Module 5 Flashcards
Adaptations of the Proximal convoluted tubule for selective reabsorption
1) Epithelial cells contain mitochondria to produce ATP
2) Epithelial cells contain microvilli - increase SA:V
3) Contain numerous and variety of cotransport proteins
4) Short diffusion pathway in one epithelial cell
role of loop of henle
Ascending limb actively transports Na+ out into medulla - decrease water potential in medulla
Water moves down potential gradient from descending limb into medulla ( only descending limb permeable to water)
Specialised features of the pre synaptic bulb
Many mitochondria
Lots SER (packages neurotransmitter into vesicles)
Large no. of vesicles
lots calcium ion channels
What is acetycholineesterase
found in synaptic cleft, breaks down acetylcholine to ethanoic acid and choline
What is spatial summation
Action potentials arrive from several pre-synaptuc neurones
What is temporal summation
Several action potentials from one pre-synaptic neurone
What does becoming habituated to a stimulus mean
Repeated stimulation caused synapse to run out of vesicles containing neurotransmitter, syanpse fatigued
behavioural mechanisms ectotherm to control body temp
burrow / expose to sun
orientate SA
curl into ball reduce heat loss
wet skin - evaporates to cool
physiological mechanism endotherms to control body temp
Sweat produced - evaporation (plants)
Vasodilation / vasoconstriction
Hairs erect to trap air increases insulation
Shivering releases heat
Enzymes in hepatocytes that render toxic molecules less toxic
Function of liver
Catalase - hydrogen peroxide to oxygen and water
Cytochrome p450 - group of enzymes break down drugs H - this cause side effects as cytochrom p450 used in other metabolic roles
How is alcohol broken down and where
Function of liver
In the liver in hepatocytes
1 - ethanol dehydrogenase > ethanal
2 - ethanal dehydrogenase > acetate (used in links reaction)
H atoms released form rNAD
4 functions of liver
Deamination
break down alcohol
enzymes in hepatocytes render toxic molecules less toxic
stores glycogen
Deamination equation
Amino acid + oxygen > keto acid + ammonia
Explain how germination occurs to produce new shoot
1 - water absorbed by seed, releases gibberellin
2 - gibberellin travels to aleurone layer in seed > amylase produced
3 - Amylase breaks starch to glucose > used in protein synthesis (growth)
Explain the mechanism of auxin in stem elongation
Auxin promotes active transport of H+ ions (by ATPase) into cell wall
Low ph causes enzymes to break bonds within cellulose > cell wall less rigid
> means water can enter osmosis > inc turgor pressure and stem elongation
Explain mechanism of auxin in geotropic response in roots
Auxin moves to lower side of root (geotropic - gravity)
other side elongates root bends downwards
Commercial uses of gibberellin
Spray sugar cane > stems elongate (more sugar)
Brewing : produce amylas to break starch to maltose
Make conifers reproductively active, seed formation
