Archivo de la categoría: biology

Endocrine system

Today, in our biology class we learnt about the endocrine system. We had to do some activities and we did it in groups. I was with Cata Rela and Tomi Borda. Here is our work :)

  1. Hormones are chemical substances that help to regulate processes in the body.
  2. Glands that secrete hormones:


3. Effects of Adrenaline: Prepares body for action – ‘fight or flight’.

Adrenaline is the hormone secreted in ‘fight or flight’ situations. It’s secreted when you are frightened, excited or keyed up. Adrenaline effects could be: increased breathing, increased pulse rate, widened pupils, increased blood glucose concentration and increased pulse rate. These people are secreting adrenaline since they are in an exciting situation in which they have to act quickly.

Excretion and Kidneys

In biology, we are seeing a new topic: Excretion and Kidneys. We had to read a webpage containing information about the topic and also play with an animation (Male’s blog).  Here are some revising questions about the topic.

1) a) Define the terms excretion and egestion

  • Excretion as removal from organisms of the waste products of metabolism (chemical reactions in cells including respiration), toxic materials, and substances in excess of requirements.
  • Egestion as the passing out of food that has not been digested or absorbed, as faeces, through the anus

1) b) The kidney is an excretory organ. It produces urine that contains urea. State where in the body urea is formed and what is formed from.

Urea is formed in the liver from excess amino acids.


In Biology we are studying respiration and we had to do this task.  I was with Luna, 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.


Digestive system: Diarrhoea and Cholera

In biology, we are seeing a new topic, Diarrhoea and Cholera. As an introduction, we had to see this VIDEO and answer some questions. Here is my work!


1) Name signs/symptoms caused by cholera.

Diarrhoea, vomiting, weakness, dehydration

2) State ways in which the bacterium spreads in the village.

Through the water in the river, women carried water from the river to their houses where it was used to drink and cook, flies spread it on their feet,

3) What is diarrhoea?

Is the loss of watery faeces and minerals. It happens when not enough water is absorbed from the faeces. Diarrhoea is the second largest cause of death of young children in the world.

4) How does the cholera bacterium cause diarrhoea?

  1. Cholera bacteria are ingested and multiply
  2. The bacteria attach  to the wall of the alimentary canal
  3. The bacteria releases a toxin
  4. The toxin causes Chloride ions to be released
  5. The release of ions causes water to move into the lumen by osmosis
  6. There is now a lot of water in the canal (watery diarrhoea). The blood contains too little chloride ions and water.

5) How did the boy treated his father?

First, he made the water safe by filetering it and then boiling it. Then, he mixed half a tea-spoon of salt and sixty spoons of sugar in one liter of clean water (he gave his father the salts he had lost)

6) Name the different actions which the boy taught to the people in the village to prevent the disease.

Putting chlorine drops on water and waiting half an hour, always wash their hands with water soap and safe water before eating and after going to the bathroom, to wash their hands before cooking, protect the food from flies.

7) Name the bacterium that causes cholera

Vibrio cholerae