Excretory

Question 1

Osmoregulation

Answer 1

The control of water and salt balance in the body to maintain homeostasis.

Question 2

Excretion

Answer 2

The removal of metabolic wastes (like nitrogen compounds) from the body.

Question 3

Osmosis

Answer 3

The diffusion of water across a semipermeable membrane from an area of low solute concentration to high solute concentration.

Question 4

Osmolarity

Answer 4

The total solute concentration of a solution (measured in moles of solute per liter of solution).

Question 5

Isosmotic

Answer 5

Equal solute concentration inside and outside, No net water movement

Question 6

Hyposmotic

Answer 6

Lower solute concentration outside, Water moves into cell → cell swells/bursts

Question 7

Hyperosmotic

Answer 7

Higher solute concentration outside, Water moves out of cell → cell shrivel

Question 8

Osmoregulators

Answer 8

Actively maintain internal osmolarity, even if the environment changes (e.g., freshwater fish, humans).

Question 9

Osmoconformers

Answer 9

Their body fluids match the surrounding environment’s osmolarity (e.g., most marine invertebrates).

Question 10

Stenoaline

Answer 10

Can only tolerate a narrow range of salinity (e.g., goldfish).

Question 11

Euryhaline

Answer 11

Can survive wide ranges of salinity (e.g., salmon, which move between salt and fresh water).

Question 12

Andrybiosis

Answer 12

The ability of some organisms (like tardigrades) to survive extreme dehydration by going dormant until rehydrated.

Question 13

Ammonia

Answer 13

High Toxicity, A lot of water, low energy cost, fish and aquatic animals

Question 14

Urea

Answer 14

Moderate, Medium amount of water, moderate energy cost, mammals + amphibians

Question 15

Uric acid

Answer 15

Low toxicity, very little water needed, high energy cost, birds,reptiles, insects

Question 16

Filtration

Answer 16

Blood pressure forces water and small solutes out of the blood into the excretory tubule.

Question 17

Reabsorption

Answer 17

Useful molecules (like glucose, water, salts) are reabsorbed into the blood.

Question 18

Secretion

Answer 18

Additional wastes and toxins are actively transported from blood into the tubule.

Question 19

Excretion

Answer 19

The final urine (waste + unneeded materials) is eliminated from the body.

Question 20

Protonphridia

Answer 20

Flatworms, excretory structures in some invertebrates that filter waste and regulate water balance.

Question 21

Metanephrdia

Answer 21

Earthworns, Collect fluid from coelom and excrete it through external openings.

Question 22

Malpighian tubules

Answer 22

Insects, Tubes that remove nitrogen waste from hemolymph and conserve water.

Question 23

Ureter

Answer 23

Carries urine from kidneys to bladder.

Question 24

Urinary bladder

Answer 24

Stores urine until excretion.

Question 25

Urethra

Answer 25

Carries urine from bladder to outside of the body.

Question 26

Renal Cortex

Answer 26

Outer layer of kidney; contains most of the nephron structures.

Question 27

Renal medulla

Answer 27

Inner region; contains loops of Henle and collecting ducts.

Question 28

Renal pelvis

Answer 28

Funnel-like chamber that collects urine and passes it to the ureter.

Question 29

Nephrons

Answer 29

A nephron is the functional unit of the kidney — it’s the tiny structure that filters blood, removes wastes, and balances water and salts.

Question 30

Glomerulus

Answer 30

Capillary network where blood is filtered by pressure.

Question 31

Bowman capsule

Answer 31

Surrounds the glomerulus and collects the filtrate.

Question 32

Proximal tubule

Answer 32

Reabsorbs nutrients, ions, and water from the filtrate back into blood.

Question 33

Descending loop of henle

Answer 33

Permeable to water, not salt → water leaves, filtrate becomes concentrated.

Question 34

Ascending loop of henle

Answer 34

- Permeable to salt, not water → salt leaves, filtrate becomes dilute.

Question 35

Distal tub

Answer 35

Regulates ions (Na⁺, K⁺, pH); fine-tuning of filtrate composition.

Question 36

Collecting duct

Answer 36

Final concentration of urine; water is reabsorbed as needed.

Question 37

Aquaporin

Answer 37

Channel proteins in cell membranes that allow water to pass quickly in or out of cells.

Question 38

Countercurrent exchange

Answer 38

The opposite flow of filtrate and blood in the loop of Henle that helps maximize water and salt reabsorption.

Question 39

Antidiuretic hormone

Answer 39

Hormone from the pituitary gland that increases water reabsorption in the kidneys (makes urine more concentrated).