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

Natural Selection: Principles of Adaptation

Natural selection is the principle that variations in the biology or behavior of a species result in some individuals possessing traits that confer an advantage in survival. This process is highly dependent on the environment.

Individuals with these advantageous traits are more likely to survive, prosper, and reproduce. Over time, the population becomes dominated by individuals exhibiting these beneficial biological or behavioral characteristics. Offspring of the same species can be born with mutations, introducing new variations. Natural selection drives populations to become adapted, or increasingly well-suited, to their environments over time. This process relies on the environment and requires existing... Continue reading "Understanding Natural Selection and Brain Functions" »

The Human Sensory System: Receptors and Organs

Understanding Sensory Receptors

Sensory receptors are specialized structures responsible for detecting changes (stimuli) in the world around us and converting them into nerve impulses. These impulses then travel to a higher nerve center where perception begins. Sensory receptors can be simple groups of nerves or, more often, special cells that join together to form the sensory organs.

Classification of Sensory Receptors

Receptors are typically classified based on the type of stimulus they detect:

• Photoreceptors: Detect light stimuli and are found in the eyes.
• Mechanoreceptors: Stimulated by changes in movement, such as pressure, contact, or sound waves. These include receptors in the skin, muscles, and

Arthritis: Inflammation of the Joints

Arthritis is a condition where the joints become inflamed, swollen, and warm to the touch. It can also cause decreased mobility and joint deformities.

Osteoarthritis: A Common Type of Arthritis

Osteoarthritis is a chronic, non-inflammatory condition characterized by progressive degeneration of the cartilage and joints.

Gout: Painful Inflammation of Joints

Gout is a type of arthritis that involves painful inflammation of the joints. It usually begins abruptly and is accompanied by redness and swelling.

Rheumatism: Similar to Osteoarthritis

Rheumatism is similar to osteoarthritis but typically occurs in individuals between the ages of 25 and 55.

Osteoporosis: Decrease in Bone Mass

Osteoporosis is a condition characterized... Continue reading "Common Types of Arthritis and Other Joint Conditions" »

Enzymes: Proteins that Function as Biological Catalysts

1) Singer and Nicolson's fluid mosaic model of the membrane proposed that membranes consist of protein molecules embedded in a fluid bilayer of phospholipids

2) Which component is a peripheral protein?

D

3) Which component is cholesterol?

D

4) Which component is a protein fiber of the extracellular matrix?

A

5) Which component is a microfilament (actin filament) of the cytoskeleton?

C

6) Which component is a glycolipid?

B

7) Which of the following most accurately describes selective permeability?

Only certain molecules can cross a cell membrane.

8) Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?

CO2

9) Which of the following allows water to move much faster across cell membranes?

aquaporins

10) Diffusion... Continue reading "Understanding Cell Membrane Components and Functions" »

What is Cytology?

Cytology is the study of the internal structure and function of individual cells.

What is Histology?

Histology is the study of the microscopic structure of tissues.

What is Anatomy?

Anatomy is the study of the structure and relationship between body parts. There are several sub-disciplines within anatomy:

Surface Anatomy

Surface anatomy is the study of the external features of the body.

Regional Anatomy

Regional anatomy is the study of anatomy based on regions of the body. It involves the study of the superficial and internal features in a specific area of the body.

Pathological Anatomy

Pathological anatomy is the medical specialty concerned with the diagnosis of disease based on the gross and microscopic examination of tissues.

What

Fundamentals of Ecology

Ecology is the scientific discipline in which the relationships among living organisms and the interactions they have with their environments are studied.

Key Concepts

The biosphere consists of all life on Earth and all parts of the Earth in which life exists, including land, water, and the atmosphere. A habitat is an area where an organism lives.

Ecosystem Components

Abiotic factors are nonliving factors in an organism’s environment, while biotic factors are living factors in an organism’s environment.

Levels of Ecological Organization

Ecological studies focus on several levels:

• Organism
• Population
• Community
• Ecosystem
• Biome
• Biosphere

Energy Flow in Ecosystems

Producers and Consumers

Autotrophs (producers) make their own food, while... Continue reading "Ecology Essentials: Interactions, Energy Flow & Cycles" »

Understanding Key Biological Systems and Health Concepts

Intestines

The intestines are a long, continuous tube running from the stomach to the anus. Most absorption of nutrients and water happens in the intestines. The intestines include the small intestine, large intestine, and rectum.

Excretory System

The excretory system is a passive biological system that removes excess, unnecessary materials from the body fluids of an organism.

Liver

The liver's main job is to filter the blood coming from the digestive tract before passing it to the rest of the body. The liver also detoxifies chemicals and metabolizes drugs.

Double Circulation

Double circulation describes the process where blood is first pumped into the lungs, where it becomes oxygenated, and... Continue reading "Key Biological Systems and Health Concepts Explained" »

Digestive System Diseases

Oral Cavity

• Tooth Decay

  Tooth enamel is destroyed by acids produced by bacteria that break down food fragments stuck between teeth. Tooth decay causes cavities to form, and bacteria in the cavities can then destroy the teeth.

• Gingivitis

  Inflammation of the gums caused by vitamin deficiencies or poor dental hygiene.

Stomach

• Gastroenteritis

  An infection affecting the stomach or intestine, caused by bacterial toxins. Symptoms include diarrhea, vomiting, abdominal pain, and fever.

• Gastritis

  Irritation of the gastric mucosa causing pain, acidity, and a burning sensation. Often caused by smoking, drinking alcohol, eating spicy foods, or taking medicine.

• Stomach Ulcer

  Damage to the gastric mucosa which causes the stomach cavity to come

Unit 3: Lessons 1

Bioelements

Atoms are linked together to form elements. A chemical element is formed by similar atoms.

Biomolecules

Atoms are linked together to make molecules. There are two types of molecules: inorganic and organic.

Cell

This is the smallest unit of living matter that can exist freely in a medium, as it can carry out all the functions of living beings.

Multicellular Levels

• Tissue: A group of cells similar in structure that work together to perform a specific function.
• Organ: Several tissues grouped together to make a structure with a specific function.
• Organ System: A group of organs with closely related functions.
• Organism: The complete unit of the living being.

Unit 3: Lesson 2

Enzymes

Most chemical reactions in living beings would... Continue reading "Essential Building Blocks of Life: From Atoms to Organisms" »