Edexcel International A Level Biology

Topic Questions

International A LevelBiologyEdexcelTopic Questions7. Respiration, Muscles & the Internal EnvironmentThe Internal Environment

The Internal Environment

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1a
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The kidney is an organ involved in the excretion of waste materials and in the regulation of blood volume and plasma concentration.

The functional unit of the kidney is the nephron.

The diagram shows a single nephron.

q2a-unit-5-oct-2020-edexcel-ial-biology

(i)

In which part of the kidney are structures W and X located?

(1)

  ☐ A cortex
  ☐ B inner medulla
  ☐ C outer medulla
  ☐ D renal pelvis

(ii)

In which structure does ultrafiltration take place?

(1)

  ☐ A W
  ☐ B X
  ☐ C Y
  ☐ D Z

(iii)

Which structures form part of the loop of Henle?

(1)

  ☐ A X only
  ☐ B X and Y
  ☐ C Y only
  ☐ D Y and Z

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1b
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Urea is a toxic substance that is excreted from the body.

Explain how ultrafiltration removes urea from the blood.

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1c
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The kidney controls blood volume and plasma concentration by regulating the loss of water in urine.

Some mammals have adaptations to their kidneys that enable them to live in different habitats.

The table shows information about two small mammals.

Mammal Urine
concentration
/ mOsmol dm−3		 Relative number of mitochondria in the thick ascending loop
of Henle		 Sodium ion concentration of extracellular fluid in the medulla
/ mmol dm−3
brown rat 2900 3.6 45
kangaroo rat 5500 5.5 95


Deduce why the kangaroo rat is more successful than the brown rat at living in desert habitats.

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2a2 marks

Homeostasis is the state maintained by living systems.

Feedback mechanisms are involved in maintaining homeostasis.

Describe the difference between a negative feedback mechanism and a positive feedback mechanism.

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2b1 mark

Which statement about the homeostasis of thermoregulation when the human body temperature is 37°C is correct?

  ☐ A thermoregulation is no longer required
  ☐ B the body no longer generates any heat 
  ☐ C the body will be generating more heat than it can lose 
  ☐ D the body temperature is maintained in a dynamic equilibrium 

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2c4 marks

The health of a kidney can be determined by measuring the glomerular filtration rate (GFR).

This method measures the rate at which a small molecule called creatinine is filtered from the blood.

(i)

Explain how small molecules like creatinine are filtered from the blood in the glomerulus.

(3)

(ii)

In 15 hours, a person excreted 1960 mg of creatinine in the urine.

Calculate the GFR for this person.

Give your answer to 3 significant figures.

(1)

Answer ..................................................

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2d5 marks

In type II diabetes, body cells take up less glucose in response to insulin.

Many people with type II diabetes are overweight or obese.

Some of these individuals have been given surgery to help weight loss.

A clinical trial investigated the effect of surgery on the uptake of glucose by body cells in the presence of insulin.

This trial used groups of people who were non‐diabetic, people in the early stage of diabetes (pre‐diabetic) and people who were type II diabetics.

Group Mean uptake of glucose / a.u.
Before surgery After surgery
 Non‐diabetic 1.07 ± 0.29 1.39 ± 0.58
 Pre‐diabetic 0.55 ± 0.32 1.30 ± 0.88
 Type II diabetic 0.40 ± 0.24 1.10 ± 0.87

(i)
Comment on the results of this trial.

(3)

(ii)
Calculate the difference that surgery makes to the mean uptake of glucose in the non‐diabetic group and the type II diabetic group.

(2)

Answer ....................................................

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3a1 mark

The kidney is involved in the process of homeostasis in a mammal.

Antidiuretic hormone (ADH) is required for homeostasis.

How many of these parts of the kidney respond to ADH?

  • Bowman’s capsule
  • collecting duct
  • loop of Henle
  • proximal tubule
  ☐ A 1
  ☐ B 2 
  ☐ C 3 
  ☐ D 4 

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3b2 marks

The electron micrograph illustration shows a transverse section of part of a proximal tubule.

edexcel-ial-unit-5-june-2021-q4b

(i)

Name the process by which the fluid moves from the plasma into the renal tubule (nephron).

(1)

(ii)

Name the structures labelled S.

(1)

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3c3 marks

A student compared the left renal veins of two individuals.

(i)

The diameter of the left renal vein of one individual was 4.71 mm.

Calculate the cross-sectional area of this vein.

(2)

(ii)

The cross-sectional area of the left renal vein of the second individual was 0.194 cm2.

Calculate the difference in the cross-sectional area in the left renal vein of these two individuals.

(1)

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3d3 marks

The table shows the concentration of glucose and urea in the blood plasma, glomerular filtrate and urine of an individual.

Substance Concentration in blood plasma
/ g dm-3		 Concentration in
glomerular filtrate
/ g dm-3		 Concentration in urine leaving collecting duct
/ g dm-3
glucose 1.50 1.50 0.00
urea 0.30 0.30 21.00

Explain the concentration of glucose and urea in the urine.

Use the information in the table to support your answer.

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3e2 marks

An individual produced 0.83 cm3 of urine each minute.

Calculate the volume of urine produced by this individual in 24 hours.

Assume the urine production is at a constant rate.

Give your answer in dm3, to two significant figures.

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4a
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The kidneys perform important roles in filtering the blood and maintaining fluid levels in the body.

Each kidney contains up to a million functioning units called nephrons.

Each nephron consists of a filtering unit of tiny blood vessels called a glomerulus that is attached to a tubule.

The diagram shows part of a human kidney.

(i)

Draw an arrow on the diagram to show the location of a single Bowman’s capsule (renal capsule).

kidney

(1)

(ii)
Where in the kidney are most amino acids reabsorbed from the nephron?

(1)

  ☐ A Collecting duct
  ☐ B Distal tubule 
  ☐ C Loop of Henle 
  ☐ D Proximal tubule 

(iii)
Which row shows the correct pathway taken by a water molecule through the kidney nephron?

(1)

      Route through nephron negative negative negative negative negative rightwards arrow
  ☐ A  collecting duct  proximal tubule  distal tubule  glomerulus
  ☐ B  glomerulus   proximal tubule  distal tubule  collecting duct
  ☐ C  glomerulus   distal tubule  collecting duct  proximal tubule
  ☐ D  proximal tubule   glomerulus  distal tubule  collecting duct

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4b
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Explain how the loop of Henle acts as a countercurrent multiplier to produce concentrated urine.

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4c
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Describe how ADH is involved in the control of the water potential of the blood.

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5a
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Ecstasy (MDMA) is a recreational drug that can have serious toxic effects.

The effect of MDMA on ADH concentration in blood has been studied.

In one study, each person in a group of volunteers was given MDMA. The MDMA and ADH concentrations in the blood were measured.

The graph shows the results of this study.

q3a-unit-5-oct-2020-edexcel-ial-biology

(i)

Estimate how long it takes the MDMA concentration in the blood to become 0.0 μg dm−3.

(1)

(ii)

Calculate the rate of removal of ADH from the blood between 4 and 8 hours.

(2)

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5b
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Taking MDMA causes a person to be very thirsty. This can lead to swelling of the brain, which can be fatal.

The table shows some laboratory results for one case in which a person suffered swelling of the brain.

Time since
taking MDMA
/ hours		 ADH concentration
/ pmol dm−3		 Sodium ion concentration
in the blood
/ mmol dm−3		 Appearance of the
brain in computed
tomography (CT)
9 4.5 112 Swollen
96 1.2 131 Normal


Comment on the role of ADH in MDMA-induced brain swelling.

Use the information in the graph and table as well as your own knowledge to support your answer.

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