Nerve nets

Question 1

Example of organism with nerve net

Answer 1

Hydra

Question 2

Radial symmetry?

Answer 2

Symmetrical in a circle

Question 3

Characteristics of hydra

Answer 3

No CNS- has nerve net
Demonstrates radial symmetry
Contains ganglion cells

Question 4

Characteristicsaof nerve net in hydra 6

Answer 4

One type of nerve cell
Cells have short extensions, joined
Unmyelinated cells
Slow impulse transmission
Not many receptors or effectors
Responds to limited numb of stimuli
Impulse can travel bidirectionally

Question 5

Ganglion cells and characteristics 3

Answer 5

Type of nerve cell: short extensions
joined to each other branching in different directions, provides connections in various directions

Question 6

Conduction speed in nerve nets, cause?

Answer 6

Relatively slow: 5m/s
Unmyelinated cells

Question 7

Axons of which organisms were used for experiments + why 2

Answer 7

Squids, they have giant axons
Large enough to connect electrodes to

Question 8

How very experiments on ‘giant’ axons carried out 2

Answer 8

Micro electrodes used to stimulate the axon
Cathode ray oscilloscope measures p.d across membrane

Question 9

Examples of stimuli that hydra can detect

Answer 9

Light
Chemicals
Physical contact

Question 10

Purpose of hydra being able to detect stimuli

Answer 10

Sense its environment and act accordingly

Question 11

Overall speed of responses in hydra, why

Answer 11

Slow: slow conduction bc via propagation and bidirectional impulses slow transmission