Notes, summaries, assignments, exams, and exercises for Biology for Baccalaureate

Producers

Producers: Organisms that make their own autotrophic organic matter from inorganic matter.

Consumers

Consumers: Heterotrophs that feed on living organic matter.

• Herbivores (primary consumers): Animals that eat plants.
• Carnivores (secondary consumers): Animals that feed on herbivores. There may also be third- and fourth-order consumers.
• Omnivores: Animals that eat both plants and other animals.

Decomposers

Decomposers: Heterotrophic organisms that feed on detritus and convert it into inorganic compounds.

Food Chains and Food Webs

Food chains: Used to show who eats whom in an ecosystem. In each chain there are different levels, called trophic levels. At the first level are the producers; the higher levels are consumers.

Food web: A set of interconnected...

Key Stages in Embryonic Development

The union of sperm and egg creates the zygote, marking the beginning of embryonic development.

Key Developmental Milestones

• Implantation: The embryo attaches to the endometrium (lining of the uterus). Approximately 70% of zygotes and early embryos are eliminated naturally, ensuring only the fittest reach the end of gestation.
• Nervous System Formation: During the third week of pregnancy, the neural plate forms on the surface ectoderm. This structure develops into two configurations: the neural tube (central nervous system) and the neural crest (peripheral nervous system).
• Myelination and Growth: By mid-pregnancy, neurons begin to be covered in myelin. This process continues through the first two years of life,

Meaning of Trophic Terms

Trophic refers to nutrition and food. A food chain represents the feeding relationships between different species, illustrated by diagrams and arrows showing the path and direction of energy and matter in an ecosystem.

Food Web Complexity

Food chains are rarely linear. Since many species are consumed by various others, they connect to form a trophic network or food web.

Trophic Levels

Species are grouped according to their common food sources. These levels include:

• Producers: Green plants that create their own energy (Autotrophs).
• Consumers: Organisms that feed on external sources (Heterotrophs), including primary herbivores and secondary carnivores.
• Decomposers: Bacteria, fungi, and protozoa that break down and absorb complex

Defining Health and Illness

Currently, the WHO defines health as a state of complete physical, mental, and social well-being, not merely the absence of disease.

Disease is defined as an altered state of health, meaning a temporary or permanent loss of physical, mental, or social well-being.

The quality of life of a person is broadly defined as the degree of comfort, happiness, and satisfaction, which allows them to act and feel their life positively.

Life expectancy at birth is an estimate of the average years a group of people born in a given year would live, assuming current health and social conditions in the area being studied remain constant.

Genetic and Congenital Conditions

Genetic diseases are due to alterations in the genome (e.g., Down...

DNA Replication and Transcription Initiation

Initiation: Unwinding the Double Helix

Initiation begins at specific regions or points of origin (Ori) on the DNA. Specialized proteins recognize and break the hydrogen bonds between the base pairs at the initiation point.

At the point where the DNA unwinds, tension is created, which is resolved by topoisomerase and gyrase. The SSB protein prevents the strands from re-coiling.

A Y-shaped replication bubble is formed. Replication begins when RNA polymerase recognizes the promoter region, which includes a central sequence.

Elongation: Synthesizing New DNA Strands

A new DNA chain is synthesized for each original strand. The DNA polymerases (I, II, III) have two main functions:

• Polymerase activity: Join the

Gene mutations: alterations in the sequence of nucleotides within specific gene loci.
Substitutions: transitions, and transversions.
Frameshift pattern: insertions and deletions.

Genomic mutations: variations in the number of chromosomes.

Euploidies: alterations in the normal chromosome set. Monoploidy: one chromosome of each pair (n). Polyploidy: contain more than one complete chromosome set (triploid, tetraploid).

Aneuploidy: gain or loss of one or more chromosomes. Trisomies: an extra chromosome, such as XXY (Klinefelter syndrome), triple X, or karyotype XYY. Monosomy: a missing chromosome.

Chromosomal mutations: cause changes in the structure of chromosomes.
Deletions: loss of a segment of a chromosome.
Duplications: a segment appears more than...

VIRUS H5N1

1a) Genetic Changes and Protein Expression

Changes are mutations of genetic material. Proteins are bound to gene expression. Genetic mutations must occur, or changes in proteins result from the translation process.

b) Immunity to H5N1

No person has been documented as having been infected with H5N1 antigens and subsequently acquired immunological memory that protects them.

2. Vaccine Efficacy and Viral Mutation

A vaccine produces a primary immune response (antigen-antibody) and a vaccinated person acquires immunological memory to respond effectively to the infection. Therefore, injecting a non-replicating virus (which possesses the same antigen) is difficult. In the case of the H5N1 virus, if it mutates easily, the vaccine might no longer...

1. Eukaryotic Cell Membranes and External Structures

1.1 Plant Cell Walls

The cell wall provides structural support and protection for plant cells.

• Function: Confers rigidity and prevents the cell from swelling or bursting in hypotonic environments.
• Composition: Primarily composed of cellulose, pectin, and a hemicellulose matrix.

Layers of the Cell Wall

• Middle Lamella: Integrated with pectins and proteins.
• Primary Wall: Cellulose fibers cohesive with polysaccharides (hemicellulose and pectin).
• Secondary Wall: May contain lignin, waxes, cutin, and suberin. It features narrow channels known as plasmodesmata.

1.2 Extracellular Matrix in Animal Cells

Also known as the glycocalyx, this structure is composed of glycoproteins and is essential for cell recognition...

Hemophilia

Hemophilia is a disorder that prevents or significantly slows blood clotting. It is manifested through bleeding—internal or external—often caused spontaneously. There are two main components involved in blood coagulation: platelet function and plasma clotting factors. Hemophilia is currently incurable and typically requires lifelong replacement therapy adapted to the patient's needs.

Treatment Types for Hemophilia

• On-demand treatment: administration of clotting factor after the first symptoms or after a bleeding event.
• Prophylactic treatment: routine administration of clotting factor to prevent bleeding episodes.

Sources of Clotting Factor Concentrates

There are two ways to obtain clotting factor concentrates:

• Plasma-derived: purified

The Concept of Health and Disease Factors

The World Health Organization (WHO) defines health as a state of physical, mental, and social well-being. A malfunction in any of these areas determines an imbalance that can cause physical and mental disorders and trigger disease.

Factors Involved in Health

1. Subjective Perception: Each person perceives their health subjectively depending on their way of being. With aging, individuals often have a greater perception of their health status.
2. Genetic Inheritance: Every human being has a genetic inheritance received from their parents. This inheritance partly determines the health status of the individual; if genes have alterations, they may lead to the presence of pathologies.

Genetic and Congenital Diseases

• Genetic