Communicable diseases Flashcards
Name the four types of pathogens. (1)
- Bacteria
- Fungi
- Protista
- Viruses
What ways can we use to classify bacteria? (2)
- Gram-positive/gram-negative (1)
- Basic shape (like spherical, rod…) (1)
Which pathogens are:
- The most dangerous to plants (1)
- Non-living (1)
- Eukaryotic organisms (1)
- Fungi (1)
- Viruses (1)
- Fungi/protista (1)
Describe how viruses damage tissues. (3)
- Inserts genetic material into (host cell’s) DNA (1)
- Viruses rapidly produced inside cell. (1)
- Cell bursts, allowing viruses to attack other cells. (1)
Protista, like viruses, take over cells and cause them to burst and release newly created protista. What is the difference in how protista operate compared to viruses.
Viruses insert genetic material into the host cell’s DNA to reproduce (1), while protista digest the host cell’s contents while reproducing. (1)
Pathogens like bacteria and fungi release toxins. How do these toxins damage cells? Describe one factor. (1)
- Attacks genetic material (preventing cell division) (1)
- Causes enzymes to become inactive (1)
- Break down cell membranes (1)
Describe two bacterial diseases (name, plant/animal, brief explanation). (6)
- Bacterial meningitis; animal disease, meninges (brain) infected causing blood poisoning. (3)
- Ring rot; plant disease, destroys most of the crop and leaves fields unusable for a long time. (3)
- Tuberculosis; animal disease, destroys lung tissue and suppresses the immune system. (3)
Describe two viral diseases (name, plant/animal, brief explanation). (6)
- Tobacco-mosaic virus; plant disease, reduces yield/growth by attacking leaves/flowers/fruits. (3)
- Influenza/flu; animal disease, ciliated epithelial cells in the gaseous exchange system are infected, leaving the body vulnerable to secondary infections. (3)
- Human immunodeficiency virus; animal disease, gradually destroys the immune system, leaving the body vulnerable to other infections (e.g TB, cancer). (3)
What is AIDS and how does it link to HIV? (2)
AIDS stands for Acquired Immunodeficiency Syndrome (1) and is the worst form of HIV. (1)
Describe two protist caused diseases (name, plant/animal, brief explanation). (6)
- Tomato/potato late blight; plant disease, fungal-like hyphae penetrate the host cells of the crop. (3)
- Malaria; animal disease, carried by mosquitos (vector), invading red blood cells, the liver and the brain. (3)
Describe two fungal diseases (name, plant/animal, brief explanation). (6)
- Black sigatoka; plant disease, hugely reduces (banana) yield by attacking leaves, penetrating them with hyphae and turning them black. (3)
- Ring worm; animal disease, creates crusty and circular areas on the skin. (3)
- Athlete’s foot; animal disease (form of human ring worm), digests the moist, warm skin between the toes, causing cracking and scaling. (3)
How can a disease be transferred directly from one individual to another? Describe one way. (1)
- Direct contact (contact with bodily fluids, skin to skin contact). (1)
- Inoculation (through a break in the skin, animal bites, sharing needles). (1)
- Ingestion (drinking something contaminated). (1)
- Spores (infected plants may leave spores of protists or fungi in the soil, they may be carried in the wind/water/animals). (1)
How can a disease be transferred indirectly from one individual to another? Describe one way. (1)
- Fomites (pathogens transferred by inanimate objects, such as cosmetics and bedding). (1)
- Droplet infecton (healthy individuals may breathe in droplets containing pathogens from other people coughing/sneezing). (1)
- Vectors (water and animals can carry diseases, transferring them to individuals). (1)
Name three factors that raise the probability of someone or a plant catching a communicable disease. (3)
- Overcrowded working/living conditions. (1)
- Poor nutrition. (1)
- Compromised/weakened immune system. (1)
- Climate change. (1)
- Socioeconomic factors. (1)
- Planting crops that are susceptible to disease. (1)
- Poor mineral nutrition of plants. (1)
- Damp, warm conditions. (1)
Callose deposition is a physical defence used by plants. Describe how this works to minimise infection. (6)
- (When attacked) the plant rapidly produces callose (a polysaccharide). (1)
- Callose is deposited between cell walls and membranes (1) surrounding infected cells (1).
- Pathogens are prevented from entering healthy cells, due to the barrier. (1)
- Lignin is added to make the barrier thicker/stronger. (1)
- Callose seals sieve plates/plasmodesmata. (1)
Describe one chemical defense that plants use. (2)
- Insecticides; toxic to insects (and fungi). (2)
- Insect repellents; repels insects that may be acting as vectors. (2)
- Antibacterial compounds; breakdown/disrupt the cell walls of bacteria (e.g lysosomes, defensins). (2)
- Antifungal compounds; break down chitin in fungal cell walls (e.g chitinases). (2)
Fill in the blanks about blood clotting and wound repair (8):
When platelets come into contact with ___ from the damaged blood vessel, it ___ to it and secretes susbtances. One of these is an enzyme that causes a cascade of reactions that lead to the formation of a ___ network that traps ___. A ___ is also released, causing the smooth muscle to contract (___), reducing blood supply so the wound ___ out, forming a tough scab. ___ cells begin to grow over the scab and vessels regrow.
- Collagen (1)
- Adheres (1)
- Fibrin (1)
- Platelets (1)
- Neurotransmitter (1)
- Vasoconstriction (1)
- Dries (1)
- Epidermal (1)
Explain how mast cells trigger an inflammatory response. (5)
- Releases histamines; causes vasodilation (in blood vessels). (1)
- Causes redness, swelling (blood vessels become more leaky) and increased temperature. (1)
- Higher temperatures prevent pathogenic reproduction. (1)
- Releases cytokines; attracts white blood cells to the site. (1)
- The white blood cells carry out phagocytosis. (1)
Fill in the blanks about phagocytosis (5):
Phagocytes recognise the non-self proteins (___) on the surface of pathogens. The pathogen is ___ by the phagocyte, enclosed in the vacuole, forming a ___. A lysosome combines with it, forming a ___. Enzymes from the lysosome ___ the pathogen.
- Antigens (1)
- Engulfed (1)
- Phagosome (1)
- Phagolysosome (1)
- Digest (1)
How are antigen presenting cells created? (2)
What is the purpose of antigen presenting cells? (1)
- Antigens from the digested pathogen combine with MHC in the cytoplasm of the macrophage. (1)
- This forms an MHC/antigen complex, which makes up an APC. (1)
- The antigens trigger further immune responses by stimulating other cells. (1)
How do antibodies defend the body by creating antigen-antibody complexes? (4)
- Acts as an opsonin; allowing for the antigen-antibody complex to be easily engulfed. (1)
- Prevents pathogens from efficiently invading host cells. (1)
- Acts as agglutinins; causes the antigen-antibody complexes to clump together, making it so multiple can be digested by phagocytes at once. (1)
Acts as anti-toxins; binds to toxins released by pathogens, making them harmless. (1)
Explain the purpose of T helper cells. (2)
(Once their receptors have binded to antigens on APCs,) T helper cells produce interleukins (1), which attract/stimulate macrophages to engulf antigen-antibody complexes and stimulate the production of other T cells. (1)
What are cell mediated immunity and humoral immunity (specific immune) responses to? (2)
Cell mediated immunity; cells that have been changed in some way (e.g virus, mutation). (1)
Humoral immunity; antigens found outside cells (bacteria, fungi, APCs). (1)
Describe how cell mediated immunity works. (5)
- (During the non-specific immune response) macrophages process antigens, forming APCs. (1)
- Some of the receptors on T helper cells will fit the antigens, allowing them to bind and produce interleukins. (1)
- The production of interleukins causes T cells to divide rapidly by mitosis. (1)
- This forms clones of the activated T helper cells (carrying the correct antigen to bind to the particular pathogen). (1)
- Cloned cells may produce interleukins, become T memory cells or stimulate the production of T killer cells (that are specific to the presented antigen). (1)
