Biology activity pag. 177

In our biology class, we have been studying coordination and response. Here’s the activity I did with Jose.


a) In which direction does this synapse allow a nerve impulse to travel?

The nerve impulse travels from the left to he right as the vesicles release the neurotransmitter into the synaptic cleft. Then the neurotransmitters attached to the receptor moleculed in the relay neurone.

b) Describe the roles of the parts labelled A and B in transmitting a nerve impulse from one neurone to the next.

The vesicles contain the neurotransmitters.

The receptors receive the neurotransmitters and trigger a nerve impulse in the relay neurone until it reaches the next synapse.

c) Suggest the role of the mitochondria shown in the diagram.

The mitochondria is where respiration takes place and where energy is released for the neurone to transmit nerve impulses.

Nervous System

The central nervous system

The central nervous system is made up of the brain and spinal cord.

And the peripheral nervous system is made up of nerves and receptors.

The CNS is made up of neurones that coordinate the massages travelling through the nervous system.

The three types of cells, neurons are:


  • The sensory neurone: Transmit impulses inwards from sense organs to the CNS


  • Motor neurone: Transmitting impulses from the CNS to muscles and glands elsewhere in the body


  • Relay neurone: Transmit the electrical impulses generated by the stimuli to other nerves.


Osmosis in potato strips

On our Biolgy class we had been seeingthe process of Osmosis, and to finish we went to the lab and made an experiment to see how it was that Osmosis worked. Juan Cruz and I were asked to complete these exercises on the experiment we did in class.

  1. Cut 4 puedes of potato 4cm long, 0,5 wide, 0,2 high. Se were given half piece of potato and we had to cut into four pieces of specific measures.
  2. Place 2 pieces in the Petri dish labelled CS. Potato strips had to placed into the Petri dish with a concentrated solución.
  3. Cover the pieces with the solution CS. We had to pour the solution on the Petri dish and cover the potato strips.
  4. Place 2 pieces in the Petri dish labelled DW. We had to place the twovother remaining strips in the Petri dish.
  5. Cover with the solution DW. We had to pour the solution on the Petri dish and completly cover the potato strips.
  6. Wait for 20-30 minutes.
  7. Remove pieces from the Petri dish CS and DW. The potato strips had to be taken out of the Petri dish containing the different solutions.
  8. Record the results in the table:

This is the result table where we wrote what happened to the potato strips when merged into the solution






Osmosis is the process where water molecules move from a region of higher water potential (diluted solution) to a region of lower water potential (concentrated solution), through a partially permeable membrane. We see this present in the experiment. The potato strips that were covered with the CS solution were in a concentrated solution, and this causes for osmosis to take place, water from the potato strip diffues through the partially permeable membrane to create a balance between high and loswater potentials. Causing the strip to shrink and become softer and flaccid. But on the other hand the potate strip on the Petri with the CW solution was on a diluted solution, and this causes for water to diffuse from the outside to the inside, this way the strip absorbed more water and become bigger and more stiff. 

When osmosis takes place in animal cells, those in a hypertonic solution (with more solute, concentrated) release water and shrink. And those in a hypotonic solution (less solute, more concentration in the cell) absorb lots of water and burst. We also see this in plants, but unlike the animal cells, plant cells don’t burst because of the prescense of cell walls, which protect and give shape to the cell.

In the following pictures we show the materiales, and different steps of the experiment.



Food Tests

During our Biology class we went to the lab where we tested milk for, starch, using iodine solution, reducing sugars, using benedict solution and also proteins using biuret solution and bioling it for two minitues. Our conclusion were that milk does not contain starch, it contains reducing sugars and proteins. We completed the charts below and took some pictures during and after the expirement.

A Iodine Solution White Orange Starch is not present
B Benedict Solution White Purple Milk contains reducing sugars
C Biuret Solution White Orange/Yellow Proteins are present


Test for starch iodine solution Orange Black
Test for protein biuret solution Blue Orange/Yellow
Test for reducing sugars benedict solution Blue Purple

This are all three different test tubes with milk and the different solutions we used to test for components.

These are all the test tubes when the tests are completed, we can see that milk only contains reducing sugars and proteins.

  These are the test tubes when the solutions are added