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Introduction to cell theory--the idea that 1) all living things are made of one or more cells, 2) cells are the basic unit of life and 3) all cells come from other cells. Explore the roles that Hooke, Leeuwenhoek and others played in developing cell theory.

Hooke and Leeuwenhoek were two of the first scientists to use microscopes to study the microscopic world of cells. Hooke coined the term "cell" after observing the tiny compartments in cork, while Leeuwenhoek discovered a variety of living creatures in pond water, blood, and other samples. They contributed to the cell theory by suggesting that cells are the fundamental units of life and structure, and that all living things consist of one or more cells that originate from other cells by division. 

All living things are made up of cells, which is the smallest unit that can be said to be alive. An organism may consist of one single cell (unicellular) or many different numbers and types of cells (multicellular).

These two short online tutorials discuss how the earth rotates and then the earth's revolutions.

In the first URL, the YouTube video explains why earth has spring, summer, autumn and winter seasons. The second URL summarizes the key takeaway points.

In this video we’re going to discover how to factorise quadratics that don’t have 1 as the coefficient of the x-squared term. These are called non-monic quadratics. We can do it by trial and error and just spotting the factors, but this takes a lot of trial an error. Luckily there is a different method we can use instead, which we will looks at in this video.

Introduction to the cell.

Outcomes

In this course you will learn how to:

1. Solve quadratic equations by factorisation.
2. Solve quadratic equations by using the quadratic formula.
3. Solve simultaneous equations involving quadratic equations
4. Solve word problems involving quadratic equations.

Even though molecules, proteins, viruses, and cells are all tiny, there are significant size differences between them. The diameter of a water molecule is roughly 0.28 nanometers. The diameter of the protein hemoglobin is roughly 5 nanometers. The diameter of the HIV virus is roughly 120 nanometers. A red blood cell is 6-8 micrometers.

By the end of this unit you will be able to:

• Solve equations with a single variable which are called linear equations
• Solve equations with a single variable that is squared (quadratic equations) by factorisation.

By the end of this unit you will be able to:

• Solve a quadratic equation by completing the square.