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

Negative and Positive Feedback in Hormonal Regulation

Negative feedback: This is the most widespread type and occurs when increased hormone levels, above a certain value, inhibit hormone secretion. Positive feedback: In this case, an increase in the values of a hormone causes an increase in its secretion. This type of regulation occurs in special situations, such as ovulation.

Immune System Barriers

The immune system can recognize and usually eliminate altered elements of itself.

In humans and higher vertebrates, three types of defensive barriers are distinguished: primary, secondary, and tertiary. Their function is to prevent the entry and development of pathogens.

Primary Barriers

• The skin: The first defensive barrier that prevents the entry of

Understanding the Digestive System

The human digestive system is a complex network of organs and glands working together to process food and absorb vital nutrients. Let's explore its key components and functions.

Key Digestive Organs

The Esophagus

The esophagus is a muscular tube that passes behind the trachea. Its primary role is to transport the bolus (chewed food) from the pharynx down to the stomach. The walls of the esophagus produce mucus, which facilitates the smooth transit of food.

The Stomach

The stomach is a muscular, J-shaped sac that expands significantly when filled with food. Its inner walls are lined with numerous glands that produce gastric juice, essential for digestion. The stomach communicates with the esophagus through the cardiac

Ecosystem Dynamics: Matter and Energy Flow

Flow of matter and energy in the ecosystem: Environmental inorganic compounds and organic matter are processed in photosynthesis, then returned to the environment and can be reused by producers. Plants transform solar energy, which is stored and then ceded to the environment, where it cannot be used by living things.

Types of Pyramids

Energy: Each rectangle represents the energy stored. The rectangle representing producers is always larger. Each trophic level provides sufficient energy to support the level above it.

Biomass: These pyramids are constructed using data on the amount of biomass at each trophic level. These pyramids can sometimes be reversed.

Numbers: These rectangles represent the number of...

The Circulatory System: Blood and Its Components

Composition of Blood

Blood is a red liquid that constantly circulates through blood vessels. It transports cells, nutrients, and oxygen, while collecting carbon dioxide and other waste products that must be expelled. Blood is formed by plasma and blood cells.

• Plasma: Transports nutrients and supports the blood cells.
• Blood Cells:
  • Red Blood Cells (Erythrocytes): Responsible for oxygen transport.
  • White Blood Cells (Leukocytes): Including neutrophils, monocytes, and lymphocytes, crucial for the immune system.
  • Platelets (Thrombocytes): Essential for blood clotting.

Blood Vessels

Blood vessels form a network of channels that distributes blood throughout the body, comprising three main types:

• Arteries: Carry

Health and Disease: A Comprehensive Overview

Health Encompasses: Sickness absence and well-being in physical, mental, emotional, social, spiritual, sexual, and environmental aspects.

Risk Factors for Health

• Food rich in fat and/or sugar
• Tobacco and/or drug use
• Lack of hygiene
• Stress

International Sanitary Conference (Paris, 1851)

Accomplishments:

• Development of public health policies with laws governing food handling and potable water.
• Creation of the National Institute of Health.
• Methods for preventative health planning, including vaccination and infection control.
• Improved diagnostic techniques.
• Drug development.
• Promotion of better nutritional habits for a healthy life.

Infectious Diseases

Infectious diseases are caused by microorganisms and are transmitted...

The Stages of Evolution and Speciation

The evolution of changes in living things that occur over time, leading to new species, can be distinguished in four stages:

1. Production of Evolutionary Change

   Natural selection favors certain individuals while harming others. Both still belong to the same species.

2. Genetic Isolation of the New Population

   To constitute a new species, it's imperative that members of the new species do not reproduce with the originals. This occurs when the new settlement becomes genetically independent. Various types of barriers include:

   • Geographical Barriers

     Prevent physical contact between populations (among individuals).

   • Sexual Barriers

     Due to anatomical differences that prevent mating or lack of synchrony in the fertile period,

What is Embryology?

Embryology is the branch of biology that studies the development of an organism from a fertilized egg. It encompasses several key concepts:

• Ontogeny: The transformations that the embryo undergoes during development.
• Phylogeny: The evolutionary history of a species.

Historical Theories of Development

Historically, two main theories attempted to explain embryonic development:

• Preformationism: This theory argued that a miniature version of the organism, called a "homunculus," was present in either the sperm or the egg. Scientists who believed in this were called "animalculists." In 1699, Danlenpatius proposed this theory.
• Epigenesis: This theory proposed that adult body structures were not preformed in the gametes but developed gradually.

Animal Kingdom: Invertebrate Zoology Review

Please review this questionnaire at home. Do not bring it on the day of the exam.

1. All animals are:
   • Autotrophs
2. Which of these animals has radial symmetry?
   • A sea anemone
   • A butterfly
   • A rabbit
   • A snail
3. An animal has bilateral symmetry if…
   • One line can be drawn to divide the animal into halves that are mirror images.
4. How does a cnidarian capture prey?
   • By paralyzing prey with venom.
5. How are coral reefs created?
   • From the skeletons of dead corals.
6. Which of these is a phylum of worms?
   • Annelida
7. Which of these characteristics is shared by all worms?
   • They have a brain.
8. Which of the following describes the feeding behavior of cnidarians?
   • They are carnivores.
9. The bodies of cnidarians have:
   • Radial symmetry.
10. What do earthworms do to soil?

Genetics Vocabulary

• Gene: The basic physical and functional unit of heredity, composed of DNA.
• Chromosomes: Thread-like structures of DNA and proteins found in the nucleus of most living cells.
• DNA: The molecule that carries genetic instructions for development and function.
• Karyotype: A visual representation of all chromosomes within a cell, used to identify chromosomal counts.
• Genotype: The specific genetic makeup of an organism that determines its traits.
• Phenotype: Observable physical characteristics, such as eye color, hair color, or height.
• Dominant: A gene that expresses its trait even if only one copy is present.
• Recessive: A gene that only expresses its trait when two copies are present.
• Homozygous: Having two identical versions of a gene (

Number and Quantity Prefixes

• Mono-, Uni- (one):
  • Monodiplopia: Double vision that occurs only in one eye.
  • Unilateral: Confined to one side only.
• Bi-, Di- (two, twice, double):
  • Diplopia: Double vision.
  • Bilateral: Affecting two sides.
• Tri- (three):
  • Trigeminal nerve: The fifth cranial nerve, providing sensory innervation to the face, divided into three main branches.
• Quad-, Quadra-, Tetra- (four):
  • Quadrant: Areas divided for descriptive purposes into quadrants.
  • Tetradactyl: Having four fingers or toes on a hand or foot.
• Multi- (many):
  • Multicellular: Composed of many cells.
• Poly- (too much, many):
  • Polyuria: Excessive excretion of urine.
• Hemi-, Semi- (half or partly):
  • Hemiplegia: Paralysis of one side of the body.
  • Semicomatose: State of drowsiness and inaction, requiring