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

Mental and Neurodegenerative Disorders

Schizophrenia typically appears after adolescence. It is a personality disorder in which individuals fail to distinguish the real from the imaginary world, often experiencing delusions and obsessions. Dementia involves the gradual loss of mental capacity and intellectual functions. This includes senile dementia (occurring at 80 years or older) and presenile dementia (occurring before the age of 80).

Neurodegenerative Diseases

Neurodegenerative conditions are caused by neuronal destruction or dysfunction in determined Nervous System (SN) areas. Common types include:

• Parkinson's: This affects nerve cells in the substantia nigra (nucleus niger). These neurons control involuntary movement and muscle coordination.

1. The Internal Environment

The internal environment is a set of fluids surrounding the cells of an organism. From it, cells extract the nutrients and oxygen they need and dump the waste and carbon dioxide produced in metabolism.

In people, the internal environment consists mainly of interstitial fluid and the circulating fluids: blood and lymph.

• Interstitial Fluid: It is a liquid, with defensive and nutritious duties, which lies between the cells. It originates from the blood that has been filtered through the thin walls of capillaries.
• Blood: It is a means of transport of substances, passing through the body in line with the blood vessels.
• Lymph: It is a liquid that is formed from interstitial fluid, circulating through the lymph vessels or ducts

Key Digestive Functions

The digestive system is responsible for performing essential digestive functions. These include the following processes:

• Ingestion: The entry of food into the digestive tract through the mouth. Here, food is crushed by the teeth and mixed with saliva.
• Digestion: The transformation of food into simpler substances, called nutrients, so they can be used by cells. Digestion occurs through two types of actions:
  • Mechanical: Involves cutting, grinding, and mixing food. These actions are conducted primarily in the mouth and stomach. They cause physical changes in foods, such as reducing their size and mixing components to facilitate chemical action.
  • Chemical: Consists of the transformation of food into simpler compounds through the

The global average temperature is approximately 15°C. Earth's water exists in a liquid state or is stored as ice at the poles. The atmosphere is an essential factor for life. Key biological concepts include:

The Biosphere and Bioelements

• The Biosphere: The region of the Earth where life exists.
• Bioelements: Chemical elements that constitute living beings.

Molecular Composition of Life

• Vitamins: A group of organic molecules with a variable chemical nature.
• Inorganic Molecules: Water is the major component of living organisms, varying between 70% and 90% by weight. Mineral salts are involved in fundamental processes such as muscle contraction.
• Organic Molecules: Sugars and carbohydrates provide energy. Glucose and fructose join together to form lactose.

The Vertebrate Nervous System

Vertebrates possess a tubular nervous system. The cephalic part of the tube is wide and forms the brain, while the subsequent, narrow, and long section is the spinal cord. It is divided into:

• Central Nervous System (CNS): Brain and spinal cord.
• Peripheral Nervous System (PNS): Ganglia and nerves.

Central Nervous System

The CNS is protected by two types of coverings: bone and membranes. The bony coverings include the skull (protecting the brain) and the vertebrae (protecting the spinal cord). The protective membranes, called meninges, consist of three layers: the dura mater, arachnoid, and pia mater. Between these layers lies the cerebrospinal fluid.

Brain Structure

In the brain, gray matter is located in the periphery,...

The Life and Legacy of Gregor Mendel

Gregor Mendel, an Austrian-born biologist, established the laws governing heredity. He presented his work in 1866, but it was initially ignored because it was produced while scientists were primarily focused on classifying animals and plants. After being ignored, in 1868 he was devoted to religion. American researchers, about 30 years later, named him when they were to publish their work and realized that Mendel had reached the same conclusions. In his honor, these principles were called Mendel's Laws.

Key Genetic Concepts and Definitions

• Genetics: The part of biology that studies how hereditary traits are transmitted.
• Purebred: When the two alleles for a given character are equal.
• Alleles: One of the variations

Biological Reproduction Mechanisms

Defining Reproduction

Reproduction is the biological ability of forming new living beings (SV SV).

Sexual Reproduction

Sexual reproduction involves special cells called gametes.

Asexual Reproduction

Asexual reproduction does not involve gametes. It is highly effective in producing a large number of offspring but results in no genetic variety between them.

Asexual Reproduction in Animals

Asexual reproduction is very rare in animals.

Division or Fragmentation

Division or Fragmentation: Occurs when the animal is broken or fragmented into two or more pieces, and each piece regenerates the missing part. For example, Planaria.

Budding

Budding: A bulge grows from an animal's body part, develops, and separates to form a new animal....

Central Nervous System and Brain Anatomy

CNS: The brain is the part of the nervous system housed within the central skull or cranium.

The Medulla Oblongata

The medulla oblongata (also known as the rachidian bulb) is the prolongation of the spinal cord. In it, there are several areas of gray matter surrounded by white matter. The rachidian bulb is responsible for regulating various bodily functions such as heartbeat, blood pressure, and pulmonary ventilation, among others.

The Brain Stem

The brain stem encompasses several parts of the brain located between the medulla and the cerebrum. These parts regulate states of sleep and wakefulness, monitor visual and auditory reflexes, facilitate communication between the brain and other parts of the nervous...

Cellular Motion Structures

Cells can move using either changes in the viscosity of the cytoplasm (pseudopods) or by means of flagella and cilia.

• Pseudopods: These are cytoplasm elongations produced by changes in cytoplasm viscosity, which, in turn, are due to changes in proteins of the cytoskeleton.
• Cilia and Flagella: These are mobile organelles attached to the cell membrane. They consist of a basal corpuscle and a string-like structure that projects out of the cell, composed of the cell membrane and a series of microtubules.
• The Centrosome: This organelle is constituted by two small cylinders positioned perpendicular to each other. Each cylinder is called a centriole, which is made up of nine sets of three microtubules. The centrosome controls

Organism Response to Stimuli

Organisms have systems that allow them to collect information from within and outside their bodies and respond to changes that occur.

Key Concepts

• Stimulus: Any factor capable of triggering a response in an organism. This can be physical or chemical.
• Response: The action an organism performs as a reaction to the stimulus received.
• Sensation: The ability to receive stimuli (e.g., sight, hearing, touch, smell, and taste).
• Perception: A function that requires the interpretation of a stimulus by the brain and the elaboration of complex responses.

Sense Organs and Receptors

Sense organs are responsible for receiving environmental stimuli. Receptors are cells within these organs that capture and transmit the stimulus to the brain...