Notes, summaries, assignments, exams, and exercises for Biology for Baccalaureate

Anatomy and Structure of the Human Brain

• Electrical Impulses: Transmit nerve signals to the brain.
• White Matter: Formed by the extensions of brain nerve cells.
• Gray Matter: Located on the surface of the brain, formed by the accumulation of nerve cell nuclei.
• Cortex: The gray matter forming the cerebral cortex, composed of 6 layers of neurons approximately 4 mm thick; this is where consciousness resides.
• Blood Supply: Vessels that traverse the surface of the brain.
• Meninges: Membranes that envelop the gray matter, where blood vessels are distributed.

Brain Capacity and Function

The human brain is three times larger than that of a gorilla (1800 cm³). Thought is a complex operation involving the association areas of the cortex, which connect different...

Understanding Species in Biology

A taxonomic category, a species is defined as a set of natural populations that can interbreed, either in reality or potentially, and which are reproductively isolated from other similar groups. When individuals can cross, it means their descendants are also fertile. The term "potentially" relates to natural conditions that might prevent crossing between two populations of the same species. All individuals of a species share similar anatomical and morphological features.

The Monera Kingdom: Prokaryotic Life

The Monera kingdom is constituted by the vast majority of prokaryotes. Their cells are bacteria, tiny living things. They are the most abundant organisms and have spread throughout the biosphere. There are species...

Types of Asexual Reproduction

• Bipartition: Unicellular organisms divide into two parts from a single cell.
• Budding: Occurs in both unicellular and multicellular organisms.
• Fragmentation: The parental organism spontaneously divides, with each part giving rise to a descendant.
• Regeneration: Multicellular organisms reform missing parts caused by an injury.
• Sporulation: Successive division of the mother cell nucleus.

Gastrulation and Embryonic Development

During gastrulation, cells of the blastula move and arrange themselves into layers (embryonic germ layers), which are destined to form future organs.

Diploblasty and Triploblasty

• Diploblasty: The gastrula has two layers: the outer (ectoderm) and inner (endoderm), which form all adult organs.
• Triploblasty:

Sweat

Sweat glands are located in the skin, opening to the epidermis through pores. These glands are mainly concentrated in areas like the forehead, armpits, palms, and soles of the feet. Each gland consists of a thin tube called a glomerulus, which extracts fluid from blood capillaries. This fluid contains compounds like urea and water, similar to urine but more dilute. From the glomerulus, sweat travels through channels to the pores and is released as droplets.

Regulating Urine Concentration

Urine concentration depends on the permeability of the collecting tubules, regulated by the antidiuretic hormone vasopressin. Increased osmotic pressure stimulates vasopressin secretion, increasing the permeability of the collecting tubules. This leads...

Requirements for Alveolar Ridge Abutments

Abutment teeth: In a fixed prosthesis, forces normally absorbed by the missing tooth will be transmitted to the abutment teeth through pontics, connectors, and retainers.

Ideally, an abutment should be a living tooth. Endodontically treated teeth are more susceptible to fractures. These teeth are obliged to support the forces directed to the missing tooth in addition to the forces they target themselves.

Supporting tissues must be healthy and free of inflammation, with no mobility. The evaluated structures should take into account three factors: the crown-root ratio, the configuration of the root, and the supporting bone.

Essential Criteria for Abutment Teeth

Crown-Root Ratio Standards

The crown-root ratio...

Genetics and Heredity

Genetics is the science that studies how traits are inherited. Besides hereditary traits, external factors, including the environment, cause changes. Species variation is the manifestation of differences between individuals of the same species. The main causes are genetic variations.

Continuous and Discontinuous Variation

Continuous variation occurs when a trait has slightly different manifestations, like hair or skin color. Discontinuous variation occurs when a trait is clearly expressed as different and is genetically determined, not changing during an individual's life.

Phenotypic and Genotypic Variations

Phenotypic variations are observable traits (weight, height, color) resulting from the environment and genotype. Genotypic

Macrophages and Their Functions

Macrophages originate from blood monocytes and form in the tonsils, spleen, and lymphatic vessels. They then migrate to different tissues where they are given different names. They release a substance (interleukin 1) which behaves as a second messenger that acts on the hypothalamus by altering its thermostatic function and resetting it to a higher level, causing a temperature rise. This increase stimulates the activity of leukocytes (white blood cells) and decreases the amount of iron (Fe) in the blood, which is an essential element for bacterial growth.

The Inflammatory Response Mechanism

The Inflammatory Response is a local reaction caused by the penetration of pathogens. It involves the connective tissue, blood...

Chromosomes: Structure and Function

Chromosomes are structures formed from DNA during nuclear division. They consist of condensed chromatin fibers. Before cellular division occurs, DNA replication takes place, resulting in two identical DNA fibers known as chromatids, which are linked by a centromere. Later, these two chromatids separate, and each gives rise to an individual chromosome. Their primary function is the distribution of genetic information from the mother cell to the daughter cells.

Interphase

• G1 Phase: Begins when the cell is born after division. It involves the synthesis of proteins and mRNA, the presence of a diplosome, and the potential for the cell to enter the G0 phase.
• S Phase: DNA duplication occurs. The DNA condenses to form

Infectious Agents and Microorganisms

Each disease is caused by a specific microorganism, and each generates different pathological effects. Infectious agents, germs, or microbes are parasites that invade the body and reproduce, damaging tissues and causing disease symptoms.

Pro-pathogenic Microorganisms

• Viruses: Cellular parasites that are extremely small and difficult to eliminate without destroying the host cell. Retroviruses are a specific type of RNA virus.
• Phages: Viruses that exclusively infect bacteria.
• Bacteria: Prokaryotic single-celled organisms that can reproduce without invading other cells. Common shapes include cocci, bacilli, vibrios, and spirilla.
• Protozoa and Fungi: Eukaryotic organisms. Protozoa are unicellular (e.g., rhizopods,

Animal Diversity: Key Invertebrate Groups

Sponges (Porifera)

Sponges have radial symmetry or are asymmetrical. Their body is a sack inside which an atrial cavity opens to the exterior through the osculum. The body wall contains pinacocytes and pores (ostia) through which water enters. Choanocytes (collar cells) create a continuous stream of water through the sponge. Sponges have a non-cellular intermediate layer (mesohyl or mesoglea) with amoebocytes that digest food, produce gametes, and produce spicules.

Sponges reproduce both asexually and sexually.

Types of Sponges

• Calcareous sponges: calcium carbonate spicules
• Hexactinellid sponges: silica spicules
• Demosponges: silica spicules and spongin fibers

Cnidarians

Cnidarians exist as polyps and medusae....