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

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...

Endocrine Glands

Pituitary Gland

The pituitary is a small gland located at the base of the brain. The anterior pituitary secretes growth hormone, prolactin, follicle-stimulating hormone (which stimulates egg production), and luteinizing hormone (responsible for ovulation during the menstrual cycle). The neurohypophysis synthesizes oxytocin, which induces uterine contractions during labor, and regulates urine via the antidiuretic hormone.

Thyroid Gland

The thyroid is a gland located in the neck (upper part of the trachea). It produces thyroxine, which regulates body metabolism and promotes growth, and calcitonin, which decreases the concentration of calcium in the blood.

Parathyroid Glands

These are four small cell masses localized within the thyroid....

Internal Environment

The internal environment is the set of surrounding cells and liquids of an organism. Cells extract the nutrients and oxygen they need from it, and discharge waste and carbon dioxide produced during metabolism. The interstitial fluid originates from blood that has been filtered through the thin walls of blood capillaries.

Homeostasis

Homeostasis is a set of mechanisms whose mission is to maintain a constant internal environment, meaning that its properties do not vary. The maintenance of these properties is called homeostasis, and the task is performed by different devices and systems of the organism.

Veins and Arteries

Arteries and veins differ in that arteries carry blood from the heart to the various organs of the body, and...

Cells: Fundamental Units of Life

Cells are the basic structural and functional units that constitute living things. Based on their distinct structure, cells are classified as prokaryotic (e.g., bacteria) and eukaryotic (found in other living organisms). Eukaryotic cells are generally larger and more complex than prokaryotic cells. The most significant difference is the presence of a nucleus in eukaryotic cells, indicating a more evolved structure.

Essential Cellular Functions

Cells perform three primary functions:

• Nutrition: The process of obtaining materials for growth and energy to perform various cellular activities.
• Interaction (Relationship): The ability of cells to perceive and respond to environmental stimuli, allowing for adaptation.
• Reproduction:

The Central Nervous System

The Central Nervous System (CNS) is the central control and coordination center of the organism. It is able to perceive stimuli and develop responses. It consists of the brain, where responses are made conscious and voluntary, and the spinal cord, where responses are involuntary.

The brain is protected by the skull and covered by three membranes called meninges. Between two of these, cerebrospinal fluid circulates inside the brain. Three regions are distinguished within the brain: the cerebrum, cerebellum, and medulla oblongata.

The Peripheral Nervous System

The Peripheral Nervous System (PNS) consists of nerves, both sensory and motor. According to their origin, nerves are called:

• Cranial Nerves: Those that come from

The Circulatory System

The circulatory system carries nutrients and O₂ and collects waste products and CO₂. It is composed of:

The Heart

The heart is a muscular and hollow organ that drives blood. It is formed of three layers: the myocardium (muscle layer), the pericardium (outside), and the endocardium (inside). It is divided into four chambers: two atria and two ventricles, separated by the tricuspid valve (right) and the mitral valve (left). The vena cava and pulmonary veins reach the atria. Blood exits the ventricles through the aorta and pulmonary arteries.

Blood Vessels

• Arteries: These carry blood from the heart to the body, progressively branching into arterioles. They have three layers: connective tissue, muscle, and endothelium.
• Veins:

Producers and Consumers

Producers are autotrophic organisms, such as plants and algae, that fabricate their own organic matter from inorganic carbon dioxide and mineral salts.

Consumers are heterotrophic organisms that feed on living organic matter. There are different types:

• Herbivores, also called primary consumers, are animals that eat plants.
• Carnivores, or secondary consumers, feed on animals and may include herbivores.
• Third-order consumers (tertiary) and fourth-order consumers.

Decomposers and Detritivores

Decomposers are heterotrophic organisms, such as fungi and bacteria, that feed on detritus (remains of living organisms or excrement) and transform it into inorganic matter.

Detritivores are small animals, like worms or slugs; they do not...

Food Relations

Producers

Autotrophs: Organisms that produce organic matter from inorganic matter.

Consumers

Heterotrophic organisms:

• Herbivores: Primary consumers (plant eaters).
• Carnivores: Secondary consumers (eat herbivores).
• Omnivores: Consume both plants and animals.

Decomposers

Heterotrophs: Organisms that consume detritus and transform it into inorganic materials (e.g., fungi, bacteria).

• Detritivores: Organisms like earthworms and slugs that partially transform inorganic matter.

Trophic Chains and Webs

• Food Chain: A linear series of organisms where each is consumed by the next.
• Food Web: A complex network of interconnected food chains within an ecosystem.

Energy Transfer

• Respiration: Energy used to sustain the organism, with some released as heat.
• Debris:

Pepsin: An enzyme responsible for digestion.
HCL (cloridico acid) activates the pepsin and promotes its action to facilitate the breakdown of food and fiber on the other hand destroys the bacteria it may contain.
Digestive processes in the small intestine:
The small intestine is a tube about 6 or 7 meters Pirolo extending from the ileocecal valve shaft that separates the large intestine. It is divided into three sections:
-Duodenum: the first portion.
-jejunum: the longest stretch.
-ileum: is the final part which flows into the large intestine.
LIVER: it is an organ that is located on the right side of the abdomen and partially covers the stomach. It produces bile, which is poured into the duodenum through the ampulla of vater. The secretion...

Cell Types

Eukaryotic Cells

Eukaryotic cells (found in animals and plants) are characteristic of the cells of organisms. Their structure is evolved and complex.

Prokaryotic Cells

Prokaryotic cells are very simple and primitive and have few structures inside.

Differences Between Prokaryotic and Eukaryotic Cells

• Size: Eukaryotes are typically 10µm and larger, while prokaryotes are around 1µm.
• Nucleus: Prokaryotes have no true nucleus (genetic material is not isolated from the cytoplasm by a nuclear membrane), while eukaryotes have a true nucleus.
• Organelles: Cellular organelles (such as the Golgi apparatus, mitochondria, etc.) are present in eukaryotic cells but not in prokaryotic cells.
• Cell Wall: Prokaryotes have a strong cell wall (often containing