6.3-6.4

Question 1

Bacteria

Answer 1

Prokaryote (no real nucleous), divides by binary fission.
Cause: eye/ear infections, cholera.

Question 2

Viruses

Answer 2

Acellular (needs a host cell to carry out functions of life)
Can have DNA or RNA
Mutate, evolve, and recombine quickly.
Cause: Flu, HIV/AIDS, herpes.

Question 3

Fungi

Answer 3

Eukaryotes (reproduce by spores)
Cause: mold, ringworm.

Question 4

Protozoa

Answer 4

Simple parasites
Cause: malaria, toxoplasmosis

Question 5

Transmission of pathogens

Answer 5

Inhaled droplets
Direct contact
Bodily fluids
Animal vectors
Blood contact
Ingested

Question 6

Primary defence against the pathogens

Answer 6

Skin and mucous membrane

Question 7

Mucuous membrane

Answer 7

Nose, mouth, pelvic area
Sticky mucus traps invadors
Ph not favourable to pathogens
Lysozome,, enzymes that breakdown pathogens.
Natural organisms, competitive exclusion

Question 8

Skin

Answer 8

Continuous, hard to find opening
Many layers
Dry
Ph not favourable to pathogens
Lysozomes
Natural organisms

Question 9

Cuts and blood clotting

Answer 9

Opening which pathogens can enter
Platelets and damaged tissue release clotting factors
Blood clots at the wound site prevent excessive blood loss.

Question 10

Clotting factors from platelets

Answer 10

Clotting factors release series of reactions
Fibrin fibres form a mesh across the wound site
Fibre fibres capture blood cells and platelets forming a clot.
Presence of air clot dires and forms scab with healing shields under
Cascade results in rapid conversion of fibrinogen to fibrin by thrombin.

Question 11

Atherosclerosis

Answer 11

Degenerative disease
Artery wall damaged
Macrophages release growth factors -> growth of fibrous tissue
Cholesterol builds up in damaged areas
Forms plaque and artery wall loses elasticity

Question 12

Coronary Thrombosis

Answer 12

Build up of cholesterol and plaque
Lumen narrows
Blood can’t flow
If plaque ruptures, blood clotting is triggered (Thrombosis)

Question 13

Coronary Heart Disease

Answer 13

clots in coronary arteries
Vessels are damaged by cholesterol deposition
Deposits reduce vessel diameter and increase blood pressure
The stress damages arterial walls
The vessels wall loses elasticity and forms atheroschelortic plaques
If plaque ruptures, blood clotting occurs forming thrombus.
If thrombus blocks blood flow, myocardial infarction results.

Question 14

White blood cells

Answer 14

Leukocytes
Cells of the immune system defending the body against infectious diseases and foreign materials.
Types exist
All produced and derived from a multipotent cell in the bone marrow (hematopoietic stem cell).
Found throughout the body, including blood and lymphatic system.

Question 15

Ingestion of pathogens by phagocytic white blood cells gives non-specific immunity to diseases

Answer 15

If pathogen enters body, first line of defence are phagocytic leukocytes.

Question 16

Phagocytic Leukocytes

Answer 16

Chemotaxis attracts the phagocytes to the area of invasion
Response to proteins produce by pathogen
Phospholipids released by damaged cells

Phagocyte attaches to the pathogen’s cell surface proteins and then engulfs it. The fluid nature of the plasma membrane allows this.

Phagosome forms.
Vesicle that contains the pathogen.
Lysosomes deposit the enzymes into the phagosome.

Digestive enzymes break down the pathogen and waste products are expelled by exocytosis.

Question 17

Phagocytosis

Answer 17

Involves phagocyte
Detecting foreign material and moving towards it by chemotaxis
F.M is ingested by endocytosis
Lysosomes attach to the ingested vesicle and release enzymes into it
Digest and breakdown F.M
Remains are expelled

Question 18

Production of antibodies by lymphocytes in response to particular pathogens gives specific immunity

Answer 18

Antigen is substance or molecule found on a cell or virus surface that causes antibody formation.

Antibody is a globulare protein that recognises a specific antigen and binds to it as part of an immune response. Specific to certain antigens

Question 19

Clonal selection

Answer 19

Each type of lymphocyte recognises one specific antigen. When invaded the corresponding lymphocycte responds.
It makes many clones of itself to produce antibodies to the pathogen.
Some cloned cells remain as memory cells.

Question 20

Antibiotics blocking processes that occur in prokaryotic cells

Answer 20

Antibiotics are designed to disrupt structures or metabolic pathways in bacteria and fungi:
cell walls and membranes
protein synthesis
DNA/RNA synthesis

Question 21

Viruses and antibiotics

Answer 21

Viruses have a different structure to prokaryotes. They lack metabolism and cannot be treated with antibiotics

Question 22

Antibiotic resistance

Answer 22

Example of evolution by natural selection
Bacteria mutate and resistance naturally arises
Bacteria divide rapidly
Over time strains of bacteria can become resistant to multiple strains of bacteria.

Question 23

Effects of HIV on immune system and methods of transmission

Answer 23

HIV attacks the immune system. Individuals affected find it harder to fight off infections and diseases.
AIDS is a syndrome caused by HIB. Develops when the HIV is advanced. Last stage of HIV where body can no longer defend it self.

No cure yet.

Question 24

HIV

Answer 24

Retrovirus
Inserts own RNA into host cell
Attacks T-helper cells
HIV RNA is inserted into the marcophage genome
Transcription now includes the HIV’s code.