Energy search

In addition to cellular organization, organisms to stay alive need energy, which is obtained from foods or from photosynthesis.

The way organisms obtain food can be classified as:

  • Autotrophs: Living things like plants and algae that nourish themselves through photosynthesis.
  • Heterotrophs: Living beings, who seek energy by feeding on other living beings because they are unable to produce energy alone (through photosynthesis).

Ability to respond to stimuli

Living things must have the ability to respond to stimuli. And this reaction is made in the most varied ways.

At plants, for example, they have no nervous system, so they have less elaborate responses than those of animals, but it can react with movements, as with the sleeper or sensitive, which closes when touched; or even present a phenomenon known as phototropism (light-oriented plant growth).

Phototropism, light-oriented plant growth.

This ability to respond to environmental stimuli we call irritability.

The animals have more complex responses to environmental stimuli because they have a nervous system. Have sensitivity. We are able to distinguish sounds, colors, smells and tastes, among other things. Even animals that lack vision, hearing or other well-developed senses can have structures that allow them to perceive the environment around them. Planarians, a type of flat, non-parasitic worm, for example, do not have eyes but have ocellus, structures that do not form images, but provide a perception of luminosity, allowing them to orient themselves by light.


Reproduction is one of the characteristics common to all species of living beings. Having puppies, that is, having offspring, is important to ensure the occupation of the environment and to remain as a species. If it leaves no offspring, as older individuals die, the species tends to disappear. Hence the importance of reproduction for maintaining the existence of the species.

Therefore, preservation projects such as the Ibama Tamar Project should be valued. This project aims to preserve sea turtles by following the spawning season, caring for their nests, and campaigning for the protection of these animals to ensure their reproduction and consequently the maintenance of the species.

Playback Types

Sexual reproduction is one in which there is participation of special cells, the gametes. Gametes are cells that carry part of the genetic material that will form a new being. In the animal, the male gamete is the sperm and the female gamete is the egg.

The union of gametes, which gives rise to a new being, is called fertilization. Fertilization can be internal, ie the male gamete meets the female gamete within the female's body, or externalIn other words, the male gamete finds the female gamete outside the female's body.

Sexual reproduction of frogs with external fertilization.

The male toad massages the female's abdomen to release its eggs in the leaf while the male deposits the sperm on them.

THE asexual reproduction It does not involve these special steps, the gametes; it just depends on the cells.

Regeneration, a type of asexual reproduction, occurs, for example, in planarians.

Renewing in planarians: If this animal's body is cut into a few pieces, each can originate an entire planarian.

Sexual reproduction is more advantageous for the species than asexual reproduction. While asexual reproduction originates individuals genetically equal to its predecessors, sexual reproduction produces individuals different from its parents. For example, you are not exactly the same as your father or mother, although you may have many characteristics of each.

Genetic variability, produced by sexual reproduction, is always advantageous because it increases the chance of adaptation of the species to possible changes in the environment. Genetic variability is fundamental to the evolution of organisms. Understand this better!