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

Contraceptive Method Analysis

Advantages:

• Fertility returns after stopping use.
• Decreases premenstrual congestion of the breasts and belly, reducing associated pain.
• Does not interfere with intercourse.
• Regulates the menstrual cycle.
• Decreases menstrual bleeding.
• High rate of effectiveness (98%).

Disadvantages:

• Is not accepted by the Catholic Church.
• Some medications interfere with its action.
• Must be taken daily for a period of time.
• They are readily available.
• Side Effects: Weight gain, headache, inflammation of the vagina, facial spots, decreased sexual desire, etc.

Contraindications:

• Pregnancy.
• Uterine or breast cancer.
• Cholecystitis, liver damage.
• Circulatory disorders: varicose veins, thrombosis, etc.
• Absence of rule (amenorrhea) for any reason.
• Bronchial

Mechanical Methods

Mechanical methods: devices that act as a physical barrier, preventing the passage of sperm into the uterus and preventing pregnancy.

1. Condom

Condom: a thin, elastic sleeve placed over the penis to prevent fertilization; it acts as a contraceptive method and helps reduce the spread of sexually transmitted infections.

Usage

Place the condom over the penis before intercourse; ejaculation deposits semen into the condom.

Advantages

• Very accessible and available without a prescription.
• No hormonal side effects.
• Can be used as a supplementary contraceptive method.
• Provides protection against many sexually transmitted infections (STIs).
• Fertility returns immediately after discontinuation.
• Does not require medical supervision; can be used

Principles of Cell Theory

• The cell is the structural unit of living things.
• The cell is the functional unit of living things.
• Every cell comes from another existing cell.
• The cell is the genetic unit of living things.

Levels of Biological Organization

These correspond to different degrees of complexity in which matter is organized. They are grouped into abiotic and biotic levels.

Classification of Cell Types

• Prokaryotes: These lack a nucleus (coreless).
• Eukaryotes: These contain a nucleus. They can be classified as animal or plant cells.

Essential Cell Organelles

Endoplasmic Reticulum: Composed of flattened sacs and tubular conduits. It includes the smooth reticulum (involved in lipid synthesis) and the rough reticulum (containing ribosomes for protein...

HIV Replication Cycle in T Cells

When the Human Immunodeficiency Virus (HIV) enters the body, it reaches the bloodstream and is distributed throughout the organism. The mechanism of action within T lymphocytes occurs in the following steps:

1. Attachment: Viral GP120 proteins bind to the CD4 receptors on the surface of the T lymphocyte.
2. Fusion and Entry: The virus fuses with the cell membrane, allowing the viral nucleocapsid to enter the cell's cytoplasm.
3. Uncoating: The nucleocapsid breaks down, releasing the viral RNA genome and essential enzymes like reverse transcriptase and integrase.
4. Reverse Transcription: Reverse transcriptase synthesizes a single DNA strand using the viral RNA as a template.
5. DNA Synthesis: The original RNA strand is degraded,

Understanding Species and Biological Variation

A species is a group of organisms that can reproduce with each other and whose offspring are fertile.

Key Characteristics

The characteristics that allow us to distinguish one individual from another are called characters.

• Discontinuous variation: Occurs if the character can be used to divide the members of one species into two or more distinct groups.
• Continuous variation: Occurs if the differences between individuals are very small and gradual.

Hereditary vs. Acquired Characters

• Hereditary characters: Transmitted generation after generation, although they may not appear in every generation.
• Acquired characters: Not transmitted to offspring.

Genetics and Karyotypes

The genetic information responsible for...

Core Concepts of Population Ecology

• Population: A group of individuals of the same species inhabiting a given area at a given time.
• Birth: The number of births in a proportional population within a given time.
• Mortality: The number of dead individuals in a population during a given period.
• Habitat: The environment where an individual or group typically develops.
• Density: The number of individuals per unit of area or volume, depending on the ecosystem.

Interpopulation Relations

These interactions define how species coexist within a community:

• Symbiotic Relationships: Interactions where one or both species are closely associated.
• Antagonistic Relationships: Interactions where one or both species are harmed.

Types of Symbiosis

• Mutualism: Occurs when two

Autoimmunity is an error in the immune system where it is unable to recognize certain molecules. As a result, it may originate serious diseases and even cause the death of the animal due to autoantigens.

Molecular Mimicry and Autoimmune Diseases

Molecular mimicry occurs as many microbes, such as bacteria and viruses, have developed strategies to form molecular complexes (mainly proteins) that are very similar to those in the body of the infected animal. People suffer from autoimmune diseases when certain types of proteins associated with the MHC membrane affect their cells. Examples include:

• Multiple Sclerosis: Affecting brain tissue and the spinal cord.
• Psoriasis: Affecting the skin.
• Rheumatoid Arthritis: Affecting connective tissue.
• Juvenile Diabetes:

Coordination Systems

Nervous System

The nervous system consists of nervous tissue, develops rapid responses, and these responses are short-lived. It acts through nerve impulses.

Endocrine System

The endocrine system consists of endocrine glands. It produces responses that are very slow but durable. It acts through chemical messengers.

Elements of Coordination

Receiver (Receptor)

The structure able to perceive stimuli and transmit them to the nerve centers.

Central Nervous System (CNS)

The body responsible for receiving information received by the receptors, processing and preparing it, and transmitting a series of responses to the effector organs.

Effector

The body responsible for carrying out the answer. There may be two types of effectors:

• Muscle: Produces

Plant Growth Regulators and Synthesis

Plant Hormones: Auxin, cytokinin, ethylene, abscisic acid, and gibberellins.

Sites of Synthesis: Apical shoots, roots, fruits, stems, and young leaves in all types of tissues.

Main Functions:

• Regulate stem and root growth.
• Encourage the growth of lateral branches.
• Ethylene release promotes maturation.
• Controls the opening and closing of stomata.
• Regulates seed germination.

Factors Influencing Activity:

• Light activates the mechanism of action.
• Activated by red light and high temperature.
• Activated by auxin.
• Drought increases concentration.
• Action activated by long photoperiod.

The Hypothalamus and Pituitary Gland

Hypothalamus Function

The Hypothalamus receives information about the body's condition and regulates metabolic...