Notes, summaries, assignments, exams, and problems for Biology

Divisions of the Nervous System

Central Nervous System

Consists of the brain and spinal cord. It is responsible for receiving and processing information to control bodily functions.

Peripheral Nervous System

Consists of a set of nerves that connect the central nervous system with other organs of the body.

Components of the Central Nervous System

The brain is housed in the skull. The main parts are the cerebrum, the cerebellum, and the medulla oblongata.

The Cerebrum

Appears divided into two hemispheres. The outer part consists of gray matter that receives information from sense organs. The inner zone contains white matter.

The Cerebellum

Located below the cerebrum. The cerebellum coordinates movements such as walking and allows us to maintain balance.... Continue reading "Nervous System: Structure, Function, and Health" »

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.

The Human Genome Project (HGP)

The Human Genome Project (HGP) aimed to map and sequence all the genes of human beings.

Key Genetic Concepts

• Genome: The complete set of genes of an individual organism.
• Proteome: The entire set of proteins originating from the genome.

The human genome contains fewer than 30,000 genes. The genetic differences between humans and other species are lower than initially expected.

Present and Future Applications of HGP Discoveries

The possibilities offered by these discoveries include:

• Genetic Testing: To determine the likelihood of developing specific diseases.
• Gene Therapy: Techniques used to correct defective genes.
• Genetic Diagnosis: Essential for pre-transplantation screening.
• Knowledge of Human Evolution: Providing deeper

Evolutionism

According to biology, fixism maintained that the existing living species were independent and immutable and that they had always existed with the same basic characteristics.

From the works of Lamarck and Darwin, evolutionism emerged. It holds that the universe and life in all its manifestations, and therefore all species, are the result of change and adaptation. This theory is called evolution and argues that species living today come from others who have disappeared, and these in turn from another, until reaching the first living organisms. For evolution, all living creatures belong to a single large family that has developed over Earth's history.

Early Evolutionary Theories

Scientists disagree on:

• The mechanisms causing species diversification.

Key Concepts in Genetics and Variation

Variations

Differences among individuals within a species.

Phenotypic Variations

Observable differences within individuals of a population (e.g., weight, height, color). These are the result of the environment and the influence of their genotypes.

Genotypic Variations

New features individuals acquire in each generation, typically caused by recombination and/or mutations.

Gene Pool

The sum total of genotypes of all individuals within a given population.

Mutations

Changes that occur in the genetic material. These can be spontaneous or induced and may act favorably or unfavorably on the development of a living being.

Genome

The entire genetic material contained in the cells of a particular organism.

Natural Selection

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GENETIC ENGINEERING: Genetic engineering is defined as the set of technologies to manipulate the genetic material of a living being, ie modifying genes. This manipulation is basically: "Introducing new genes in a genome. -Remove existing genes in a genome. -Changing the information in a particular gene. The new genetic combinations are introduced into organisms capable of transmission to subsequent generations. Also called recombinant DNA technology, because most techniques rely on DNA fragments recombine. INSTRUMENTS OF GENETIC ENGINEERING: .- Restriction enzymes can recognize a specific DNA fragment and cut. Using different restriction enzymes can get different DNA fragments. Each restriction enzyme recognizes a specific sequence of nucleotides... Continue reading "Genetic engineering" »

The Digestive System

The digestive system is a set of organs and associated glands. It is responsible for converting food into simple, readily usable substances by the body. From the mouth to the anus, the digestive tract is about eleven meters in length.

Digestion Process

Digestion begins in the mouth. The teeth grind the food, and secretions from the salivary glands initiate and wet the chemical decomposition. Then, the bolus crosses the pharynx, goes into the esophagus, and then into the stomach. The stomach is a muscular bag, with a capacity of about two pints under normal conditions, which secretes potent gastric juice. In the stomach, food is agitated until it becomes chyme.

Small Intestine

At the outlet of the stomach, the digestive tract... Continue reading "Human Body Systems: Digestion, Excretion, Respiration" »

DNA technology refers to laboratory techniques that allow combining DNA from different origins, even from different species, into a single DNA molecule. Typically, only a few genes are transferred to other cells.

Applications of DNA Technology

In Agriculture

DNA technology has already been applied to many plants, producing new varieties with improved characteristics:

Protection against certain pests: These plants manufacture proteins or substances that protect them from attack by insects, diseases, or viruses. Herbicide resistance: Crops are not affected by herbicides, allowing for easier weed removal. Improved food characteristics: Producing foods with better characteristics or that are healthier. Increased tolerance to adverse conditions: Obtaining... Continue reading "Uses of DNA Technology in Key Sectors" »

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

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