Unit 2 Flashcards
Describe how antibodies are produced in the body following a viral infection (6)
- Virus contains antigen
- Virus is engulfed by macrophage
- presents antigen to B-cell
- B-cell divides by mitosis
- Plasma cells produce antibodies
- Specific to antigen
Describe how HIV is replicated after it has entered a human cell (4)
- Reverse Transcriptase uses HIV RNA to make DNA copy
- DNA used to make HIV RNA copies
- and HIV proteins made at host ribosomes
- Budding off from membrane of host cell
What is a vaccine? (1)
A small dosage of antigens to stimulate production of antibodies
Give two ways in which pathogens can cause disease when they enter the body of their host (2)
- Damage cells/tissues
- Produce toxins
Phagocytes and Lysosomes are involved in destroying microorganisms. Describe how (3)
- Phagocytes engulf pathogens
- enclosed in a vaccine
- lysosomes have enzymes
- that digest molecules
Describe how B-lymphocytes respond when they are stimulated by antigens (4)
- Divide by mitosis
- to produce plasma cells
- plasma cells produce antibodies
- and memory cells
Describe the role of macrophages in stimulating B-lymphocytes (1)
- The antigen in membrane is presented to lymphocytes
The destruction of T-cells by HIV leads to the death of an infected person. Explain how (2)
- Not enough T-cells to produce antibodies
- Person cannot fight infections
Give two factors other than cost that should be considered when selecting an antibiotic to treat a bacterial disease (2)
- Side effects
- How much resistance the bacteria have built up
Name the process by which bacterial cells divide (1)
Binary fission
Describe how the Golgi apparatus is involved in the secretion of enzymes (1)
The golgi apparatus modifies the protein
Describe how the RER is involved in the production of enzymes (2)
- RER has ribosomes to make proteins (like an enzyme)
Describe how you could use cell fractionation to isolate chloroplasts from the leaf tissue (3)
- Homogenisation by grinding up the cells in a blender in a cold, isotonic, buffered solution
- Remove debris by filtration
- 2nd pellet formed from ultracentrifugation (has the chloroplast)
Name the structures in a eukaryotic cell that cannot be identified using an optical microscope (2)
- mitochondria
- ribosome
- E.R.
- lysosome
Describe how phospholipids are arranged in a plasma membrane (2)
- Phospholipids are arranged in a bilayer
- Hydrophobic tails face inside
- Hydrophilic head faces outside
Explain why a person with mitochondrial disease can only exercise for a short time (2)
- They cannot produce much ATP if they have damaged mitochondria
- The ATP is needed for muscle contraction
Explain why a transmission electron microscope was used to produce the image in the figure above (2)
- High resolution
- Can see the internal structure of organelles
In coaliac disease, microvilli in epithelial cells are damaged. Explain why people with coaliac disease have low concentrations of amino acids in their blood (2)
- Damaged microvilli means they have less surface area of absorption
- due to less protein channels
- less amino acids are absorbed
Name the type of bond that joins amino acids together in a polypeptide (1)
Peptide
Describe the function of a chloroplast (2)
- The site of aerobic respiration
- Release ATP for active transport
Why can electron microscopes produce an image with higher resolution than optical microscopes? (1)
- Electrons have shorter wavelengths than light
Describe how you could make a temporary mount of a piece of plant tissue to observe the position of starch grains in the cells when using an optical microscope (4)
- Add a drop of water to the slide
- Obtain a thin section of plant tissue and place on the slide
- stain with iodine in potassium iodide
- Lower coverslip using a mounted needle
Explain why it is important that the plant tissue was thin (or 1-cell thick) (1)
To allow light to pass through so it can be seen by an optical microscope
What do both Eukaryotic and Prokaryotic cells have?
- Plasma membrane
- Cytoplasm
- Ribsomes
- DNA and RNA
