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

Sex Determination Mechanisms

Haploid-Diploid Sex Determination

In this system, the total number of chromosomes in a cell determines the sex of a new individual.

X Chromosome to Autosome Ratio

Sex is determined by the ratio between the number of X chromosomes and the total number of autosomes.

Environmental Sex Determination

In this system, individuals are affected by several environmental variables after fertilization. Generally, the most influential of these is temperature. However, other factors, such as the number of hours of daylight, nutrition, humidity, and the pH of water can also affect sex determination.

Inheritance Linked to Sex

Genes found on sex chromosomes are transmitted differently in males and females because these chromosomes differ... Continue reading "Sex Determination and Inheritance Patterns" »

Evolutionary Biology: Core Principles

1. What is a fossil? A fossil is the preserved remains of an organism.

2. Natural Selection: Natural selection refers to the adaptation of species in different environments. Only the fittest organisms survive to reproduce.

3. Evolutionary Structures:

• Homologous Structures: Structures that share the same evolutionary origin and arrangement of function.
• Analogous Structures: Body parts that have similar functions but do not share a common evolutionary ancestor.
• Vestigial Structures: A body part that no longer serves its original purpose but was likely useful to an ancestor.

4. Darwin's Theory of Evolution: Darwin's theory posits that each living being adapts to its environment. Observations of tortoises and finches... Continue reading "Evolution, Taxonomy, and Plant Anatomy: Key Concepts" »

Ecologists Study Relationships

Ecologists study the environment at different levels of organization.

What is Ecology?

• Ecology is the study of the interactions among living things and between living things and their surroundings.

Levels of Organization

• An organism is an individual living thing, such as an alligator.
• A population is a group of the same species that lives in one area.
• A community is a group of different species that live together in one area.
• An ecosystem includes all of the organisms as well as the climate, soil, water, rocks, and other non-living things in a given area.
• A biome is a major regional or global community of organisms characterized by the climate conditions and plant communities that thrive there.

Ecological Research Methods

Ecological... Continue reading "Understanding Ecosystems: From Organisms to Ecological Succession" »

white blood cells           red blood cells              platelets

Digestive System

Mouth. Salivary-Amylase (carbohydrates). Mechanical and chemical.

Epiglottis. Esophagus. Stomach. Pepsin (protein). Both. Small intestine. Lipids, proteins, carbs, nutrients digestion. Amylase, trypsin (protein), lipase (fat), maltase (disaccharides), peptidase (amino acids).

Large intestine, water absorption. Rectum. Anus. Liver. Secretes bile. Amylase, catalase, lipase, proteases. Chemical. Gall bladder. Store bile. Pancreas. Secretes enzymes to the large intestine. Amylase, trypsin, lipase. Chemical.

Respiratory System

Nasal cavity. Pharynx. Epiglottis. Larynx. Trachea. Bronchus. Bronchioles. Lungs. Diaphragm.

Understanding the Respiratory System

Nervous System Control of Breathing

1. What type of nervous system is involved in breathing, and is it a conscious or unconscious process?

The autonomic nervous system primarily controls breathing. It acts as the brain’s unconscious control center for vital functions like respiration.

Airway Structure: Trachea, Bronchi, Bronchioles

2. What do the trachea, bronchi, and bronchioles resemble?

The airways of the lungs, including the trachea, bronchi, and bronchioles, resemble the branches of a tree. Air passes through the trachea (windpipe), which then splits into two main bronchi, one for each lung. These bronchi further divide into smaller and smaller tubes called bronchioles, much like tree branches. At the end... Continue reading "The Respiratory System: Breathing Mechanics & Lung Facts" »

Anabolic Reactions & Biomolecules

A reaction where two molecules join is anabolic and produces NH₂. Glucose and starch are carbohydrates (CH). Glucose + fructose = sucrose. Unsaturated fats increase HDL levels. An amino acid has an H and R group bonded to a carbon atom, along with NH₂ and COOH. Adenine, cytosine, guanine (thymine in DNA and uracil in RNA). Saponifiable lipids include phospholipids, fats, and waxes.

Factors Affecting Enzyme Activity

• Temperature
• pH levels
• Substrate concentration

Four Main Biomolecule Groups

Carbohydrates, lipids, proteins, and nucleic acids.

Cell Biology Concepts

Schleiden. Kingdoms with cells containing mitochondria: Animalia, Plantae, Fungi, and Protoctista. Organelles of endosymbiotic origin: mitochondria and chloroplasts.... Continue reading "Biomolecules, Genetics, and Ecology Essentials" »

Phonetics is the study of sounds made by the human vocal apparatus, used in speech. These are called speech sounds. This science tries to describe how they are made, to classify them and to give some idea of their nature. Phonetics is a more general discipline than phonology, in that it is concerned with speech sounds without reference to their function or role in any particular language.

Different branches of phonetics can be recognized. Acoustic phonetics studies the transmission of speech sounds through the air from the speaker to the hearer and is thus concerned with measuring and analyzing the movement and vibration of air. This involves investigation within the framework of physics. Auditory phonetics is the study of the hearing of speech... Continue reading "Phonetics and Phonology: Understanding Speech Sounds and Their Functions" »

Shoulder Injuries and Conditions

Glenohumeral Subluxation

Excessive translation of the humeral head without complete separation from the joint. May occur anteriorly, posteriorly, or inferiorly (most common is anterior).
Mechanism of Injury (MOI): Forced abduction and external rotation; direct blow to shoulder

Anterior Glenohumeral Dislocation

Head of humerus is forced out of its articular capsule past the glenoid and downward to rest under the coracoid process.
Injuries: Torn capsular and ligamentous tissue, possible rotator cuff and/or long head biceps tendon avulsion, possible injury to brachial plexus, possible tear (almost always a labral tear).
MOI: Direct impact to posterior shoulder, forced abduction and external rotation

Bankart Lesion

Detachment... Continue reading "Shoulder Injuries and Conditions: A Comprehensive Guide" »

Myth 1: Everything is an Adaptation Produced by Natural Selection

We tend to assume that all characteristics of plants and animals are adaptations that have arisen through natural selection. Many are neither adaptations nor the result of selection at all.

Argument 1: Not everything is an adaptation

→ Male nipples

Argument 2: Multi-Skilled Genes

We have multi-skilled genes which have more than one function.

Myth 2: Natural Selection Is the Only Means of Evolution

Before we were told all of the 10 facts were myths, we already thought this was not right, because science can also change evolution with the advanced technology we have nowadays.

Myth 3: Evolution Leads to Ever-Greater Complexity

→ No -. Evolution gets rid of what we don’t use (example:... Continue reading "Debunking Common Myths About Evolution" »