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

HIV and AIDS: Transmission and Impact

HIV enters the body through blood, vaginal secretions, semen, and the placenta. It can stay in the nucleus of the cells it infects and remain there "sleeping" indefinitely. Among the cells that the virus infects and destroys are those responsible for defending against infection, such as white blood cells. For this reason, it produces immunodeficiency, which leaves patients vulnerable.

Treatment and Prevention of STDs

Currently, all sexually transmitted diseases, except AIDS, can be treated effectively with antibiotics. Avoiding sex or using condoms are measures to prevent the spread of STDs.

The Local Response to Wounds

Phagocytes are a type of white blood cell found in the blood and tissues under the skin;...

Taxonomy and Systematics: Classification Principles

Taxonomy is a scientific discipline concerned with the classification of living things, based on a hierarchical system of groups sorted according to their similarities.

The Linnaean System of Classification

The current system is based on that proposed in 1735 by Carolus Linnaeus. Living things are grouped into taxonomic categories:

• Species are included in genera.
• Several genera comprise the family.
• Families are grouped into orders.
• Orders are grouped into classes.
• The next category is the phylum (for animals and protists) or division (for plants and fungi).
• The highest taxonomic level is the kingdom.

Taxonomy helps establish relationships within different groups according to shared morphological, physiological,...

Infectious Disease Prevention and Treatment

Infections can be treated with antiseptics, which kill microorganisms but can only be applied to the skin's surface. Antibiotics are substances that selectively attack bacteria and can be ingested or injected. Penicillin was the first known antibiotic. The English physician Jenner invented vaccines, which involve injecting small amounts of dead or fragmented pathogens.

Healthy Habits

• Eat in moderation at least three times a day, always including breakfast.
• Eat a balanced diet with the appropriate proportion of nutrients.
• Sleep eight hours a day.
• Exercise moderately to maintain muscle tone.
• Maintain a proper weight for your age, sex, and build.
• Practice proper hygiene.
• Avoid snuff, alcohol, and other drugs.

Ecosystem Components and Definitions

An ecosystem is a complex system formed by living organisms, the environmental factors of their habitat, and the relationships established between them.

• Biotope: The physical environment in which living things develop.
• Biocenosis: The living component of an ecosystem.
• Habitat: The specific place where a species lives.
• Ecological Niche: The functional role or profession of a species within its ecosystem.

The establishment of interactions between these components is the fundamental factor that sustains ecosystems.

The Cycle of Matter

1. Inorganic compounds in the environment are transformed into organic matter by autotrophs.
2. Herbivores obtain matter by feeding on plants.
3. Carnivores obtain matter by feeding on other animals.

Blood Composition and Its Vital Role

Blood is a red liquid that circulates throughout the blood vessels. It plays a crucial role in the body by transporting essential nutrients and oxygen to cells, while also collecting carbon dioxide and other waste products for removal.

Blood primarily consists of two main components: plasma and blood cells.

Plasma: The Liquid Matrix of Blood

Plasma is a yellowish liquid that serves as the transport medium for various vital substances, including nutrients, hormones, enzymes, and waste products throughout the body.

Types of Blood Cells

Blood cells are primarily produced in the bone marrow. There are several distinct types, each with specialized functions:

• Red Blood Cells (Erythrocytes): These cells contain a protein

Lesson 4: Human Body Systems

Respiratory Apparatus

Function: The exchange of gases. It takes in oxygen and releases carbon dioxide.

Phases of Respiration

• Inhalation: Air passes through the nasal cavity, pharynx, larynx, trachea, bronchi, and bronchioles.
• Gas Exchange: Takes place in the alveoli, which are in contact with blood vessels. Oxygen passes from the alveoli to the capillaries, while carbon dioxide passes from the capillaries to the alveoli.
• Exhalation: Air travels from the alveoli through the bronchioles and respiratory paths to the outside.

Note: Inspiration is when air enters the lungs; expiration is when air leaves the lungs.

Diseases of the Respiratory System

Common conditions include respiratory tumors, colds, inflammation, pneumonia,...

Nutritional Components: Organic and Inorganic

Nutrients are chemical compounds found in foods that all cells need to live. They are classified according to their origin:

Organic Nutrients

Carbohydrates

Carbohydrates (or carbs) are primary sources of energy and are consumed frequently. Examples include the sugar found in fruits, pasta, etc.

Proteins

Proteins are essential in the human diet, found in meat, dairy, legumes, eggs, and cereals. They serve several critical functions:

• Structural: Necessary for growth, tissue repair, etc.
• Contractile: Involved in muscle contraction.
• Transportation: Enables the transport of oxygen.
• Catalytic: The enzymes that regulate chemical reactions of metabolism are proteins.

Lipids (Fats)

Lipids are found in vegetable oils,...

The Life Cycle of Living Beings

Living beings are born, grow, reproduce, and die.

How Living Beings Originate

Living beings originate from others similar to themselves.

Modes of Birth:

• Mammals: Born from the womb (viviparous).
• Oviparous: Born when the egg hatches.
• Plants: Born when the seed germinates.

Growth in Living Organisms

Growth is the process where an organism increases in volume and size.

• Unicellular Organisms: Grow when their cells increase in size.
• Multicellular Beings: Grow when their cells divide (cell division).

Nutrition: Incorporating Food for Energy

Nutrition is a fundamental property of living things, involving the incorporation of food to obtain energy and matter.

Autotrophic Nutrition

Occurs when living things produce their own food (e....

Evolutionary Theories: The new science emerges, taxonomy, which was visible and obvious similarities between living organisms in different parts of the world. Lamarck: Theory of the Inheritance of Acquired Characteristics states that organisms react against environmental change by developing, creating, or enhancing a particular organ, while abandoning the use of an organ leads to its atrophy or disappearance. Key Aspects of Evolutionary Theory by Darwin and Wallace:

• Changes by Chance: In a population, there are different characters or varieties among individuals.
• Selection: This mechanism chooses the characters that confer an adaptive advantage, allowing reproduction and transmission to the next generation.
• Gradualism: Individuals carrying adaptive

The Relationship Function: Capturing Stimuli and Responding

The relationship function allows human beings to capture specific changes (stimuli) that occur within or outside the body and respond as best as possible. Stimuli are variations in the environment, both external and internal, capable of triggering a response.

Categories of Stimuli

• Physical: Such as light, temperature, and sound.
• Chemical: Such as the presence or absence of chemicals in the internal or external environment; for example, water, salts, or pollutants.
• Biotic: Caused by the presence or absence of other living organisms.

Sensory Receptors and Stimulus Detection

Sensory receptors are specialized structures that capture both external and internal stimuli.

Receptor Classification by