Hormonal Communications

Question 1

Suggest and explain why the cell continues to secrete insulin even when there is no further glucose intake (2 marks)

Answer 1

1. as long as blood glucose remains high
2. atp is still present so K+ channels remain closed
3. exocytosis still being triggered by Ca+

Question 2

Describe two similarities in the action of plant and animal hormones in cell signalling (2 marks )

Answer 2

1. hormone bonds to receptor
2. causing enzyme reactions
3. may have effect on more than one location

Question 3

Describe the mechanisms that produced the responses to light in cress seedlings that grew towards light , and a human closing their eyes to bright light (7 marks)

Answer 3

PLANT 
1.tip of shoot produces auxin 
2. diffusion down the shoot 
3. greater auxin on shaded part of stem
4. auxin causes cell elongation
HUMAN
1. retina detect lights
2. depolarisation across sensory neurone
3. relay neurone causes an effect of and depolarisation of muscle fibres 
4. muscle contracts

Question 4

Outline the events that occur after the synthesis of an insulin molecule until it is ready to be secreted from the pancreatic cell ( 3 marks )

Answer 4

1. transported to golgi
2. modified in golgi
3. packaged in golgi vesicles
4. vesicles transported to plasma membrane

Question 5

State where in a pancreatic cell insulin molecules are synthesised (1 mark)

Answer 5

rough endoplasmic reticulum

Question 6

Name the endocrine tissue in the pancreas that is responsible for secretion of hormones (1 mark)

Answer 6

islets of Langerhans

Question 7

Describe how glucagon is involved in the regulation of blood glucose concentration in a person who is able to regulate their their blood glucose concentration correctly (5 marks)

Answer 7

1. when blood glucose concentration decreases glucagon is released by alpha cells in islets of langerhans in the pancreas
2. promotes the conversion of glycogen to glucose in liver cells
3. 5 gluconeogenesis
4. negative feedback inhibits secretion of glucagon
5. glucagon reduces insulin secretion

Question 8

Describe how negative feedback is used to control blood glucose concentration (6 marks)

Answer 8

1. beta cell receptors detect change in blood glucose concentration
2. if higher glucose beta in pancreas release insulin
3. uptake of glucose by effector cells
4. enters through glucose transport proteins glucose converted to glycogen/glucogenesis
5. if lower , alpha cells release glucagon
6. conversion of glycogen to glucose / glucogeonesis
7. glucose leaves cells

Question 9

Explain how a person with type 2 diabetes could control the condition by modifying their diets. (3 marks)

Answer 9

1. decrease starch intake
2. because starch has the greatest effect on blood glucose concentration.
3. have a medium amount of sugars
4. limiting sucrose as it causes an increase in insulin and will make cells responsive ( to insulin )

Question 10

Suggest how the adrenaline molecule can cause different effects in target cells (2 marks)

Answer 10

1. different tissues have different types of receptors
2. second messengers may be different
3. second messengers activate other enzyme reactions

Question 11

Describe the different ways in which the pancreas acts as both an endocrine and an exocrine gland (5 marks)

Answer 11

ENDOCRINE:
1. hormones directly released into the blood
2. beta cells secret insulin
3. alpha cells secrete glucagon
4. islets of langerhans monitor blood glucose concentration
EXOCRINE:
1. fluid released into duct
2. release triggered by nervous stimulation
3. pancreatic secretions into gut

Question 12

Describe the sequence of events leading to the secretion of insulin from a beta cell (4 weeks)

Answer 12

1. glucose phosphorylated to produce ATP
2. ATP blocks K+ potassium channels so they build up and can’t leave
3. Ca2+ channels open so the ions enter
4. Ca2+ result in exocytosis