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

Fundamental Scientific Concepts

Biological Foundations

Cells and Life Functions

Cells are the basic structural, functional, and biological units of all known organisms. They are composed of organic and inorganic compounds.

The vital functions of living beings include:

• Nutrition: The process of obtaining and processing nutrients.
• Reproduction: The biological process by which new individual organisms are produced from their parents, ensuring the survival of the species.
• Relation: How living beings communicate and interact with their environment and each other, often involving the nervous system.

Organism Classification

The five biological kingdoms are:

• Monera
• Protoctists
• Fungi
• Plants
• Animals

Animal classification is used to sort and identify characteristics....

The Human Body: Essential Systems & Functions

Blood: Composition and Vital Roles

Blood is a viscous, red, and salty fluid that flows inside blood vessels. An average person has approximately 5 liters of blood, involved in various vital functions, among which stand out:

• Nutrition: Transports nutrients from the digestive system to every cell in the body.
• Respiration: Conducts oxygen (O2) from the lungs to the cells and carbon dioxide (CO2) produced by cells back to the lungs.
• Excretion: Collects waste products from cells and transports them to excretory organs for external elimination.
• Defense: Carries the body's defense cells, protecting against pathogens.
• Thermoregulation: Involved in regulating body temperature by distributing heat or facilitating

Male Reproductive System

The male reproductive system is responsible for producing sperm and testosterone. It is involved in the fertilization process and shares several organs with the urinary system. Some organs are external, while others are located in the abdominal cavity.

Spermatozoa Production

Sperm production occurs in the seminiferous tubules of the testes. It begins at puberty and continues throughout life, though production decreases with age. Sperm travel through the vas deferens to the urethra, where they mix with fluids from the seminal vesicles and prostate. In each ejaculation, 200 to 300 million sperm are expelled; within the female reproductive tract, they can live for 2–4 days.

• Head: Contains a nucleus with chromosomes and an

Body Tissues and Their Specialized Roles

Cells within the human body are specialized to carry out specific processes. In a simplified view, based on their function, we can distinguish the following essential tissues:

• Integumentary Tissue: Covers the outside of the body, providing protection.
• Mucosa: Protects internal cavities, such as those in the digestive and respiratory tracts.
• Adipose (Fat) Tissue: Its cells accumulate fat, serving as a vital food reserve and insulation.

Understanding Nutrition: Fueling the Body

Nutrition encompasses the processes that allow us to use and transform the substances we need to stay alive and maintain bodily functions.

Infectious Disease Transmission: How Pathogens Spread

Infectious diseases are contagious because...

Ecological Factors

Characteristics of the environment that affect all living things, can be abiotic or biotic. Abiotic are the physical and chemical conditions that influence living beings. Biotic are those who share the same environment.

Limiting Factor

The factor closest to the value at which an organism cannot thrive.

Adaptation

The evolutionary adaptation of organisms to a given environment.

Eurioic Organisms

Organisms that have a wide tolerance to changes in their environment.

Stenoic Organisms

Organisms that have a narrow margin of tolerance to changes in their environment.

Adaptations to Water Scarcity

• Water stored in tissues
• Drought-resistant seeds
• Large and deep roots
• Small plants with hard leaves born in spring
• Resistant structures to desiccation
• Low

Core Concepts in Classical Genetics

Genetics:

The branch of biology responsible for the transmission of hereditary traits from one generation to the next.

Gene:

A fragment of DNA information that determines a character. It produces a protein responsible for determining a character, such as eye color or hair color.

Alleles:

The different variants of a gene.

Dominant Inheritance:

Occurs when one gene has greater strength to manifest itself than another gene.

Dominant Gene:

The allele that has more power to manifest itself (expressed even in heterozygotes).

Recessive Gene:

The allele that has less force to become apparent (expressed only in homozygotes).

Intermediate Inheritance:

The pattern in which both genes have the same force to manifest themselves, resulting

1. The Human Respiratory Pathway

Explain the pathway of air in our body and why it is beneficial to breathe through the nose:

It is highly recommended to breathe through the nasal cavities (nasal pits) rather than the mouth. This is because the nasal hairs (iletxoek) filter and clean the incoming air, while the rich blood supply warms (epelago) and moistens it. These cavities connect directly to the interior of the pharynx.

The Larynx and Voice Production

The pharynx connects to the larynx, which is a structure made of monitoring cartilage (kartilago). Inside the larynx lie the vocal folds (vocal cords), which vibrate to produce sound. Thus, the larynx is the primary organ of the voice.

The Trachea and Bronchial Tubes

Following the larynx is the...

Structure of Eukaryotic Cells

The cells of animals and plants are known as eukaryotic cells. They share several fundamental components:

• Plasma Membrane (Cell Membrane): A thin membrane that separates the cell contents from the surrounding environment. It regulates the entry and exit of substances.
• Cytoplasm: The region inside the cell membrane, containing a great variety of structures immersed in a solution called hyaloplasm (or cytosol). Many of these cellular structures are surrounded by membranes and are called organelles.
• Nucleus: The largest and most visible structure. Its contents are separated from the rest of the cytoplasm by a double membrane.

Animal Cell Components

• Mitochondria: Oval-shaped organelles with a double membrane delimiting an

Bioelements: The Building Blocks of Matter

Bioelements are the chemical elements that make up living matter. Of all known elements, only 27 are considered bioelements. They are categorized into three types:

• Primary: Carbon (C), Oxygen (O), Hydrogen (H), Nitrogen (N), Sulfur (S), and Phosphorus (P), which are present in 98% of living organisms.
• Secondary: Calcium (Ca), Iron (Fe), Sodium (Na), and Potassium (K), present in 3.9%.
• Trace Elements: Cobalt (Co), Zinc (Zn), and Silicon (Si), present at 0.1%. These are essential; without them, organisms become ill or die.

Biomolecules: The Molecules of Life

Biomolecules are formed by the combination of bioelements. They are classified into two main groups:

• Organic: Carbohydrates, lipids, proteins, and nucleic

Infectious Diseases

Bacteria: Single-celled organisms that can cause diseases through toxins.

Mushrooms: Unicellular or multicellular organisms causing fungal infections, thriving in moist environments.

Protozoa: Single-celled parasites found in aquatic environments.

Viruses: Non-cellular entities requiring a host cell to reproduce.

Modes of Transmission

Direct contact, inanimate objects, contaminated water or food, airborne pathogens, animal transmitters.

Internal Defenses

Nonspecific: Phagocytes acting against any microorganism.

Specific: Lymphocytes producing antibodies against specific microorganisms.

Noninfectious Diseases

Body System Dysfunctions

Respiratory: Asthma, chronic bronchitis.

Bones and Joints: Osteoarthritis, osteoporosis, cancer.

Deficiencies

Caused...