The removal of cell waste

4.1. What does excretion consist of? Cell activity produces waste products like carbon dioxide or urea. These substances are toxic for the organism if they accumulate. The function of excretion is…

Write names and formulas. Matter and its properties

Escribe las formulas correspondientes sin subíndice. Por ejemplo CO2 se escribe CO2. Remember what you have learnt about the formulas and names of binary compounds and do the following activities: Give…

Force and pressure

6.1. The efficiency of force When a force is applied, the effect caused depends not only on the magnitude of the force, but also on the surface area to which it is applied. The relationship between…

The need for energy. Sources of energy

3.1. The need for energy through history In prehistoric times, human beings, who were nomadic hunter-gatherers, needed no other energy than fire to keep them warm and cook their food. Centuries later,…

Choose. The history of energy

Choose the correct answer: What was the first source of energy for humans? Which machine ushered in the industrial revolution? What is the most important source of energy for the Earth, and not just for…

Look. Territorial changes between 1914 and 1923

Look at the map. Which empires gained territory between 1914 and 1923? Which lost land?

Interpret. The economic crisis and the nazism

What is the link between unemployment and the popularity of the Nazi Party between 1924-1933? What other factors helped boost votes?

The rebels' objectives

The government formed after the coup must be completely apolitical, made up of military personnel (...). The first order of business will be revising recently passed legislation, especially that related…

Audición musical. Johann Sebastian Bach: Tocata y fuga en Re menor. [...]

Audición musical. Johann Sebastian Bach: Tocata y fuga en Re menor. Tocata La música barroca: la melodía acompañada

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