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

Operation of the Nephron

Filtration of blood occurs as it passes through the glomerulus. Substances pass into the renal tubule, small molecules but not large molecules or cells. This process forms the primary urine.

Reabsorption of useful substances, such as glucose, amino acids, and over 90% of the water, takes place along the renal tubule.

Secretion of noxious substances, such as urea or some mineral salts, from the capillaries into the renal tubule, continues along the entire duct, so that inside it, concentrated urine is formed. This is drained into a collecting duct, common to many nephrons, which flows into the renal pelvis. As a result of the process, blood from the kidneys, via the renal veins, is cleansed of waste products.

Average Domestic

Interstitial

DNA and Chromosomes

DNA (deoxyribonucleic acid) is the biomolecule containing the genetic instructions for building proteins. Proteins, especially enzymes, regulate all life processes, including growth, tissue repair, and reproduction. DNA resides in the nucleus of eukaryotic cells as part of the chromosomes.

Chromosomes are composed of chromatin, a complex of DNA and proteins. When a cell is at rest, chromatin is dispersed within the nucleus, making chromosomes invisible. Before cell division, DNA replicates, and chromatin condenses into shorter, thicker fibers, forming visible chromosomes. Due to DNA replication, each chromosome comprises two identical arms called chromatids, joined by a centromere.

Karyotype

The number, shape, and size of chromosomes...

Airway

Includes a conduction pipeline connecting it with the exterior lungs, which are:

• The nasal cavities: Two open cavities covered by nasal mucous. They communicate with the exterior through the nostrils and with the pharynx through the choanae (posterior openings).
• The pharynx: It is a common respiratory tract through the digestive tube and the epiglottis. The epiglottis is located above the larynx and prevents food from entering during swallowing, thus avoiding choking.
• Larynx: Communicates with the trachea and contains some folds (vocal cords) that vibrate and emit sounds.
• The bronchial tree: It consists of two bronchi that penetrate the lungs and branch into increasingly smaller bronchioles. The cells of the walls secrete mucus and have cilia,

Water and Salts

Water

More than half of our body is water. Water is used for carrying out chemical reactions and for transporting substances.

Mineral Salts

Make up the hard and solid parts of our bodies.

Glucids

Glucids are bio-molecules made up of carbon, hydrogen, and oxygen.

Types of Glucids

• Monosaccharides: The simplest glucids.
• Disaccharides: The union of two monosaccharides.
• Polysaccharides: Many monosaccharide molecules joined together.

Proteins

Proteins have carbon, hydrogen, nitrogen, oxygen, and a smaller proportion of sulfur.

They are made of the joint of many molecules called amino acids.

Functions of Proteins

• Are an important part of cell structure.
• Defense.
• Transporting substances.

Lipids

Lipids are a group of different substances. Lipids are not...

Levels of organization refer to the different degrees of complexity in organized matter.

• Subatomic level: Particles that make up atoms (protons, neutrons, electrons).
• Atomic level: Formed by atoms; the smallest constituents of matter that retain their properties.
• Molecular level: Molecules resulting from the binding of different atoms. There are two types:
  • Inorganic: Found in non-living or dead material (water and mineral salts).
  • Organic: Found only in living matter, usually polymers, chains formed by the union of a similar type of monomer molecules.
• Cellular level: The first level with life.
• Tissue level: Groups of cells with the same function and similar structure.
• Organ level: Different tissues are grouped for a particular function.
• System level:

The Male Reproductive System

Components

The male reproductive system produces sperm, sex hormones, and semen. Its key components include:

• Testicles: Two glands housed in the scrotum that produce sperm and testosterone.
• Genital Tracts: The epididymis and vas deferens collect and transport sperm from the testicles to the urethra.
• Attached Glands: The prostate and seminal vesicles produce secretions that enable sperm maturation and create semen.
• Penis: The external organ that deposits sperm into the female vagina. Erectile tissue expands during sexual excitement, causing an erection. The glans is protected by the foreskin.

Sperm Production

Sperm production occurs in the seminiferous tubules of the testicles. Sperm travel from the seminiferous tubules...

Chemistry

Physical and chemical changes

1. Physical change is a change in form or state where no new substance is formed, while a chemical change produces a new substance.

2. Clues of a chemical change include gas production, color change, temperature change, formation of a precipitate, and light production.

3. Oxygen gas relights a glowing splint, carbon dioxide turns limewater cloudy, and hydrogen gas produces a popping sound with a burning splint.

4. The chemical families on the periodic table are alkali metals, alkaline earth metals, halogens, and noble gases.

5. A diatomic molecule is a molecule made of two atoms of the same element; the diatomic molecules are H₂, N₂, O₂, F₂, Cl₂, Br₂, and I₂.

6. An ion is a charged particle formed when an atom gains or loses

Biodiversity Origins: Early Theories

Fixist Theory: Species Immutability

Proposes that species are immutable and have remained unchanged throughout time. Variations include:

• Creationism

  The belief that living things were created by a divine entity. This idea is largely rejected by the scientific community.

• Intelligent Design

  A creationism movement asserting that a creative intelligence is responsible for the complexity of the universe and life. Proponents argue that some biological characteristics are too intricate to have arisen from natural processes, a claim widely considered pseudoscience.

• Catastrophism

  Proposed by Georges Cuvier, this theory suggests that Earth has experienced several catastrophic events, leading to the extinction of species and

Allele Frequencies

Change in allele frequencies can be caused by:

• Natural selection
• Mutation
• Gene flow
• Genetic drift

Viral Reproduction

Steps of viral reproduction:

1. Attachment
2. Entry
3. Integration
4. Synthesis of viral components
5. Viral assembly
6. Release

Antibody Variable Regions

Primary function of the variable regions in antibodies: To bind specifically to antigens and determine the antibody's specificity.

Immunity

Innate Immunity

Innate (aka nonspecific) immunity is present at birth and functions the same way regardless of the pathogen. It involves:

• Phagocytosis
• Inflammation

In response to injury and/or pathogens, innate immune cells release paracrine signaling molecules such as cytokines and histamine that trigger inflammation. External pathogen features that can be...

Central Nervous System

Cerebrum

The cerebrum interprets information sent by sensory receptors, regulates muscle activity, and is involved in emotional and intellectual processes. It has two hemispheres joined by the corpus callosum, which is made up of neuron axons. The cerebrum also has a superficial layer of gray matter called the cerebral cortex.

Thalamus and Hypothalamus

The thalamus and hypothalamus produce hormones and control the endocrine system.

Cerebellum

The cerebellum controls motor coordination, posture, and balance. It has two hemispheres and a central zone.

Brainstem

The brainstem connects the brain to the spinal cord. It includes the medulla oblongata, which regulates blood pressure, heartbeat, and respiration.

Hemispheric Specialization

There...