Relationship, Coordination, and Reproduction in Organisms
The role of relationship allows living things to capture changes (stimuli) and produce a response. Elements of the relationship:
- Incentives: These are variations in the environment, which may be internal or external, physical, chemical, and biotic.
- Receivers: These are structures that capture the stimuli (in animals, these are the sense organs).
- Coordinators: These organs receive information from receptors and send it to the effectors (nervous system and endocrine system).
- Effectors: These are the structures that carry out the response (in animals, these are the muscles and glands).
The response may be:
- Motor: The response is a movement (locomotor system and muscles).
- Secretory: The response is the production of a substance (discharge) by the glands.
Coordination Systems
- Animals:
- Nervous system: Regulates and coordinates the functions of the organism. It is made up of neurons and transmits nerve impulses.
- Endocrine system: Regulates and coordinates the functions of the organism using chemical substances. It is formed by endocrine glands that produce hormones.
The Nervous System
The nervous system is the set of organs and structures formed by nerve cells. It coordinates, gathers information, prepares, and transmits responses to effectors. The vertebrate nervous system consists of nerve centers (brain and spinal cord) and nerves (sensory and motor).
The Endocrine System
The endocrine system is the set of organs that produce hormones. Hormones are chemicals produced by endocrine glands.
The Musculoskeletal System
Invertebrates have an exoskeleton. They do not grow continuously but undergo molting, which is the process by which insects become larger by shedding their exoskeleton and forming a new, larger one. Vertebrates have an internal skeleton formed by bones. Muscles are organs that have the ability to contract and relax and are used to execute movements.
Responses in Plants
In plants, responses to stimuli can be of two types:
- Tropisms: Responses where there are changes in the direction of plant growth. The main types of tropism include phototropism, geotropism, hydrotropism, and thigmotropism.
- Nasties: Transient responses of certain areas of the plant in response to external stimuli.
Reproduction
Reproduction is the function by which parent individuals give rise to new individuals, similar to them, called offspring.
There are two types of reproduction:
- Asexual: Only one individual participates, and there are no gametes.
- Sexual: Two individuals participate, and there are gametes.
Stages of Sexual Reproduction in Animals and Plants
- Gamete formation: This involves the production of eggs and sperm.
- Fertilization: The union of a male gamete and a female gamete.
- Embryonic development: This is where the zygote is formed, which develops into a new individual. It can be oviparous, viviparous, or ovoviviparous.
- Postembryonic Development: The growth of the individual until it becomes an adult.
Stages of Asexual Reproduction
- In animals:
- Excision: A being is divided into different parts, each forming a complete individual.
- Gemmation: A bud is formed, and thus another individual forms.
- In plants:
- Vegetative: The ability to form new individuals from a piece of the parent plant.
- Spores: Spores are formed from a cell and develop into another individual.
Sexual Reproduction in Plants
The reproductive organs of plants are the pistil (female reproductive organ), which contains the ovary with ovules that form the female gametes, and the stamen, which is the male reproductive organ. It is formed by a filament that holds the anther, where pollen grains originating from male gametes are located.
Pollination is the process by which pollen grains from the anthers travel to the pistil of the same flower or another. If the pollen grain is deposited on the pistil of the same flower, it is called self-pollination. If it reaches the pistil of another flower, it is called cross-pollination. It may occur via wind, which requires plenty of pollen, or via animals, where pollen must fall at a precise point. For the seed to germinate, oxygen, suitable temperature, and humidity are needed.
Advantages and Disadvantages of Asexual Reproduction
- Advantages:
- It can be done without another organism.
- Only an abundance of food and good conditions are necessary.
- The process is effective and rapid.
- Disadvantages:
- The descendants are identical, and any negative environmental change can harm the entire species.
Advantages and Disadvantages of Sexual Reproduction
- Advantages:
- Offspring have characteristics of both parents. This means that when there is a negative environmental change, the entire species will not necessarily die.
- Disadvantages:
- It is a process of chance.
- Many gametes must be produced.
- One of the gametes must be mobile.
- A watery medium is required for fertilization.