random Flashcards
explain the function of lysosomes in cells
lysosomes contain enzymes to break down pathogens
using hydrolytic enzymes
and can break down old organelles`
explain why different antibodies need to be produced to give immunity to new strains
antibodies are specific to antigens so the variable region to the antibody is complementary to antigen
explain how vaccination programmes can help to contril the spread of infecctions deasieases
aims to vaccinate the whole population
to develop long term immunity
vaccine allows most people to have an immune response to the antigen
how does the oxygenator carry out functions of gas exchange?
oxygen moves into the blood and carbon dioxide moves from the blood by diffusion and there is a short diffusion pathway
difference of structure of tunica media of muscular artery and aorta in terms of function
tunica media of aorta has more elastic fibres and this allows the aorta to stretch during ventricular contraction
explain how the structure of collagen fibre provide skin with strenghth
covalant bonds between collagen molecules
covalent bonds are strong
overlapping molecules
suggest why it is important to plants that water has a high latent heat of voporisation
plant leaves heat up and this leads to cooling effect
why is it important for the control of the cardiac cycle that there is a shrt delay at the AVN after impulses have been sent out by SAN
atria and venticals do not contract at the same time and this allows the atria to empty compleatly
explain how the blood pressure changes
1)opening of the tricuspid valve: pressure in right ventrical becomes lower than right atrium
2)opening of pulmonary(semilunar) valve: pressure in right ventrical becomes higher than pressure in pulmonary artery
3)help flow of blood: to prevent backflow
what is meant by polysaccirides
large number of monosaccharides
features of nonself antigens
stimulate immune response
usually glycoproteins
recognized by phagocytes
list all the structures through which a blood clot in the left atrium must travel to reach the blood vessels supplying the brain
atrioventricular valve-
left ventrical
semilunar valve
aorta
explain why blocking a small artery in the brain leads to brain damage
lack of oxygen
explain how the primary transcript is modifyed to form mRNA
removal of introns
why is it necessary for cholride ions to enter the red blood cell as hydrocarbonate ions leave
it replaces the negative ion
explain how specialised cells in the gas exchange syestem prevent harmful microscopic particles from reaching the alvoli
production of mucus by goblet cells
mucus is sticky and traps the dust particles
the cilia waft the mucus away
describe how the process of translation results in the formation of a polypeptide
-two codons at a time are exposed to the large subunit
-each tRNA brings a specific amino acid
-a tRNA anticodon binds to the mRNA codon
-complementary base pairing occurs through hydrogen bonds
-second tRNA brings another amino acid(next to the first one)
-peptide bond formation between the two amino acids
difference. between scanning electron micrograph and transmission electron micrograph
SEM- shows 3d veiws
TEM-showing 2D
why glucose molecules need to be cotransported with Na+ when it enters the cell through the membrane protein
glucose is moving agaisnt a concentration gradient
movement poward by inward movement of Na+
explain how microvilli increase the uptake of glucose into an intestinal epithelial cell
increase in surface area so more transport