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

Diffusion

Diffusion is the net movement of molecules from a region of high concentration to a region of low concentration. This is a passive cell movement, meaning cells do not need to use energy for it.

Concentration Gradient

The concentration gradient is the difference in the concentration of molecules between two places.

Factors Affecting Diffusion

• Distance molecules travel (shorter distances enhance diffusion)

• Concentration gradient (a steeper gradient increases the rate)

• Surface area (larger areas facilitate more diffusion)

• Temperature (higher temperatures increase kinetic energy, speeding up diffusion)

• Size of molecule (smaller molecules diffuse more rapidly)

Osmosis

Osmosis is a special type of diffusion, specifically the passage of water molecules... Continue reading "Cell Transport & Plant Nutrition: Essential Biological Processes" »

Characteristics of a Balanced Diet

To maintain a balanced diet, consider the following:

• Eat five moderately sized meals a day to aid digestion.
• Consume a variety of foods from all food groups, following the recommended amounts in the food pyramid or food wheel.
• Incorporate fruits and fresh vegetables daily for essential vitamins.
• Choose fiber-rich foods to promote healthy bowel movements.
• Include unsaturated fats and limit saturated fats and cholesterol to reduce the risk of cardiovascular diseases.
• Consume carbohydrate-rich foods like bread, pasta, rice, and legumes regularly.
• Minimize sugar intake.
• Moderate salt consumption to prevent high blood pressure.
• Reduce the intake of processed and sugary foods (cakes, sweets, etc.).
• Drink 1.5 to 2 liters of

Anatomy and Physiology: Understanding Body Functions

Physiology is the study of how organisms, organ systems, organs, cells, and biomolecules carry out the chemical and physical functions that exist in a living system. This is the general definition. Specifically, human physiology is the science of the mechanical, physical, and biochemical functions of humans. Most of the foundational knowledge in human physiology was provided by animal experimentation.

Physiology is closely related to anatomy. Anatomy is the study of form, and physiology is the study of functions. Physiology and anatomy are intrinsically linked and are studied in tandem to provide a comprehensive understanding of living systems.

The Human Skeleton: Structure and Vital Roles

The... Continue reading "Human Body Systems: Anatomy, Physiology, and Essential Functions" »

Understanding Our Senses

What do all the senses have in common?

The eye, the ear, the nostrils, and the tongue are organs adapted to capturing specific stimuli. They have a high concentration of specialized receptors.

The Ear

Outer ear: flap, external ear canal. Middle ear: eardrum, ossicles (small bones). Inner ear: semicircular canals, cochlea, Eustachian tube.

Why Avoid Loud Noises?

Loud noises can eventually cause hearing problems and, in extreme cases, a perforated eardrum.

How Do We Perceive Colors?

Inside our eyes are cells that function as sensors in the retina, called rods and cones.

Rods and Cones

• Rods: Activated in darkness, allowing us to distinguish black, white, and shades of gray. They enable us to perceive contrast.
• Cones: Work during

Bacillus Anthracis and Anthrax Disease

Key Characteristics of Bacillus Anthracis

Bacillus anthracis is a bacterium that causes anthrax disease. This bacterium has several defining characteristics:

• It is rod-shaped.
• It can form spores that allow it to survive in adverse conditions for long periods of time.
• It produces potent toxins that can be harmful to humans and other animals.

How Anthrax is Transmitted

The transmission of Bacillus anthracis can occur in various ways, primarily through contact with infected sources:

• Direct contact with infected animals or contaminated animal products such as wool, hide, or meat.
• Inhalation of the bacteria's spores.
• Contact through cuts in the skin (cutaneous exposure).

Clinical Forms of Anthrax

The disease it causes,... Continue reading "Understanding Anthrax: Bacterium Characteristics and Semen Analysis for Fertility" »

Mutations: Changes in DNA Sequence

Mutations are changes in the DNA sequence of a cell that can be transferred to other cells resulting from it. These alterations are fundamental to genetic variation and evolution.

Types of Mutations

1. According to the Effect on the Individual

• Harmful Mutations: These affect the basic structures of individuals and can cause severe health issues or even death.
• Beneficial Mutations: These enhance an individual's survival and reproductive success. They are crucial for the genetic variability and adaptation of a population.
• Neutral Mutations: These do not significantly affect the survival or reproductive fitness of the individual, either positively or negatively.

2. According to the Cells They Affect

• Germline Mutations:

DNA-RNA: Chemical Composition

Formed by deoxyribonucleotides made up of phosphate, deoxyribose, and nitrogenous bases (adenine, guanine, cytosine, thymine), and by ribonucleotides made up of phosphate, ribose, and uracil.

Molecular Structure

Double-stranded structure and single.

Types

1. Nuclear DNA found in chromatin, mitochondrial DNA in mitochondria, plastid DNA in chloroplasts.
2. Messenger (mRNA), transfer, ribosomal.

Cell Location

1. Chloroplast, mitochondria, nucleus.
2. Cytoplasm, free or associated with ribosomes.

Function

1. Contains the organism's genetic info.
2. Synthesizes proteins according to genetic info in DNA.

Replication

Molecule of DNA replicates in the nucleus.

1. The double helix of DNA opens and the strands separate.
2. Free nucleotides attach to the separated

List the Most Important Functions of Blood

• Heating: transporting or regulating body heat
• Transport nutrients and O2 to the cell
• Defense mechanism against pathogens
• Transport CO2 waste from cells
• Transport of hormones: insulin

Why the Circulatory System is Vital

• Because it keeps the cells provided with what they need and removes what they need to get rid of.
• By blood is the means by which some organs influence other organs to perform functions (HORMONES)

Identify the Main Types of Blood Vessels

Observe the Blood Components

A. CENTRIFUGATION...

PLASMA... Continue reading "Understanding the Circulatory System: Functions and Types" »

Cell Structure and Function

Cell Membrane

The cell membrane is a dynamic structure known as the fluid mosaic model, consisting of:

• Phospholipid Bilayer: Forms the basic structural framework.
• Proteins: Integral proteins (embedded in the membrane) and peripheral proteins (attached to the membrane surface).
• Cholesterol: Provides stability and regulates fluidity.
• Carbohydrates: Often attached to proteins (glycoproteins) or lipids (glycolipids) for cell recognition.

Energy Flow and Metabolism

• Energy Flow: From sunlight to producers (photosynthesis) and then through consumers (cellular respiration).
• Matter Cycling: Carbon, nitrogen, and other elements cycle through living organisms and the environment.
• Metabolism Types: Anabolism (building molecules) and Catabolism