Review Question Week 7

Question 1

Four facts about endotherms

Answer 1

a. include mammals and birds.

b. usually maintain a constant body temperature that is higher than that of their environment.

d. generate heat from the breakdown of food and other metabolic reactions.

e. have high metabolic rates.

Question 2

True or false: In a countercurrent exchange system, the fluids in two tubes flow in opposite directions.

Answer 2

True

Question 3

Water moves (two answers)

Answer 3

1. from regions of low solute concentration to regions of high solute concentration
2. from regions of high water concentration to regions of low water concentration

Question 4

Osmoregulation

Answer 4

The control of osmotic pressure through regulation of water and solute levels

Question 5

The internal body fluids of an osmoconformer can best be described as having…

Answer 5

roughly the same total solute concentration as the external environment

Question 6

The internal solute concentrations of osmoregulators are

Answer 6

either higher or lower than the solute concentration of the external environment

Question 7

Order of movement in the salt exertion in the shark rectal gland

Answer 7

Primary active; secondary active; facilitated diffusion

Question 8

Distal convoluted tubule

Answer 8

Main function: Selective secretion and reabsorption of ions from the filtrate back into the blood

Tubular secretion primarily add substances to the blood

Segment of the nephron in the kidney

Question 9

Proximal convoluted tubule

Answer 9

First structure to receive filtrate after it leaves Bowman’s capsule

Most reabsorption of water and nutrients FROM the filtrate to go back into the blood

Result: Filtrate is much more concentrated with waste now

First segment of the nephron in the kidney

Question 10

Ureter

Answer 10

Carries urine out of the kidney

Question 11

True or false: Endotherms regulate their body temperature, whereas ectotherms do not.

Answer 11

False
Ectotherms do regulate their body temperature, but mostly behaviorally (e.g., basking, seeking shade) rather than metabolically.

Question 12

True or false: Endotherms can be active for longer periods than ectotherms.

Answer 12

True
Endotherms can sustain activity longer because they generate internal heat and ATP at high metabolic rates.

Question 13

True or false: Endotherms can be active over a broader range of external temperatures than ectotherms.

Answer 13

True
Endotherms stay active across a wide range of environmental temperatures by regulating body temperature internally.

Not ectotherms because conformity ≠ tolerance or performance.

Question 14

True or false: Ectotherms can have higher core body temperatures than endotherms depending on environmental conditions.

Answer 14

True
Ectotherms (e.g., reptiles in the sun) can temporarily reach higher body temperatures than endotherms depending on environmental conditions.

Question 15

True or false: Endotherms must eat more frequently than ectotherms.

Answer 15

True.
Endotherms require more frequent food intake to fuel heat production and maintain a high metabolic rate

Question 16

Osmosis

Answer 16

a. the movement of water from areas of lower solute concentration to areas of higher solute concentration

Question 17

TRUE or FALSE: Osmoconformers tend to live in environments with variable solute concentrations

Answer 17

False

Osmoconformers: internal solute concentration closely matches that of their surrounding environment.
They do not actively regulate internal osmolarity

If environmental solute concentration changes frequently or drastically, osmoconformers lack strong internal regulation so they can’t compensate for these changes.

Rapid changes:
Water would move rapidly in or out of their cells by osmosis
Cells could swell, shrink, or malfunction
Normal physiological processes would be disrupted

They need a stable solute concentration environment

Question 18

The internal solute concentrations of osmoregulators are

Answer 18

either higher or lower than the solute concentration of the external environment

Question 19

Bowman’s capsule

Answer 19

Surrounds the glomerulus and collects filtrate (water and small solutes) from the glomerulus. This filtrate is the start of urine production.

The filtrate that is produced is blood plasma without proteins or cells (but has lots of ions)

Part of the nephron in the kidney

Question 20

A countercurrent flow system between substance A and substance B…

Answer 20

maximizes the exchange by having A and B flow in opposite directions

Question 21

If the fluid inside of a cell has a 5% solute concentration, what would happen if the cell was placed in a solution with a 10% solute concentration?

Answer 21

Water molecules would leave the cell by osmosis.

Question 22

For osmoregulators: True or false: They are restricted to environments with stable solute concentrations.

Answer 22

False

Osmoregulators are defined by their ability to live in environments with changing or extreme solute concentrations.

Osmoregulators actively control the solute concentration of their body fluids using physiological mechanisms.

They do not rely on environmental stability and can maintain internal balance even when external salinity changes

Question 23

For osmoregulators: True or false: Animals that maintain body fluid solute concentrations that are higher than that of the external environment and animals that maintain body fluid solute concentrations that are lower than that of the external environment are both considered to be osmoregulators.

Answer 23

True
An osmoregulator is defined by active control, not by whether internal solute concentration is higher or lower than the environment.

Freshwater animals regulate by keeping internal solute levels higher than their environment

Marine fish regulate by keeping internal solute levels lower than seawater

Both require physiological mechanisms and energy, so both are osmoregulators.

Question 24

For osmoregulators: The osmotic pressure between the inside and outside of internal cells is usually similar.

Answer 24

True
Cells must maintain similar osmotic pressure inside and outside to prevent excessive water movement.

If pressures differed greatly:
Cells could swell and burst
Or shrink and malfunction

Maintaining near-equal osmotic pressure is essential for normal cellular function.

Question 25

For osmoregulators: True or false: Some organisms can switch between acting as an osmoconformer and an osmoregulator depending on environmental conditions.

Answer 25

True Some organisms can: Osmoconform when conditions are stable Osmoregulate when conditions change (e.g., shifts in salinity) Ex. starfish This flexibility allows survival in environments like estuaries where salinity fluctuates.

Question 26

For osmoregulators: True or false: An osmoregulator uses more energy to control body fluid solute levels than an osmoconformer

Answer 26

True Osmoregulators: -Actively transport ions -Produce specialized urine -Use pumps and membranes that require ATP Osmoconformers rely mostly on passive processes and therefore use less energy for solute balance.

Question 27

What is an advantage that ectotherms have over endotherms of the same size?

Answer 27

They require much less food

Question 28

What would happen if you placed a trout (freshwater fish) into a saltwater tank at the aquarium and made some observations?

Answer 28

The fish would lose water and look wrinkled The fish has a lower solute (salt) concentration than the saltwater so water (via osmosis) moves out of the fish

Question 29

The overall purpose of the shark Na+ and Cl- system of transporters is to…

Answer 29

Remove the sodium and chloride ions from the body

Question 30

Which segment is most permeable to water but not to salts: a. Distal convoluted tubule b. Renal pelvis c. Descending limb of the loop of Henle d. Ascending limb of the loop of Henle

Answer 30

c. Descending limb of the loop of Henle because it has many aquaporins but not many ion/salt pumps

Question 31

Renal Medulla

Answer 31

Contains the loops of Henle and collecting ducts Inner region of the kidney Without it, the kidney could only produce dilute kidney Establishes and maintains an osmotic gradient in the kidney Allows water reabsorption from filtrate, especially under the influence of antidiuretic hormone (ADH) Enables production of concentrated urine

Question 32

Loop of Henle

Answer 32

Descending limb of the loop of Henle is most permeable to water but not to salts Establishes the concentration gradient in the medulla in the nephron, allowing the kidney to conserve water and concentrate urine.

Question 33

The Glomerulus

Answer 33

Receives blood entering the nephron Filters proteins and cells out of blood, prevents large molecules from leaving the blood Blood pressure is the primary driving force for filtration here Surrounded by Bowman's capsule

Question 34

TRUE or FALSE: Cells regulate their internal osmotic pressure by controlling the solute concentration inside of the cell.

Answer 34

True Osmotic pressure depends directly on solute concentration, and cells can actively regulate what solutes are inside them. If a cell did not regulate its internal solute concentration, water would rush in or out uncontrollably, causing the cell to swell, shrink, or burst. Controlling solute concentration is the most effective way for cells to regulate their internal osmotic pressure.

Question 35

How do typical cells osmoregulate?

Answer 35

By moving solutes across membranes

Question 36

What is the primary driving force for filtration at the glomerulus?

Answer 36

Blood pressure

Question 37

For osmoconformers: True or false: They often actively regulate the concentrations of particular ions in their body fluids

Answer 37

False Their ion concentrations generally reflect the surrounding seawater, rather than being tightly controlled by energy-requiring transport. "often actively regulate" overstates the amount of control

Question 38

For osmoconformers: True or false: Their internal osmotic pressure matches that of the surrounding environment.

Answer 38

True Isosmotic: Their overall solute concentration matches the surrounding water, so there is no net water movement by osmosis.

Question 39

For osmoconformers: True or false: They use less energy to regulate osmotic pressure than osmoregulators.

Answer 39

True Because osmoconformers do not maintain a different overall osmotic pressure from their environment, they avoid constant active pumping of water and solutes. This makes them energetically cheaper than osmoregulators, which must actively maintain internal conditions different from the environment.

Question 40

For osmoconformers: True or false: They do not have to adapt to the solute concentrations in the external environment.

Answer 40

True They allow their internal osmotic pressure to change with the environment. So “do not have to adapt” means: they do not need to expend energy to maintain a different internal solute concentration than their surroundings.

Question 41

For osmoconformers: True or false: Most marine invertebrates are osmoconformers

Answer 41

True Many marine invertebrates (e.g., jellyfish, echinoderms) live in stable ocean environments. Because ocean salinity doesn’t change much, osmoconforming is a successful strategy.

Question 42

What are the four ways animals gain water?

Answer 42

1) Eating food 2) Cellular respiration 3) Drinking water that has a lower solute concentration than the body fluids 4) Osmosis, such as across the gills of freshwater fish

Question 43

Collecting duct

Answer 43

Final segment of the nephron in the kidney that transports urine and adjusts water and solute content under hormonal control. In renal medulla region

Question 44

Freshwater bony fish: True or false: Chloride cells in the gills actively pump chloride ions into the body.

Answer 44

True Freshwater fish lose ions to the environment by diffusion. Chloride cells (ionocytes) in the gills actively transport Cl⁻ (and Na⁺) into the body against their concentration gradients. This helps maintain proper internal ion concentrations.

Question 45

Freshwater bony fish: True or false: They drink water to replenish water supplies

Answer 45

False Freshwater fish constantly gain water by osmosis because they are higher solute relative to the environment Drinking water would worsen the problem. Instead, they do not drink and excrete excess water as large volumes of dilute urine.

Question 46

Freshwater bony fish: True or false: They maintain body fluid solute concentrations that are higher than that of the surrounding water

Answer 46

True Their internal fluids are hyperosmotic relative to freshwater. This difference is what causes water to enter their bodies by osmosis

Question 47

Freshwater bony fish: True or false: They are osmoregulators.

Answer 47

True Freshwater bony fish actively regulate their internal osmotic conditions. They maintain internal conditions that differ from the environment, which defines an osmoregulator.

Question 48

Freshwater bony fish: True or false: They tend to gain water through osmosis.

Answer 48

True Because their internal solute concentration is higher than freshwater, water moves into the fish by osmosis across gills and skin.