Biology - Review Qns - 6

Question 1

What are signaling molecules?

Answer 1

Multicellular organisms produce signaling molecules as a form of intercellular communication.

Question 2

What do Signaling molecules do

Answer 2

Signaling molecules transmit information about an internal or external stimulus to other cells, including, ultimately, the effector cells, which enact the response.

Question 3

How are signalling molecules classified?

Answer 3

Signalling molecules can be classified according to their chemical structure, their source and their mode of transmission.

Question 4

Describe Animal Hormones

3 Points

Answer 4

Animal hormones:
• are produced by organs and glands in animals
• can be hydrophilic or hydrophobic
• involve autocrine, paracrine or endocrine modes of transmission.

Question 5

Describe Plant Hormones

3 Points

Answer 5

Plant hormones:
• are produced in a variety of cells in plants
• can be hydrophilic or hydrophobic
• are transported cell-to-cell or via the xylem and/or phloem.

Question 6

Describe Neurotransmitters

4 Points

Answer 6

Neurotransmitters:
• are produced by neurons in animals
• are hydrophilic
• involve paracrine transmission
• transmit the signal to various types of cells form synapses with neurons.

Question 7

Describe Cytokines

4 Points

Answer 7

Cytokines:
• are produced by immune cells such as lymphocytes and macrophages
• have an overall hydrophilic structure
• involve autocrine, paracrine or endocrine modes of transmission
• elicit a variety of immune cell responses such as inflammation, leukocyte differentiation and antiviral activity.

Question 8

Describe Pheromones

4 Points

Answer 8

Pheromones:
• are produced by various specialized cells depending on the species
• are excreted outside the organism
• diffuse through the air to other individuals
• typically only elicit a response in another individual of the same species.