UNIDAD 9. FUNCTIONS OF LIVING THINGS

INTERACTION AND REPRODUCTION

1. FUNCTION OF REPRODUCTION

The function of reproduction is the set of processes to perpetuate the species.

2. THE REPRODUCTION IN ANIMALS

Depending on the complexity of the animals, they can be reproduced by three mechanisms:

Asexual reproduction: it is performed by poorly developed animals, and are reproduced from a single parent with two processes:a) Fragmentation: typical starfish, where a fragment can lead to a new individual.

b) Budding: typical of sponges and corals. Buds appear in the parent, resulting in a new individual. It can be attached to the parent and form a colony, or separated and isolated individuals generate.

Sexual reproduction: most animals have this type of reproduction, and usually have separate sexes. An individual female, a female gonad or ovary produces female sex cells or eggs, and a male individual with a male gonad or testis produces male sex cells or sperm. The union of egg and sperm cell generates a new egg or zygote, which will lead to a new individual with intermediate characteristics of both parents.Some species are hermaphroditic, and the same individual presents two gonads, but not selfed, but sometimes acts as male female and others. This is the case, the worms or snails.

Alternant reproduction: It is typical of jellyfish or cnidaria. Where generations formed by budding alternant with generations that produce male and female cells which origin to a zygote by sexual reproduction.

3. THE REPRODUCTION IN PLANTS

Plants can make 3 types of reproduction:

Asexual reproduction: from a single plant will get other equal to the first. This can be achieved by several mechanisms, including:a) Bulbs: as onions or garlic.b) tubers or underground stems: as the potato.c) stolons: like strawberries. They are trailing stems that take root when contact with the ground and form a new plant.d) Stems: as geraniums, stems from being introduced into the earth.e) Grafts: as the pear trees where the trunk of a species (rose) introduces a stalk of another variety (wild rose) and appears more resilient intermediate variety.

Sexual reproduction: Characteristic of flowering plants, in which the player device in the same flower. The reproductive masuclino are the stamens and the gynoecium the female where the eggs are fertilized and form seeds.

Alternant reproduction: It is typical of non-flowering plants such as mosses and ferns. In both plants alternating two individuals, one formed from an asexual spore called gametophyte, which produces sex cells that generate zygote. When this germinates gives rise to another individue named sporophyte, which produces asexual spores.

4. FUNCTION OF INTERACTION

It is the set of processes to obtain outside information to develop appropriated responses.

5. THE INTERACTION IN ANIMALS

It is performed by the action of the nervous system and endocrine system.

The nervous system consists of three types of organs: a) Receptor organs that capture the information from the outside. They are the sense organs, which receive light, chemical, thermal, mechanical stimuli, etc.

b) Coordinating organs that process information and develop appropriated responses. They are the brain (control intelligence, memory, etc.), cerebellum (controls voluntary movements such as running, take things, etc), medulla (control function of the heart, lungs, etc.), spinal cord (control reflex actions such as closing the lid when you enter something), and nerves.

c) Effector organs that run the answers. These are the muscles and glands.

The endocrine system consists of a set of endocrine glands that produce chemical substances called hormones, which travel through the blood and reach all the organs, but only act in certain organs called target organs. The endocrine system is responsible for changes in animals, such as the metamorphosis of insects or frogs.

6. THE INTERACTION IN PLANTS

Plants have not nervous system but do have endocrine system, which allows them to interact with their environment. Although plants can not move, they can make small movements. These can be of two types: a) Tropisms: movements that are influenced by the direction of the stimulus. For example, the movement of sunflower following the sun (fototropismos), growth of roots down (geotropismos). b) nasties: movements that are not influenced by the direction of the stimulus. Eg, closure of the mimosa when the petals of the flower are touched.