Unknown Student Guide Questions Flashcards
What are the 3 layers separating plasma from filtrate?
The capillary endothelium, the basement membrane on which the capillary cells lie, and the inner layer of the Bowman’s capsule
Describe the inner layer of the Bowman’s capsule
Consists of podocytes, with foot-like processes which surround the capillaries but which have spacious gaps between them called filtration slits
Describe adaptations in the tubules
Cuboidal epithelial cells which line tubule walls have many microvilli on the side in contact with the filtrate, and infoldings of the cell surface membrane on the side next to the capillaries. These adaptations increase the S.A. for reabsorption. The cells have many mitochondria to supply ATP for active transport
What must a microorganism do to be pathogenic?
1) enter the host 2) colonise host tissue 3) evade host defences 4) cause damage to host tissue
What is the difference between polymorphs and macrophages?
Polymorphs, more abundant but short lived, remain in blood until there is an infection when they move out of capillaries to site of infection. Monocytes are blood cells that can move out of blood capillaries into surrounding tissue where they develop into macrophages
How are antigen-antibodies like the lock and key model?
For each antigen on the surface of a pathogen. there is a lymphocyte that carries a special protein receptor on its cell surface membrane that is complementary in shape.
Where do B cells mature?
In the Bone marrow
Where do T cells mature?
in the Thymus
What happens after lymphocytes are sensitised?
A specific gene is activated, mRNA synthesized and proteins are produced. These proteins are either antibodies in B cells or membrane receptors in T cells. This process takes time. The sensitised lymphocyte is then cloned by mitosis.
What do antibodies do?
Some neutralise toxins produced by bacteria, some clump or agglutinate bacteria before they are engulfed by phagocytic cells (antibodies are agglutinins), some attach to viruses to prevent entry of host cells, some destroy bacterial cell walls causing cell lysis, some antibodies attach to bacteria enabling phagocytic cells to identify them
What are antigens / antibodies?
Antigens are foreign while antibodies are produced in body by b cells
Why can being given the wrong blood cause agglutination?
Anti-a and anti-b are agglutinins
What is the difference between agglutination and clotting?
Agglutination is the sticking together of RBC, clotting involves the formation of fibrin and only involves RBC in that they might become enmeshed in network of fibres
Outline auxin action
Produced in cells of the apical meristem. diffuse down shoot towards zone of elongation. bind to specific receptors on cell surface membrane of newly formed cells. this causes membrane pumps to move hydrogen ions out into cellulose cell wall. the acidification of cell walls activates agents which loosen the linkages between cellulose microfibrils, allowing slippage between them, and making cell wall more flexible. the cells absorb water by osmosis and the flexible cell walls allow the cells to expand as the water exerts increased hydrostatic pressure against them. the more auxin that is received in the zone of elongation, the more this effect allows cells to expand
What does positively phototrophic mean
Grows towards light
