Biology Exam questions Flashcards
Give two ways in which pathogens can cause disease
Release toxins
Viruses inject themselves into host cells and replicate cuasing lysis killing the cells/tissues
Putting bee honey on a cut kills bacteria. Honey contains a high concentration of sugar. Use your knowledge of water potential to suggest how putting honey on a cut kills bacteria
Water potential in bacteria cells is higher than in the honey. High WP in bacteria Low Hp in honey.
Water leaves cell by osmosis (Move from an area of high water potential to an area of low water potential)
Loss of water stops metabolic reactions resulting in death of the cell
Describe how B lymphocytes respond whe they are stimulated by antigens
- Divide by mitosis form clones
produce plasma cells
plasma cells make antibodies and produce memory cells
Describe the difference between active and passive immunity
Active involves memory cells passive does not.
Passive involves antibody introduced into body from outside source (e.g vaccine).
active immunity is long term because antibody produced in response to antigen
passive short term because antibody (given) is broken down
active can take time to develop/work passive is fast acting.
HPV is the main cause of cervical cancer. describe how giving this vaccine leads to production of antibody against HPV
Vaccine contains antigen
antigen is displayed on APC cells
specific helper t cell detetcts antigen and stimulates specific b cell.
B cell goes through mitosis and forms clone to give plasma cells
plasma cells produce antibody
Explain why the number of HIV particles in the blood
rise during the first months of infection
Remains low beetween 1 and 7 years after infection
HIV is invading cells which make new viruses. cells release viruses into blood.
Virus remains dormant/exsists as provirus/exsists as DNA in host DNA. virus stays in cells
A person developed a large number of infections about 9 years after he first became infected with HIV. Explain why
HIv destorys T cells more free viruses producved leas to fall in T cells so fewer T cells activate B cells/memory cells
Reduced/no antibody production, immune system not working properly/inability to fight infection.
Why are monoclonal antibodies referred to as monoclonal
Antibodies produced from a single clone of B cells/plasma cells
Using knowledge of protein stucture explain why monoclonal antibodies are specific
Antibody structure: specific primary structure/order of amino acids
specific teritary 3D structure
so only binds to complimentary antigen
