Biology revision points and complete definetions of all questions and biological problems

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Biology revision points and complete definetions of all questions and biological problems

Characteristics of living organisms.

Living things are called Organisms. Living organisms have Seven characteristics that make them different from non-living things:

IT is much easier to learn them in this abbreviation: MRS GREN.

Movement: This is very easy to see in most animals, but it is not easy to see in plants way in movement. Movement may occur when the organism needs some kind of source to live better may be for food and hunting for shade and even to hide from predators. Most plants are rooted to the ground so the whole plant cannot move. But parts of plants may slowly perhaps only the contents of their cells move. So that you only see the movement under a microscope.

Respiration: This means that they break down food inside their cells, sometimes by combining it with oxygen. This releases energy from the food, and the organisms can use this energy to carry out the rest of the seven characters.

Sensitivity:  Living organisms are sensitive towards their surroundings. They can sense changes in their surroundings and respond to this change. This is sometimes also called Irritability. The changes they sense are of many types, such as temperature, light intensity, sound, day length and the presence of chemicals and the amazing sense of danger when predators are around.

Growth: Living organisms grow. Some of the nutrients they feed on provide them with the energy needed to help the cells in the organisms to grow, and to build new cells, so that the organisms grow larger.

Reproduction: Living organisms reproduce, every kind of living organisms is able to make new organisms like it self, either by self dividing or in other words Asexually or by having a partner like in most cases male and female will out go and reproduce Sexually.

Excretion: Living organisms excrete, chemical reactions take place inside the cells of an organism, some of the substances made during or by the reactions which are chemically done can be poisonous, so the organism needs to get rid of those substances.

Nutrition: Living organisms need to feed. They need to take in substances from their surroundings. They use these substances for growth, or as a source of energy to continue on living properly and to out go all the other characteristics.

Classifying living organisims.

No body knows how many different kinds, or species of living organisms there are on earth. About 1.4 million different species have been described and named. But many biologists think that this may only be one tenth of the species on earth! We have almost certainly discovered most of the large land animals, but there are probably many animals living in the deep oceans which have never been seen by humans. And biologists estimate that there are certainly millions of insects and smaller animals and plants that have not yet been discovered.

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To make it easier to study this organism's biologist has sorted them into groups. This sorting is called Classification. Living organisms have evolved over 100 of millions of years. Living organisms are all related to one another biologist classify them by putting closely related organisms in to the same group.

The vertebrates

One group of the organisms is the vertebrates. The vertebrates all belong to a large group or phylum, called chordates. The chordates all have a stiffening rod that runs along inside the upper surface of their body. In the vertebrates this rod has been replaced by ...

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