Topic 9.2 Chemical Control in Animals

Question 1

The hormone adrenaline is unable to pass through cell membranes.
When liver and muscle cells are exposed to adrenaline, the enzyme glycogen phosphorylase breaks down glycogen.
Describe how adrenaline causes liver cells to increase the concentration of glucose in the blood. (3 marks)

Answer 1

• adrenaline binds to receptors on membrane / cell surface
• second messenger cAMP involved
• activates glycogen phosphorylase
• glucose diffuses out of cells

Question 2

Compare the mechanisms used in hormonal and nervous coordination in mammals. (3 marks)

Answer 2

Hormonal / nervous
- chemical / electrical impulses
- transported in blood / via neurones
- slow speed of transmission / fast speed
- long lasting response / short lived
- wide spread effect / localised

Question 3

Given thyroxine is able to enter the cell,
How does thyroxine increase the secretion of adrenaline from adrenal glands? (4 marks)

Answer 3

• can enter so it’s hydrophobic
  -thyroxine binds to receptors
• enters the nucleus
• activates transcription factor / stimulates transcription
• increased protein synthesis
• synthesise more adrenaline

Question 4

What are endocrine glands?

Answer 4

Releases hormones

Question 5

What are exocrine glands?

Answer 5

Secreting digestive juices like enzymes

Question 6

What is the definition of hormones?

Answer 6

Chemical messengers released by glands travelling via blood towards target cell by binding complementary receptors

Question 7

Which parts of the brain will help to coordinate endocrine functions?

Answer 7

Hypothalamus and pituitary gland

Question 8

What are the 2 types of hormones?

Answer 8

protein based and lipid based

Question 9

What are examples of protein based hormones?

Answer 9

Adrenalin
melatonin
FSH
ADH
LH

Question 10

What are examples of lipid based hormones?

Answer 10

steroid hormones like
oestrogen

Question 11

Where are steroid (lipid) hormones derived from/made of?

Answer 11

cholesterol

Question 12

Where are protein based lipids derived from/made of?

Answer 12

multiple amino acid chain
tyrosine and tryptophan

Question 13

Describe the process of hydrophilic hormones

Answer 13

• a cascade of reactions
• binds to complementary receptor
• changes shape of G protein
• it becomes complementary to adenylyl cyclase
• breaks down ATP to cAMP
• cAMP is a second messenger, binds to kinase enzyme
• catalyse reaction

Question 14

Do cells have the same genes and how do they have different functions?

Answer 14

All have the same 46 chromosomes
but depends on what genes are switched on and off
hence gene expression

Question 15

What do transcription factors do?

Answer 15

promote transcription and translation

Question 16

Describe the process of hydrophobic hormones causing synthesis?

Answer 16

It can diffuse through the cell membrane
It binds to complementary steroid receptor
Forming hormone receptor complex
Enters nucleus - act as transcription factor
triggers more transcription