Question 1

How does ion composition of pre-urine differ from hemolymph?

Accepted Answer

Pre-urine is formed by the filtration of fluid from the hemolymph in the Malpighian tubules, so it has a similar ion composition to the hemolymph. The Malpighian tubules actively transport ions such as K⁺, Na⁺, and Cl⁻, so there may be some changes in ion concentration between the hemolymph and pre-urine, but overall their compositions are similar.

Question 2

The products of filtration in the renal corpuscle enter the renal tubule through which of the following structures?

Accepted Answer

The Bowman's capsule is the structure in the nephron that surrounds the glomerulus, where filtration occurs. The products of filtration, including water, electrolytes, and waste products, enter the renal tubule through the Bowman's capsule. The proximal convoluted tubule, loop of Henle, and collecting duct are all parts of the renal tubule, but they do not receive the products of filtration directly from the renal corpuscle.

Question 3

Freshwater fish dilute ammonia and excrete it in a watery urine.Both freshwater and saltwater fish get rid of ammonia through diffusion across the gills.Humans convert ammonia to urea and excrete it in the urine.Birds convert ammonia to uric acid and excrete it.Why is it important for birds to get rid of ammonia?

Accepted Answer

Ammonia is toxic to birds and can cause damage to tissues and organs if not excreted properly. Uric acid is less toxic and less soluble in water, making it a better option for birds to excrete.

Question 4

Water loss from insect surface is minimal due to which of the following structures?

Accepted Answer

Chitin and the cuticle form a waterproof and protective layer on the insect's surface, reducing water loss through evaporation. Tracheae and spiracles are the respiratory system of insects and allow gas exchange, but they can also lead to water loss. A proteinaceous epidermis is not sufficient to prevent water loss. A small surface area/volume relationship may help to reduce water loss, but it is not a specific structure on the insect's surface.

Question 5

For filtration to take place through the fenestrated capillaries of the renal corpuscle,

Accepted Answer

Filtration through the fenestrated capillaries of the renal corpuscle occurs due to a higher pressure inside the glomerulus (the capillary bed) compared to the pressure in the renal tubule. This pressure difference allows for the filtration of small molecules from the blood into the renal tubule. Other factors such as the size and charge of molecules also play a role in filtration, but pressure is the primary driving force.

Question 6

Figure 42.1 
-Where does filtration take place in the figure above?

Accepted Answer

The answer of Figure 42.1 
-Where does filtration take place...

Question 7

On a very hot,dry day,you lose ________ through the skin.

Accepted Answer

On a very hot, dry day, the process of evaporation causes the loss of both water and electrolytes through the skin in order to regulate body temperature. Therefore, option A (water and electrolytes) is the correct answer.

Question 8

In flour beetles and desert locusts,how is water conserved?

Accepted Answer

The answer of In flour beetles and desert locusts,how is...

Question 9

Malpighian tubules form pre-urine,which is further processed by which of the following anatomical structures?

Accepted Answer

After the Malpighian tubules form pre-urine, it is then transported to the hindgut where further processing occurs, including reabsorption of water and nutrients, and elimination of waste products. Therefore, the correct answer is A) hindgut. B) hemolymph is the blood-like fluid in arthropods that transports nutrients and metabolic waste, but it does not process pre-urine. C) The rectal gland is only found in marine animals like sharks and functions to eliminate excess salt. D) Chloride cells are specialized cells found in the gills of fish that regulate ion transport, but they do not process pre-urine.

Question 10

Insects maintain water and electrolyte balance through which anatomical structures?

Accepted Answer

Insects maintain water and electrolyte balance through Malpighian tubules located in their digestive system. These structures function similarly to kidneys in vertebrates by removing waste and excess ions from the insect's body.

Question 11

Through studies on the Malpighian tubules,researchers found that K⁺ accumulated on the inner face of the tubule,against its concentration gradient.What can you infer about the mechanism of transport?

Accepted Answer

The fact that K⁺ is actively transported against its concentration gradient suggests that the movement of potassium into the lumen of the Malpighian tubules is an energy-requiring process. Therefore, option B is the correct choice. Options A, C, and D are not supported by the given information and are thus incorrect.

Question 12

There are microvilli on the luminal (apical)surface of the epithelium that lines the lumen of the proximal tubule.Microvilli are structural features designed to

Accepted Answer

Microvilli increase the surface area of the luminal surface of the epithelium lining the renal tubules, which allows for a greater amount of solute reabsorption. This is especially important in the proximal tubule where a significant amount of the filtered fluid is reabsorbed. The microvilli also house membrane proteins that facilitate the active transport of solutes, but their main function is to increase the surface area for reabsorption.

Question 13

Reabsorption of water in the hindgut of insects is controlled by which of the following?

Accepted Answer

Osmotic gradients created by ion pumps control the reabsorption of water in the hindgut of insects. This occurs in the Malpighian tubules, which actively transport ions into the tubules, creating an osmotic gradient that draws water in. The water and ions are then reabsorbed back into the hemolymph in the hindgut. Therefore, choice A is the correct answer as it directly addresses the mechanism that controls water reabsorption in the hindgut.

Question 14

Proper functioning of body cells and processes requires solute concentrations to be maintained within a narrow range.Which of the following solutes would be absorbed by the proximal tubule of the kidney nephron?

Accepted Answer

The proximal tubule of the kidney nephron absorbs sodium, which is essential for maintaining proper solute concentrations in the body. Triglycerides are a type of fat and are not absorbed by the proximal tubule. Urea is a waste product that is mainly excreted by the kidney, but it is primarily reabsorbed in the loop of Henle, not the proximal tubule. Carbon dioxide is a gas that is not absorbed by the proximal tubule or any other part of the nephron.

Question 15

The filtrate formed in the renal corpuscle is analogous to the ________ formed in Malpighian tubules.

Accepted Answer

The filtrate formed in the renal corpuscle is similar to the pre-urine formed in Malpighian tubules as both are the initial product of the filtration process in respective excretory systems. Hemolymph is not structurally related to the renal or Malpighian tubular excretory systems. Uric acid is a nitrogenous waste that may be excreted in the urine of mammals or in the feces of birds or reptiles. The hypertonic solution is not comparable to the filtrate formed in either excretory system.

Question 16

The loop of Henle dips into the renal cortex.This is an important feature of osmregulation in terrestrial vertebrates because

Accepted Answer

The differential permeabilities of the ascending and descending limbs of the loop of Henle are important in establishing an osmotic gradient. This gradient allows for the kidney to regulate water and electrolyte balance in terrestrial vertebrates. The loop of Henle plays a critical role in this process, and its location in the renal cortex allows for efficient regulation of water and electrolyte balance. The other options (A, C, D) are not accurate descriptions of the function of the loop of Henle in osmoregulation.

Question 17

A potassium ion gradient is set up in the Malpighian tubules through an active transport process.As a result,potassium concentration is higher in the lumen of the tubules than in hemolymph.How would the potassium gradient affect water movement?

Accepted Answer

The answer of A potassium ion gradient is set up...

Question 18

Different habitats pose certain challenges to animal survival.For instance,terrestrial insects must maintain water balance by minimizing evaporation.How do insects minimize water loss?

Accepted Answer

Terrestrial insects minimize water loss by having a cuticle covered by a waxy hydrophobic layer, which helps to prevent water from evaporating from their bodies. Keeping the spiracles open would actually increase water loss, as these are the openings through which insects exchange gases with the environment. Eating more plant material high in water content would provide temporary relief, but does not address the long-term issue of water conservation. Excreting nitrogenous waste as urea is a mechanism used by some animals for excretion, but it is not directly linked to water conservation.

Question 19

The functional unit of the kidney is

Accepted Answer

The nephron is the basic functional unit of the kidney. It is responsible for filtering blood, reabsorbing important nutrients and fluids, and excreting waste products from the body. The other options, such as the renal corpuscle and loop of Henle, are structures within the nephron that help carry out these functions. The ureters are tubes that transport urine from the kidneys to the bladder, but they are not considered the functional unit of the kidney.

Question 20

What is the organ responsible for regulating water and electrolyte balance in terrestrial vertebrates?

Accepted Answer

Kidneys are responsible for regulating water and electrolyte balance in terrestrial vertebrates. They filter waste products from the blood, reabsorb valuable substances, and regulate the concentration of electrolytes and fluid levels in the body. Chloride cells, Malpighian tubules, and rectal glands are involved in osmoregulation in other types of animals, but not in terrestrial vertebrates.

Quiz 42: Water and Electrolyte Balance in Animals