Leaf drop

When fall arrives and the days are shorter, deciduous trees decrease chlorophyll pigment production allowing other pigments present in the leaf to become apparent, resulting in non-green colored foliage. These other pigments include carotenoids that are yellow, brown, and orange. Anthocyanin pigments produce reds and purple colors, though they are not always present in the leaves.

The beginning of leaf drop starts when an abscission layer is formed between the leaf petiole and the stem. This layer is formed in the spring during active new growth of the leaf, it consists of layers of cells that can separate from each other.


Pathogenic bacteria

Bacteria that cause disease are called pathogenic bacteria. Bacteria can cause diseases in humans, in other animals, and also in plants.

Example: Tuberculosis
Tuberculosis is an infectious disease caused by a bacterium called Mycobacterium tuberculosis. Affects your lungs, but it can affect other parts of your body such as your skin or other organs.


Cell structures


 1. What’s the difference between prokaryotic and eukaryotic cells? 2. What’s a Golgi bodies? 3. What does cytoplasm do? 4. What is the cell membrane? 5. What are the difference between plant and animal cells? 6. What are the similarities between plant and animal cells? 7. What is a nucleus? 8. What is the function of the mitochondria in cells?

A Scientific Naming System

 There are many different kinds of living things on our planet. Scientists organize them into groups, or classify them. Every living things that has been identified has two names, a genus name and a species name.

For example, Homo sapiens, is the genus species name for humans. Every scientific name is written with the first word, the genus, capitalized and the second word, the species, in lower case.

This way of grouping and naming things is called taxonomy. By using taxonomy, all species in the world are named using the same formulas and language. This way every scientist knows what another scientist is talking about – even if the scientists are from different countries and speak different languages.