Unit 5: Living beings                                                      1   2   3   4   5

4. The vital functions

a) Nutrition function

It involves all the processes to obtain the energy and the substances that living beings need to stay alive and grow.

According to this function, we can distinguish between two kinds of living beings:

       - Autotrophic organisms

 Autotrophs produce their own organic matter from inorganic matter.

The most important kind of autotrophic nutrition is photosynthesis.

They are plants, algae and some bacteria.

       - Heterotrophic organisms

 Heterotrophs take organic matter made by other living beings.

They are animals, fungi and many microorganisms,

like protozoa and some bacteria.

In order by the type of food they eat, the heterotrophic organisms

are classified into:

    - Herbivores (they eat plants; e.g. cows)

    - Carnivores (they eat meat; e.g. lions)

    - Omnivores (they eat meat and plants; e.g. humans)

    - Saprophytes (they eat decaying organic matter; e.g. fungi)

b) Interaction function

It is a group of processes, which allows living beings:

- To interact with their environment (with other living beings and with their

   surroundings)

- To perceive what is happening in the inside of the organism itself.

They have sensitivity; that is they are able to react to different circumstances.

The change able to cause a reaction in an organism is called stimulus

and the reaction itself is called response.

c) Reproduction function

Living beings are able to create descendants in order to assure the survival of their species.

There are two types of reproduction:

 - Asexual reproduction

Only an individual creates the descendants.

These individuals are genetically identical to their progenitors.

It can be able through specialized cells (spores) or not (fragmentation)

It is typical of bacteria, plants like ferns and some invertebrates, among others.

      - Sexual reproduction

There are two individuals of different sex.

They produce a sexual cell called gamete (ovule and spermatozoid).

Both gametes join together to make a zygote. A new individual will grow from that zygote.

The descendants are similar, but no identical to their progenitors.

Plants and vertebrates belong to this group.

4.1. Complete the following sentences related to the function of nutrition:

a.  There are two types of nutrition: ……………………… nutrition, natural to ……………………….and……………………nutrition, characteristic of ……………………

b. The organisms which have autotrophic nutrition make the ……………….

    matter that they need from……………..……matter

c. ………………………… is the most important kind of autotrophic nutrition.

d. Plants and other photosynthetic organisms use energy from

   the……………….

e. They obtain the inorganic matter from the ……………………. (carbon dioxide

    and ………………) and from the ………....... (mineral salts and …………………...)

f. Organisms with…......................... nutrition depends on the organisms with …....................nutrition to live, because they feed up of ............. 

4.2. Mark which of the following creatures have autotrophic nutrition

        and which ones have heterotrophic nutrition.

Now, listen and indentify which sentence corresponds to each type of reproduccion.

4.5. Listen and relate each sentence with the correspondent vital function: