Hormonal Communication (OCR A Level Biology)

Banting and Best pioneered experiments into the functions of the pancreas.

In one experiment, they removed the pancreas of dogs. Shortly afterwards, the dogs developed the symptoms of diabetes.

• Banting ground up the removed pancreas to produce an extract.
• He called the extract “isletin”.
• The isletin was then injected into dogs that had had their pancreas removed.
• He then tested the blood glucose concentration.

The graph below is a summary of the results.

Which of the following statements correctly explains these results?

1. Isletin is made in the α cells in the islets of Langerhans.
2. Isletin reduces blood glucose concentration.
3. The effects of isletin are short-lived.

The hormone ecdysone is synthesised in the prothoracic glands found in the upper thorax of some invertebrates and is released into haemolymph. It is then transported to cells near the surface of the body and causes the loss of the exoskeleton so that a new exoskeleton can form.

Which of the following statements explains how ecdysone is able to act on cells near the surface of the body?

1	Ecdysone is synthesised by specialised neurosecretory cells.
2	Ecdysone is soluble in haemolymph because it is a polar molecule.
3	Ecdysone is complementary to cell surface receptors on cells throughout the body of some invertebrates.

Which of the following is/are interventions in the control of blood glucose concentration?

Statement 1: Insulin injection

Statement 2: Regular cardiovascular exercise

Statement 3: Glucagon injection

A one year old child displays fatigue and excessive thirst over a period of time. A urine test reveals the presence of glucose.

What is the most likely diagnosis? 

The microscope images below are taken from four different tissue types.

Which image, from A-D, shows pancreatic tissue?

Some diabetic individuals do not produce insulin. In an experiment, a woman with diabetes drank a sugary solution. The glucose concentration in her blood was measured at regular intervals. The results are shown below:

Which of the following statements explains why the concentration of glucose decreased after 60 minutes even though this woman’s blood contained no insulin?

1. Glucose is used in (cellular) metabolism
2. Glucose enters cells where it is converted
3. Glucose is excreted in the urine

The statements below describe the events which occur in response to a drop in blood glucose concentration.

Which row shows the correct order of the events listed?

I	Adenylyl cyclase is activated
II	G proteins are activated
III	Glucagon binds to receptors on the cell surface membrane of liver cells
IV	An enzyme cascade is initiated
V	ATP is converted to cAMP
VI	Glycogen in hydrolysed to release glucose

	Statement
A	III	II	I	V	IV	VI
B	III	I	II	V	IV	VI
C	III	II	IV	I	V	VI
D	IV	II	I	V	VI	III

When blood glucose levels are high, insulin is released from the β-cells of the pancreas.

Which of the following events would not occur in response to insulin production?

The graph shows the blood glucose concentrations of a type 1 diabetic person and a non-diabetic person, at regular intervals after drinking a glucose drink.

Between 0.7 hours and 1 hour on the graph, which process is taking place in the liver of the non-diabetic which is not taking place (or taking place at a reduced rate) in the diabetic?

Addison's disease is an autoimmune disease in which the immune system attacks the outer cortex of the adrenal gland. Some of the symptoms of Addison's disease may include:

• Fatigue
• Muscle weakness

Which of the following provides the most plausible explanation for these symptoms?

Which of the rows, A to D, correctly describes the events that take place in the ꞵ cells of the pancreas when blood glucose levels increase?

	ꞵ cells of pancreas	Voltage-gated calcium channel
A	High concentration of ATP, potassium channels open	Repolarisation and voltage-gated calcium channel open
B	High concentration of ATP, potassium channels close	Depolarisation and voltage-gated calcium channel open
C	High concentration of ATP, potassium channels close	Depolarisation and voltage-gated calcium channel close
D	Low concentration of ATP, potassium channels open	Repolarisation and voltage-gated calcium channel close

Addison’s disease is a disorder during which the adrenal glands do not produce enough hormones, due to the immune system attacking certain areas of tissue. A person with Addison’s disease may have hypotension (low blood pressure).

Which of the following statements could explain the observation?

The table below shows the concentration of glucose in the blood of a person with healthy blood glucose regulation, and an individual with diabetes.

	Concentration of glucose in the blood /gdm3
Time/h	Healthy blood glucose	Diabetic
0.0	0.08	0.14
0.5	0.08	0.14
1.0	0.08	0.14
1.5	0.13	0.18
2.0	0.07	0.17
2.5	0.08	0.16
3.0	0.08	0.16
3.5	0.08	0.15
4.0	0.08	0.15

Which of the following, A to D, explains this data ?

Scientists are investigating the use of stem cells in the treatment of diabetes mellitus. 

Which statement(s) correctly explain(s) why stem cells are suitable for the treatment of diabetes mellitus?

1	Both pluripotent and totipotent stem cells can be grown in the laboratory.
2	Embryonic stem cells are not rejected by the body.
3	Adult stem cells can differentiate into ꞵ cells in the pancreas

Hyperglycaemia is also known as high blood glucose concentration.

Which statement(s) could explain the occurrence of hyperglycaemia?

1	An increased number of GLUT4 transporters in cell surface membranes.
2	K+ channels are open.
3	Glycogenolysis occurs in liver cells.