Notes, summaries, assignments, exams, and problems for Biology

Genetic Variations

All individuals within a population possess unique characteristics that distinguish them from one another. These individual differences are called variations and result from an individual's genetic makeup and environmental influences.

Types of Variations:

• Genotype: These are inherited differences passed from parents to offspring and are contained within an individual's genes.
• Phenotypic and Environmental: These variations result from the interaction of genes with the environment. In most cases, the phenotype does not fully express the genotype.

Gene Pool

Each individual in a population carries a unique combination of genes. The gene pool represents the sum of all genes within a population.

Populations evolve through changes in their... Continue reading "Understanding Genetic Variations, Gene Pools, and Stem Cells" »

Vital Functions of Living Beings

Vital functions refer to the specific actions that support life. There are three main functions:

1. Nutrition: Living beings obtain the matter and energy necessary to sustain life through this function.
2. Interaction: Living beings relate to their surrounding environment through this function.
3. Reproduction: Individual living beings are produced; this ensures the perpetuation of the species.

Biomolecules: The Building Blocks of Life

Biomolecules are the fundamental components of living organisms. They are mainly composed of carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus.

Organic Biomolecules

Organic molecules are exclusive to living beings. There are four main types:

1. Carbohydrates (Saccharides)

   These are the most

Pulmonary Ventilation Explained

Pulmonary ventilation refers to the processes that facilitate airflow between the atmosphere and the alveoli through inspiration and expiration.

Physiology of Breathing

Breathing is performed by muscles that change the volume of the chest cavity, creating pressures that move air in and out of the lungs. During normal breathing, at rest, inspiration is active, while expiration is passive.

The diaphragm, the main inspiratory muscle, causes the movement of the rib cage down and out, changing the size of the chest cavity horizontally. Other muscles involved in ventilation include the intercostal muscles, abdominal muscles, and accessory muscles.

Respiratory System Anatomy

Respiratory organs are responsible for transporting... Continue reading "Breathing Basics: Anatomy, Physiology, and Common Ailments" »

Health and Disease

Until recently, health was defined as "the absence of disease." However, the World Health Organization (WHO) has developed a more comprehensive definition. Health is a state of complete physical, mental, and social well-being.

Disease, on the other hand, is the state in which a person's health is altered, whether due to physical or social causes. We can distinguish three types of diseases:

• Physical diseases: Produced by injury, infection, or a degenerative process in the body. They are classified into:
  • Infectious diseases: Caused by a pathogen that reproduces within our body.
  • Non-infectious diseases: Due to other causes.
• Mental illness: Caused by a malfunction of the brain, resulting in a decline in mental capacity or some alteration

The Journey of Pregnancy: From Conception to Birth

Gestation, commonly known as pregnancy, commences with fertilization and culminates in childbirth. This remarkable process brings about profound changes. What begins as a single cell, the zygote, progressively develops into an embryo, then a fetus, and ultimately a fully formed human being.

Typically lasting around nine months, pregnancy involves significant physiological transformations for the mother. These changes are driven by the fetus's development and growth, the vital exchange of nutrients and waste through the placenta, and the mother's body preparing for childbirth and lactation.

Early embryonic development is primarily regulated by estrogen and progesterone, initially produced by the... Continue reading "Human Reproduction: Pregnancy, Childbirth, Contraception, and Fertility" »

These measures are designed to protect individuals from electrical hazards. They can be implemented at the facility or personal level. Protection must be provided against direct contact (accessible parts or insulation failure) and indirect contact from arcing. Measures must also be taken to prevent power surges or over-current, high voltage drops, burns due to overloading, etc.

Protection Against Direct Electrical Contacts

These measures are designed to prevent the risk of contact with live parts (according to Standard 20460-4-41):

• Protection by insulation of live parts: This must be an insulator that can only be removed by destroying it; lacquer varnish is not sufficient.
• Protection by barriers or enclosures: All equipment and connections must

Breathing Process

Breathing: The process of obtaining energy in which we inhale oxygen and exhale carbon dioxide.

Respiratory System

Processes:

• Nostrils: Air enters through the two nostrils. Hair inside warms the air. The interior is lined by:
  • Pituitary Mucosa: Mucus-secreting glands capture dust and moisten the air.
  • Pituitary Yellow: Mucosa has nerve endings that detect odors.
• Pharynx: A duct that connects the nostrils, oral cavity, larynx, esophagus, and middle ear. Muscles and elastic fibers direct air into the trachea.
• Larynx: Formed by cartilage. The mucosa of the larynx has folds that form the vocal cords.
• Trachea: Composed of cartilage and lined by ciliated epithelium that produces mucus. This removes impurities from the outside through the cough

Fetal Development Stages

Overview

Fetal development primarily involves rapid body growth, tissue differentiation, and the formation of organs and systems. The fetal period is marked by significant growth, especially in the final weeks.

Viability

Fetal viability refers to the ability of a fetus to survive outside the uterus (after premature birth). Fetuses weighing less than 500g at birth typically do not survive. With postnatal care, some fetuses born weighing less than 500g may survive. Many term pregnancies with low birth weight result from intrauterine growth retardation (IUGR). The majority of fetuses born weighing between 1500g and 2500g survive but may experience complications. Prematurity is a common cause of morbidity and perinatal death.... Continue reading "Fetal Development Stages: A Comprehensive Guide" »

Seasonal Isolation

Response:

Species: The name given to each of the groups that divide the sexes, i.e., the limitation of the generic in a particular field of morphology. In biology, a species is the basic unit of biological classification.

Variations: These are the distinctive features that occur in individuals of the same species. These changes or differentials in characteristics of individuals relate to those who show up. Even though their heredity plays an important role in the transmission of hereditary or genetic characteristics, there is no chance, or a very remote one, that there are individuals the same as those around us.

Adaptation: A biological adaptation is an anatomical structure, physiological process, or behavioral trait of an organism... Continue reading "Understanding Biological Species and Genetic Concepts" »

Ammonia: Upper Respiratory Irritant and Health Risks

Certain substances primarily affect the upper respiratory tract, without impacting the lower respiratory tract (throat or bronchi). Due to their extraordinary solubility in water, these substances are completely absorbed by the nose and throat, allowing air to reach the lungs practically pure. Ammonia is a prime example of such an irritant.

Ammonia: Chemical Profile and Characteristics

Formula: NH₃
Synonym: Anhydrous Ammonia

Characteristics: A colorless gas with a pungent, hot, and suffocating odor. It can be liquefied under pressure.

Sources of Exposure

• Chemical Manufacturing: Used in the manufacture of fertilizers, as a solvent in textiles, leather, pulp, and paper manufacturing, and as a stabilizer