithelial cells of throat & lungs. Viral RNA hijacks cell biochemistry to produce new virions. Cell lysis releases virions

5-7 days of headache, coughing, sneezing, sore throat, vomiting, fever, muscular/joint pain

65
Q

What causes malaria

A

Female Anopheles mosquito acts as vector for Plasmodium spp. protoctista when it transfers saliva to another organism during feeding. Parasite reproduces asexually in red blood
cells in liver, causing lysis.

66
Q

What causes potato/tomato late blight and what causes ringworms of potatoes

A

Blight: The protoctista Phytophthora infestans behaves similarly to a fungus. Mainly transmitted via spores.

Ring rot: Sepedonicus subspecies of the bacterium Clavibacter michiganensis. Mainly transmitted by planting infected seeds/ contact with fomites. Plant-to-plant transmission is rare.

67
Q

What causes bacterial meningitis

A

Often meningococcal bacteria A, B, C, W, X, Y, Z. Also caused by pneumococcal bacteria & Haemophilus influenzae type b (Hib) bacteria. Affects meninges
(protective membranes around brain).
Transmitted by droplet infection & direct contact with saliva e.g. kissing. Usually spread by carriers of the bacteria who
are not ill & occasionally by individuals with meningitis.

68
Q

how are Communicable pathogens transmitted directly

A

inhalation droplet infection, skin to skin contact exchange of fluids, penetrate skin actively using enzymes or passively through wounds, hair follicles or sweat glands

69
Q

How are communicable pathogens transmitted indirectly

A

Consumption of contaminated food and drink, via Vector, spores

70
Q

How do you live in conditions affect disease transmission

A

Overcrowding increases direct transmission.

Climber determines which organisms can survive e.g. malaria is more prevalent in tropical countries were mosquitoes the vector can breed and social factors influence how quickly people are treated, which can increase/decrease direct transmission

71
Q

Name for physical barriers to pathogen entry in plants

A

Cellulose cell walls, lignified layer, waxy up a cuticle, old vascular tissue is blocked to prevent pathogens from spreading inside the plant

72
Q

Describe to mechanical responses to infection in plants

A

Guard cells close stomata.

The thick polysaccharide callose is produced & deposited between the cell wall & plasma membrane to increase entry distance/ limit spread.

73
Q

what is necrosis

A

Injury activates intracellular enzymes in
plants that kill cells near the site of infection to prevent pathogen from spreading.
Necrosis of woody tissue is known as
canker.

74
Q

describe the chemical defendes planys use against pathogens

A

Terpenoids (essential oils) e.g. menthols act as antibacterials.

Phenols e.g. tannin inhibit insects from attacking by interfering
with digestion.

Alkaloids e.g. caffeine & morphins deter herbivores from feeding because they taste bitter.

Defensins (cysteine-rich proteins) inhibit transport channels.

Hydrolytic enzymes e.g. chitinases break down cell wall of invading organisms

75
Q

name 5 barriers to infection in animals

A

skin is tough keratin layer

Blood clotting prevents pathogens from entering through skin lesions.

Hydrochloric acid in stomach kills bacteria.

Harmless bacteria in gut & on skin surface increase interspecific competition with pathogens.

Mucous membranes trap pathogens and may secrete antimicrobial enzymes.

76
Q

what are expulsive reflexes

A

Body attempts to force foreign substances out:

Irritation of mucous membranes in nostrils causes sneezing.

Irritation of ciliated epithelium in respiratory tract causes coughing

77
Q

name 4 ways the nonspecific immune system responds to infection

A

inflammation
phagocytosis
digestive action of lysozymes
production of interferon (antiviral agent)

78
Q

outline the process of inflammation

A
  1. Damaged vessels release histamines,
    causing vasodilation.
  2. Blood flow & permeability of blood vesselsincrease.
    3.White blood cells & plasma move into the infected tissue.
79
Q

how does blood clotting occur

A

Blood platelets form plug & release chemicals that enhance clotting e.g. thromboplastin.

  1. Prothrombin changes into thrombin, its active form.
  2. Fibrinogen changes into insoluble fibrin whichcovers wound
80
Q

Name the 2 types of white blood cell involved in phagocytosis

A

Neutrophils
Macrophages (can become
antigen-presenting cells)

81
Q

How does phagocytosis destroy pathogens?

A

Phagocyte moves towards pathogen which may have been marked by opsonins via chemotaxis.
2. Phagocyte engulfs pathogen via endocytosis to form a
phagosome.
3 Phagosome fuses with lysosome (phagolysosome).
4 Lysozymes digest pathogen.
5. Phagocyte absorbs the products from pathogen hydrolysis.

82
Q

Explain the role of antigen-presenting cells (APCs).

A

Macrophage displays antigen from pathogen on its surface (after hydrolysis in phagocytosis).
Enhances recognition by Ty cells, which cannot directly interface with pathogens/ antigens in body fluid.
Secrete cytokines that are involved in stimulating specific immune response.

83
Q

What are lysozymes?

A

Digestive enzymes. Found in lysosomes
as well as many secretions e.g. tears &
mucus. Damage bacterial cell walls,
causing osmotic lysis.

84
Q

Outline how to prepare blood to be observed under a

microscope.

A

1 Smear a drop of blood onto a slide
using a spreader held at 45°
2. Add leishman stain then a buffer.
Rinse.

85
Q

Name the 2 types of specific immune response.

A

cell-mediated

humoral

86
Q

Outline the process of the cell-mediated response.

A
  1. Complementary Ty lymphocytes bind to foreign antigen on APC.
  2. Cell signaling via secretion of interleukins stimulates:
    a. clonal expansion of complementary Ty cells (rapid mitosis): become memory cells or trigger humoral response.
    b. clonal expansion of cytotoxic T cells (Ta): secrete enzyme perforin to destroy infected cells.
87
Q

Outline the process of the humoral response.

A
  1. Complementary Ty lymphocytes bind to foreign antigen on antigen-presenting T cells.
  2. Release cytokines that stimulate clonal expansion (rapid mitosis) of complementary B lymphocytes.

3 B cells differentiate into plasma cells.

  1. Plasma cells secrete antibodies with
    complementary variable region to antigen.
88
Q

Describe the structure and function of B and T lymphocytes.

A

Many specific receptors & immunoglobulins on surface.

B cells differentiate into plasma cells to secrete antibodies.

3 types of T cell: T helper (secrete cytokines), T killer (secrete perforin), T regulator (suppress other immune cells to prevent autoimmune disease)

89
Q

what is an antibody describe its structure

A

Proteins secreted by plasma cells.
Quaternary structure: 2 ‘light chains’ held by disulfide bridges, 2 longer ‘heavy chains’.

Binding sites on variable region of light chains have specific tertiary structure complementary to an antigen. The rest of the molecule is known as the constant region.

90
Q

How do antibodies lead to the destruction of a

pathogen?

A

Agglutinins form antigen-antibody complexes to enhance phagocytosis.

Activation of complement.

Opsonins mark microbes for phagocytes.

Antitoxins make toxins insoluble via
precipitation/ neutralisation

91
Q

What are memory cells?

A

Specialised Ty/ B cells produced from primary immune response.

Remain in low levels in the blood.

Can divide very rapidly by mitosis if organism encounters the same pathogen again.

92
Q

Contrast the primary and secondary immune response.

A

secondary response:
Faster rate of antibody production.
Shorter time lag between exposure & antibody production.
Higher concentration of antibodies.
Antibody level remains higher after the secondary response.
Pathogen usually destroyed before any symptoms.

93
Q

compare and contrast passive and active immunity

A 
passive: no memory cells and antibodies not replaced when broken down =
short term
immediate
antibodies from extermal source
no direct contact w antigen necessary

active: memory cells produced = long term
time lag
lymphocytes produce antibodies
needs direct contact with antigen

both: both involbe antibodies and can be natural or artificial

94
Q

give examples of passive and active immunity

A

Passive natural: antibodies in breast milk/ across placenta.
Passive artificial: anti-venom, needle stick injections.
Active natural: humoral response to infection.
Active artificial: vaccination.

95
Q

Define “autoimmune disease’ and give examples.

A

Immune system produces antibodies against its own tissues.

Rheumatoid arthritis: immune system targets synovium lined joints, causing inflammation.

Lupus: results in inflammation throughout body.

96
Q

explain the principles of vaccination.

A

vaccine contains dead/ inactive form of a pathogen or antigen.

Triggers primary immune response.

Memory cells are produced and remain in the boloodstream, so secondary response is rapid & produces higher concentration of antibodies.

Pathogen is destroyed before it causes symptoms.

97
Q

Define endemic and epidemic.

A

Endemic: disease occurs routinely in ¿
geographical area.

Epidemic: temporary rapid increase in
incidence of disease in a geographical
area.

98
Q

What role do vaccines play in preventing epidemics?

A

Routine vaccination of 80-90% of population reduces available carriers of pathogen, resulting in herd immunity.

Limited by country’s resources.

Vaccinating close contacts of infected individual limits spread of pathogen, but raises issues of distributive justice.

Programs have changed to account for informed consent & maximum beneficence even during epidemic.

99
Q

List some possible natural sources of medicines.

A

microorganisms e.g. streptomycin, neomycin,

chloramphenicol = various species of Streptomyces genus

fungi e.g. penicillin

plants e.g. Taxol for chemotherapy = yew, quinine for malaria = cinchona, digoxin for heart arrhythmia = foxglove

Maintaining biodiversity means new natural treatments can be discovered in the future

100
Q

What is personalised medicine and synthetic biology?

A

Personalised medicine: genome sequencing has enabled scientists to predict an individual’s response
to disease/ certain medicines so
prescriptions can be targeted.

Synthetic biology: engineering that targets biochemical processes

101
Q

What are the benefits of using antibiotics to treat bacterial infection?

A

Effectively reduce population of bacterial colony. Used widely since discovery of penicillin in mid-20th century.

Bacteriostatic antibiotics prevent protein synthesis/ inhibit formation of nucleic acids = inhibit growth

Bactericidal antibiotics prevent formation of peptidoglycan cross-links in cell walls = osmotic lysis.

102
Q

What are the risks of using antibiotics to treat bacterial infection?

A

Overuse of antibiotics increases
selection pressure for resistant strains of
bacteria. Antibiotic-resistant infections
e.g. caused by MRSA & Clostridium
difficile are difficult to treat.

103
Q

ppq: define the term parasite

A

lives; in / on, host ;

gains nutrition / feeds , from (host) ;

at the expense of / harms (host) ;

104
Q

(¡i) ppq

Explain why the human body’s primary defences do not prevent the entry of Plasmodium into the body.

A

mosquito / vector / Anopheles, feeds on blood ;
breaks skin / skin cannot act as barrier / mosquito pierces
skin / mosquito bites skin ;

105
Q

ppq Suggest why malaria is much more common in tropical areas than in other parts of the world

A

suitable / AW, climate / temperature , for, mosquito / vector
/ Anopheles ; ora
more mosquitoes live there / AW; ora
idea of relatively poor so methods of prevention less
effective;

106
Q

ppq Suggest two reasons why governments in parts of the world other than tropical are are also becoming increasingly concerned about malaria.

A

climate change / global warming / AW , may result in
spread to other parts of the world / AW:

idea that (non-malaria) countries fund anti-malaria
measures via international aid
resistance of, parasite to drugs / mosquito to
insecticides:

107
Q

ppq (i)
In patients with IDA, anemia is caused by the destruction of erythrocytes (red blood cells) by phagocytosis.
Suggest why erythrocytes that contain Plasmodium are more likely to be destroyed by
phagocytosis than healthy erythrocytes.

A

different chemicals that attract phagocytes released from infected erythrocytes

108
Q

describe how the structure of antibodies allows rhem to perform their function ppq

A

2 light chains and 2 heavy chains / 4 polypeptide
chains ;
2
variable region allows , binding / attachment, to
antigen ;
3
two variable regions allow binding of more than
one (of the same) antigen ;
4
variable region on different antibodies allows specificity
to different antigens ;
5
constant region allows , recognition by / attachment to /
binding to , (named) phagocytes ;
6
hinge (region) allows flexibility ;
7
disulfide, bonds / bridges , hold , polypeptides / light
and heavy chains , together;

109
Q

ppq outline the mode of action in defending the body against pathogens by describing the processes of neutralisation and agglutination

A

neutralisation
cover / block , binding site / antigen / receptor site (on
pathogen) ;
bind to toxins ;
prevent, binding / entry, to (host) cell ;

agglutination
clump / bind together , (many) pathogens ;
(clump) too large to
enter (host) cell / cross
membranes ;
increase likelihood of being consumed by (named)
phagocyte / more can be consumed by phagocyte at
once;

110
Q

ppq complete passage Some vaccines contain a dead or weakened form of a pathogen. The ????? on the cell surface of the pathogen are still able to trigger the production of ????? antibodies
in the person being vaccinated.
Cells called ????? cells are also produced, which retain the ability to divide and produce the antibodies quickly, should the pathogen return.

A new ????? of pathogen can arise if there is a ????? in the
DNA of the pathogen. If this happens, the original vaccine is not likely to be effective.

A

Some vaccines contain a dead or weakened form of a pathogen. The ANTIGEN on the cell surface of the pathogen are still able to trigger the production of SPECIFIC antibodies
in the person being vaccinated.
Cells called MEMORY cells are also produced, which retain the ability to divide and produce the antibodies quickly, should the pathogen return.

A new STRAIN of pathogen can arise if there is a MUTATION in the
DNA of the pathogen. If this happens, the original vaccine is not likely to be effective.

111
Q

(b) The term immunity is often used when describing how vaccines work.
In a piece of school homework a student wrote:
“Bacteria can evolve quickly and many are now immune to antibiotics.
Explain why the student’s use of the word ‘immune’ was incorrect.

A

immunity involves / bacteria do not have , lymphocytes /
white blood cells / antibodies / memory cells /
plasma cells / an immune system ;

2
(correct term is) resistant ;
3 bacteria are unicellular / only multicellular organisms
(can) have an immune response;

112
Q

ppq Why are phagocytes described as a secondary defence against pathogens?

A

involved after pathogen has entered the body

113
Q

ppq (ili) Why is the response involving phagocytes regarded as non-specific?

A

(a) (ili)
(phagocytes) able to, digest / break down / engulf /
target / deal with, a range of / many
different, pathogens ; ora

114
Q

ppq (iv) Explain how phagocytes, such as those shown in Fig. 3.1, are able to pass from the blood into the tissue fluid.

A

lobed / narrow, nucleus:
(cells) can change shape ;

can squeeze / move / fit / AW . between cells
/through pores , in (walls of) capillaries ;
histamine makes, capillary walls /
endothelium, leaky ;

115
Q

ppq (v) Bacterial pathogens initially attach to receptors on the surface of phagocytes.
Describe the process by which a pathogen is destroyed after it has become attached to
the surface of a phagocyte.
In your answer you should describe clearly the sequence of events that takes
place.

A 
(pathogen) engulfed / enveloped / surrounded
by cytoplasm (from phagocyte) ;
2
endocytosis/phagocytosis;
3
(formation of) phagosome/phagocytic
vacuole / phagocytic vesicle ;
4
(phago) lysosomes
5
(lysosomes / phagosome) move towards /
fuse with (each other) ;
6
(named) enzyme(s) / lysins / hydrogen
peroxide / free radicals (in lysosomes);
7
(pathogen) digested / broken down /
hydrolysed:
8
(to) amino acid / sugar / glucose / fatty acid /
glycerol;
9
(break down products) absorbed / AW (into
or
cytoplasm)
unwanted products removed (by exocytosis);
10
cytoskeleton involved in (endocytosis/
movement of vesicles) ;
QWC key points in sequence ;
116
Q

ppq (b) The infective agent that causes TB is not easily destroyed by phagocytes.
(i) Name the infective agent that causes TB.

A

mycobacterium

117
Q

ppq Describe how the infective agent that causes TB is transmitted from one individual to another.

A

droplets (containing pathogen) ;
(released by) coughing / sneezing;
inhaled by (uninfected) , individual / AW;

118
Q

ppq (i) The highest incidence of TB is associated with the low income group.
Suggest three reasons why the incidence of TB is higher in the low income group.
1

A

overcrowded / AW (living space) ;
poorly ventilated (living space) ;
poor diet / malnourished ;
poor health ;

homelessness;
idea that more likely to consume, meat / milk,
from infected cattle ;
idea of vaccination / medical treatment, more
difficult to access ;

119
Q

ppq Malaria is a disease caused by a eukaryotic parasite.

(a) State two features of the malarial parasite that indicate that it is not a prokaryote.

A

nucleus / nuclei:
other named organelle /
membrane bound organelles ;

linear chromosomes ;
DNA, associated with / AW, histones / protein ;
80S / 22nm / large, ribosomes ;
large cells / AW;
no cell wall:
120
Q

ppq (b) In a piece of word-processed homework, a student stated that one species of parasite that
causes malaria is called: plasmodium vivax

State one error made by the student.

A

capital letter on, specific name / Vivax;

not italicised / not underlined ;

121
Q

ppq (c) The malarial parasite is carried by an insect, the female Anopheles mosquito.
Describe how the mosquito transmits the malarial parasite to a human.

A

(mosquito), is vector;
Plasmodium / parasite, present in (mosquito), saliva /
salivary gland ;
idea that infected mosquito, feeds on / bites, human ;
Plasmodium / parasite, passes (from saliva) to blood ;

122
Q

ppq (il)
In order to fight the spread of malaria, insecticides have been used in areas where the
Anopheles mosquito breeds.
One problem that can occur when using insecticides in this way is the development of
insecticide resistance.
Suggest one other reason why some people might be concerned about using
insecticides.

A

destruction of a species is, morally / ethically, wrong ;
might cause unintended health problems in humans ;
might harm, other / unintended, species ;
idea of bioaccumulation/biomagnification;

123
Q

ppq Suggest how the effects of insecticide use on a population of Anopheles mosquitoes
could be measured and state the step that should be taken in order to produce valid
and reliable results,

A

Field investigation
F1
(sampling) before and after insecticide treatment:
F2 idea of, unbiased / random, sampling of population ;
F3 example of sampling technique ;

F4 (sampling in) different, times / weather ;

F5 large number of samples taken ;
F6 idea of standardised sampling procedure ;

F7 idea of preventing counting same individual more than
once ;
F8
idea of capture - recapture ;
F calculate mean / calculate standard deviation / apply
statistical test ;

124
Q

ppq M
pmt.physicsandmathstutor.com
& N
(a) Lymphocytes are important components of the immune system and can be classified into
B lymphocytes and T lymphocytes.
For each of the statements in the table below, identify whether the description applies to:

only B lymphocytes
only T lymphocytes
both B and T lymphocytes
neither.

form part of immume response
matured in thymus
secrete substances which kill infected cells
manufacture antibodies
undergo clonal expansion
activate other lymphocytes
A

form part of immume response BOTH

matured in thymus only T (lymphocytes)

secrete substances which kill infected cells only T (lymphocytes)

manufacture antibodies only B (lymphocytes)

undergo clonal expansion BOTH

activate other lymphocytes only T (lymphocytes)

OCR AS-level Biology (12 decks)

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