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

The Human Circulatory System

The circulatory system is responsible for distributing food and oxygen around the body and collecting waste products from cells. It consists of blood, the heart, and blood vessels (arteries, veins, and capillaries).

Blood Tissue and Its Components

Blood is a tissue formed by a liquid, plasma, and a set of cells: red blood cells, white blood cells, and platelets.

• Plasma: Composed of 90% water and dissolved substances such as nutrients, salts, waste products, hormones, etc.
• Red Blood Cells (RBC): Responsible for transporting oxygen.
• White Blood Cells: Responsible for phagocytizing microbes and producing antibodies.
• Platelets: Essential for blood clotting.

Heart Anatomy and the Cardiac Cycle

The heart muscle contracts to empty...

Understanding Biological Reproduction

Reproduction is the fundamental process by which living descendants arise, similar to themselves. This process guarantees the survival of the species by transmitting genetic information.

Asexual Reproduction

Asexual reproduction involves a single parent and creates identical copies of itself. Gametes are not needed. Descendants arise from the division of the organism or one of its cells.

Key Types of Asexual Reproduction

• Bipartition: Cell division into two identical cells (e.g., bacteria and protozoa).
• Sporulation: Successive divisions of the nucleus. Each new nucleus and cytoplasm is enveloped by a membrane, forming a spore that gives rise to a new individual (e.g., fungi, algae, mosses, ferns).
• Gemmation (Budding)

The Human Circulatory System

The circulatory system handles transport within the body. It is built by blood vessels—a network of numerous conduits reaching all cells—and the heart, an organ that pushes blood through them.

The Internal Environment and Interstitial Plasma

Cells of any living organism are immersed in a medium from which they get all the nutrients they need and into which they discharge excretion substances originating from their metabolic reactions. In multicellular organisms like humans, this is called the internal environment. It consists of interstitial plasma, a liquid medium located in the space between cells.

The interstitial plasma must be continually renewed to prevent nutrient exhaustion and the accumulation of toxic...

Epithelial Tissue

Epithelial tissue is composed of cells tightly bound to each other and lacks blood vessels. The nutrition of these cells is derived from the underlying tissue through the basement membrane.

Lining Epithelium

This tissue lines the outer and inner surfaces of the body. It performs various functions such as protection, absorption of nutrients, and the reception of stimuli. The main types are:

• Simple: Formed by a single layer of cells.
• Stratified: Formed by several layers of cells, such as the superficial layer of the skin.

Glandular Epithelium

These cells are specialized in the secretion of substances outside the cell and form glands. They can be:

• Endocrine: Secrete hormones and have no ducts.
• Exocrine: Release their products externally.

1. Apparatus Involved in Nutrition

Through their combined action, the body’s systems incorporate nutrition and nutrients used to maintain an optimal functional state. Nutrition is a complex process involving different systems of our body: the respiratory apparatus, the digestive system, the circulatory system and the excretory system.

• Digestive system: is responsible for breaking down food and turning it into simpler substances.
• Respiratory system: deals with gas exchange and provides oxygen.
• Circulatory system: its role is to transport oxygen and usable food substances through the blood to the various cells of our body, where they will be used.
• Excretory system: is responsible for eliminating waste substances from the blood it transports.

2. Digestive

Tertiary Barriers: The Specific Immune Defense

The tertiary barrier, the body's last line of defense, comprises organs like the thymus, spleen, and lymph nodes. These organs produce or complete the development of two types of leukocytes: B lymphocytes and T cells. These cells act on pathogens in a highly specific manner, can distinguish between self and non-self (antigen), and retain memory.

Antigen Recognition and Attack

An antigen is any molecule genetically foreign to the body, meaning it is not recognized as self and has the potential to cause antibody formation. The recognition of antigens and the attack on the invader are coordinated actions carried out by macrophages, B cells, and T cells.

Antibody Production (Immunoglobulins)

B cells, stimulated...

Cellular Nutrition: Voluntary and Involuntary Feeding

Cell nutrition is nurtured voluntarily and involuntarily through the proportioning of essential nutrients (lipids, vitamins, proteins, carbohydrates, etc.) to the cell.

Role of Nutrients

• Energy: Powers the cell to perform its functions (Carbohydrates or lipids).
• Restoration: Restores cell structure that is damaged and needs replacement.
• Regulatory: Allows the cell to perform chemical reactions (Vitamins and mineral salts).

Importance of Various Diets

Why We Need All Types of Nutrients

We require a variety of nutrients such as vitamins, carbohydrates, and lipids for optimal cellular function.

Nutrients Detailed

Carbohydrates (HC/Glucides)

Source: Primarily plants (e.g., rice).

Energy Function

Provide...

1. Cell Membrane Fatty Acids in Reindeer Legs

In plants, unsaturated fatty acids predominate in homeotherms. The temperatures at which lipids solidify depend on their degree of unsaturation. Highly saturated lipids solidify at higher temperatures than less saturated fats with equivalent chain lengths.

Adaptation to Low Temperatures

Many groups of animals, bacteria, and plants that live at low temperatures deposit lipids with lower saturation levels than those living at higher temperatures. This is an adaptation to avoid the deleterious hardening of lipids. A hardening of cell membranes and intracellular components may adversely affect vital biophysical properties. Many enzymes are bound to membranes, and the solidification of the lipid membrane...

Digestive Tract Diseases

Dental Health and Caries

Dental caries is an infectious disease caused by bacteria that affects the hard tissues of teeth. Bacteria feed on carbohydrates in the mouth and produce acids that cause cavities in teeth.

Constipation

Constipation is a disorder that hinders the evacuation of the stool. It is due to the excessive absorption of water by the intestine, which causes a dry, hard stool.

Ulcers

Ulcers are open sores on the inner walls of the digestive tract; they occur in the stomach and duodenum.

Gastroenteritis

Gastroenteritis is an inflammation of the membranes lining the inner stomach and intestine. It is due to an infection caused by viruses or bacteria.

Cirrhosis

Cirrhosis is a chronic disease that involves the progressive...

1.1. Types of Nucleic Acids

• DNA: Contains deoxyribose as the pentose sugar; nitrogenous bases are adenine, guanine, cytosine, and thymine.
• RNA: Contains ribose as the pentose sugar; nitrogenous bases are adenine, guanine, cytosine, and uracil.

1.3. Deoxyribonucleic Acid (DNA)

DNA contains all the genetic information necessary for the operation and development of a living being. In most eukaryotic organisms, DNA is found in the nucleus as chromatin or chromosomes, depending on the cell cycle stage; it is also present in mitochondria and chloroplasts. Its structure was established by Crick and Watson.

Features:

• Each molecule consists of two polynucleotide chains coiled into a double helix. The pentose and phosphate groups form the external skeleton,