Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

B4-B6 > B6.3 (2) > Flashcards

B6.3 (2) Flashcards

b6.3.6 onwards

1
Q

what is the purpose of the leaf cuticle? (3)

A
  • prevents uncontrolled water loss
  • ensures water does not collect on the leaf so that microbes do not collect there (as it will be damp)
  • physical barrier to prevent pathogens from entering leaf
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

why is it important that leaf cuticle prevents pathogens passing through?

A
  • so pathogens cannot have direct contact with epidermal cells
  • less chance of infection
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

how does the leaf cuticle prevent water collecting on the surface? (and why is that important)

A
  • is hydrophobic

- as fungal pathogens need standing water for spore germination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

define a cell wall (in terms of plant defenses)

A
  • structural barrier made of cellulose, which gives strength and flexibility and shape
  • physical barrier preventing pathogens from entering
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what does the cell wall contain?

A

a variety of chemical defences which activate rapidly when the cell detects pathogens
cellulose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

give 4 examples of physical plant defences

A
  • spike
  • thorn
  • stinging cells
  • bark
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

difference between chemical and physical defences?

A

physical defences prevent microorganisms from entering

chemical defences are substances secreted by the plant that kill microorganisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

how does bark act as a physical defence?

A

external layer of dead cells that forms a barrier against infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

give 5 types of chemical defences in plants

A
  • insect repellants
    (repel insect vectors that carry disease)
  • insecticides (kill insects)
  • antibacterial compounds
    (kill bacteria)
  • antifungal compounds
    (kill fungi)
  • poisons
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

how do anti microbial substances protect a plant from pathogens?

A

may kill the pathogen or prevent it from reproducing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

can plants produce anti-microbial substances?

A

yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what are the 4 main ways plant diseases can be detected and identified?

A
  • observation
  • microscopy
  • DNA analysis
  • identification of antigens, using monoclonal antibodies
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

define the term diagnosis

A

correctly identifying the existence of disease in an organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

how is observation used to identify plant diseases?

give advantages and disadvantages

A
  • finding visual symptoms

adv - quick, cheap, easy
dis - similar symptoms for different diseases
not accurate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

how is microscopy used to identify plant diseases?

A

identifying pathogen by looking at its shape

- electron gives better diagnosis than light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

advantages and disadvantages of usinig microscopy to identify plant diseases? (in comparison to observation with naked eye)

A

adv - much more accurate

dis

  • may be slower (sample must be given to lab)
  • require equipment
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

downside of identifying plant diseases in the field?(visually/microscope)

A

only identified once symptoms are apparent (so plant is infected + may have spread)

18
Q

how is DNA analysis used to identify plant diseases?

A

idea that…
- a map of the genome of the plant is produced
- can identify DNA of pathogen
- therefore can diagnose plant

19
Q

how is antigen identification used to identify plant diseases?

A
  • detect antigens (proteins) found on the surface of pathogens
  • through chemical analysis which may use monoclonal antibodies
  • as specific antigens are found on specific pathogens
20
Q

why are plant lab tests useful?

and give one disadvantage

A

can identify the pathogen before it causes significant damage to the crop

  • but can be slow + expensive
21
Q

give 5 non-specific defence systems of the human body against pathogens

  • and briefly describe what each of them do
A

1) skin (a physical barrier)
- dry, dead outer cells are difficult for pathogens to penetrate

2) acid in stomach
- contains strong HCL acid (kills almost all pathogens - ie. from food/drink/mucus)

3) cilia and mucus in airways
- mucus trap smaller microorganisms
- cilia moves up to throat + swallowed

4) nasal hairs
- keep out dust + larger micro-organisms

5) tears
- contain lysozymes (destroy bacteria cell wall)

22
Q

what are non-specific defense mechanisms in the body?

A

responses that prevent the entry of all microorganisms (and preventing them from causing disease)

23
Q

what key features does the skin have to kill pathogens? (2)

A
  • produces antimicrobial secretions (sweat)
  • natural (not harmful) microorganisms which outcompete pathogens for resources
24
Q

what are platelets (and where are they made)?

A
  • small fragementsof cells
  • made in the bone marrow
  • which help blood to clot
25
Q

what do platelets do? (and how do they do it) (4)

A
  • change blood protein fibrinogen into fibrin
  • to form a network of fibres in the cut
  • which causes red blood cells to be trapped in fibres = clot
  • clot hardens to form a scab
26
Q

what is the role of the immune system when defending the human body against disease? (2)

A
  • destroys pathogens when they gain entry + the toxins they produce
  • protect in case the same type of pathogen invades in future
27
Q

what is the immune system’s main form of defence?

A

white blood cells

28
Q

what are the two types of white blood cells and what does each one do?

A

Phagocytes - engulf micro-organisms

Lymphocytes - produces antitoxins and and antibodies

29
Q

describe what a phagocyte does in more detail

A
  • engulfs pathogen
  • and enzymes within it digest the micro-organism

IS NON-SPECIFIC (destroys all pathogens)

30
Q

describe what a lymphocyte does in more detail

A

Don’t need to know: HAS 2 types of cells

  • T cells and B cells

Need to know: B CELLS - make antibodies and antitoxins
- remember the correct antiBODY for the specific anitgen

Don’t need to know: T CELLS - remember the antigen (act as memory cells)

31
Q

what can antibodies do?

A
  • bind to pathogen’s antigen on surface
  • ‘mark’ pathogen
  • or make pathogen burst
  • or make pathogens clump together (easier for phagocyte to find them)
32
Q

what do antitoxins do?

A

bind to toxins released by the pathogen + neutralise it

33
Q

what is the role of plasma cells in the immune system response

A

secrete large quantities of antibodies

- from B lymphocyte cells

34
Q

Explain why there are so many different kinds of lymphocyte cells. (3)

A
  • each antibody binds to only one type of antigen (and one microorganism/pathogen)
  • so every time a new type of pathogen enters, a different lymphocyte makes a new antibody to fight it
  • so a new B cell is needed to make the antibody
35
Q

what does it mean if the body is immune to a disease?

A
  • body has antibodies to that disease
  • and so if pathogen detected, it produces many antibodies fast enough that it kills pathogen before has time to develop unto an illness
36
Q

define an antigen

A

a protein unique to a cell found on the cell surface/membrane

  • which allows the body to recognise the cell
37
Q

what is the key-word to describe lymphocytes?

A

SPECIFIC (responds to one pathogen only)

38
Q

what is a primary response to a pathogen? (definition)

A

the reaction of the immune system when it first detects an antigen (antibody concentration rises slowly)

39
Q

why is the secondary response different to the primary response? (to the same pathogen)

A
  • as the body still remembers the last
    infection
  • so some antibodies may still be present
  • memory cells are present from the last infection (can make antibodies fast)
40
Q

what feature of platelets allow them to carry out their defence functions?

A
  • proteins on surface that help them clump together to heal a would
  • secrete proteins that result in a clotting cascade
41
Q

how are lymphocytes and phagocytes adapted to their function?

A

lymphocyte = large nucleus (to remember antibody to make)

phagocyte = small nucleus (large area to engulf pathogens)

  • contain enzymes
  • can change shape easily

B4-B6 (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions