Comprehensive Guide to Earth Science and Evolution

Posted on Aug 23, 2024 in Biology

Continental Drift Theory

Paleolithic evidence: Identical fossils of land-based organisms were found in continents situated far apart.

Geological evidence: Continents fit together along their coastlines and continental shelves. Rocks of the same age and type appear on each side of the line where they were joined.

Paleoclimatic evidence: Continents situated in the South Pole of Pangea have glacial moraines from the same age.

Wilson Cycle

Two cyclical processes of rifting and reuniting of supercontinents during Earth’s history.

  • Continental rifting: The rift has caused depressions which resulted in the formation of deep lakes at the bottom of the valley.
  • Extension of the ocean basin
  • Closing of the ocean basin
  • Continental collision

Faults

Fractures in the rocks on the Earth’s surface where blocks have been displaced. Produced when tectonic forces are greater than the resistance of the rocks.

Dip-Slip Faults

  • Normal: Hanging wall block moves down relative to the footwall block.
  • Reverse: Hanging wall block moves up relative to the footwall block.
  • Vertical: The plane of the fault is vertical.

Folds

Created when rocks deform because of compressional stresses.

Rock Cycle

Rocks formed by external processes are called exogenous rocks.

Rocks formed by internal processes are called endogenous rocks.

Metamorphism & Tectonic Plates

Process where the type of minerals in rocks change because of high pressure, it is called isochemical.

Volcanic Risk

The danger and violence of volcanic eruptions depend mostly on the viscosity of magma and the quantity of gases it contains.

  • Hawaiian eruption: Viscosity and gas content are low.
  • Vulcanian eruption: Viscosity is intermediate.
  • Plinian eruption: Viscosity and gas content are high.

Karst Landforms

Depend on the presence of particular types of rocks rather than the climate, they are found in areas with soluble rocks.

Cell Theory

  • All living things are formed of one or more cells.
  • Cells are the smallest and simplest living things.
  • Cells come from pre-existing cells.

Cell Structure

  • Membrane: Thin layer that separates the cell from the external environment.
  • Genetic material: Made up of molecules, contains information necessary to control cellular activity.
  • Cytoplasm: Semi-liquid interior of the cell, contains biological molecules that are needed to carry out biochemical reactions.
  • Ribosome: Particle in cells where proteins are produced.
  • Centriole: Involved in reproduction and cell movement.
  • Mitochondria: Double membrane-bound organelles involved in cellular respiration and energy production.
  • Vacuole: Space in the cytoplasm that usually contains fluid.
  • Organelle: Structure found in a eukaryotic cell that performs specific functions.
  • Centrosomes: Small tubes are produced, they contain the centrioles.
  • Chloroplasts: Organelles with a double membrane, photosynthesis occurs in them.

Mitosis

Two daughter cells are produced from a parent cell. It is vital that an exact copy of the genetic information is transmitted to daughter cells, then the nucleus is divided.

  • Prophase: First stage, genetic material forms chromosomes. The nucleus disappears. Protein fibers appear to make a mitotic spindle. The nuclear membrane disappears.
  • Metaphase: Condensed chromosomes move along the mitotic spindle that connects the two centrosomes. Chromosomes attach to spindle fibers.
  • Anaphase: Spindle fibers pull the sister chromatids to opposite poles of the cell.
  • Telophase: Final stage. The nucleus reappears. Two daughter cells are formed.

Meiosis

Process of cell division when a diploid cell with 2n chromosomes divides into four daughter haploid cells with n chromosomes.

  • Reduction division: Produces cells with half the number of chromosomes.
  • Second division: Is normal mitosis, each chromosome splits into chromatids, each daughter receives one set of chromatids.

Mendel’s Laws

  • Principle of Uniformity: When two purebred individuals are crossed, all of their offspring have identical phenotypes and genotypes.
  • Principle of Segregation: Two heterozygous individuals from the first generation of offspring are crossed, the second generation is produced that is composed of two different phenotypes.
  • Principle of Independent Assortment: Two individuals that have two or more different traits are crossed, the transmission of each trait is independent from the other ones.

Blood Groups

  • A → AA, AO
  • B → BB, BO
  • AB → AB
  • O → OO

Autosomal Disorders

  • Patau Syndrome: People with trisomy 13 (three copies of chromosome 13). Symptoms: intellectual disability, genital, finger, feet and brain deformations, missing palate.
  • Affecting Women: Turner Syndrome: One X chromosome. Symptoms: sterility, short height. Frequency: 1-3300 births.
  • Affecting Men: XYY Syndrome: One X chromosome and two Y chromosomes. Symptoms: very tall, learning disabilities, and aggressiveness.

Structure of DNA

Made up of two chains of nucleotides, they are twisted around each other in a double helix.

Replication of Genetic Information

DNA duplicates itself, in order to occur, the DNA molecule that each daughter cell receives must contain the same sequence of nucleotides.

Genetic Code

Relationship between the sequence of nitrogenous bases in DNA and the sequence of amino acids that make up proteins.

Characteristics:

  • Is universal
  • Is a continual line with no breaks between the codons

Genetic Engineering

Techniques used to manipulate genetic material in order to change an organism’s traits.

Basic Principles of Darwinism

Based on natural selection.

  1. Individuals that make up populations have anatomical, physiological, and behavioral differences.
  2. Each type of organism produces more offspring than actually survive to reproductive age.
  3. Competition between newborn individuals for space and food.
  4. Individuals whose variations help them to survive are favored over those who are not adapted.
  5. Surviving individuals produce the next generation.

Horse Evolution

  • Four toes on its front feet and three on its back feet
  • Three toes on its feet
  • Three toes, but only the middle one rested on the ground
  • One toe per foot (atrophied)

Evidence of Evolution

  • Anatomical and morphological: Homologous, analogous, and vestigial organs.
  • Fossil evidence: Organisms in the past were different from today’s organisms. Species change over time.
  • Embryonic: Some embryos are similar, there is a clear evolutionary relationship between them.
  • Biogeographical: Groups of organisms that are isolated geographically evolve differently to form new species.
  • Molecular: The greater the molecular similarity between two groups, the closer their evolutionary relationship.

Present-Day Theories of Evolution

  • Neo-Darwinism: Natural selection does not act on the individual in isolation, but on the population it belongs to.
  • Origin of New Species: The changes over time cause the formation of new species.
  • Macroevolution: Causes the appearance of new species.
  • Microevolution: Large groups of different species because of drastic changes.

The Appearance of Human Beings

Characteristics of Hominids

  • Bipedal and upright position

Characteristics of Homo Genus

  • Capacity to use tools and instruments
  • Evolved hands with an opposable thumb
  • Brain capable of sending orders to muscles
  • Foramen magnum (+brain)

Chronological Appearance of Homo Genus

  • Homo habilis: Used rudimentary tools and instruments made of stone.
  • Homo erectus: Carved stones and controlled fire.
  • Homo sapiens: Specialized tools of stone, created cave paintings.

Adaptations

Water Scarcity

Water is scarce in arid zones where there is little rainfall and moisture in the ground and also in cold zones, organisms develop special adaptations to obtain water and reduce its loss.

Temperature Changes

If temperatures are too cold or hot, biological processes cannot be carried out. Organisms adapt by:

  • Searching for warmer zones
  • Growing underground
  • Hibernation
  • Coming together to increase the temperature around them

Sunlight

Important for photosynthesis. Not all species need the same amount of light, they adapt.

Varying Salt Concentration

Controls the amount of water that goes in and out of an organism’s cells. If the environment has too much salt, they die, and if it is too low, they cannot survive.

Lack of Oxygen

At high altitudes, there is less oxygen, the body adapts so that it can receive the right amount of oxygen.

Lack of Food

Food is scarce at certain times of the year. Organisms adapt by:

  • Storing food in hidden places
  • Migrating
  • Storing energy reserves in their bodies

R-Strategists

Use environmental resources efficiently and can quickly produce numerous populations (e.g., desert plants).

K-Strategists

Well adapted to the environment. Stable populations with controlled growth. Few offspring (birds and mammals).