BIOLOGY 2A03 FINAL EXAM
QUESTIONS AND ANSWERS 2026
VERIFIED.
Marine (saltwater) environments - ANS animals tend to gain salts and lose water
Freshwater environments - ANS animals tend to lose salts and gain water
Terrestrial environments - ANS animals tend to lose water
The role of epithelial tissues - ANS form the boundary between animal and environment
Elasmobranchs - ANS osmoconformers but are strict ionic regulators. Salt levels
maintained at low levels. Osmotic concentrations largely due to organic solutes.
Teleosts - ANS are osmoregulators and can counter passive water and ion fluxes to
maintain homeostasis
Terrestrial organisms - ANS first line of defence against water loss is the integument (body
covering) and the ability to resist passive water loss to the environment. Amniotes (mammals,
1
,birds and reptiles) have a specialization of the integument, the keratinized stratum corneum,
which creates a waterproof layer. Keratinocytes differentiate to form part of this thickened
external layer
Transcellular transport - ANS movement through the cell, across membranes
Paracellular transport - ANS movement between cells
The kidney and urinary system of mammals - ANS filtration, reabsorption, secretion,
excretion
Plasma volume - ANS regulation, thus influencing our mean arterial pressure
Osmotic balance - ANS kidneys determine the volume of urine to produce, and therefore
water balance
Ion balance - ANS extracellular fluid osmolarity; controls loss of ions that have important
roles
pH balance - ANS by retaining or excreting H+ or HCO3-
Excretion - ANS of metabolic nitrogenous wastes and water soluble toxins
Hormone production - ANS renal hormones, renin which controls blood pressure,
erythropoietin which regulates red blood cell synthesis
Gluconeogenesis - ANS leading to glucose production during fasting
2
, Mammalian kidney - ANS it has two layers: the outer cortex and the inner medulla. As
urine is produced, it is collected by minor calyces which join together to form major calyx. Urine
leaves the kidney via the ureter, and passes into urinary bladder for storage. Urine leaves the
animal through the urethra
Mammalian nephron - ANS individual tubular structure that produces urine. There may
be millions of nephrons across our 2 kidneys. By the time urine leaves the nephron, it is fully
formed. Main nephron vasculature is the glomerulus
Cortical nephrons - ANS make up 85% of our nephrons
Juxtamedullary nephrons - ANS make up 15% of our nephrons
Glomerular filtration - ANS blood pressure forces water and solutes across the wall of the
glomerular capillaries and into the capsular space
Reabsorption - ANS the removal of water and solutes from the filtrate and their
movement across the tubular epithelium and into the peritubular fluid
Secretion - ANS the transport of solutes from the peritubular fluid across the tubular
epithelium and into the tubular fluid
Filtration occurs at the glomerulus - ANS wall of glomerular capillary retains blood cells
and large macromolecules but lets liquid components and small solutes into the lumen of the
Bowman's capsule. Fenestrated glomerular capillaries are very leaky; membrane of the
podocyte cells with "foot processes" form part of filtration structure too. Mesangial cells control
blood pressure and filtration in glomerulus. Filtrate flows from Bowman's capsule into the
proximal tube of nephron
3
QUESTIONS AND ANSWERS 2026
VERIFIED.
Marine (saltwater) environments - ANS animals tend to gain salts and lose water
Freshwater environments - ANS animals tend to lose salts and gain water
Terrestrial environments - ANS animals tend to lose water
The role of epithelial tissues - ANS form the boundary between animal and environment
Elasmobranchs - ANS osmoconformers but are strict ionic regulators. Salt levels
maintained at low levels. Osmotic concentrations largely due to organic solutes.
Teleosts - ANS are osmoregulators and can counter passive water and ion fluxes to
maintain homeostasis
Terrestrial organisms - ANS first line of defence against water loss is the integument (body
covering) and the ability to resist passive water loss to the environment. Amniotes (mammals,
1
,birds and reptiles) have a specialization of the integument, the keratinized stratum corneum,
which creates a waterproof layer. Keratinocytes differentiate to form part of this thickened
external layer
Transcellular transport - ANS movement through the cell, across membranes
Paracellular transport - ANS movement between cells
The kidney and urinary system of mammals - ANS filtration, reabsorption, secretion,
excretion
Plasma volume - ANS regulation, thus influencing our mean arterial pressure
Osmotic balance - ANS kidneys determine the volume of urine to produce, and therefore
water balance
Ion balance - ANS extracellular fluid osmolarity; controls loss of ions that have important
roles
pH balance - ANS by retaining or excreting H+ or HCO3-
Excretion - ANS of metabolic nitrogenous wastes and water soluble toxins
Hormone production - ANS renal hormones, renin which controls blood pressure,
erythropoietin which regulates red blood cell synthesis
Gluconeogenesis - ANS leading to glucose production during fasting
2
, Mammalian kidney - ANS it has two layers: the outer cortex and the inner medulla. As
urine is produced, it is collected by minor calyces which join together to form major calyx. Urine
leaves the kidney via the ureter, and passes into urinary bladder for storage. Urine leaves the
animal through the urethra
Mammalian nephron - ANS individual tubular structure that produces urine. There may
be millions of nephrons across our 2 kidneys. By the time urine leaves the nephron, it is fully
formed. Main nephron vasculature is the glomerulus
Cortical nephrons - ANS make up 85% of our nephrons
Juxtamedullary nephrons - ANS make up 15% of our nephrons
Glomerular filtration - ANS blood pressure forces water and solutes across the wall of the
glomerular capillaries and into the capsular space
Reabsorption - ANS the removal of water and solutes from the filtrate and their
movement across the tubular epithelium and into the peritubular fluid
Secretion - ANS the transport of solutes from the peritubular fluid across the tubular
epithelium and into the tubular fluid
Filtration occurs at the glomerulus - ANS wall of glomerular capillary retains blood cells
and large macromolecules but lets liquid components and small solutes into the lumen of the
Bowman's capsule. Fenestrated glomerular capillaries are very leaky; membrane of the
podocyte cells with "foot processes" form part of filtration structure too. Mesangial cells control
blood pressure and filtration in glomerulus. Filtrate flows from Bowman's capsule into the
proximal tube of nephron
3
