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

Non-specific defenses

act against any type of microorganism or foreign particle. This action is carried out by phagocytes: white blood cells that trap and eliminate pathogenic microorganisms. This process is called phagocytosis.

INFLAMMATORY RESPONSE

is a non-specific defense mechanism. When pathogens get through the external barriers, the blood cells dilate to increase the blood flow. The result is pus.

Specific defenses

act against specific microorganisms or foreign molecules. Other types of leukocytes, called lymphocytes, produce proteins called antibodies. Antibodies are specific for each microorganism and destroy or inactivate the invading agents.

INCUBATION - this is the time between the moment the pathogenic agents invade organisms and the... Continue reading "Understanding Body Defenses and Diseases: A Comprehensive Guide" »

Cell Organization and Structure

Cells in Humans (Eukaryotic Cells)

Cell Membrane

The outermost membrane, a lipid bilayer, controls what enters and exits the cell. This structure is also used in vaccine production to hold mRNA.

Mitochondria (Mitochondrion)

The powerhouse of the cell, responsible for ATP (Adenosine triphosphate) production. The ATP production rate depends on the folds of cristae. Some cells, like liver cells, have multiple mitochondria. The mitochondrion contains a matrix, a thick liquid with a high concentration of enzymes that facilitate ATP production.

Lysosome

The cell's recycle bin.

Golgi Apparatus

Packages proteins for transport in and out of cells.

Rough Endoplasmic Reticulum

Creates proteins.

Smooth Endoplasmic Reticulum

Creates... Continue reading "Cell Biology: Structure, Function, and Chemical Reactions" »

Human Eye Structure and Function

Key Components:

• Conjunctiva: Thin, transparent membrane lining the front of the sclera. It's moistened by tears, produced in the tear glands, which contain lysozyme, an enzyme that kills bacteria.
• Pupil: Opening in the iris through which light passes. It controls the amount of light entering the eye and appears black due to the black pigment of the choroid.
• Lens: Clear structure that allows light into the eye. It's made of stiff jelly and can change shape to focus light.
• Iris: Colored part of the eye that responds to light.
• Cornea: Transparent, protective layer at the front of the eye.
• Suspensory Ligaments: Fibers supporting the lens. When pulled tight, the lens is thin; when loosened, the lens is thicker.
• Ciliary Muscles:

Ecology

The scientific study of how organisms interact with each other and with their non-living environment.

Ecological Niche

The manner in which an organism uses the resources in, and is influenced by the conditions of its habitat.

Habitat

The physical place, or type of place, where an organism lives.

Physical Adaptation

Genetically-inherited characteristics that enable a given organism to survive and reproduce using a given niche.

Niche Partitioning

The division of niches between species so as to cut down on competition.

Resource

A material that is used, and potentially used up.

Environmental Conditions

Background features of the habitat.

Fundamental Niche

The largest array of resources an organism can utilize.

Realized Niche

The actual set of resources... Continue reading "Ecology: The Study of Organism Interactions and Adaptations" »

Nucleus:

Converts genetic material, controls all the cell, and contains nucleolus.

Mitochondria:

Converts solar energy in food to usable compounds.

Chloroplast:

Converts solar energy to chemical energy stored in food.

Cytoskeleton:

Maintains cell shape and helps cell move.

Ribosomes:

Synthesize proteins.

Endoplasmic Reticulum:

Assembles proteins and lipids.

Vacuoles and Vesicles:

Store materials.

Centrioles:

Organize cell division.

Cell Membrane:

Regulates materials that enter and leave the cells.

Golgi Apparatus:

Packages proteins and lipids for storage or transport out of the cell.

Cell Wall:

Shapes, supports, and protects cell.

Lysosomes:

Break down and recycle macromolecules.

Cytoplasm:

Gel-like mixture, surrounded by cell membrane, contains hereditary... Continue reading "Functions of Cell Organelles" »

Thalamus

Regulates communication between several parts of the brain and the endocrine system.

Corpus Callosum

Structure made of nerves that bridges two hemispheres.

Hippocampus

Part of the limbic system, responsible for long-term memory.

Cerebellum

Responsible for motion, balance, and new learning. Exterior grey matter, interior grey matter.

Brainstem

Several regions including medulla oblongata (elongates into the spinal column). Location of several centers of involuntary nervous control.

Hypothalamus

Master gland of the endocrine system, controlling most of its activity.

Two Cerebral Hemispheres

Surfaces known as cerebral cortex and comprised of grey matter. Folder structure made of rounded gyri and recessed sulci divide the lobes.

Spinal Cord

Brings messages... Continue reading "Understanding the Human Brain and Nervous System" »

Chemical Evolution

Artificial Selection and Evolution

Possible Misconceptions

• Populations evolve, not individual organisms. Individuals may have certain heritable variations, but they do not evolve these traits during their lifetime.

Evidence of Evolution

The Study of Fossils

Support for Evolution

• Charles Darwin proposed a possible explanation for the origin of species, explaining various data and suggesting areas for further research.
• The theory of evolution suggests that all organisms on Earth share a common ancestor.

Fossil Record

• Fossils provide significant evidence of evolutionary change, offering a record of species that existed long ago.
• Ancient species often show similarities to species living today.
• Not all extinct fossils have modern counterparts, and some ancient