Fertilization, Plant Anatomy, Animal Nutrition, and Metazoa
Types of Fertilization
Types of fertilization:
- External without a partner (invertebrates): Gametes are fertilized and float together in the water.
- External with a partner (aquatic mobile species): The female deposits eggs, and the male releases sperm over them.
- Internal with a partner (mammals): Sperm enter the female’s genital tract.
Plant Anatomy Definitions
Definitions:
Root: The underground organ that fixes the plant to the soil. It absorbs water and dissolved mineral salts, forming a fluid called raw sap, which is transported to the leaves through the stem.
Stem: Allows connection and performs the transport of nutrients throughout the plant. It also serves as support, raising the leaves and fruits from the ground. There are two types of conducting tissues in the stem:
- Xylem: A set of woody vessels that transport raw sap.
- Phloem: Transports processed sap.
Leaf: Food is produced here through photosynthesis. The raw sap is transformed into elaborated sap, which is then distributed throughout the plant. The leaf also performs gas exchange and transpires.
Stomata: Allow gas exchange and regulate the quantity of water. They open and close according to conditions (moisture/open – dry/closed). The largest number of stomata is on the underside of the leaf because this is where the plant’s perspiration occurs.
Flower: A set of modified leaves designed to protect gametes and facilitate fertilization. Parts of a flower:
- Perianth: Protects the fertile parts and attracts insects.
- Androecium: Male reproductive apparatus.
- Gynoecium: Female reproductive apparatus formed by one or more carpels (modified leaves where ovules are located).
Pollination: Carries pollen grains from the stamens to the stigmas of the carpels.
Since the majority are hermaphrodites, there are two types of pollination:
- Direct: When the flower self-pollinates.
- Cross-pollination: When flowers pollinate each other.
Systems of pollen transport:
- Anemophilous Pollination (Wind)
- Entomophilous Pollination (animals, insects). It is not necessary to produce as much pollen.
Animal Nutrition Process
Process of animal nutrition:
Digestion: Macromolecules (starch, proteins) in food must be fragmented into simple molecules to penetrate the cell membranes.
Respiration: Inside the cells, cellular respiration occurs. The objective is to extract energy from nutrients. It provides the necessary O2 and removes CO2.
Circulation: For the resulting nutrients from digestion and O2 to reach every cell, an internal transport medium must exist. This is blood in vertebrates and hemolymph in invertebrates (the circulatory fluid).
Excretion: Removes waste substances from cellular metabolism. Excretory substances are transported in internal fluids.
Open and Closed Circulatory Systems
Open and Closed Circulatory Systems:
Open: Blood leaves the vessels and places itself in direct contact with the cells. Most invertebrates have this type.
Closed: Blood flows inside the vessels and does not come into direct contact with the cells. Annelids and vertebrates have this type.
Single and Double Circulation
Single and Double Circulation:
Single: When blood passes only once through the heart to complete the entire body circuit.
Double: When there are two circuits: one between the heart and lungs, and another between the heart and the rest of the body.
Metazoa Classification
Metazoa Classification:
Invertebrates:
- No vertebral column.
- Have an exoskeleton.
- Examples: Insects, mollusks.
Vertebrates:
- Fish: Fins, external fertilization (eggs), ectothermic.
- Amphibians: Legs, external fertilization, ectothermic.
- Reptiles: Legs, internal fertilization (eggs inside the mother), ectothermic.
- Birds: Legs, internal fertilization, endothermic.
- Mammals: Legs, internal fertilization, endothermic.