excretion ppq

Question 1

The kidney is one of the organs of excretion in vertebrate animals.
Fig. 2.1 shows a light micrograph of a section through a kidney cortex.
i. Name the parts of the kidney labelled A and B.

Answer 1

A = glomerulus
B = bowman’s capsule

Question 2

Sodium ions and glucose are both reabsorbed into the blood from proximal convoluted tubules (PCTs)
in the kidney.
i. A student designed an experiment to investigate the effect of temperature on the rate of glucose
diffusion through dialysis tubing.
State two factors that would need to be controlled in this experiment

Answer 2

.initial glucose concentration
.volume of solution

Question 3

Describe the structural difference between alpha and beta glucose molecules.

Answer 3

alpha glucose has H above ring and OH below ring on C1

Question 4

Sulthiame is a drug that inhibits the enzyme carbonic anhydrase.
Fig. 2.2 shows the role of carbonic anhydrase in the PCT of the kidney.
Using the information in Fig. 2.2, what can you conclude about the likely effect of sulthiame on the
reabsorption of sodium ions in the PCT?

Answer 4

.less + ions in PCT cells
.less facilitated diffusion of Na+ into cells
.less active transport of Na+ into blood

Question 5

The measurement of kidney filtration rate provides an indication of the health of the kidneys.
A filtration rate of below 60 cm3 min−1 for three consecutive months or more is a sign of chronic kidney
disease.
A patient was found to have the following kidney filtration rates:
Month 1: 54.00 cm3 min−1
Month 2: 4.85 × 10−5 m3 min−1
Month 3: 1.12 cm3 s−1
Month 4: 9.70 × 10−7 m3 s−1
Do these results suggest the patient has chronic kidney disease?
Explain your conclusion using the information given.

Answer 5

No because month 3 is above 60cm3 min-1

48.5
67.2
58.2

Question 6

19.3 is a light microscope image of kidney tubule cells.
Fig. 19.3
i. State three structures within the tubule cells that are not visible in this image.

Answer 6

mito
ribosomes
ER

Question 7

. Fig. 22.1, below and on the insert, is a cross section of part of the cortex of a mammalian kidney.
Fig. 22.1
i. Which letter identifies the region with the highest hydrostatic pressure?
[1]
ii. Which two letters identify regions that do not contain plasma proteins?

Answer 7

A
BD

Question 8

Studies of the cell surface membranes of the distal convoluted tubule have provided the following
evidence:
*Sodium-potassium pumps:
– move potassium ions from the blood to the tubule fluid
– move sodium ions from the tubule fluid to the blood
– use ATP in these processes.
*Sodium-calcium co-transport proteins:
– move calcium ions from the tubule fluid to the blood
– move sodium ions into the tubule fluid
– use the electrochemical gradient of sodium ions to drive this process.
i. Using this information and your own knowledge, compare the processes occurring in the proximal
and distal convoluted tubules.

Answer 8

similarities:
.both use active transport
.both involve co-transport

difference:
.DCT uses Ca2+ ions
.DCT involves ions only

Question 9

Nephrogenic diabetes insipidus is a disease of the kidney that affects the regulation of water potential
in the blood. One cause is lithium poisoning. Lithium ions enter the kidney tubules through sodium
channels.
This prevents the cells of the collecting duct from responding to ADH in the blood.
State and explain one symptom you would expect to observe as a result of nephrogenic diabetes
insipidus.

Answer 9

.high volume of urine due to less aquaporins in the plasma membrane

Question 10

Fig. 22.2 shows a podocyte from the kidney. The many gaps between the microscopic processes form
fenestrations in the Bowman’s capsule.
Fig. 22.2
i. Explain why podocytes are usually unable to undergo mitosis.

Answer 10

.there cells are already differentiated
.it would alter size of gaps
.it would cause less ultrafiltration

Question 11

Studies show that after damage by infection or injury, it is possible for nephron tissues to be
regenerated. Adult stem cells are involved in this process.
What features of adult stem cells make them suitable for regeneration of tissues in the kidney?

Answer 11

.adult stem cells are multipotent and so can differentate into any cell within the kidney

Question 12

The process of ultrafiltration in the kidney shares similarities with the formation of tissue fluid.
* Describe the similarities and differences between ultrafiltration and the formation of tissue fluid

Answer 12

similarites:
.small molecules are filtered from blood
.both use capillaries
.large molecules stay in the blood
.hydrostatic pressure is higher than oncotic pressure

differences:
.filtrate enters bowmans capsule and then the PCT in the kidney but tissue fluid enters intercellular space
.blood is filtered through 3 layers in ultrafiltration but 1 for tissue fluid

Question 13

. A person’s glomerular filtration rate (GFR) provides an indication of the health of their kidneys.
The GFR is a measure of the volume of blood that can be filtered by the kidneys every minute.
GFR can be estimated by monitoring the blood concentration of creatinine, which is a breakdown
product of creatine phosphate in muscles.
i. Suggest two characteristics of a patient that must be taken into account when using this GFR
measurement to diagnose kidney damage.
Explain why each characteristic must be considered.

Answer 13

age
gender

Question 14

Explain why the presence of albumin in the urine indicates kidney damage.

Answer 14

large proteins shouldn’t enter the bowmans capsule

Question 15

State one function of the distal convoluted tubule.

Answer 15

absorption of ions

Question 16

Fig. 19.1 is a diagram of a nephron from a mammalian kidney.
Fig. 19.1
Which letter or letters label areas of the nephron which are directly affected by ADH?

Answer 16

M

Question 17

Explain, with reference to Fig. 19.2, why some foods affect urine production.

Answer 17

.salted crips and boiled sweets reduce WP of blood
.cause increased release of ADH
.ADH causes production of aquaporins in collecting duct so more water is reabsorbed
.bread increases WP of blood

Question 18

Describe how the endocrine and nervous systems work together to increase water reabsorption
from the collecting duct.

Answer 18

.hypothalamus causes release of ADH from pituitary aldosterone released from adrenal cortex
.ADH released from pituitary gland
.ADH binds to receptors on the cell membrane of collecting duct cells increasing permeability to water

.hypothalamus is part of NS
.osmorececptors in the hypothalamus dectect low WP in blood and ADH is produced

Question 19

Suggest which of the diuretics, X, Y or Z, would be the most effective at reducing a
person’s blood pressure. Explain your choice.

Suggest which of the diuretics, X, Y or Z, would be the most appropriate for use by a
person with type II diabetes. Explain your choice.

Answer 19

Y
reduces blood volume the most

X
does not raise blood glucose conc

Question 20

Explain why peritoneal dialysis can use active transport and diffusion while haemodialysis relies on
diffusion alone

Answer 20

peritoneal wall is made up of living cells and so produces ATP to carry out AT

Question 21

Suggest one advantage and one disadvantage of a kidney transplant compared to dialysis

Answer 21

.better quality of life
.organ rejection

Question 22

Fig. 17.1 is a diagram of the external view of a mammalian liver.
Identify, with reasons, each of the blood vessels labelled A – C in Fig. 17.1.

Answer 22

hepatic vein due to blood leaving

hepatic artery as blood entering via narrow vessel

hepatic portal as blood entering via branched vessel

Question 23

During the cycle ornithine moves into organelle D and citrulline moves out of the organelle.
Suggest the method by which these molecules move into and out of the organelle during the cycle.
Give reasons for your choice.

Answer 23

via active transport as they need to be moved in and out of D more quickly than diffusion

Question 24

How has the ammonia that is used in step 1 been formed?

Answer 24

removing NH2 group from amino acid

Question 25

• Using the information, deduce why and how catalase activity is regulated inside the liver cells.

Answer 25

.large quantites of hydrogen peroxide and high num of catalase would cause vigouros reaction and lots of oxy produced very quickly

.isolation of catalase in peroxisomes
.released in small quantities
.cell can limit expression of catalase
.limiting enzyme conc and so reduces rate

Question 26

Describe two ways in which the liver tissue damaged by cycasin is different from normal liver tissue.

Answer 26

.large gaps
.cell death

Question 27

Explain why bilirubin production and processing is an example of excretion

Answer 27

metabolic waste is produced from haem and is removed from the body

Question 28

The liver is an organ with a wide variety of functions.
Fig. 18.1, in the insert, shows a light micrograph of a section of normal human liver.
Fig 18.1
i. Identify the structures labelled N and O in Fig. 18.1.

Answer 28

central vein
hepatocyte

Question 29

The walls of the structure labelled M in Fig. 18.1 are lined with cells.
Suggest and explain how these cells are adapted to carry out their function.

Answer 29

thin cells for short diffusion distance

Question 30

) Use the letter or letters from Fig. 6.1 to identify:
(i) the region or regions where glucose is selectively reabsorbed into the blood capillaries
…………………………………………………………………………………………………………………….. [1]
(ii) the region or regions present in the cortex
…………………………………………………………………………………………………………………….. [1]
(iii) the region or regions where podocytes are located.

Answer 30

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QJKL
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Question 31

Explain how the longer loop of Henle is able to assist the desert kangaroo rat in preventing
excessive water loss

Answer 31

more ions pumped out of ascending limb
.bulids up greater WP gradient
.more reabsorption of water

Question 32

Explain the changes in fluid composition shown in Table 3.1 and Table 3.2.

Answer 32

.large molecules cannot leave blood
.all glucose is reabsorbed at PCT
.all amino acids is reabsorbed at PCT
.urea conc increases due to movement into tubule

Question 33

The blood in the glomerulus has a high ………………………………………………. pressure,
which forces small molecules, such as glucose and …………………………………………….. ,
out of the glomerulus and into the lumen of the Bowman’s capsule. This process is
known as ……………………………………………… .
In the proximal convoluted tubule, the glucose, most of the ……………………………………….. and
some of the salts are reabsorbed into blood ………………………………………………. that surround
the nephron at this point

Answer 33

hydrostatic
water
ultrafiltration
water
vessels

Question 34

ADH is released in response to a decrease in the water potential of the blood plasma.
(i) State precisely where the cells that detect a decrease in the water potential of the blood
plasma are found.
……………………………………………………………………………………………………………………. [1]
(ii) Name the cells that detect this decrease.

Answer 34

hypothalamus
osmoreceptor

Question 35

Which part(s) of the nephron corresponds to each of the statements in the table below?

walls are impermeable to water
glucose is reabsorbed into the blood
ADH acts on the walls
contains podocytes
most of the water is reabsorbed into the blood

Answer 35

ascending limb
PCT
DCT
bowmans capsule
PCT

Question 36

With reference to Fig. 2.1, explain the role of the loop of Henle in the production of urine.

Answer 36

.cause a decrease in WP
.ascending limb active transport out of ions
.descending permeable to water water is removed
.water is removed from filtrate

Question 37

Suggest why a high intake of protein in the diet will be likely to result in a high
concentration of urea in urine.

Answer 37

.leads to large amount of amino acids
.cannot be stored
.so amine group is converted into ammonia

Question 38

Explain how the glomerulus is able to perform its function.

Answer 38

.afferent arteriole is wider then efferent arteriole
.build up of hydrostatic pressure

Question 39

Suggest the effects of complete kidney failure on the composition of the blood.

Answer 39

high urea
.high ions

Question 40

Describe the features of the glomerulus and Bowman’s capsule that allow them to
perform their function effectively.

Answer 40

.undergo ultrafiltration
.afferent arteriole is wider then efferent arteriole
.high blood pressure in glomerulus

Question 41

ADH is a hormone that is produced by specialised nerve cells known as
…………………………………………. cells. These cells detect changes in the water
potential of the blood flowing through the …………………………………………. . If the water
potential of the blood is too low then ADH is released.
ADH is not secreted immediately into the blood but passes along the
…………………………………………. of the specialised nerve cells to the
………………………………………………. ………………………………………………. gland, from where it is
released into the blood.
ADH acts on the cells of the …………………………………………. …………………………………………. .
The ADH molecule attaches to receptors on the …………………………………………. of these
cells and causes protein channels known as …………………………………………. to insert
themselves into the membrane. Water passes through these channels by
…………………………………………. and a smaller volume of more concentrated urine is produced.

Answer 41

osmoreceptor
hypothalamus
axons
posterior pituitary
collecting duct
membrane
aquaporins
osmosis

Question 42

Suggest where ADH is removed from the blood and describe what then happens to the ADH
molecule.

Answer 42

.delt in liver
.hydrolysis
.deamination