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

Understanding Sensory Receptors

Quimioreceptors: Sensitive to chemicals.

Mechanoceptors: Sensitive to mechanical stimuli, such as pressure and sound.

Photoreceptors: Sensitive to light.

Thermoreceptors: Sensitive to temperature variations.

Nociceptors: Sensitive to intense pressures and are responsible for pain.

Types of Receptors

• Interoceptors: Located inside the body, particularly in the viscera, responsible for collecting information about the internal state of the organism (e.g., hunger and thirst).
• Exteroceptors: Located on the surface of the body, responsible for collecting stimuli from the outside, such as light, sound, and temperature.

Eye Anatomy

Light enters the eye through the cornea, which acts as a convex lens to diverge light rays to a...

Evolutionary Biology and Genetic Fundamentals

Evolution: These are processes of progressive, continuous changes in the characters of species or populations over time. Adaptation: This refers to the structural capacity of the body that allows it to live and adapt to its environment. Note: A remarkable study about something; a note or explanatory book. Objection or warning.

Genetic Mechanisms and Heredity

Mutation: It has its origin in sudden changes that take place at the gene or chromosome level. Genes: Every human being has approximately 30,000 genes that determine the growth, development, and functioning of our physical and biochemical systems. Chromosomes: The core of every human sex cell contains 23 chromosomes. DNA: It is constituted by a...

Protista

Protista

• - Presents eucariotic cells
• - Representatives: protozoa and algae
• - Mostly unicellular

Protozoa

• - Eukaryotes
• - Unicellular
• - Heterotrophs

Classification

Protozoans are classified by the presence of organelles used for locomotion:

• 1) Rhizopods: move by means of pseudopodia. Ex: Amoeba, which causes amebiasis (transmitted by contaminated water and food).
• 2) Ciliates: move by means of cilia. Ex: Paramecium.
• 3) Sporozoans: do not have locomotor structures. Ex: Plasmodium (malaria) and Toxoplasma gondii (toxoplasmosis).
• 4) Flagellates: move by means of flagella. Ex: Trypanosoma cruzi (Chagas disease).

Note: Reproduction is asexual.

Algae (Microscopic)

• - Eukaryotes
• - Unicellular
• - Autotrophic

• 1) Euglenophytes (mostly freshwater; some are part of the

Population, Community, and Ecosystem

A population is a group of individuals of the same species living in a specific area. A community is a set of populations inhabiting the same area. The biotope is the physical environment occupied by a community, characterized by specific environmental conditions. An ecosystem encompasses both the community (biocenosis) and the biotope, including the interactions of organisms with each other and their environment.

Habitat and Optimal Conditions

A habitat is the specific environment where an organism finds the necessary conditions for life. Optimal conditions, regarding a given environmental factor, are the values at which a species thrives, reproduces effectively, and experiences high offspring survival....

The Nervous System: Structure and Function

The nervous system is a vast and complex network of neurons. Its basic component is nerve tissue, and its primary function is to interpret, store, and respond to information received from the external environment and the internal state of the body.

Neurons: The Units of Communication

Neurons are the anatomical and physiological units of the nervous system. They possess the property of excitability—the ability to perceive stimuli and produce responses based on the generation and transmission of electrical nerve impulses.

• Impulse Transmission: A stimulus generates a small electrical current in the neuron membrane, which propagates rapidly along the axon to the synaptic button, reaching another neuron,

Biological Functions of Proteins

Structural Function

Proteins are essential components of plasma membranes, working alongside phospholipids and cholesterol. There are two main types of membrane proteins: peripheral proteins, located on the exterior or interior surfaces, and integral proteins, which are housed within the phospholipid bilayer.

Why is the water molecule a dipole? It is because electrons are closer to the more electronegative oxygen atom, resulting in positive and negative charges for hydrogen and oxygen respectively.

Enzymatic Function

Enzymes are globular proteins that catalyze metabolic reactions. A catalyst is a substance that accelerates chemical reactions. In our organism, only enzymes can perform this function. While chemical...

1. The Blood Circulatory System

Blood Vessels and Heart

1.1 Composition of Blood

Blood is a reddish liquid composed of:

• Plasma: Constitutes 55% of the blood. It is a yellowish liquid consisting of water, mineral salts, proteins, glucose, etc.
• Blood Cells: Constitute 45% of the blood.

Blood Cells:

• Red Blood Cells (or Erythrocytes/Hamaties): Transport oxygen ($\text{O}_2$). They contain hemoglobin.
• White Blood Cells (or Leukocytes): Defend the body.
• Platelets (or Thrombocytes): Prevent bleeding.

1.3 Functions of Blood

• Transporting nutrients (via red blood cells).
• Transporting gases.
• Controlling bleeding (via platelets).
• Distributing body heat.

2. Diseases

Anemia

• Symptoms: Paleness, tiredness, spots on nails, nosebleeds.
• Grounds: Lack of iron, resulting in insufficient

Tissues: Types, Structure and Function

Tissue: a group of cells that assemble and function together. Between cells is the intercellular substance (extracellular matrix). Cells can be closely packed together or separated by this intercellular material.

Epithelial Tissue

Epithelial (covering) tissues form protective layers such as skin (the outer layer). They also form mucous membranes that line internal cavities and surfaces, and they include secretory tissues (glands). Epithelial tissues are made of crowded cells with little intercellular substance and may be arranged in one or several layers.

Nervous Tissue

Nervous tissue consists of neurons and supporting cells. It transmits nerve impulses and is responsible for coordination, sensation, and the...

Human Sensory Receptors and Body Systems

Sensory Receptors: Body's Information Gateways

Sensory receptors detect environmental changes, or stimuli, that can be captured by an organism. Our nerve cells are sensitive receptors, often denominated as such. These include:

Types of Sensory Receptors

• Interoceptors (internal)
• Exteroceptors (external)
• Mechanoreceptors
• Chemoreceptors
• Thermoreceptors
• Photoreceptors

The Skin: Our Largest Sensory Organ

The skin, our body's largest organ, consists of two primary layers: the epidermis, which is the outermost surface layer, and the dermis, located beneath the epidermis. The epidermis is composed of epithelial tissue and forms various appendages, including:

Skin Layers and Appendages

• Nails
• Hair
• Sweat glands
• Sebaceous glands

Tactile

11 Diseases of the Excretory System

When the excretory organs malfunction, poisonous substances are stored within the body. The most frequent causes of diseases in the excretory pathways are due to functional alterations or the presence of certain microorganisms. These diseases include:

Renal Colic

It is produced by the accumulation of stones or calculi of different minerals. The stones may remain in the kidney or travel down the urinary tract. The condition is very painful, especially when urinating, when calculi become lodged in the ureter, as they cause a blockage. The main causes are metabolic disturbances, low water intake, and eating certain foods.

Cystitis

This is inflammation of the wall of the bladder or a urinary tract infection caused...