Notes, summaries, assignments, exams, and exercises for Biology for Secondary education

1. Health and Disease

When all organs and body systems function correctly, we consider ourselves healthy. If any part of the body is impaired and cannot perform its function properly, it causes disease. When a person becomes ill, characteristic symptoms of the disease appear, often accompanied by some deterioration. Key factors in maintaining health include:

• A proactive approach to health.
• Adopting healthy habits and lifestyles.
• Personal characteristics such as age or hereditary factors.
• An effective health system.

2. Disease Categories

Diseases can be categorized in various ways:

• Infectious: Caused by microorganisms that enter the body and can be transmitted from person to person.
• Non-infectious: Not caused by microorganisms and therefore not transmitted

The Mouth Cavity and Pharynx

The mouth cavity contains the teeth and tongue. Dentition is made up of hard parts embedded in the jaw and covered by dental enamel. The tongue is a powerful muscle that contains taste receptors. The pharynx is a cavity common to both the digestive and respiratory systems.

The Esophagus and Stomach

The esophagus is a muscular conduit that connects the pharynx to the stomach. Regarding the digestive tract, the stomach is a widening of the tract that binds to the esophagus through a valve called the pylorus.

The Small and Large Intestines

The Small Intestine

The small intestine is a tube bending over 6 meters in many loops. It is divided into three regions: the duodenum, the jejunum, and the ileum.

The Large Intestine

The...

Nucleic Acids: Life's Genetic Blueprint

What Are Nucleic Acids?

Nucleic acids are vital macromolecules that store and transmit genetic information. They are polymers formed by the union of repeating monomeric units called nucleotides.

Understanding Nucleotides: Building Blocks

Nucleotides, the fundamental components of nucleic acids, are composed of three parts:

• Carbohydrate (Pentose Sugar): This is a five-carbon sugar. In RNA (Ribonucleic Acid), the sugar is ribose. In DNA (Deoxyribonucleic Acid), the sugar is deoxyribose.
• Phosphate Group (P): A molecule containing phosphorus and oxygen.
• Nitrogenous Base (BN): A nitrogen-containing molecule with basic properties. The main nitrogenous bases are:
  • Adenine (A)
  • Guanine (G)
  • Cytosine (C)
  • Thymine (T) - primarily

The Living Organisms

Nutrition Types

• Autotrophs: Organisms that make their own food.
• Heterotrophs: Organisms that require complex organic matter.

Reproduction and Cellularity

• Asexual Reproduction: Involves a single individual.
• Sexual Reproduction: Involves two individuals (or gametes).

Cellular Structure

• Unicellular: Formed by a single cell.
• Multicellular: Consisting of many cells.

The Vertebrates

Vertebrates are multicellular organisms with eukaryotic cells and heterotrophic nutrition. They are capable of movement.

Classes of Vertebrates

• Fish: Have fins.
• Mammals: Body covered with hair or fur.
• Birds: Have feathers and wings.
• Amphibians: Have moist and fine skin.
• Reptiles: Body covered with scales.

Characteristics of Fish

Fish are fusiform, have fins, their body...

Core Concepts in Ecology

Ecology

The study of interactions between organisms and their environment.

Population

All individuals of the same species living in a specific area.

Community

A group of different populations of species interacting with each other within the same habitat or medium.

Abiotic Factors

Non-living physical and chemical conditions that influence living organisms.

Limiting Factor

An environmental factor that is closest to the minimum or maximum tolerance level for an organism, thereby restricting its growth, distribution, or population size.

Adaptation

An evolutionary process where organisms develop traits that enhance their survival and reproduction in specific environmental conditions.

Euryoic Organisms

Organisms that can tolerate a wide...

Stages of Childbirth

Expulsion (Second Stage of Labor)

The fetus is pushed outward by uterine contractions and by the force exerted by the mother pushing her diaphragm. This stage usually lasts about 15 to 30 minutes. It concludes when the baby is born and takes its first breath.

Placental Delivery (Third Stage of Labor)

Between 5 to 15 minutes after the baby's birth, the placenta is expelled, along with the remaining uterine lining.

Childbirth Complications

Inadequate Dilation of the Cervix and Vagina

To alleviate this problem, the mother may be given the hormone oxytocin, which causes uterine contractions and cervical dilation.

Umbilical Cord Clamping

If the umbilical cord is compressed, the blood flow between the mother and fetus is cut off. If this...

Cellular Biology: Functions, Nutrition, and Systems

All living things are composed of cells. In multicellular organisms, cells consist of a plasma membrane, nucleus, cytoplasm, and organelles. Cells perform vital functions necessary for life: nutrition, relationships, and reproduction. In multicellular beings, cells are grouped into tissues, tissues into organs, organs into systems, and finally, all these form a complete living being.

Internal Environment and Homeostasis

The internal environment is regulated by homeostatic mechanisms, which are controlled by the brain. Nutrients from the digestive tract are broken down into simpler substances that are absorbed into the animal's internal environment. Aquatic animals obtain oxygen dissolved in water,...

Macronutrients and Essential Nutrients

1. Carbohydrates: Energetic Fundamentals

Simple Sugars (Carbohydrates)

• Candy, crystal sugar.
• Soluble in water.

Complex Carbohydrates

• Not sweet or crystalline.
• A union of simple carbohydrate molecules.

2. Lipids

• Insoluble in water and have an oily appearance.
• Fats: High-energy molecules based on chemical composition.
• Differences in Fats:
  • Saturated fat: Animal origin.
  • Unsaturated fats: Vegetable origin.
• Lipid components of cell membranes.
• Lipids with regulatory function.

3. Proteins: Structural Molecules

• Important structure molecules.
• Formed by the union of simpler molecules called amino acids.
• There are 20 amino acids; 12 can be synthesized in the diet, and 8 are essential.

4. Vitamins

• Essential for the proper functioning of

Fundamental Ecological Concepts

Key Ecological Definitions

• Biosphere: The set of all creatures that inhabit the Earth.
• Microorganisms: Bacteria or protozoa.
• Ecosystem: All living beings that inhabit a particular place, interacting with their environment.
• The Ecosphere: The set of all ecosystems on our planet.
• Ecosystems: Composed of biocoenosis and biotope.
• Biocoenosis: The living community within an ecosystem.
• Biotope: The inorganic part of an ecosystem.
• Habitat: The physical location within an ecosystem where individuals of a particular species live.
• Ecological Niche: The role of a species in the ecosystem. It is defined by behavior, the type of food consumed, where food is sought, etc.

Abiotic Factors in Ecosystems

These are the non-living components...

Biological Response Mechanisms

The Function Relationship

The function relationship involves roles that enable a living being to receive information from its external or internal environment and respond appropriately to ensure its survival. Within this function, we distinguish the stimulus, the receptor (which captures the stimulus and passes information), and the effector (which executes the most appropriate response).

Stimuli

A stimulus is a change in the environment surrounding a body or within it.

Types of Responses

Responses can be classified as:

• Static: Responses where no movement is produced.
• Dynamic (Taxias): Responses involving movement. These can be positive (approach to the stimulus) or negative (withdrawal from the stimulus).

Cellular Movements

Types...