Archivo de la categoría: biology

The Eye as a Sense Organ

In Biology we are studying the eye as a sense organ. Male gave us some activities to do in pairs. I was with Cata.

1. Structure of the eye.

2.  Functions of the eye structures.

3. Booklet page 9 exercise 3. 

4. Animation showing how the eye works.  

5. Booklet page 9 exercise 2: The cornea bends or refracts the light rays for the lens to bend and focus them on the fovea (if there is a bright light, on cones) or throughout the retina (if there is dim light, on rods).

6. VIDEO explaining the pupil reflex.

-stimulus: a bright light. >> receptor: cones >> coordinator: brain >> effector: radial and circular muscles >> effect: circular muscles contract while radium relax >> response: the pupil constricts.

-stimulus: a dim light. >> receptor: rods >> coordinator: brain >> effector: radial and circular muscles >> effect: circular muscles relax while radium contract >> response: the pupil gets dilated.

CIRCULAR MUSCLE vs RADIUM MUSCLE: Antagonistic muscles

7. Booklet page 9 exercise 1c: In the dark room light is focused all over the retina, where the rodes are. Rodes are stimulated the, but rodes are of black and white vision only. So Jasmin seed only shapes, not colours.

8. Animations to learn how the eye focuses on a nearby and a distant object.

9. Booklet page 9 exercise 2b: If a close object is focused, the light rays coming will be diverging so they will need a lot of bending. The cornea will bend them and focus them on the lens and the lens will need to be thick so it bends more. The ciliary muscles contract, the suspensory ligaments go slack and the lens becomes shorter and fatter.

Booklet page 10 exercise 4a: Lens and cornea

10.  Booklet page 10 exercise 5: 

a. light receptors bring out electrical impulses.




Nervous System

In Biology we started working with the Nervous System. Here is an entry on Male´s blog with a few interactive activities and videos.


1.a. Key Parts of the Control Center; The Receptors; The neurons and nerve cells;


Sensory Neuron: transmits nerve impulses from receptors to coordinators.


Relay Neuron: Transmits nerve impulses from Sensory Neurons to Motor Neurones.

Motor Neurones: Transmits nerve impulses from the central nervous system (brain &  spinal cord) to effector nerve cells.

c. Reflex Action:

Stimulous >> recept cells >> coordinators (CNS) >> effector cells

d. Synapse:

A synapse is what happens when chemical signals pass from one cell to another. It occurs in the synaptic cleft, which is the tiny gap between the pre-synaptic neuron and the post-synaptic neuron.
Every pre-synaptic neuron has vesicles inside, near the pre-synaptic membrane. Each vesicle contains thousands of neurotransmitters. When the pre-synaptic neuron gets “excited” by an axon potential it’s vesicles diffuse through the cell membrane and release their content into the  synaptic cleft.
Following, the tiny receptors of the post-synaptic neuron interact with the neurotransmitters. These ones bind into the receptors and cause an action as result. Likelihood can be increased and the cell becomes activated firing an action potential or it can be decreased.
Finally, the neurotransmitters molecules left in the synaptic gap drift away by diffusion, or go back to the vesicles to be reused by a process called re-uptake, or are broken down by enzymes and component parts go back to the pre-synaptic neuron.

Respiratory System

In Biology we are studying the Respiratory System.

Here is a post of Male’s blog that explains very well the topic with some tests and activities! (STUDY FROM HERE)

This is a table showing the Gaseous Exchange:






Comparing the amount of carbon dioxide in inspired and expired air we lead to a:

HYPOTHESIS: The expired air contains more carbon dioxide than the inspired air.

LIMEWATER:     clear ——-CO2——-> cloudyimage3



In Biology we are studying respiration and we had to do this task.  I was with Cata, Tomas and Mara. The following are the answers.

  1. The cells in our body need energy to: Contract muscles, so we can move; make protein molecules by linking together amino acids into long chains; repair damaged tissues through cell division so we can grow; carry on active transport; transmit nerve impulses, so we can transfer information quickly; to produce heat  inside the body, to keep the body temperature constant if the environment is cold.

3. When we run in a race, for example, we need a lot of oxygen in order to release energy to contract our muscles. We keep on running, maybe faster, and we need every time more and more energy. Our heart starts to beat faster because we need energy to reach our blood more quickly since we are constantly losing it. But eventually we can’t breath more quickly than we have been doing. There is when we produce “extra energy” by anaerobic respiration. Glucose is broken down without combinating it with oxygen. This action releases lactic acid and energy. “Oxygen Debt” is this action. When we “borrow” some extra energy without “paying” for it with oxygen. As a consequence of this we have a lot of lactic acid left in our muscles and blood which can be broken down by combinating by aerobic respiration.



Diarrhoea and Cholera

In Biology we started a new topic: Cholera. Here is a task Make gave us and there we have some questions we must answer. These ones:


1) Name signs/symptoms caused by cholera.                                                Diarrhoea (sign), vomiting (sign), feeling sick (symptom), high temperature (sign), irregular heart-beats (sign), dehydration (sign).

2) State ways in which the bacterium spreads in the village.                                The bacteria(Vibrio cholerae) spreads because of flies (agents) that transport it, because non-purified water also transport it, shaking hands that are not clean, not washing hands before and after eating or going to the bathroom…

3) What is diarrhoea?                                Diarrhoea is a sign caused by cholera that may give you a hint that you are suffering from this disease.

4) How does the cholera bacterium cause diarrhoea?                                                                       The cholera bacteria which lives and breeds in the small intestine produces a toxin that stimulates the cells lining the intestine to secrete chloride ions. Then the ions accumulate in the lumen of the small intestine and increase the concentration of the fluid in the lumen lowering its water potential. When this water potential becomes lower than the one of the blood flowing through the vessels in the wall of the intestine, water moves out of the blood into the lumen of intestine by osmosis. So large quantities of water are lost from the body in the watery faces.


5) How did the boy treated his father?          He filtrated and cleaned the water because at 100°C the bacteria’s enzymes become denatured and they die. He also added salt to the water in order to give the minerals back. Then he made his father drink it to calm dehydration and soon he got better. 

6) Name the different actions which the boy taught to the people in the village to prevent the disease. Clean  and filtrate water, wash hands, wash food before cooking and make sure that it boils, eat hot…